LETTER AND WORD PERCEPTION
ADVANCES
IN PSYCHOLOGY 4 Editors
G . E. STELMACH P. A. VROON
NORTH-HOLLAND PUBLISHING COMPANY AMSTERDAM * NEW YORK * OXFORD
LETTER AND WORD PERCEPTION Orthographic Structure and VisualProcessing in Reading
Dominic W. MASSARO Glen A. TAYLOR Richard L. VENEZKY James E. JASTRZEMBSKI and
Peter A. LUCAS Wisconsin Research and Development Center for Individualized Schooling Universityof Wisconsin
1980
NORTH-HOLLAND PUBLISHING COMPANY AMSTERDAM * NEW YORK * OXFORD
Copyright 1980 -The Board of Regentsof the University of Wisconsin System Copyright is claimed until 1990. Thereafter all portionsof this work covered by this copyright will be in the public domain. Thiswork was developed under agrant from the National Institute of Education, Department of Health, Education, and Welfare. However, the content does not necessarily reflect the position or policy of that Agency, and no official endorsement of these materials should be inferred.
ISBN: 0 444 85493 2
Publishers:
NORTH-HOLLAND PUBLISHING COMPANY AMSTERDAMoNEW YORK. OXFORD Sole distributors for the U.S.A. and Canada: ELSEVIER NORTH-HOLLAND, INC. 5 2 VANDERBILT AVENUE, NEW YORK, N.Y. 10017
Library of Congress Cataloging in Publieation Data
Main entry under title:
Letter and vord perception. (Advances in psychology ; 4) Includes bibliopaphical references and indexes. 1. Reading. 2. Word recognition. 3. English langupee--Alphabet. 4. Reading, Psychology of. I. M688az.0, Dominic W. 11. Series: Advauces in psychology (Amsterdam) 4. LBlO#O.L47 428.4 80-14350
PRINTED IN THE NETHERLANDS
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Preface
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t o c o m p l e t e l y a n a l y z e w h a t w e d o when w e r e a d would a l m o s t b e t h e acme of a psychologist's achievements, f o r i t would b e t o d e s c r i b e v e r y many o f t h e m o s t i n t r i c a t e w o r k i n g s o f t h e human m i n d , a s w e l l a s t o u n r a v e l t h e t a n g l e d s t o r y of t h e most remarkable s p e c i f i c performance t h a t c i v i l i z a t i o n has learned i n a l l its history. T h e s e w o r d s a r e no l e s s a p p r o p r i a t e t o d a y t h a n t h e y were when Edmund Burke Huey confronted the challenge of understanding reading i n 1 9 0 8 . And a l t h o u g h m o s t l i t e r a t e s o c i e t i e s d e v o t e v a l u a b l e f i n a n c i a l and human r e s o u r c e s t o u n d e r s t a n d i n g r e a d i n g , i t o f t e n seems a s i f w e a r e n o n e a r e r t o It achieving t h i s goal. However, some p r o g r e s s i s a p p a r e n t . is g e n e r a l l y a g r e e d t h a t r e a d i n g i n v o l v e s t h e u t i l i z a t i o n o f a along with the a c t i v e v a s t range of performance s k i l l s a p p l i c a t i o n o f t h e knowledge r e s o u r c e s o f t h e r e a d e r . The g o a l f o r t h e r e s e a r c h e r , i s t o d e s c r i b e e a c h o f t h e s k i l l s an d t o e v a l u a t e how k n o w l e d g e c o n t r i b u t e s t o t h e s k i l l e d p e r f o r m a n c e . Our r e s e a r c h i n v e s t i g a t e s how k n o w l ed g e o f t h e o r t h o g r a p h y ( r u l e s of spelling) i s a c t i v e l y e n g a g e d i n l e t t e r and word As m i g h t be expected, our perception of s k i l l e d readers. r e s e a r c h e n t e r p r i s e had i t s s h a r e o f b o t h s u b s t a n t i v e a d v a n c e s i n our understanding of b a s i c psychological p r o c e s s e s an d distracting glances a t some of t h e mind's bewildering inconsistencies. Our g o a l i n t h i s m o n o g r ap h i s t o c o m m u n i c a t e b o t h t h e p r o g r e s s a n d some o f t h e d i s t r a c t i o n t h a t we
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experienced. Because o f t h e d e t a i l e d p r e s e n t a t i o n s o f v a r i o u s d e s c r i p t i o n s of orthographic s t r u c t u r e , t h e extended s e r i e s of e x p e r i m e n t a l s t u d i e s , and t h e f i n e - g r a i n e d a n a l y s e s o f t h e c o n t r i b u t i o n o f many d e s c r i p t i o n s o f o r t h o g r a p h i c s t r u c t u r e , p i e c e m e a l p u b l i c a t i o n s o f t h i s r e s e a r c h e f f o r t would h a v e b e e n inappropriate. T h i s monograph p r o v i d e s t h e c h a l l e n g e o f n o t o n l y communicating a p r o t r a c t e d r e s e a r c h e n t e r p r i s e b u t a l s o a n i l l u m i n a t i n g and i n t e r n a l l y - c o n s i s t e n t a c c o u n t o f how r e a d e r s u t i l i z e knowledge o f o r t h o g r a p h i c s t r u c t u r e i n l e t t e r and word p e r c e p t i o n . The s u c c e s s o f t h i s work w i l l b e e v a l u a t e d by t h e r e s e a r c h e r , and m u s t s t a n d t h e t e s t o f i t s a p p l i c a b i l i t y t o reading i n s t r u c t ion. G i v e n t h e r e l a t i v e l y l a r g e number o f new e x p e r i m e n t a l s t u d i e s t o be reported, w e decided t o omit t h e unimportant d e t a i l s o f t h e method, p r o c e d u r e , and r e s u l t s i n t h e a c t u a l However, s i n c e d i s c u s s i o n of t h e experiments i n Chapter 4 . t h i s i n f o r m a t i o n i s s t i l l o f i n t e r e s t t o many p o t e n t i a l r e a d e r s and r e s e a r c h e r s , i t h a s b e e n p l a c e d i n a p p e n d i c e s a t t h e end o f Chapter 4 . Each e x p e r i m e n t a l s t u d y i s numbered i n C h a p t e r 4 and i t s a p p e n d i x is g i v e n t h e same number. By p l a c i n g unnecessary d e t a i l s i n a p p e n d i c e s , i t is e a s i e r t o m a i n t a i n t h e l o g i c a l c o n t i n u i t y i n t h e p r e s e n t a t i o n of t h e e x p e r i m e n t a l s t u d i e s . When n e c e s s a r y , t h e r e a d e r c a n a l w a y s t u r n d i r e c t l y t o t h e r e l e v a n t appendix f o r a d d i t i o n a l i n f o r m a t i o n . I n a d d i t i o n , Appendix 5 . 1 g i v e s t h r e e p e r f o r m a n c e m e a s u r e s f o r e a c h o f o u r 200 s t i m u l u s i t e m s so t h a t t h e i n t e r e s t e d i n v e s t i g a t o r can t e s t a d d i t i o n a l d e s c r i p t i o n s of orthographic s t r u c t u r e with these data. Since sublexical position-sensitive single-letter and b i g r a m c o u n t s a r e i m p o r t a n t components o f o r t h o g r a p h i c s t r u c t u r e , Appendix 5 . 2 and 5 . 3 p r e s e n t n o r m a t i v e c o u n t s b a s e d on a s a m p l e o f r o u g h l y o n e m i l l i o n words o f printed text. The o n l y c o u n t s c u r r e n t l y a v a i l a b l e i n p r i n t a r e T h e s e c o u n t s s h o u l d be based on a s a m p l e o n l y 2 % a s l a r g e v a l u a b l e t o r e s e a r c h e r s and educators interested i n the n o r m a t i v e s t r u c t u r e o f Eng 1i s h o r t h o g r a p h y The p r i m a r y o b j e c t i v e o f t h i s monograph i s t h e p r e s e n t a t i o n o f o u r new e m p i r i c a l and t h e o r e t i c a l r e s e a r c h . Because o f s p a c e l i m i t a t i o n s , we were u n a b l e t o r e v i e w much o f t h e o t h e r r e l e v a n t r e s e a r c h i n l e t t e r and word p e r c e p t i o n . For r e v i e w s o f t h i s r e s e a r c h , t h e r e a d e r is r e f e r r e d t o A l l p o r t ( 1 9 7 9 ) , Baron ( 1 9 7 8 ) , E s t e s ( 1 9 7 7 , 1 9 7 8 ) , G i b s o n and L e v i n ( 1 9 7 5 ) , Henderson ( 1 9 7 7 ) , J o h n s o n ( 1 9 7 7 1 , K r u e g e r ( 1 9 7 5 ) ,
.
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PREFACE
Massaro (1979).
(1975, 1978, 1979b, i n p r e s s ) , and P o l l a t s e k and
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T h i s r e s e a r c h is t h e outcome of c o n t r i b u t i o n s o f f i v e time, t h e need t o relatively disparate researchers. In u n d e r s t a n d l e t t e r and word p e r c e p t i o n became t h e d r i v i n g , f o r c e a n d o u r o r i g i n a l b i a s e s a n d b e l i e f s were e v e n t u a l l y m o d i f i e d b y tests. If this actual experimentation and theortical c o n t r i b u t i o n b e n e f i t s r e a d i n g r e s e a r c h h a l f a s much a s i t b e n e f i t e d e a c h o f t h e p a r t i c i p a n t s from t h e c o l l a b o r a t i v e e f f o r t s , then t h e p r o j e c t can be considered t o be a success. T h i s r e s e a r c h e f f o r t h a s been s u p p o r t e d by f u n d s from t h e National I n s t i t u t e o f E d u c a t i o n t o t h e W i s c o n s i n R e s e a r c h an d Dev el o p m en t C e n t e r f o r I n d i v i d u a l i z e d S c h o o l i n g , U n i v e r s i t y o f J a c k Wende and Rod W i s c o n s i n , Madison, W is co n s i n 53706 U.S.A. McCoy c o n t r i b u t e d t o t h e d e v e l o p m e n t o f t h e c o m p u t e r - c o n t r o l l e d research f a c i l i t i e s . D a v i d K l i t z k e was r e s p o n s i b l e f o r some o f t h e computer programming, S u s a n C h i c o n e t e s t e d some o f t h e s u b j e c t s . J e n n i f e r A r g e l a n d e r e d i t e d and D o r i s K i n g t y p e d t h e manuscript using a not always straightforward computer-editing system. Bob C a v e y d r e w the many graphs. Don A n d e r s o n c o n t r i b u t e d t h e ABC p r i n t .
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Contents vi i
PREFACE 1.
READING A N D I N F O R M A T I O N PROCESSING
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A n I n f o r m a t i o n Processing Model of Reading 2.
V I S U A L INFORMATION
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Early W o r k 11 Feature Analysis 13 Letter F e a t u r e s 1 4 3.
Orthographic S t r u c t u r e
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Statistical Redundancy 2 4 P h o n o l o g i c a l l y Based D e s c r i p t i o n s 29 Rule-Governed R e g u l a r i t y 30 P h o n o l o g i c a l C o n s t r a i n t s 30 S c r i b a l C o n s t r a i n t s 31 Morphemic Featukes 3 2 Psychological Assumptions 34 D i c h o t o m y I s s u e 34 A n Initial Algorithm for Rule-Governed R e g u l a r i t y 35 4.
EXPERIMENTAL S T U D I E S
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Massaro e t a l . 1979 S t u d i e s 38 S t u d y 1: I n i t i a l R e p l i c a t i o n s 47 P r o c e d u r e 47 O r t h o g r a p h i c S t r u c t u r e 49 Similarity Effects 51 T a r g e t - C a t c h D i f f e r e n c e s 55 I n f o r m a t i o n P r o c e s s i n g Model 5 5 S t u d y 2: P r e c u e V e r s u s P o s t c u e 6 1 Orthographic Structure 63 S i m i l a r i t y E f f e c t s 64 T a r g e t Versus Catch T r i a l s 65 I n f o r m a t i o n P r o c e s s i n g Model 6 6 S t u d y 3: Mixed-Case 67 O r t h o g r a p h i c S t r u c t u r e 69 S i m i l a r i t y E f f e c t s 70 S t u d y 4 : L i m i t e d V i e w i n g Time 7 1 Orthographic Structure 71 S i m i l a r i t y E f f e c t s 72 Target Versus Catch T r i a l s 7 3 Discussion 73 S t u d y 5 : S p e e d e d RT T a s k w i t h Good V i s u a l I n f o r m a t i o n 7 3 Procedure 76 O r t h o g r a p h i c S t r u c t u r e 77 S t u d y 6: S p e e d e d RT T a s k w i t h Poor V i s u a l I n f o r m a t i o n 77 P r o c e d u r e 78 O r t h o g r a p h i c S t r u c t u r e 78 S t u d y 7 : H i g h - A c c u r a c y RT T a s k with Poor Visual Information 79 P r o c e d u r e 79 O r t h o g r a p h i c S t r u c t u r e 79 Summary o f A c c u r a c y a n d R e a c t i o n Time E x p e r i m e n t s 8 0 Overt Judgments 81 S t u d y 8: T y p i c a l i t y R a t i n g s 8 2 S t u d y 9: P o s i t i o n a l - F r e q u e n c y R a t i n g s Study 1 0 : R e g u l a r i t y Versus Positional-Frequency Judgments 87 Summary o f O v e r t J u d g m e n t E x p e r i m e n t s
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Appendix 4.1 D e t a i l s o f Method, P r o c e d u r e , a n d R e s u l t s o f S t u d y 1: I n i t i a l R e p l i c a t i o n 9 1 Method 9 1 R e s u l t s 94 A p p e n d i x 4.1A Rules for t h e Selection of O r t h o g r a p h i c a l l y Regular and I r r e g u l a r S t r i n g s 96 Appendix 4.18 T h e 2 0 0 S t i m u l u s Items Used i n S t u d i e s 1-10 97 Appendix 4.2 D e t a i l s o f Method, P r o c e d u r e , and R e s u l t s o f S t u d y 2: P r e c u e V e r s u s P o s t c u e 9 9 Method 9 9 R e s u l t s 100 Details o f Method, P r o c e d u r e , a n d Appendix 4.3 R e s u l t s o f S t u d y 3: M i x e d - C a s e 101 Method 01 Results 101 Appendix 4.4 D e t a i l s o f Method, P r o c e d u r e , a n d R e s u l t s o f S t u d y 4: L i m i t e d V i e w i n g T i m e 1 0 3 Method 103 Results 103 Appendix 4.5 D e t a i l s o f Method, P r o c e d u r e , a n d R e s u l t s o f S t u d y 5 : S p e e d e d RT T a s k w i t h Good V i s u a l I n f o r m a t i o n 1 0 5 Method 105 R e s u l t s 106 D e t a i l s o f Method, P r o c e d u r e , a n d Appendix 4.6 R e s u l t s o f S t u d y 6 : S p e e d e d RT T a s k w i t h Poor V i s u a l I n f o r m a t i o n 108 Method 108 R e s u l t s 108 Appendix 4.7 Details o f Method, P r o c e d u r e , a n d R e s u l t s o f S t u d y 7: H i g h - A c c u r a c y RT T a s k w i t h P o o r V i s u a l I n f o r m a t i o n 111 Method 111 R e s u l t s 111 Appendix 4.8 D e t a i l s of Method, P r o c e d u r e , a n d R e s u l t s o f S t u d y 8 : T y p i c a l i t y R a t i n g s 113 Method 113 R e s u l t s 114 A p p e n d i x 4.8A The P s e u d o w o r d s Used i n S t u d y 8 1 1 5
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CONTENTS Appendix 4.88 Directions for Typicality Ratings Without Words and for Typicality Ratings with Pseudowords 116 Appendix 4.8C Directions for Typicality Ratings with Words 117 Appendix 4.9 Details of Method, Procedure, and Results of Study 9: Positi,onal-Frequency Ratings 118 Method 118 Results 118 Appendix 4.9A Directions for Positional-Frequency Ratings 119 Appendix 4.10 Details of Method, Procedure, and Results of Study 10: Regularity Versus Positional-Frequency Paired-Judgments 120 Method 120 Results 121 Appendix 4.10A Regularity Instructions for Paired-Judgments 122 Appendix 4.108 Positional-Frequency Instructions for Paired-Judgments 123
5.
STRUCTURAL DESCRIPTIONS
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Descriptive Measures 125 Type Versus Token Counts 128 Scale of Frequency 130 Position-Sensitive Versus Position Insensitive Counts 132 The Most Effective Frequency Measure Frequency Versus Regularity 138 Within Class Analysis 140 Word Frequency 141 Multiple Regression 141 Summary 142
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Appendix 5.1 Stimulus Items and Results 143 Appendix 5.2 Single-Letter Positional Frequencies Three-letter Words 150 Four-letter Words 152 Five-letter Words 154 Six-letter Words 156 Seven-letter Words 158
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CONTENTS Appendix 5.3 Bigrarn Positional Frequencies Three-letter Words 161 Four-letter Words 172 Five-letter Words 188 Six-letter Words 205 Seven-letter Words 224 6.
SUMMARY AND CONCLUSIONS
REFERENCES 249 GLOSSARY 263 AUTHOR INDEX 269 SUBJECT INDEX 275
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1
Reading and Information Processing
The p r o c e s s e s by w h i c h w o r d s a r e r e c o g n i z e d d u r i n g r e a d i n g h a v e c o n c e r n e d p s y c h o l o g i s t s and e d u c a t o r s f o r almost a c e n t u r y . The b a s i c a s s u m p t i o n i s t h a t a t h o r o u g h u n d e r s t a n d i n g o f t h e p r o c e s s e s i n v o l v e d i n word r e c o g n i t i o n w i l l a f f o r d a m a j o r a d v a n c e i n t h e u n d e r s t a n d i n g o f how p e o p l e r e a d . Every m a j o r t r e a t i s e o n r e a d i n g f r o m Huey ( 1 9 0 8 / 1 9 6 8 ) t o G i b s o n an d Levin (1975) h a s d i s c u s s e d t h i s issue a t l e n g t h , b u t g e n e r a l l y h a s c o n c l u d e d , a s d i d Huey ( 1 9 0 8 / 1 9 6 8 , p. 1 0 2 ) , t h a t " i t i s v e r y d i f f i c u l t t o draw f i n a l c o n c l u s i o n s c o n c e r n i n g v i s u a l perception i n reading.. R e c e n t l y two d i f f e r e n t p a n e l s w h i c h recommended f u n d i n g priorities in b a s i c s k i l l s research t o the National Institute o f E d u c a t i o n a s s i g n e d h i g h p r i o r i t i e s t o s t u d i e s o n word recognition. Consequently, a high p r i o r i t y c u r r e n t l y is being g i v e n t o o b t a i n i n g a b e t t e r u n d e r s t a n d i n g o f word r e c o g n i t i o n w i t h s t r e s s on t h e basic s t a g e s of v i s u a l i n f o r m a t i o n processing. I n f o r m a t i o n p r o c e s s i n g d u r i n g r e a d i n g is c u r r e n t l y t h e p r i m a r y c o n c e r n o f many e x p e r i m e n t a l p s y c h o l o g i s t s , and t h e r e f o r e , a n e x p a n d i n g body o f e x p e r i m e n t a l d a t a i s b e i n g b r o u g h t t o b e a r on t h e s e q u e s t i o n s . S i n c e word r e c o g n i t i o n f o r m s a b r i d g e b e t w e e n v i s u a l i n f o r m a t i o n p r o c e s s i n g s k i l l s an d i t i s i m p o r t a n t f o r u n d e r s t a n d i n g how t h e two comprehension, r e l a t e t o each o t h e r . R e s e a r c h o n word r e c o g n i t i o n p r o c e s s e s is s e e n a s h a v i n g a h i g h p o t e n t i a l f o r improving r e a d i n g i n s t r u c t i o n . Good an d po o r r e a d e r s h a v e b e e n shown t o d i f f e r i n p e r f o r m a n c e o n a v a r i e t y of general t a s k s b u t u n t i l r e c e n t l y , l i t t l e attempt has b e e n made t o e x p l o r e how c h i l d r e n w i t h d i f f e r e n t l e v e l s o f reading a b i l i t y might d i f f e r in b a s i c word r e c o g n i t i o n p r o c e s s e s . We b e l i e v e t h a t b a s i c word r e c o g n i t i o n p r o c e s s e s ,
.."
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CHAPTER 1
once d e f i n e d f o r c o m p e t e n t a d u l t r e a d e r s , c a n be used t o a s s e s s word r e c o g n i t i o n a b i l i t i e s o f good and p o o r r e a d e r s i n t h e elementary grades. ~f good and poor r e a d e r s u t i l i z e t h e same p r o c e s s e s , b u t d i f f e r i n speed or a c c u r a c y , t h e n r e m e d i a t i o n methods b a s e d o n common a p p r o a c h e s t o r e a d i n g i n s t r u c t i o n would be w a r r a n t e d . However, i f fundamental d i f f e r e n c e s i n v i s u a l recognition processes a r e found, then t o t a l l y d i f f e r e n t r e m e d i a l methods would be r e q u i r e d . The o v e r a l l o b j e c t i v e of t h i s r e s e a r c h p r o j e c t i s t o a s s e s s how t h e r e a d e r ' s h i g h e r - o r d e r knowledge of t h e l a n g u a g e i n t e r a c t s with lower-level perceptual analyses during reading. The s p e c i f i c q u e s t i o n t h a t is a d d r e s s e d i s how t h e r e a d e r ' s a b s t r a c t knowledge a b o u t o r t h o g r a p h i c s t r u c t u r e is combined w i t h t h e i n f o r m a t i o n d e r i v e d from v i s u a l f e a t u r a l a n a l y s i s i n word r e c o g n i t i o n . Orthographic structure refers t o the spelling constraints in a w r i t t e n l a n g u a g e . T h e r e is a c o n s i d e r a b l e amount o f p r e d i c t a b i l i t y i n E n g l i s h w r i t i n g , f o r example, and t h e r e a d e r may a c t i v e l y u t i l i z e t h i s i n f o r m a t i o n i n word r e c o g n i t i o n . V i s u a l f e a t u r a l a n a l y s i s r e f e r s t o t h e e v a l u a t i o n o f component p r o p e r t i e s o f l e t t e r s i n t h e c o u r s e o f l e t t e r and word r e c o g n i t i o n . Given e v i d e n c e t h a t b o t h o f t h e s e s o u r c e s o f i n f o r m a t i o n c o n t r i b u t e t o word r e c o g n i t i o n , t h e g o a l i s t o d e f i n e what i n f o r m a t i o n t h e r e a d e r a c t u a l l y u t i l i z e s ( w h a t i n f o r m a t i o n i s p s y c h o l o g i c a l l y r e a l ) and t o d e f i n e how t h e s e s o u r c e s of information a r e integrated together in reading. This r e q u i r e s examination of the psychological r e a l i t y of v a r i o u s d e s c r i p t i o n s of v i s u a l f e a t u r e s , of o r t h o g r a p h i c s t r u c t u r e , and of q u a n t i t a t i v e models t h a t d e s c r i b e how v i s u a l f e a t u r e s and o r t h o g r a p h i c s t r u c t u r e a r e i n t e g r a t e d d u r i n g word p e r c e p t i o n and r e c o g n i t i o n .
AN INFORMATION PROCESSING MODEL OF R E A D I N G
E v a l u a t i o n of t h e c o n t r i b u t i o n s o f v i s u a l f e a t u r e s and o r t h o g r a p h i c s t r u c t u r e t o word r e c o g n i t i o n r e q u i r e s t h a t we d e s c r i b e i n some d e t a i l t h e p r o c e s s e s i n v o l v e d i n r e a d i n g . The model f o r d e s c r i b i n g t h e s e p r o c e s s e s is p a r t of a more g e n e r a l l a n g u a g e p r o c e s s i n g model which h a s been d e v e l o p e d and t e s t e d over t h e p a s t few y e a r s ( M a s s a r o , 1 9 7 5 , 1 9 7 8 , 1 9 7 9 a ) . F i g u r e 1.1 p r e s e n t s a s c h e m a t i c r e p r e s e n t a t i o n of t h e s t a g e s of processing i n reading. A t e a c h s t a g e of p r o c e s s i n g , memory and p r o c e s s components a r e r e p r e s e n t e d . Each memory component ( i n d i c a t e d by a r e c t a n g l e ) c o r r e s p o n d s t o t h e i n f o r m a t i o n a v a i l a b l e a t a p a r t i c u l a r s t a g e of p r o c e s s i n g . Each p r o c e s s
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component ( i n d i c a t e d by a c i r c l e ) c o r r e s p o n d s t o t h e o p e r a t i o n s a p p l i e d t o t h e i n f o r m a t i o n h e l d by t h e memory component. The memory components a r e t e m p o r a r y s t o r a g e s e x c e p t f o r l o n g - t e r m memory which i s r e l a t i v e l y permanent and, i n a d d i t i o n , s u p p l e m e n t s t h e i n f o r m a t i o n a t some of t h e p r o c e s s i n g s t a g e s . T h i s model p r o v i d e s a framework from which h y p o t h e s e s a b o u t word r e c o g n i t i o n c a n be d e r i v e d and t e s t e d . The t y p i c a l t e x t i n r e a d i n g i s a s e q u e n c e of l e t t e r s and s p a c e s which conform t o o r t h o g r a p h i c , s y n t a c t i c , and s e m a n t i c The a v e r a g e E n g l i s h c o n s t r a i n t s of t h e w r i t t e n l a n g u a g e . r e a d e r b e g i n s a t t h e t o p l e f t - h a n d c o r n e r of t h e p a g e and r e a d s e a c h l i n e from l e f t t o r i g h t . The r e a d e r ' s e y e movements a c r o s s a l i n e a r e n o t c o n t i n u o u s b u t occur i n a s e r i e s of s h o r t jumps c a l l e d s a c c a d e s . The f i x a t i o n time between s a c c a d e s i s r o u g h l y t e n times l o n g e r t h a n t h e s a c c a d e . The t y p i c a l s a c c a d e of 1 t o 2 d e g r e e s r e q u i r e s 2 0 t o 30 msec, w h e r e a s f i x a t i o n t i m e a v e r a g e s 250 msec ( S h e b i l s k e , 1 9 7 5 ; Woodworth, 1 9 3 8 ) . I n i t i a l p r o c e s s i n g of t h e v i s u a l s t i m u l u s m u s t O C C U K d u r i n g t h e f i x a t i o n time b e c a u s e t h e s t i m u l u s p a t t e r n i s b l u r r e d d u r i n g a s a c c a d e and i t s d u r a t i o n i s t o o s h o r t f o r s u f f i c i e n t p r o c e s s i n g t o occur. During a n e y e f i x a t i o n , t h e l i g h t p a t t e r n r e f l e c t e d from l e t t e r s i s t r a n s d u c e d by t h e v i s u a l r e c e p t o r s and a p r o c e s s d e t e c t s and t r a n s m i t s v i s u a l f e a t u r e s t o p r e p e r c e p t u a l v i s u a l s t o r a g e ( s e e F i g u r e 1 . 1 ) . I n o u r model, w e c a l l t h i s i n i t i a l p r o c e s s f e a t u r e d e t e c t i o n . The f e a t u r e s a r e d e s c r i b e d a s v i s u a l b e c a u s e i t i s assumed t h a t t h e r e i s a d i r e c t r e l a t i o n s h i p between t h e s t i m u l u s p r o p e r t i e s o f t h e l e t t e r s and
LONG TERM MEMORY
t
MEMORY
F i g u r e 1.1
A s t a g e model
T
MEMORY
of r e a d i n g p r i n t e d t e x t .
CHAPTER 1
t h e i n f o r m a t i o n i n p r e p e r c e p t u a l v i s u a l s t o r a g e . The p a s s i v e t r a n s d u c t i o n of f e a t u r e d e t e c t i o n c o n t r a s t s w i t h t h e a c t i v e c o n s t r u c t i o n of t h e s u b s e q u e n t p r o c e s s i n g s t a g e s . There is no e x a c t one-to-one r e l a t i o n s h i p between t h e i n p u t and o u t p u t o f the following processing s t a g e s s i n c e these l a t e r s t a g e s a c t i v e l y u t i l i z e i n f o r m a t i o n s t o r e d i n l o n g - t e r m memory. Given t h e s e t o f v i s u a l f e a t u r e s i n p r e p e r c e p t u a l v i s u a l storage, t h e primary recognition process attempts t o transform t h e s e i s o l a t e d f e a t u r e s i n t o a s e q u e n c e of l e t t e r s and s p a c e s i n s y n t h e s i z e d v i s u a l memory. To do t h i s , t h e primary r e c o g n i t i o n p r o c e s s can u t i l i z e i n f o r m a t i o n h e l d i n long-term memory which f o r t h e a c c o m p l i s h e d r e a d e r i n c l u d e s a l i s t o f f e a t u r e s f o r e a c h l e t t e r of t h e a l p h a b e t a l o n g w i t h i n f o r m a t i o n a b o u t t h e o r t h o g r a p h i c s t r u c t u r e o f t h e l a n g u a g e . The p r i m a r y r e c o g n i t i o n process u t i l i z e s both t h e v i s u a l f e a t u r e s i n p r e p e r c e p t u a l s t o r a g e and knowledge of o r t h o g r a p h i c s t r u c t u r e i n i t s s y n t h e s i s o f t h e l e t t e r s t r i n g s . The t i m e - h o n o r e d b e l i e f t h a t r e c o g n i t i o n of l e t t e r s t r i n g s becomes p r o g r e s s i v e l y e a s i e r a s t h e s t r i n g s more c l o s e l y a p p r o x i m a t e words i m p l i e s t h a t r e a d e r s c a p i t a l i z e on t h e p r e s e n c e of o r t h o g r a p h i c structure. R e c o g n i t i o n u s u a l l y means t h e p r o c e s s o f d i s c r i m i n a t i n g , i d e n t i f y i n g , and c o r r e c t l y o r d e r i n g t h e l e t t e r s o f a l e t t e r s t r i n g ( S m i t h , 1 9 7 1 ) . Given t h i s i n t e r p r e t a t i o n o f recognition, t h e f a c i l i t a t i n g e f f e c t of o r t h o g r a p h i c s t r u c t u r e on l e t t e r - s t r i n g r e c o g n i t i o n m u s t a l m o s t b e t r u e by d e f i n i t i o n . R e c o g n i t i o n i n v o l v e s a c c e s s i n g knowledge b u i l t up t h r o u g h e x p e r i e n c e . I t is o n l y n a t u r a l t h a t a r e a d e r ' s experience w i t h t o wordlike than nonwordlike words w i l l g e n e r a l i z e more s t r i n g s . Our g o a l s i n t h i s r e s e a r c h e n d e a v o r a r e t o p r o v i d e a b e t t e r u n d e r s t a n d i n g o f t h e r e c o g n i t i o n p r o c e s s and t o e v a l u a t e which a s p e c t s o f o r t h o g r a p h i c s t r u c t u r e t h e r e a d e r knows and utilizes. The c e n t r a l a s s u m p t i o n a d d r e s s e d h e r e i s t h a t o r t h o g r a p h i c structure influences perceptual recognition (primary r e c o g n i t i o n i n our m o d e l ) , i n a d d i t i o n t o o t h e r i n f l u e n c e s a t l a t e r s t a g e s o f p r o c e s s i n g . We b e l i e v e t h a t o r t h o g r a p h i c s t r u c t u r e a l s o f a c i l i t a t e s p r o c e s s i n g from a p e r c e p t u a l t o a c o n c e p t u a l l e v e l ( s e c o n d a r y r e c o g n i t i o n i n our m o d e l ) . By f o c u s i n g on t h e f a c i l i t a t i n g e f f e c t s o f o r t h o g r a p h i c s t r u c t u r e aligned ourselves with a on v i s u a l p e r c e p t i o n , w e h a v e t r a d i t i o n o v e r 100 y e a r s o l d c o n c e r n e d w i t h how knowledge influences perception. James (1890/1950, p. 4 4 4 ) c a p t u r e d t h e s p i r i t o f t h e work begun by Wundt w i t h t h e o f t e n q u o t e d statement, "...the o n l y t h i n g s which w e commonly s e n a r e t h o s e which w e p r e p e r c e i v e . "
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In our model, t h e primary r e c o g n i t i o n p r o c e s s e v a l u a t e s t h e f e a t u r e s i n p r e p e r c e p t u a l v i s u a l s t o r a g e and compares o r m a t c h e s t h e s e f e a t u r e s t o d e s c r i p t i o n s of p e r c e p t u a l u n i t s i n l o n g - t e r m memory. A p e r c e p t u a l u n i t o r p r o t o t y p e r e p r e s e n t s e a c h o f t h e l e t t e r s i n l o n g - t e r m memory a s i t would be i d e a l l y represented in preperceptual v i s u a l s t o r a g e . The p r i m a r y recognition process seeks for each l e t t e r position the p e r c e p t u a l p r o t o t y p e t h a t p r o v i d e s t h e b e s t match t o t h e It is a t primary r e c o g n i t i o n t h a t f e a t u r a l information. orthographic s t r u c t u r e reduces uncertainty or contributes information. The outcome of p r i m a r y r e c o g n i t i o n i s , t h e r e f o r e , t h e j o i n t p r o d u c t of f e a t u r a l i n f o r m a t i o n i n p r e p e r c e p t u a l v i s u a l s t o r a g e and knowledge of l e t t e r c o n s t r a i n t s i n l o n g - t e r m memory. S i n c e t h e r e a r e a l i m i t e d number of ways t h a t s e q u e n c e s o f l e t t e r s and l e t t e r g r o u p s c a n be a s s e m b l e d t o form E n g l i s h w o r d s , knowledge of t h e s e s e q u e n c e s c a n h e l p t h e r e a d e r t o r e s o l v e t h e l e t t e r s i n s t r i n g s t h a t conform t o t h e l a n g u a g e ( c f . M a s s a r o , 1 9 7 5 , C h a p t e r 7 ) . I t a l s o h a s been h y p o t h e s i z e d t h a t t h i s knowledge c a n a s s i s t t h e r e a d e r i n d e t e r m i n i n g t h e r e l a t i v e p o s i t i o n s of l e t t e r s o n c e t h e y a r e r e c o g n i z e d ( E s t e s , 1 9 7 5 a , 1 9 7 5 b ) . For e x a m p l e , g i v e n t h e l e t t e r s &, knowledge of o r t h o g r a p h i c s t r u c t u r e d o e s n o t a l l o w t h e s e l e t t e r s t o be r e a d i n t h e o p p o s i t e o r d e r . However, G e o f f r i o n ( 1 9 7 6 ) found t h a t t h e c o n t r i b u t i o n of o r t h o g r a p h i c s t r u c t u r e is n o t d e p e n d e n t on determining t h e r e l a t i v e p o s i t i o n s of l e t t e r s . In a d d i t i o n , r e c e n t r e s e a r c h by MaSSaKO ( 1 9 7 9 a ) f o u n d a l a r g e e f f e c t of o r t h o g r a p h i c s t r u c t u r e on l e t t e r r e c o g n i t i o n b u t no e f f e c t on t h e d e t e r m i n a t i o n of r e l a t i v e s p a t i a l p o s i t i o n . In the present research, the experiments are designed such t h a t any s t r u c t u r e a t primary f a c i l i t a t i n g e f f e c t of o r t h o g r a p h i c r e c o g n i t i o n m u s t be d u e t o l e t t e r r e c o g n i t i o n and n o t p o s i t i o n uncertainty The p r i m a r y r e c o g n i t i o n p r o c e s s o p e r a t e s on a number o f l e t t e r s s i m u l t a n e o u s l y ( i n p a r a l l e l ) . The v i s u a l f e a t u r e s d e t e c t e d a t each s p a t i a l l o c a t i o n d e f i n e a s e t of p o s s i b l e l e t t e r s for that position. The p r i m a r y r e c o g n i t i o n p r o c e s s c h o o s e s from t h i s s e t of c a n d i d a t e s t h e l e t t e r a l t e r n a t i v e which h a s t h e b e s t c o r r e s p o n d e n c e i n t e r m s o f v i s u a l f e a t u r e s . However, t h e s e l e c t i o n of a b e s t c o r r e s p o n d e n c e c a n be f a c i l i t a t e d by knowledge of orthographic structure. The primary r e c o g n i t i o n p r o c e s s , t h e r e f o r e , a t t e m p t s t o u t i l i z e both t h e f e a t u r a l information i n preperceptual s t o r a g e and knowledge a b o u t t h e s t r u c t u r e of legal latter strings. A c r i t i c a l c o n c e r n i s w i t h t h e i n t e r a c t i o n of t h e s e two s o u r c e s
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CHAPTER 1
of i n f o r m a t i o n ; i n o u r m o d e l , i t is assumed t h a t t h e two s o u r c e s o f i n f o r m a t i o n make independent c o n t r i b u t i o n s t o p r i m a r y r e c o g n i t i o n ( M a s s a r o , 1 9 7 3 , 1 9 7 5 , 1 9 7 8 , 1979b; Thompson & Massaro, 1 9 7 3 ) . The p r e s e n t a n a l y s i s o f t h e f a c i l i t a t i o n o f o r t h o g r a p h i c s t r u c t u r e i n l e t t e r r e c o g n i t i o n is i d e n t i c a l i n s p i r i t t o t h e o r i g i n a l a n a l y s i s p r o v i d e d by M i l l e r , B r u n e r , and Postman ( 1 9 5 4 ) . They o b s e r v e d t h a t t h e number of l e t t e r s c o r r e c t l y r e p o r t e d from a tachistoscopic exposure increased with increases in familiarity of the letter pattern. The f a m i l i a r i t y of t h e l e t t e r s e q u e n c e s was v a r i e d by t h e d e g r e e t o which t h e s e q u e n c e a p p r o x i m a t e d p r i n t e d E n g l i s h (Shannon, 1948). U t i l i z i n g t h e t h e o r y of i n f o r m a t i o n d e v e l o p e d by Shannon ( 1 9 4 8 ) , however, t h e y o b s e r v e d t h a t t h e number o f l e t t e r s r e p o r t e d i s n o t a d i r e c t i n d e x o f t h e amount of s t i m u l u s i n f o r m a t i o n d e r i v e d from t h e e x p o s u r e i t s e l f s i n c e t h e redundancy o f c o n t e x t u a l l y c o n s t r a i n e d s e q u e n c e s i s n o t t a k e n i n t o account. M i l l e r e t a l . (1954) c a l c u l a t e d t h e redundancy o f t h e i r sequences a t each o r d e r of approximation t o E n g l i s h u sin g t h e c o u n t s g i v e n by Shannon ( 1 9 5 1 ) and c o u n t s o f t h e i r own. When p e r f o r m a n c e was c o r r e c t e d f o r r e d u n d a n c y , t h e r e was n o e f f e c t (see a l s o T u l v i n g , 1 9 6 3 ) . T h i s r e s u l t was of f a m i l i a r i t y i n t e r p r e t e d t o mean t h a t t h e amount o f s t i m u l u s i n f o r m a t i o n r e c e i v e d from t h e e x p o s u r e d i d n o t depend on t h e f a m i l i a r i t y o f the l e t t e r pattern. I n t e r m s o f o u r a n a l y s i s , o v e r two d e c a d e s l a t e r , t h e r e s u l t s c a n b e i n t e r p r e t e d t o mean t h a t o r t h o g r a p h i c s t r u c t u r e and v i s u a l i n f o r m a t i o n c o n t r i b u t e i n d e p e n d e n t s o u r c e s of i nformat i on i n r ead i n g . The c u r r e n t view was d e v e l o p e d , i n p a r t , o n t h e b a s i s o f e x p e r i m e n t s c a r r i e d o u t u s i n g t h e Reicher-Wheeler paradigm i n word r e c o g n i t i o n ( R e i c h e r , 1969; W h e e l e r , 1 9 7 0 ; Thompson & Massaro, 1 9 7 3 ) . I n t h i s paradigm, s u b j e c t s a r e p r e s e n t e d w i t h e i t h e r a t e s t word o r a s i n g l e t e s t l e t t e r f o r a s h o r t d u r a t i o n f o l l o w e d i m m e d i a t e l y by a masking s t i m u l u s and two r e s p o n s e alternatives. The r e s p o n s e a l t e r n a t i v e s b o t h s p e l l words i n t h e t e s t word c o n d i t i o n ; f o r example, g i v e n t h e t e s t s t i m u l u s WORD, t h e r e s p o n s e a l t e r n a t i v e s ---g and ---E would be presented. I n the corresponding s i n g l e test l e t t e r condition, -D i s p r e s e n t e d and f o l l o w e d by t h e r e s p o n s e a l t e r n a t i v e s g and K. I n t h e s e s t u d i e s , r e c o g n i t i o n of t h e t e s t word i s a b o u t 1 0 % b e t t e r t h a n r e c o g n i t i o n of t h e t e s t l e t t e r . i t is Given t h e t w o - a l t e r n a t i v e f o r c e d - c h o i c e c o n t r o l , assumed t h a t t h e r e a d e r u t i l i z e s o r t h o g r a p h i c s t r u c t u r e t o e l i m i n a t e p o s s i b l e a l t e r n a t i v e s d u r i n g t h e p e r c e p t i o n of t h e
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t e s t d i s p l a y (Thompson & M a s s a r o , 1 9 7 3 ) . A s a n e x a m p l e , p r e s e n t e d w i t h t h e t e s t s t i m u l u s WORD and g i v e n r e c o g n i t i o n of t e s t l e t t e r s WOR and a c u r v i l i n e a r segment of t h e f i n a l l e t t e r , t h e r e a d e r c o u l d n a r r o w down t h e a l t e r n a t i v e s f o r t h e f i n a l 0, and Q. I f 0 and Q a r e c o n s i d e r e d t o be l e t t e r t o D, orthographically i l l e g a l i n the context then D r e p r e s e n t s a n unambiguous c h o i c e . The r e a d e r w i l l t h e r e f o r e p e r c e i v e t h e word WORD g i v e n j u s t p a r t i a l i n f o r m a t i o n a b o u t t h e f i n a l letter. If t h e r e a d e r r e c o g n i z e s t h e same c u r v i l i n e a r segment i n t h e c o r r e s p o n d i n g s i n g l e t e s t l e t t e r c o n d i t i o n , h o w e v e r , any o f t h e t h r e e l e t t e r s ( D , 0 , and Q ) a r e p o s s i b l e and t h e perceptual s y n t h e s i s w i l l r e s u l t i n D o n l y one o u t of t h r e e times. What is c r i t i c a l i n t h i s a n a l y s i s i s t h a t t h e b e t t e r p e r f o r m a n c e on words compared t o s i n g l e l e t t e r s i s o b t a i n e d even though t h e v i s u a l f e a t u r a l i n f o r ma tio n a v a i l a b l e t o t h e p r i m a r y r e c o g n i t i o n p r o c e s s i s e q u i v a l e n t i n t h e word and l e t t e r conditions. The o r t h o g r a p h i c s t r u c t u r e of t h e word simply p r o v i d e s an a d d i t i o n a l b u t i n d e p e n d e n t s o u r c e of information. The f e a t u r a l information available t o the recognition process does not change with changes i n orthographic structure. In t h i s view, although o r t h o g r a p h i c s t r u c t u r e f a c i l i t a t e s word p e r c e p t i o n , i t d o e s n o t modify t h e f e a t u r e a n a l y s i s of t h e p r i n t e d p a t t e r n (Krueger & S h a p i r o , 1979; Massaro, 1 9 7 9 a ) . As ure h a v e d i s c u s s e d , one r o l e of o r t h o g r a p h i c s t r u c t u r e is c o n c e n t r a t e d i n t h e p r i m a r y r e c o g n i t i o n p r o c e s s and s e r v e s t o f a c i l i t a t e the recognition of individual l e t t e r s . In a d d i t i o n , o r t h o g r a p h i c s t r u c t u r e is f u n c t i o n a l a t l a t e r s t a g e s of p r o c e s s i n g , such a s i t s f a c i l i t a t i n g e f f e c t i n short-term memory ( M a s s a r o , i n p r e s s ) . Baddeley ( 1 9 6 4 ) , f o r e x a m p l e , showed t h a t a w e l l - s t r u c t u r e d s t r i n g o f l e t t e r s i s e a s i e r t o remember and r e c a l l t h a n a random s t r i n g . Whether o r t h o g r a p h i c structure f a c i l i t a t e s perceptual recognition is a more c o n t r o v e r s i a l i s s u e . We assume t h a t i t i s u t i l i z e d i n t h e f o l l o w i n g manner. Upon p r e s e n t a t i o n of a l e t t e r s t r i n g , t h e p r i m a r y r e c o g n i t i o n p r o c e s s b e g i n s i n t e g r a t i n g and s y n t h e s i z i n g f e a t u r a l i n f o r m a t i o n p a s s e d on by feature detection t o preperceptual visual storage. Featural information is resolved a t d i f f e r e n t r a t e s and t h e r e i s some e v i d e n c e t h a t g r o s s f e a t u r e s a r e a v a i l a b l e b e f o r e t h e more d e t a i l e d f e a t u r e s ( M a s s a r o & S c h m u l l e r , 1 9 7 5 ) . The p r i m a r y r e c o g n i t i o n p r o c e s s is faced with a succession of partial information s t a t e s . These partial visual information states are s u p p l e m e n t e d w i t h knowledge about orthographic s t r u c t u r e . Assume, f o r e x a m p l e , a n i n i t i a l g h a s been p e r c e i v e d i n a
m,
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l e t t e r s t r i n g , and t h e f e a t u r e s a v a i l a b l e f o r t h e n e x t l e t t e r eliminate a l l a l t e r n a t i v e s except c o r g . The p r i m a r y recognition process might synthesize 5 without waiting f o r f u r t h e r v i s u a l i n f o r m a t i o n , s i n c e i n i t i a l the i s n o t a c c e p t a b l e w h i l e i n i t i a l the i s . The p r i m a r y r e c o g n i t i o n p r o c e s s t r a n s m i t s a s e q u e n c e o f r e c o g n i z e d l e t t e r s t o s y n t h e s i z e d v i s u a l memory. F i g u r e 1.1 shows h o r t h e s e c o n d a r y r e c o g n i t i o n p r o c e s s t r a n s f o r m s t h i s s y n t h e s i z e d v i s u a l p e r c e p t i n t o m e a n i n g f u l form i n g e n e r a t e d a b s t r a c t memory. W e a s s u m e s e c o n d a r y r e c o g n i t i o n a t t e m p t s t o c l o s e o f f t h e l e t t e r s t r i n g i n t o a word. The s e c o n d a r y r e c o g n i t i o n p r o c e s s makes t h i s t r a n s f o r m a t i o n by f i n d i n g t h e b e s t m a t c h b e t w e e n t h e l e t t e r s t r i n g a nd a word i n t h e l e x i c o n i n l o n g - t e r m memory. Knowledge o f o r t h o g r a p h i c s t r u c t u r e c a n a l s o c o n t r i b u t e t o s e c o n d a r y r e c o g n i t i o n ; word r e c o g n i t i o n c a n o c c u r w i t h o u t c o m p l e t e r e c o g n i t i o n o f a l l o f t h e co m p o n en t l e t t e r s . G i v e n t h e l e t t e r s & and t h e v i a b l e a l t e r n a t i v e s 1. and t i n f i n a l p o s i t i o n , o n l y J makes a w o r d , an d t h e r e f o r e word i d e n t i f i c a t i o n ( l e x i c a l a c c e s s ) c a n b e . a c h i e v e d ( M a s s a r o , 1 9 7 7 ) . Each word i n t h e l e x i c o n c o n t a i n s b o t h p e r c e p t u a l and c o n c e p t u a l c o d e s . The word w h i c h i s r e c o g n i z e d i s t h e o n e whose p e r c e p t u a l c o d e g i v e s t h e b e s t m a t c h an d whose c o n c e p t u a l code is most a p p r o p r i a t e i n t h a t p a r t i c u l a r c o n t e x t . G e n e r a t e d a b s t r a c t memory c o r r e s p o n d s t o t h e s h o r t - t e r m o r w o r k i n g memory o f m o s t i n f o r m a t i o n p r o c e s s i n g m o d e l s . In our m o d e l , t h i s memory i s common t o b o t h s p e e c h p e r c e p t i o n an d reading. R eco d i n g and r e h e a r s a l p r o c e s s e s b u i l d and m a i n t a i n s e m a n t i c and s y n t a c t i c s t r u c t u r e s a t t h e l e v e l o f g e n e r a t e d a b s t r a c t memory. I t i s a l s o p o s s i b l e t o g o f r o m m ean i n g t o a visual or auditory percept in o u r model. The r e c o d i n g o p e r a t i o n c a n t r a n s f o r m t h e meaning o f a c o n c e p t i n t o i t s s u r f a c e s t r u c t u r e i n an a u d i t o r y o r v i s u a l form. Two i s s u e s c o n c e r n i n g l e t t e r a n d word r e c o g n i t i o n i n reading w i l l be addressed i n t h e present research. F i r s t , what a r e t h e v i s u a l f e a t u r e s o f l e t t e r s u t i l i z e d by t h e primary r e c o g n i t i o n p r o c e s s ? S e c o n d , how i s k n o w l ed g e o f o r t h o g r a p h i c structure psychologically r e p r e s e n t e d ? To address these i s s u e s , a n y s t u d y m u s t b e c o n c e r n e d w i t h how t h e s e s o u r c e s o f information a r e evaluated, integrated , and co m b i n ed i n perceptual recognition ( M a s s a r o , 1 9 7 9 b ) . The d i s c u s s i o n o f v i s u a l f e a t u r e s is p r e s e n t e d i n Chapter 2 and t h e d i s c u s s i o n of o r t h o g r a p h i c s t r u c t u r e i s p r e s e n t e d i n C h a p t e r 3 . The f o u r t h c h a p t e r f o c u s e s o n how t h e r e a d e r u t i l i z e s b o t h s o u r c e s o f i n f o r m a t i o n i n a v a r i e t y o f p e r c e p t u a l r e c o g n i t i o n an d o v e r t
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judgment tasks. To s u s t a i n t h e l o g i c a l c o n t i n u i t y of the p r e s e n t a t i o n of the experiments, d e t a i l s of t h e method, procedure, an d r e s u l t s a r e p l a c e d i n a p p e n d i c e s a t t h e en d of t h e c h a p t e r . The f i f t h c h a p t e r p r e s e n t s a d e t a i l e d e v a l u a t i o n Of t h e p s y c h o l o g i c a l reality of many d e s c r i p t i o n s of orthographic structure. The d a t a b a s e d e r i v e d f r o m t h e p r e s e n t e x p e r i m e n t s is a l s o p r e s e n t e d t o a l l o w a d d i t i o n a l t e s t s o f In addition, o t h e r d e s c r i p t i o n s of o r t h o g r a p h i c s t r u c t u r e . n o r m a t i v e c o u n t s o f l e t t e r and l e t t e r c l u s t e r o c c u r r e n c e s in These c o u n t s m a k e p o s s i b l e t h e measurement t e x t are presented. o f a v a r i e t y o f s t i m u l u s and t e s t i t e m s a c c o r d i n g t o a number of formal d e s c r i p t i o n s of o r t h o g r a p h i c s t r u c t u r e . The l a s t c h a p t e r s u m m a r i z e s t h e c o n t r i b u t i o n s of t h e p r e s e n t r e s e a r c h . The c e n t r a l c o n c e r n o f t h e e m p i r i c a l and t h e o r e t i c a l work p r e s e n t e d h e r e is t o e v a l u a t e t h e n a t u r e of t h e p r o c e s s e s i n v o l v e d i n l e t t e r a n d word r e c o g n i t i o n and t o d i s c o v e r how kn o wl ed g e a b o u t o r t h o g r a p h i c s t r u c t u r e is r e p r e s e n t e d and utilized.
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2
Visual Information
Most of t h e t r a d i t i o n a l research relevant to visual i n f o r m a t i o n i n r e a d i n g h a s been c o n c e r n e d w i t h t h e l e g i b i l i t y of v a r i o u s t y p e f o n t s and t e x t f o r m a t s . S p e n c e r (1969) summarizes t h i s work i n an a d e q u a t e and i n t e r e s t i n g manner and we w i l l not attempt to duplicate a d e t a i l e d coverage here. A f t e r m e n t i o n i n g a few g e n e r a l p r i n c i p l e s of t h e l e g i b i l i t y o f p r i n t e d t e x t , we w i l l p r o v i d e some d i s c u s s i o n of t h e r o l e of f e a t u r e t h e o r i e s i n d e s c r i b i n g how l e t t e r s a r e recognized. Finally, we will evaluate the functional p r o p e r t i e s o f t h e t y p e f o n t s used i n o u r e x p e r i m e n t s s i n c e t h i s i n f o r m a t i o n w i l l be n e c e s s a r y i n o u r s t u d i e s o f how v i s u a l i n f o r m a t i o n and o r t h o g r a p h i c s t r u c t u r e c o n t r i b u t e t o p e r c e p t u a l recognition.
E A R L Y WORK
Much o f t h e e a r l y work r e v e a l e d t h a t l e t t e r s a r e n o t e q u a l l y l e g i b l e . T a b l e 2 . 1 p r e s e n t s t h e r a n k o r d e r of t h e l e g i b i l i t y o f t h e l o w e r c a s e l e t t e r s i n an e x p e r i m e n t by C a t t e l l i n 1885 ( c i t e d i n Anderson & D e a r b o r n , 1952) and a n e x p e r i m e n t i n o u r l a b o r a t o r y some 90 y e a r s l a t e r . E x c e p t f o r a few of t h e l e t t e r s s u c h a s 9, 5 , and 1, t h e r e is an i m p r e s s i v e a g r e e m e n t between t h e two s t u d i e s . Both s t u d i e s found t h a t some of t h e most f r e q u e n t l e t t e r s a r e t h e l e a s t l e g i b l e . The h i g h l y f r e q u e n t x-height l e t t e r s a, c , e , 0 , and 2 w e r e p o o r l y r e c o g n i z e d i n b o t h s t u d i e s . The s i m i l a r s i z e and o v e r a l l s h a p e of t h e s e l e t t e r s c a u s e them t o be c o n f u s a b l e a n d , t h e r e f o r e , p o o r l y l e g i b l e . C a t t e l l ' s r e s e a r c h ( 1 8 8 5 ) , a s w e l l a s more
CHAPTER 2
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Table 2 . 1
Letter a b
Rank o r d e r o f d i s t i n c t i v e n e s s o f l o w e r c a s e a c c o r d i n g t o C a t t e l l ( 1 8 8 5 ) and i n t h e study.
Cattell 19 6
C
25
d e f 9 h i 1 k 1
1 22 17 24 5
m
23 11 2 10 3
Present Study
letters present
Present Letter
Ca t t e l l 18
Study
22
n
1 19 9 23
0
16
P 4 r
I
2
8
18
S
4 15 26
4
t
6 26 20 7 15 11
U
12 9
V
13
W
8
X
20 21 14
Y z
17
24
12 25 21 14 16 10
3 5 13
r e c e n t s t u d i e s by Bouma ( 1 9 7 1 ) and o u r s e l v e s , found t h a t t h e s l i m l e t t e r s g, &, 1,I,r , and t were s i m i l a r l y c o n f u s e d f o r one a n o t h e r l e a d i n g t o r e l a t i v e l y poor r e c o g n i t i o n . Finally, C a t t e l l observed t h a t l e g i b i l i t y i s h i g h l y c o r r e l a t e d with o v e r a l l l e t t e r s i z e ; contemporary s t u d i e s a l s o s u p p o r t t h i s observation. T i n k e r ( 1 9 6 5 ) a l s o n o t e d a g r e e m e n t among s t u d i e s of l e t t e r H e r e p o r t e d c o r r e l a t i o n s between .48 and .88 legibility. a c r o s s s t u d i e s u s i n g , q v a r i e t y of measurement t e c h n i q u e s and were typefaces. For i n s t a n c e , t h e l e t t e r s 4, m, 2 , g , and c o n s i s t e n t l y found t o be h i g h l y l e g i b l e w h e r e a s c , e , I,1, and n were p o o r l y l e g i b l e . Tinker concluded t h a t o v e r a l l s i z e , s i m p l i c i t y o f o u t l i n e , and t h e amount of w h i t e s p a c e e n c l o s e d by a l e t t e r a r e i m p o r t a n t d e t e r m i n a n t s o f l e g i b i l i t y . We w i l l p r o v i d e a more d e t a i l e d a n a l y s i s of l e t t e r l e g i b i l i t y and l e t t e r confusions l a t e r in t h i s chapter. Another common o b s e r v a t i o n i n e a r l y r e s e a r c h was t h a t t e x t p r i n t e d i n u p p e r c a s e l e t t e r s i s inore d i f f i c u l t t o r e a d t h a n i t s lowercase e q u i v a l e n t . Lowercase p r i n t may be more f a m i l i a r than uppercase because of differences i n f r e q u e n c y of occurrence. However, as Spencer (1969) points out, proportionately-spaced printed t e x t in c a p i t a l s occupies about 5 0 % more space than it does i n lowercase. ( U p p e r c a s e and
w
VISUAL INFORMATION I N R E A D I N G
13
l o w e r c a s e o c c u p y t h e same a m o u n t o f s p a c e i n t y p e w r i t t e n t e x t , a s i n t h e p r e s e n t m o n o g r a p h ) . The r e a d e r m u s t m a i n t a i n a l a r g e r span of apprehension i n terms of v i s u a l a n g l e i n o r d e r t o r e a d u p p e r c a s e t e x t a t t h e same r a t e a s l o w e r c a s e . G i v e n t h a t a c u i t y f a l l s off dramatically with e x t e n t i n t o t h e peripheral vision, it is n o t s u r p r i s i n g t h a t lowercase t e x t w i l l show a n a d v a n t a g e . I t would b e i n t e r e s t i n g t o compare up p er and l o w e r c a s e t e x t when t h e s i z e o f t h e l e t t e r s is a d j u s t e d t o e q u a t e f o r v i s u a l a n g l e . However, p e r f o r m a n c e may s t i l l be a t a d i s a d v a n t a g e w i t h u p p e r c a s e s i n c e on t h e a v e r a g e , t h e l a r g e r l e t t e r s w i l l b e c l o s e r t o g e t h e r an d a l l o w f o r m o r e lateral interference (the mutual degradation of the p e r c e p t i b i l i t y of a d j a c e n t l e t t e r s because of t h e proximity of t h e i r c o n t o u r s ) . The s i m p l e s t e x p l a n a t i o n is t h a t l o w e r c a s e l e t t e r s may b e s i m p l y more p e r c e p t i b l e t h a n u p p e r c a s e . J a v a 1 ( c i t e d i n S p e n c e r , 1 9 6 9 ) showed t h a t r e a d i n g i s much e a s i e r when t h e t o p h a l f , r a t h e r t h a n t h e b o t t o m h a l f , o f a l i n e of words is exposed. I t is n o t c l e a r w h e r e t h e v e r t i c a l c e n t e r was d e f i n e d , b u t w e m i g h t a s s u m e t h a t i t was i n t h e m i d d l e o f a n x - h e i g h t l e t t e r . I t would b e v a l u a b l e t o d e f i n e t h e p e r c e p t u a l m i d d l e , i . e . , t h e p o i n t a t which r e a d i n g t h e t o p a line of p r i n t is e q u a l l y and b o t t o m p o r t i o n s of e a s y . C o n s i s t e n t w i t h J a v a l ' s f i n d i n g s , Messmer (cited in Huey, 1 9 0 8 / 1 9 6 8 ) c o n c l u d e d t h a t a s c e n d i n g l e t t e r s ( e . g . , b, h) a r e " d o m i n a n t " a n d c o n t r i b u t e more t o word r e c o g n i t i o n t h a n x-height (e.g., a , 5 ) o r d e s c e n d i n g ( e . g . , g, E) l e t t e r s . Z e i t l e r ( c i t e d i n Woodworth, 1 9 3 8 ) a l s o f o u n d t h a t i n s h o r t p r e s e n t a t i o n s , a s c e n d i n g and d e s c e n d i n g l e t t e r s were more l i k e l y t o b e p e r c e i v e d ( a l s o see Huey, 1 9 0 8 / 1 9 6 8 , p p . 79-87). Javal's i d e a was t h a t a s c e n d i n g l e t t e r s a r e more e a s i l y p e r c e i v e d b e c a u s e t h e e y e t e n d s t o f i x a t e a b o v e t h e m i d d l e of t h e l i n e of p r i n t . Huey ( 1 9 0 8 / 1 9 6 8 p . 99) r e j e c t e d t h i s p r o p o s a l by c i t i . i g some s t a t i s t i c s s h o w i n g t h a t a s c e n d i n g l e t t e r s a r e much m o r e f r e q u e n t t h a n d e s c e n d i n g l e t t e r s , an d therefore, a word i s s i m p l y l i k e l y t o h a v e more i n f o r m a t i o n above t h a n below t h e m i d d l e of a l i n e o f p r i n t .
FEATURE ANALYSIS Consistent with psychologists have c h a r a c t e r i s t i c s of t h e and word p e r c e p t i o n . physical f e a t u r e s of
the tradition of psychophysics, been concerned with the visual stimulus that are functional in l e t t e r The g o a l o f t h i s work i s t o r e l a t e t h e l e t t e r s and words t o t h e i r p e r c e p t u a l
CHAPTER 2
recognition. The e a r l y w o r k e r s i n t h i s a r e a i m p l i c i t l y assumed t h a t l e t t e r s were t h e s m a l l e s t u n i t s o f v i s i b l e a n a l y s i s . In t h i s view, l e t t e r s a r e i n d i v i s i b l e u n i t s t h a t can n o t be analyzed f u r t h e r t o p r o v i d e a d e s c r i p t i o n of t h e r e l a t i o n s h i p among d i f f e r e n t l e t t e r s . I n t o d a y ' s t e r m i n o l o g y , t h i s view would c o r r e s p o n d t o a t e m p l a t e v i e w o f l e t t e r r e c o g n i t i o n . I d e a l l y , t h e r e a d e r would h a v e a t e m p l a t e c o r r e s p o n d i n g t o e a c h o f t h e l e t t e r s i n t h e l a n g u a g e and p e r c e p t u a l r e c o g n i t i o n would i n v o l v e f i n d i n g t h e b e s t match between t h e v i s u a l i n f o r m a t i o n i n t h e l e t t e r and t h e t e m p l a t e i n memory. Opposing t h e v i e w o f l e t t e r s a s i n d i v i s i b l e u n i t s i s t h e i d e a o f l e t t e r s h a v i n g a number of d i s t i n c t i v e f e a t u r e s . T h i s i d e a was g e n e r a t e d by work on t h e l i n g u i s t i c d e s c r i p t i o n o f s p e e c h s o u n d s a b o u t 3 0 y e a r s ago ( J a k o b s o n , F a n t , & H a l l e , 1 9 6 1 ) . Many s t r u c t u r a l l i n g u i s t s a t t h a t t i m e t r e a t e d phonemes a s t h e s m a l l e s t u n i t s of speech. I f phoneme u n i t s a r e i n d i v i s i b l e , then t h e physical or perceptual r e l a t i o n s h i p between two phonemes is n o t of c e n t r a l i n t e r e s t . J a k o b s o n e t al. c h a l l e n g e d t h i s p o i n t o f view by t r e a t i n g phonemes a s A relatively c o n s i s t i n g of a b u n d l e of d i s t i n c t i v e f e a t u r e s . s m a l l number of d i s t i n c t i v e f e a t u r e s c h a r a c t e r i z e d e a c h phoneme (1961) were of t h e l a n g u a g e . As a n e x a m p l e , J a k o b s o n e t a l . a b l e t o u s e j u s t n i n e f e a t u r e s t o d i s t i n g u i s h 28 phonemes i n E n g l i s h . The i d e a of d i s t i n c t i v e f e a t u r e a n a l y s i s a l s o p r o v e d productive in developing p a t t e r n r e c o g n i t i o n by machine. S e l f r i d g e and N e i s s e r ( 1 9 6 0 ) reviewed t e m p l a t e m a t c h i n g schemes and f e a t u r e analysis schemes for the r e c o g n i t i o n of l e t t e r s . These d e v e l o p m e n t s i n l i n g u i s t i c s and a r t i f i c i a l i n t e l l i g e n c e i n f l u e n c e d t h e d e v e l o p m e n t of f e a t u r e models of t h e v i s i b l e c h a r a c t e r i s t i c s of l e t t e r s .
LETTER FEATURES
A v a l u a b l e t e c h n i q u e f o r t h e s t u d y of t h e v i s u a l f e a t u r e s A of l e t t e r s i n v o l v e s t h e g e n e r a t i o n of c o n f u s i o n m a t r i c e s . c o n f u s i o n m a t r i x i n d i c a t e s what l e t t e r s w i l l be s e e n a s o t h e r l e t t e r s when e r r o r s a r e made. To i n d u c e e r r o r s , e i t h e r t h e v i s u a l i n p u t from t h e l e t t e r m u s t be d e g r a d e d o r t h e p r o c e s s i n g time a v a i l a b l e f o r r e c o g n i t i o n o f t h a t l e t t e r m u s t be l i m i t e d . To d e g r a d e l e t t e r s , t h e y h a v e been p r e s e n t e d a t r e l a t i v e l y l a r g e d i s t a n c e s o r i n p e r i p h e r a l v i s i o n . P r o c e s s i n g time i s not l i m i t e d b u t f e a t u r a l information is degraded. To l i m i t p r o c e s s i n g t i m e , l e t t e r s h a v e been p r e s e n t e d f o r a s h o r t d u r a t i o n a t a good f i g u r e - g r o u n d c o n t r a s t b u t c l o s e l y f o l l o w e d
VISUAL INFORMATION I N R E A D I N G
15
by a masking s t i m u l u s t h a t s e r v e s t o h a l t p r o c e s s i n g . The assumption i n l i m i t i n g p r o c e s s i n g t i m e is t h a t t h e r e a d e r m a k e s a n e r r o r b e c a u s e o f i n s u f f i c i e n t time t o p r o c e s s c o m p l e t e l y t h e f e a t u r a l i n f o r m a t i o n . Of c o u r s e , i t i s i m p o r t a n t t o a n a l y z e c o n f u s i o n m a t r i c i e s g e n e r a t e d from b o t h t h e s e methods and t o d e t e r m i n e whether t h e y g i v e s i m i l a r r e s u l t s . Prior t o Bouma's (1971) study, most c o n t e m p o r a r y experiments s t u d i e d t h e c o n f u s i o n s of uppercase l e t t e r s ( e . g . , G i b s o n , O s s e r , S c h i f f , & S m i t h , 1 9 6 3 ; Townsend, 1 9 7 1 ) . Bouma u t i l i z e d l o w e r c a s e l e t t e r s of t h e IBM C o u r i e r 1 0 t y p e f a c e shown Bouma p r e s e n t e d t h e l e t t e r s a t a r e l a t i v e l y i n Figure 2.1. l a r g e r e a d i n g d i s t a n c e i n one s t u d y and i n p e r i p h e r a l v i s i o n i n a n o t h e r . The c o n f u s i o n s were v e r y s y s t e m a t i c and a l l o w e d Bouma t o a s s i g n t h e l e t t e r s t o g r o u p s o f l e t t e r s t h a t were c o n f u s a b l e w i t h i n a g r o u p b u t n o t among g r o u p s . The c o n f u s i o n s among l e t t e r s were p r i m a r i l y d e p e n d e n t upon o v e r a l l l e t t e r s h a p e and size. Many o f t h e r e c o g n i t i o n c o n f u s i o n s c o u l d be d e s c r i b e d by j u s t t h r e e c l a s s e s of l e t t e r s : s h o r t or x -h e ig h t l e t t e r s , and descending letters ascending letters (ascenders), (descenders) Given an x - h e i g h t l e t t e r , a r e c o g n i t i o n conf u s i o n u s u a l l y r e s u l t e d from a n o t h e r x - h e i g h t l e t t e r and s o on. The x - h e i g h t l e t t e r s and a s c e n d e r s c a n a l s o b e b r o k e n down i n t o smaller groups a s i n d i c a t e d i n Table 2.2. Bouma a r g u e s t h a t o v e r a l l l e t t e r s h a p e is a n i m p o r t a n t d e t e r m i n a n t o f r e c o g n i t i o n c o n f u s i o n s and i n t r o d u c e s t h e c o n c e p t of e n v e l o p e . The envelope of a l e t t e r i s t h e s m a l l e s t polygon s u r r o u n d i n g a l e t t e r without indentation. For e x a m p l e , t h e e n v e l o p e f o r c would be c i r c u l a r , w h e r e a s would be e n c l o s e d by a n i n v e r t e d
.
Figure 2.1
a
c
e
m
o
r
s
u
v
w
x
z
b
d
f
h
i
k
l
t
n
Lowercase l e t t e r s o f t h e IBM C o u r i e r 1 0 t y p e f a c e used by Bouma ( 1 9 7 1 ) .
16
Table 2.2
CHAPTER 2
The s e v e n g r o u p s o f c o n f u s a b l e l e t t e r s of t h e C o u r i e r 1 0 t y p e f a c e ( a f t e r Bouma, 1 9 7 1 ) . 1. 2. 3.
4. 5.
6. 7.
a e n r d t g
s o m v h i p
z c u u k l j
IBM
x
b f y q
triangle. T h e s e e n v e l o p e s o f l e t t e r s a c c o u n t f o r some of t h e A s a n e x a m p l e , t h e g r o u p of confusable confusion e r r o r s . l e t t e r s (a, 2 , z, z) have r o u g h l y r e c t a n g u l a r e n v e l o p e s w i t h inner p a r t s . I n o r d e r t o p r o v i d e an independent a s s e s s m e n t of t h e f e a t u r a l i n f o r m a t i o n t h a t i s f u n c t i o n a l i n t h e r e c o g n i t i o n of l o w e r c a s e l e t t e r s , we c a r r i e d out a l e t t e r recognition experiment. F i g u r e 2 . 2 p r e s e n t s a photograph of t h e l e t t e r s a s t h e y a p p e a r e d i n t h e e x p e r i m e n t . A s i n g l e l e t t e r was p r e s e n t e d on e a c h t r i a l a t a r e l a t i v e l y dim i n t e n s i t y t o k e e p o v e r a l l
0123456789 :
;
?
ABCDEFGHIJKLMNO PQRSTUVWXYZ
abcdefghijklmno
pqrstuvwxyz Figure 2.2
The s e t o f c h a r a c t e r s c u r r e n t l y b e i n g used i n o u r laboratory. The c h a r a c t e r s a r e p l o t t e d a s p o i n t s is on an o s c i l l o s c o p e and t h e a v e r a g e c h a r a c t e r composed o f a p p r o x i m a t e l y 35 p o i n t s .
VISUAL INFORMATION I N READING
17
a c c u r a c y a t a b o u t 5 0 % . The t e s t l e t t e r was p r e s e n t e d a t t h e f i x a t i o n p o i n t f o r a s h o r t d u r a t i o n and no masking s t i m u l u s was presented. Three s u b j e c t s contributed a t o t a l of 296 o b s e r v a t i o n s f o r e a c h o f t h e 26 l e t t e r s o f t h e a l p h a b e t . T a b l e 2.3 p r e s e n t s t h e o v e r a l l a c c u r a c y f o r e a c h o f t h e 26 l e t t e r s , t h e f a l s e a l a r m r a t e s , t h e d ' v a l u e s , and c o n f u s i o n r e s p o n s e s t h a t o c c u r r e d more t h a n 5% o f t h e t i m e t o a g i v e n t e s t l e t t e r . One p o s s i b l e l i m i t a t i o n w i t h t h e s e d a t a and o t h e r s t u d i e s of t h i s nature is t h a t t h e l e t t e r s d i f f e r i n o v e r a l l accuracy, and t h e r e f o r e , t h e r e is n o t an e q u a l o p p o r t u n i t y f o r c o n f u s i o n s f o r e a c h o f t h e l e t t e r s . On t h e o t h e r h a n d , i t m i g h t be a r g u e d t h a t t h e o v e r a l l a c c u r a c y o f a g i v e n a l t e r n a t i v e may r e f l e c t That is t o s a y , how e a s i l y i t i s c o n f u s e d w i t h o t h e r l e t t e r s . a l e t t e r c o m p l e t e l y d i s s i m i l a r from t h e o t h e r l e t t e r s would g i v e good p e r f o r m a n c e s i n c e i t w i l l n o t b e c o n f u s e d f o r a n y o f the alternatives. R e g a r d l e s s of which i n t e r p r e t a t i o n i s more i t m i g h t be w o r t h w h i l e t o r e p e a t t h e e x p e r i m e n t reasonable, while a d j u s t i n g t h e i n t e n s i t y i n d i v i d u a l l y f o r each l e t t e r t o keep i t s performance a t 50% c o r r e c t . The p e r c e n t a g e c o r r e c t i d e n t i f i c a t i o n f o r e a c h o f t h e 26 l e t t e r s o f t h e a l p h a b e t i n T a b l e 2.3 shows t h a t r e c o g n i t i o n a c c u r a c y r a n g e d w i d e l y . T h i s r e s u l t may r e p r e s e n t a v i s u a l e f f e c t O K a d e c i s i o n e f f e c t . Some l e t t e r s may p r o v i d e more v i s u a l f e a t u r a l i n f o r m a t i o n t h a n o t h e r l e t t e r s u n d e r t h e same stimulus conditions. Alternatively, observers may d e r i v e e q u i v a l e n t amounts o f f e a t u r a l i n f o r m a t i o n from a l l l e t t e r s b u t may h a v e d e c i s i o n b i a s e s i n t h e i n t e r p r e t a t i o n of t h e f e a t u r a l information. A s a n example, o b s e r v e r s might be biased t o i n t e r p r e t t h e f e a t u r a l i n f o r m a t i o n i n terms of l e t t e r s t h a t o c c u r more f r e q u e n t l y in the language. The d e c i s i o n i n t e r p r e t a t i o n , however, appears t o be i n c o n s i s t e n t with t h e results. For e x a m p l e , t h e i n f r e q u e n t l e t t e r s 5 , y , and a v e r a g e d a b o u t 65% c o r r e c t , w h e r e a s t h e f r e q u e n t l e t t e r s e , g, 0 , and 2 a v e r a g e d a b o u t 35% c o r r e c t . I n c o n t r a s t t o what would be e x p e c t e d from a f r e q u e n c y b i a s , t h e s e l e a s t f r e q u e n t l e t t e r s are recognized much better than the more frequent l e t t e r s . This analysis provides support for the idea t h a t d i f f e r e n c e s i n accuracy a r e due t o d i f f e r e n c e s i n t h e f e a t u r a l i n f o r m a t i o n of t h e l e t t e r s . A more d i r e c t m e a s u r e of v i s u a l r e s o l u t i o n i s t o t a k e a 4 ' m e a s u r e a s p r o p o s e d by t h e t h e o r y o f & Swets, 1966; Massaro & signal detectability (Green Schmuller,. 1 9 7 5 ) . T a b l e 2.3 shows t h a t t h e s e d ' v a l u e s correlate rather highly with the percentage correct v a l u e s . Given t h e a s s u m p t i o n t h a t t h e d' v a l u e s a r e n o t i n f l u e n c e d by any d i f f e r e n c e s i n d e c i s i o n b i a s e s , t h e r e s u l t s
z
18
CHAPTER 2
T a b l e 2.3
Letter
a b C
d e f 4 h i j k 1
m n 0
P 9
r S
t U V W
X
Y 7.
P r o p o r t i o n o f times a letter was r e c o g n i z e d correctly (Hit) a n d was g i v e n a s a n i n c o r r e c t r e s p o n s e t o o t h e r l e t t e r s ( F a l s e A l a r m ) ; t h e d' a l u e ; and t h e confusion responses g r e a t e r t h a n 5% (from present study).
Hit
.372 .743 .449 .639 .365 .456 .703 .662 .277 .412 .655 .530 .628 .497 .331 .730 .649 .591 .324 .382 .554 .520 .632 .730 .686 .571
F a l s e Alarm .015 .020 .016 .011 .017 .0 20 .022 .020 .023 .017 .014 .022 .010 .013 .014 .016 ,010 .023 .010 . 0 20 .010 .015 .010 .010 .015 .010
A'
C o n f u s i o n s Greater t h a n 5%
1.85 2.72 2.05 2.64 1.79 1.94 2.56 2.46 1.42 1.92 2.61 2.10 2.66 2.24 1.78 2.78 2.71 2.24 1.87 1.76 2.46 2.16 2.66 2.94 2.67 2.51
locate the differences i n letter recognition a t a visual stage of p r o c e s s i n g . T a b l e 2.3 a l s o p r o v i d e s a n i n d e x o f t h e l e t t e r s which are confused w i t h o t h e r l e t t e r s i n t h e t a s k . For each l e t t e r , a l l c o n f u s i o n s g i v e n f o r t h a t l e t t e r g r e a t e r t h a n 5% o f t h e t i m e are presented. As a n e x a m p l e , g i v e n t h e s t i m u l u s a, s u b j e c t s r e s p o n d e d 1 4 % o f t h e time w i t h t h e a l t e r n a t i v e g a n d 7 % o f t h e time w i t h a l t e r n a t i v e g. T h i s m e a n s t h a t t h e l e t t e r a is o f t e n
VISUAL INFORMATION I N R E A D I N G
19
i n t e r p r e t e d a s e . The c o n f u s i o n s a p p e a r t o b e r e l a t i v e l y s y s t e m a t i c and t h e r e f o r e s u g g e s t w h i c h f e a t u r e s a r e f u n c t i o n a l T a b l e 2.4 p r o v i d e s a n a l o g o u s d a t a from in letter recognition. t h e p e r i p h e r a l - v i e w i n g e x p e r i m e n t c a r r i e d o u t b y Bouma o n t h e IBM C o u r i e r 10 typeface. The c o n f u s i o n s w i l l b e u t i l i z e d i n o u r l a t e r work when t h e r e l a t i v e s i m i l a r i t y b e t w e e n l e t t e r s beco m es a n i m p o r t a n t q u e s t i o n i n o u r e x p e r i m e n t s . The l e t t e r c o n f u s i o n s s u g g e s t t h a t o v e r a l l l e t t e r s h a p e i n f o r m a t i o n may b e o b t a i n e d b e f o r e c o m p l e t e l e t t e r p e r c e p t i o n ( r e s o l u t i o n ) . For example, 48% o f t h e e r r o r r e s p o n s e s t o t h e s t i m u l u s 2 were and 0 ; t h i s i n d i c a t e s t h a t s u b j e c t s saw a c i r c u l a r s h a p e o n many o f t h e t r i a l s b u t d i d n o t know w h e t h e r t h e l e t t e r was 2 , e , o r 0 . T h i s r e s u l t m i g h t b e i n t e r p r e t e d t o mean t h a t t h e o v e r a l l e n v e l o p e o f a l e t t e r i s r e s o l v e d b e f o r e d e t a i l s o f i t s component f e a t u r e s . I n d e p e n d e n t l y o f w h e t h e r a general t h e wh o l e i s g r e a t e r t h a n t h e s u m o f i t s p a r t s , impression of t h e whole ( a l t h o u g h ambiguous) is s e e n b e f o r e a l l of t h e p a r t s . T h a t a l e t t e r ' s e n v e l o p e ( n o pun i n t e n d e d ) be co m es a v a i l a b l e b e f o r e i t s d e t a i l s i s a l s o c o n s i s t e n t w i t h fourier-analysis s t u d i e s . T h e r e is e v i d e n c e t h a t i n f o r m a t i o n g i v e n by l o w s p a t i a l f r e q u e n c i e s i s p r o c e s s e d f a s t e r t h a n h i g h & Ganz, 1976; s p a t i a l frequency information (Breitmeyer Broadbent, 1 9 7 7 ) . Accordingly, low s p a t i a l f r e q u e n c i e s p r o v i d e information about o v e r a l l shape whereas high frequency information reduces uncertainty about l e t t e r d e t a i l . Either time o r a r e d u c e d f igure-ground contrast limited processing could allow envelope resolution without corresponding resolution of letter d e t a i l . I n terms o f t h e p r e s e n t a n a l y s i s , t h e r e a d e r w i l l have t o d e c i d e which l e t t e r b e s t f i t s t h e perceived b u t fuzzy envelope. For ex a m pl e, r e c o g n i t i o n o f a c i r c u l a r e n v e l o p e w i t h o u t f u r t h e r d e t a i l would b e s u f f i c i e n t t o l i m i t t h e a l t e r n a t i v e s t o t h e t h r e e l e t t e r s 2 , g , a n d 0. Given t h a t our primary m o t i v a t i o n is t o s t u d y t h e i n t e r a c t i o n of lower-level v i s u a l information with higher-order kn o wl ed g e i n l e t t e r r e c o g n i t i o n , we a r e n o t d i r e c t l y c o n c e r n e d w i t h wh i ch l e t t e r features are utilized i n perceptual recognition. T h e r e a r e now s u f f i c i e n t d a t a c o n s i s t e n t w i t h t h e i d e a t h a t l e t t e r r e c o g n i t i o n i s m e d i a t e d by f e a t u r e s ( M a s s a r o & Schmuller, 1 9 7 5 ) . F e a t u r e s a r e n o t l i m i t e d t o s m a l l co m p o n en t p r o p e r t i e s b u t c a n b e r e l a t i v e l y complex r e l a t i o n a l p r o p e r t i e s s u c h a s t h e o v e r a l l c i r c u l a r e n v e l o p e o f t h e l e t t e r s 5, g , a n d 0. Additionally, i n c o n t r a s t t o t h e common a s s u m p t i o n t h a t f e a t u r e s a r e d e t e c t e d i n a n all-or-none manner, w e p r e f e r t o view t h e f e a t u r e d e t e c t i o n p r o c e s s a s continuous. Visible f e a t u r e s may b e f u z z y so t h a t recognition consists of
e
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CHAPTER 2
T a b l e 2.4
Letter H i t
a b C
d
e f g h
i j k 1
m n 0
P 9
r S
t U
V W X
Y Z
.620 .620 .190 .830 .340 .810 .310 .800 .690 .820 .510 .260 .790 .560 .570 .840 .740 .550 .100 .590 .560 .720 .700 .320 .570 .120
P r o p o r t i o n of times a letter was r e c o g n i z e d correctly ( H i t ) a n d was g i v e n a s an i n c o r r e c t response to other letters ( F a l s e Alarm); t h e c o r r e s p o n d i n g d' v a l u e ; and t h e c o n f u s i o n r e s p o n s e s g r e a t e r t h a n 5% ( f r o m Bouma, 1 9 7 1 ) .
F a l s e Alarm .053 .024 .006 .019 .045 .013 .018 .028 .035 .008 .008 .007 .028 .026 .017 .017 .019 .015 .009 .0 1 3 .018 .016 .014 .003 .003 .004
d' 1.93 2.29 1.62 3.03 1.29 3.11 1.60 2.76 2.31 3.33 2.46 1.81 2.72 2.10 2.30 3.12 2.71 2.31 1.08 2.46 2.26 2.73 2.73 2.25 2.95 1.46
C o n f u s i o n s Greater t h a n 5%
VISUAL INFORMATION I N READING
21
a s c e r t a i n i n g t h e d e g r e e t o which t h a t f e a t u r e is p r e s e n t o r a b s e n t i n t h e s t i m u l u s . Oden and Massaro ( 1 9 7 8 ) have d e v e l o p e d a model of s p e e c h p e r c e p t i o n b a s e d on t h e i d e a of c o n t i n u o u s acoustic features. A s i m i l a r a n a l y s i s would seem t o b e a v a l u a b l e c o n t r i b u t i o n i n l e t t e r r e c o g n i t i o n , a l t h o u g h beyond t h e s c o p e of t h e p r e s e n t r e s e a r c h . For i n t e r e s t e d r e a d e r s , Oden ( 1 9 7 9 ) i n i t i a t e d a n e m p i r i c a l and t h e o r e t i c a l s t u d y o f f u z z y f e a t u r a l i n f o r m a t i o n i n l e t t e r s , and Massaro ( 1 9 7 9 a ) q u a n t i f i e d a model t o a c c o u n t f o r how c o n t i n u o u s f e a t u r a l i n f o r m a t i o n of a l e t t e r is i n t e g r a t e d w i t h o r t h o g r a p h i c c o n t e x t in l e t t e r recognition.
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3
Orthographic Structure
I n t h i s c h a p t e r we d e s c r i b e t h e f u n d a m e n t a l p r o p e r t i e s o f o r t h o g r a p h i c s t r u c t u r e and s p e c u l a t e on how t h e s e p r o p e r t i e s m i g h t f a c i l i t a t e l e t t e r and word r e c o g n i t i o n . The g o a l of t h i s d i s c u s s i o n is t o d e r i v e d i f f e r e n t m e t r i c s f o r s c a l i n g t h e o r t h o g r a p h i c s t r u c t u r e o f l e t t e r s t r i n g s b a s e d upon d i f f e r e n t a s s u m p t i o n s a b o u t how o r t h o g r a p h i c s t r u c t u r e c o n t r i b u t e s t o recognition processes. The e x p e r i m e n t s p r e s e n t e d i n C h a p t e r 4 a t t e m p t t o e v a l u a t e t h e p s y c h o l o g i c a l r e a l i t y of s e v e r a l of t h e s e measures. Central t o the discussion of t h i s chapter is the assumption t h a t s k i l l e d r e a d e r s d e r i v e information about l e g a l o c c u r r e n c e s of l e t t e r s o r l e t t e r s e q u e n c e s from r e p e a t e d e x p o s u r e s t o p r i n t e d words and that t h e y employ t h i s i n f o r m a t i o n t o f a c i l i t a t e word r e c o g n i t i o n i n normal r e a d i n g t a s k s . Our c o n c e r n h e r e is w i t h b o t h t h e d e s c r i p t i o n of t h e abstracted i n f o r m a t i o n and i t s u t i l i z a t i o n i n t h e r e c o g n i t i o n process. I n t h e d i s c u s s i o n which f o l l o w s w e c o n c e n t r a t e on two broad c a t e g o r i e s of orthographic structure: s t a t i s t i c a l redundancy and rule-governed regularity. Statistical r e d u n d a n c y a p p l i e s t o t h o s e m e a s u r e s which c a n b e d e r i v e d s o l e l y from t h e f r e q u e n c y w i t h which l e t t e r s , l e t t e r s e q u e n c e s , and words o c c u r i n n a t u r a l t e x t s . Such m e a s u r e s m i g h t b e b a s e d upon t y p e o r t o k e n c o u n t s . The m e a s u r e s m i g h t a p p l y t o l e t t e r s , l e t t e r s e q u e n c e s , o r t o any c l a s s i f i c a t i o n of t h e s e e n t i t i e s (e.g., vowel, c o n s o n a n t ) . Rule-governed regularity a p p l i e s t o t h o s e p r o p e r t i e s o f l e t t e r s and l e t t e r s e q u e n c e s which c a n be generalized from e i t h e r the phonological The c o n s t r a i n t s of E n g l i s h words o r t h e s c r i b a l c o n v e n t i o n s . l a t t e r c o n t r o l t h e s e l e c t i o n of l e t t e r s f o r e i t h e r r e p r e s e n t i n g s o u n d s o r marking g r a p h e m i c , g r a p h o t a c t i c , o r m o r p h o l o g i c a l
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CHAPTER 3
functio:is. Rule-governed r e g u l a r i t y u s u a l l y s p e c i f i e s a l e t t e r s t r i n g a s regular o r i r r e g u l a r . I n a d d i t i o n , through t h e of rules for generating legal (i.e., specification English-like) l e t t e r s t r i n g s , l e v e l s of r e g u l a r i t y c a n be defined.
STATISTICAL REDUNDANCY O r d e r e d a p p r o x i m a t i o n s t o E n g l i s h , b a s e d on a l g o r i t h m s p r o p o s e d by Shannon ( 1 9 4 8 ) , were t h e f i r s t d e s c r i p t i o n s o f o r t h o g r a p h i c s t r u c t u r e u t i l i z e d by p s y c h o l o g i s t s . Shannon ( 1 9 4 8 ) c r e a t e d a z e r o - o r d e r a p p r o x i m a t i o n t o E n g l i s h by d r a w i n g l e t t e r s w i t h r e p l a c e m e n t from a p o o l o f 27 u n w e i g h t e d symbols--the 26 l e t t e r s o f t h e a l p h a b e t p l u s a s p a c e . (In this a s i n most o t h e r s e q u e n t i a l g e n e r a t i o n t e c h n i q u e s , a n i n i t i a l I f t h i s same p r o c e d u r e is employed s p a c e symbol i s assumed.) w i t h symbols t h a t a r e w e i g h t e d a c c o r d i n g t o t h e i r f r e q u e n c i e s of occurrence i n t e x t s , f i r s t - o r d e r ap p r o x im a tio n s r e s u l t . An n - g o r d e r a p p r o x i m a t i o n i s p r o d u c e d by f i r s t s e l e c t i n g a l e t t e r s t r i n g of l e n g t h n-1. T h i s f o r m s t h e b e g i n n i n g p a r t o f t h e new s t r i n g . The t e x t i s t h e n s c a n n e d f o r t h e f i r s t o c c u r r e n c e o f t h i s i n i t i a l s t r i n g . When f o u n d , t h e n e x t l e t t e r a f t e r t h e l e t t e r s t r i n g s e q u e n c e is added t o t h e s t r i n g b e i n g g e n e r a t e d , and a n e w s e a r c h s t r i n g i s c o n s t r u c t e d by d r o p p i n g t h e f i r s t l e t t e r of t h e l a s t s e a r c h s t r i n g and a d d i n g t h e T h i s p r o c e d u r e is t h e n r e p e a t e d u n t i l a l e t t e r j u s t located. space occurs or a d e s i r e d l e n g t h reached. M i l l e r , B r u n e r , and Postman ( 1 9 5 4 ) used t h i s t e c h n i q u e t o g e n e r a t e e i g h t - l e t t e r pseudowords f o r a full-report task. Their fourth-order items like mossiant, oneticul, approximations included all quite English-like. Wallach p r e v e r a l , and f a v o r i a l , ( 1 9 6 3 ) , on t h e o t h e r h a n d , t r u n c a t e d two l e t t e r s from e a c h s t r i n g used by Miller e t a l . t h u s o c c a s i o n a l l y p r o d u c i n g a non-English s p e l l i n g ( e . g . , m o s s i a , l o r i a i ) . Although M i l l e r e t a l . ( 1 9 5 4 ) were p r i m a r i l y c o n c e r n e d w i t h i n f o r m a t i o n t h e o r y , 1973; l a t e r experimenters ( e . g . , L e f t o n , S p r a g i n s , & Byrnes, Mewhort & B e a l , 1977) h a v e a d v o c a t e d o r d e r e d a p p r o x i m a t i o n s a s psychologically relevant descriptions of orthographic structure A major s h o r t c o m i n g o f o r d e r e d a p p r o x i m a t i o n d e s c r i p t i o n s is t h e i r i n a b i l i t y t o control s t r u c t u r a l v a r i a t i o n s within approximation l e v e l s . Although any l a r g e g r o u p o f s t i m u l i g e n e r a t e d by t h i s t e c h n i q u e w i l l a p p r o x i m a t e t h e f r e q u e n c i e s o f o c c u r r e n c e of E n g l i s h l e t t e r s e q u e n c e s , t h e r e i s no m e t r i c
.
ORTHOGRAPHIC STRUCTURE
25
i n c o r p o r a t e d i n t o t h e m e th o d f o r a s s e s s i n g t h e r e l a t i v e d e g r e e of o r t h o g r a p h i c s t r u c t u r e of s t r i n g s w i t h i n o r d e r c l a s s e s . In Gilmore an d Egeth (1976), for example, zero-order a p p r o x i m a t i o n s t o E n g l i s h were used t o g e n e r a t e what t h e a u t h o r s i n t e n d e d t o be nonwords, which t h e y c o n t r a s t e d w i t h r e a l E n g l i s h words. I f no o t h e r c r i t e r i a were used t o e v a l u a t e t h e 30 s t r i n g s g e n e r a t e d f o r u s e i n t h e i r e x p e r i m e n t s , there was a 1 8 % c h a n c e t h a t a t l e a s t o n e r e a l word o c c u r r e d ( b a s e d o n t h e a s s u m p t i o n o f 1 , 5 0 0 common f o u r - l e t t e r w o r d s i n E n g l i s h ) ; t h e p r o b a b i l i t y t h a t p s e u d o w o r d s o c c u r r e d was c o n s i d e r a b l y higher. A second shortcoming of a s t r i c t p s y c h o l o g i c a l a p p l i c a t i o n of t h i s a p p r o a c h i s i t s s t r i c t r e l i a n c e o n l e f t - t o - r i g h t For e x a m p l e , g e n e r a t i o n of l e t t e r s d u r i n g word r e c o g n i t i o n . six-letter g i v e n thand th-ugh a s p a r t i a l l y p e r c e i v e d s t r i n g s , t h e p r o b a b i l i t i e s of i d e n t i f y i n g t h e t h i r d l e t t e r i n e a c h would b e t h e same i n t h a t o n l y i n f o r m a t i o n t o t h e l e f t b u t n o t t o t h e r i g h t o f any l e t t e r p o s i t i o n is r e l e v a n t . To o v er co m e t h e s e d i f f i c u l t i e s , summed b i g r a m an d t r i g r a m c o u n t s have been proposed a s metrics. Underwood an d S c h u l z ( 1 9 6 8 ) t a b u l a t e d t h e b i g r a m s and t r i g r a m s i n 2 , 0 9 0 w o r d s s a m p l e d f r o m T h o r n d i k e and L o r g e ( 1 9 4 4 ) . S i n c e e a c h s a m p l e word was w e i g h t e d by i t s f r e q u e n c y o f o c c u r r e n c e i n t e x t s , t o k e n - b a s e d b i g r a m a n d t r i g r a m c o u n t s r e s u l t e d . By summing t h e frequencies of a l l t h e bigrams or trigrams within a letter s t r i n g , a f a m i l i a r i t y index can be d e r i v e d . S u ch a p r o c e d u r e was u s e d b y A n i s f e l d ( 1 9 6 4 ) , f o r e x a m p l e , i n r e a n a l y z i n g t h e Gibson, P i c k , O s s e r , and Hammond ( 1 9 6 2 ) s t u d y o f a f u l l r e p o r t of visually-presented letter strings varying in p r o n o u n c e a b i l i t y . According t o A n i s f e l d (1964) , t h e Gibson e t al. r e s u l t s c o u l d b e a c c o u n t e d f o r a s e a s i l y by d i f f e r e n c e s i n summed b i g r a m c o u n t s a s t h e y c o u l d b y t h e s p e l l i n g - t o - s o u n d u n i t s advocated by Gibson e t a l . Gibson ( 1 9 6 4 ) , i n a r e p l y t o Anisfeld ( 1 9 6 4 1 , h o w e v e r , showed t h a t c o r r e l a t i o n s o f summed b i g r a m and summed t r i g r a m c o u n t s w i t h s u b j e c t r e s p o n s e s w e r e lo w and n o n s i g n i f i c a n t . I n a d d i t i o n , Gibson, S h u r c l i f f , and Yonas ( 1 9 7 0 ) f o u n d n e i t h e r summed b i g r a m n o r summed t r i g r a m counts t o be an adequate predictor of recognition s c o r e s f o r unpronounceable and pronounceable l e t t e r s t r i n g s . Gibson e t a l . (1970) d i d n o t provide a f a i r test of the f r e q u e n c y measures, however, b e c a u s e t h e c o u n t s were n o t a d j u s t e d f o r word l e n g t h i n a n y r e a s o n a b l e m a n n e r . Word l e n g t h a l o n e a c c o u n t e d f o r a b o u t 7 0 % of t h e v a r i a n c e i n t h e r e c a l l s c o r e s ; t h e number o f e r r o r s n a t u r a l l y i n c r e a s e d w i t h i n c r e a s e s in the length of the letter string. The s i g n i f i c a n t
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c o r r e l a t i o n o f p r o n o u n c e a b i l i t y c o u l d be d u e t o t h e s i m p l e f a c t t h a t s h o r t e r words a r e more p r o n o u n c e a b l e t h a n l o n g e r words. S u p p o r t i n g t h i s i n t e r p r e t a t i o n , S p r e e n and S c h u l z ( 1 9 6 6 ) f o u n d a n e g a t i v e c o r r e l a t i o n of .83 b e t w e e n word l e n g t h and p r o n o u n c e a b i l i t y f o r 329 common nouns. Therefore, t h e r e s u l t s o f Gibson e t a l . ( 1 9 6 2 , 1970) r e a l l y d o n o t s p e a k t o t h e i s s u e of p r o n o u n c e a b i l i t y v e r s u s o r t h o g r a p h i c s t r u c t u r e of l e t t e r s t r i n g s when s t r i n g l e n g t h i s h e l d c o n s t a n t . The Underwood and S c h u l z ( 1 9 6 0 ) t a b l e s p r o v i d e a means f o r differentiating familiar and unfamiliar strings within a p p r o x i m a t i o n c l a s s e s , b u t s u f f e r from l a c k o f a t t e n t i o n t o A common word l e n g t h o r p o s i t i o n of l e t t e r s w i t h i n a word. s u f f i x l i k e -&would h e a v i l y w e i g h t a t r i g r a m c o u n t f o r a pseudoword w h e t h e r i n i n i t i a l o r f i n a l p o s i t i o n a c c o r d i n g t o t h e s e t a b l e s , y e t i n E n g l i s h words t h i s s e q u e n c e n e v e r o c c u r s is a initially. If letter position within a word p s y c h o l o g i c a l l y r e l e v a n t v a r i a b l e , t h e Underwood and S c h u l z ( 1 9 6 0 ) t a b l e s c o u l d n o t be used f o r e x p l o r i n g t h i s f a c t o r . T h i s s h o r t c o m i n g h a s been overcome, however, in the Mayzner and T r e s s e l t ( 1 9 6 5 ) and Mayzner, T r e s s e l t , and Wolin ( 1 9 6 5 a , 1965b) t a b l e s , which give bigram, t r i g r a m , and t e t r a g r a m c o u n t s by word p o s i t i o n and by word l e n g t h f o r words from t h r e e t o s e v e n c h a r a c t e r s i n l e n g t h . Mayzner and T r e s s e l t ( 1 9 6 5 ) a l s o g i v e s i n g l e - l e t t e r p o s i t i o n a l f r e q u e n c i e s , which have been used by Mason ( 1 9 7 5 ) t o e x p l o r e d i f f e r e n c e s between good and poor r e a d e r s i n a r e c o g n i t i o n t a s k . Although Mason (1975) c o n f o u n d s r u l e - g o v e r n e d orthographic s t r u c t u r e with p o s i t i o n a l frequency, a small but s i g n i f i c a n t p o s i t i o n a l f r e q u e n c y e f f e c t r e m a i n s when t h e s e v a r i a b l e s a r e s e p a r a t e d ( M a s s a r o , Venezky, & T a y l o r , 1 9 7 9 ) . The relationships among single-letter positional f r e q u e n c y , b i g r a m p o s i t i o n a l f r e q u e n c y , and t r i g r a m p o s i t i o n a l f r e q u e n c y h a v e o n l y begun t o be e x p l o r e d . McClelland and J o h n s t o n ( 1 9 7 7 ) o b s e r v e d t h a t a c c u r a c y o f r e p o r t of f o u r - l e t t e r i t e m s was s i g n i f i c a n t l y c o r r e l a t e d w i t h summed s i n g l e - l e t t e r p o s i t i o n a l frequency b u t n o t w i t h bigram p o s i t i o n a l f r e q u e n c y . Bouwhuis ( 1 9 7 9 ) found t h a t s i n g l e - l e t t e r p o s i t i o n a l f r e q u e n c y made a s i g n i f i c a n t c o n t r i b u t i o n t o l e x i c a l d e c i s i o n s a b o u t three-letter items. R e a c t i o n times t o words d e c r e a s e d w i t h i n c r e a s e s i n f r e q u e n c y w h e r e a s r e a c t i o n times t o pseudowords increased. S i m i l a r l y , high s i n g l e - l e t t e r p o s i t i o n a l frequency i n c r e a s e d t h e number of "word" r e s p o n s e s t o b o t h words and pseudowords. These s i g n i f i c a n t c o r r e l a t i o n s were c o n s i d e r a b l y d i m i n i s h e d when b i g r a m p o s i t i o n a l f r e q u e n c y was used a s t h e p r e d i c t o r v a r i a b l e . T h e s e r e s u l t s imply t h a t t h e power o f t h e
ORTHOGRAPHIC STRUCTURE
27
bigram frequency measure ( s e e Chapter 5 ) w i t h our s i x - l e t t e r i t e m s may n o t g e n e r a l i z e c o m p l e t e l y t o s m a l l e r l e t t e r - s t r i n g lengths. It is p o s s i b l e to generate letter s t r i n g s while i n d e p e n d e n t l y v a r y i n g summed s i n g l e - l e t t e r p o s i t i o n a l - f r e q u e n c y a n d summed b i g r a m p o s i t i o n a l - f r e q u e n c y counts. W i t h some s t r a i n i n g , t h e same c a n b e d o n e f o r summed b i g r a m a n d summed trigram counts. For example, nachim h a s ( a c c o r d i n g t o Mayzner, e t al. 1 9 6 5 b ) l e g a l b i g r a m s b u t no l e g a l t r i g r a m s . Nather, on A legal t h e o t h e r hand, h a s l e g a l b i g r a m s and l e g a l t r i g r a m s . bigram o r a l e g a l t r i g r a m means t h a t t h e s p e l l i n g p a t t e r n o c c u r s w i t h f r e q u e n c i e s a b o v e z e r o i n t h e Mayzner e t a l . tables. T h e Mayzner e t a l . t a b l e s m i g h t b e b a s e d o n t o o s m a l l a sample f o r r e l i a b l e counts. C o n s e q u e n t l y , we h a v e d e v i s e d t a b l e s from t h e Kucera and F r a n c i s ( 1 9 6 7 ) m i l l i o n - w o r d l i s t and h a v e u t i l i z e d them i n t h e p r e s e n t p r o j e c t . The d e s c r i p t i o n o f t h e a n a l y s i s and t h e s i n g l e - l e t t e r and bigram t a b l e s a r e g i v e n i n Appendix 5.2 a n d 5.3. A f u r t h e r i s s u e t h a t n e e d s t o b e c l a r i f i e d is t h e r e l a t i v e importance o f t o k e n measures and t y p e measures. Token c o u n t s r e p r e s e n t a summed o c c u r r e n c e f o r some l e t t e r s e q u e n c e , r e g a r d l e s s o f t h e number o f u n i q u e w o r d s w h i c h c o n t r i b u t e t o t h i s sum. Type c o u n t s , o n t h e o t h e r h a n d , r e p r e s e n t a sum o f t h e unique words i n which a l e t t e r sequence o c c u r s , r e g a r d l e s s of t h e f r e q u e n c i e s o f occurrence of t h e words. In a l l of the e x p e r i m e n t a l work r e p o r t e d s o far t h a t used sequential redundancy m e a s u r e s , t o k e n c o u n t s have been employed. Solso and h i s c o l l e a g u e s ( S o l s o , 1979; S o l s o & K i n g , 1976; S o l s o , B a r b u t o , & J u e l , 1 9 7 9 ; S o l s o , T o p p e r , & Macey, 1 9 7 3 ; T o p p e r , Macey, & S o l s o , 1 9 7 3 ) r e p o r t some t y p e - b a s e d t a b u l a t i o n s b a s e d o n t h e K u c e r a a n d F r a n c i s ( 1 9 6 7 ) word l i s t s b u t no e x p e r i m e n t a l data. However, t h e r e i s no a p r i o r i r e a s o n f o r a s s u m i n g t h a t word t o k e n s h a v e g r e a t e r p s y c h o l o g i c a l r e a l i t y t h a n word t y p e s n o r a r e t h e r e e m p i r i c a l d a t a r e l e v a n t t o t h i s q u e s t i o n . We a d d r e s s t h i s i s s u e i n Chapter 5. T y p e - b a s e d m e a s u r e s c o u l d b e d e r i v e d from a r e p r e s e n t a t i o n of a n i n t e r n a l l e x i c o n , b u t token measures a l s o r e q u i r e t h e W h i l e i t is e x i s t e n c e o f d i s t r i b u t i o n a l i n f o r m a t i o n i n memory. r e a s o n a b l e t o a s s u m e t h a t some f o r m s o f b o t h t o k e n a n d t y p e i n f o r m a t i o n m i g h t h a v e p s y c h o l o g i c a l r e a l i t y , how t h e r e a d e r m i g h t a p p l y r a w t o k e n m e a s u r e s i n word r e c o g n i t i o n i s n o t coinpletely obvious (cf. Savin, 1 9 6 3 ) . However, some i n t e r e s t i n g a p p r o a c h e s t o u s i n g t o k e n m e a s u r e s embedded w i t h i n t y p e m e a s u r e s h a v e b e e n p r o p o s e d b y Solomon a n d P o s t m a n ( 1 9 5 2 ) , S a v i n ( 1 9 6 3 ) , and more r e c e n t l y by Landauer and S t r e e t e r
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(1973). As an example, t h e viab,le a l t e r n a t i v e s could be n a r r o w e d down t o a l l w o r d s c o n s i s t e n t w i t h t h e f e a t u r a l i n f o r m a t i o n and t h e r e a d e r m i g h t c h o o s e t h e m o s t f r e q u e n t word from t h i s s e t . B u t w h a t e v e r a p p l i c a t i o n m i g h t b e shown f o r f r e q u e n c y i n f o r m a t i o n i n word r e c o g n i t i o n , t h e s p e c i f i c r o l e o f t h e s e measures has y e t t o b e determined. I f summed f r e q u e n c y ( t o k e n o r type) is psychologically r e l e v a n t , then t h e u t i l i z a t i o n of a m e a s u r e l i k e b i g r a m f r e q u e n c y would r e q u i r e a m a x i m i z i n g process. Consider the task o f perceiving a f i v e - l e t t e r s t r i n g wh er e t h e v i s u a l i n f o r m a t i o n a l l o w s a n a c c e p t a b l e r e s o l u t i o n o f LlL2-L4L5. Assume t h a t no a l l letters except one, e.g., The u s e o f b i g r a m v i s u a l i n f o r m a t i o n is a v a i l a b l e f o r L 3 . i n f o r m a t i o n r e q u i r e s t h a t L 3 b e s e l e c t e d t o m ax i m i ze t h e sum o f t h e bigram f r e q u e n c i e s o f L 2 L 3 and L 3 L 4 , s e l e c t i n g L 3 from a pool of a l l 26 l e t t e r s . If some v i s u a l information is a v a i l a b l e f o r L 3 , then t h e pool OE a v a i l a b l e l e t t e r s might be r e s t r i c t e d t o t h o s e t h a t were c o m p a t i b l e w i t h t h e a v a i l a b l e i n f o r m a t i o n b u t o t h e r w i s e t h e s t r a t e g y would b e t h e same. For a t r i g r a m s t r a t e g y , a s i m i l a r p r o c e s s c o u l d b e u sed b u t w i t h t h e maximizing o f t h e combined f r e q u e n c i e s f o r L l L 2 L 3 + L 2 L 3 L 4 + L 3 L 4 L 5 . The c o m p l e x i t y o f t h i s s t r a t e g y d o e s n o t n e c e s s a r i l y make i t s p s y c h o l g i c a l r e l e v a n c e s u s p e c t . A p o t e n t i a l d r a w b a c k t o summed s i n g l e - l e t t e r , b i g r a m , an d t r i g r a m p o s i t i o n a l c o u n t s , p a r t i c u l a r l y where token c o u n t s a r e is t h e dominating r o l e played by a s m a l l g r o u p utilized, o f high-frequency words. For t h e f o u r - l e t t e r wor ds, a s a n example, t h e 37 most f r e q u e n t words o f t h i s l e n g t h a c c o u n t f o r approximately one-half of all tokens of four-letter wo r d s . This guarantees, on t h e average, a high, positive c o r r e l a t i o n between d i f f e r e n t s t a t i s t i c a l measures. However, low summed s i n g l e - l e t t e r positional-frequency s t r i n g s w i l l u s u a l l y b e l o w i n summed p o s i t i o n a l b i g r a m an d t r i g r a m f r e q u e n c y , b u t s t r i n g s h i g h i n summed s i n g l e - l e t t e r p o s i t i o n a l f r e q u e n c y a r e n o t n e c e s s a r i l y h i g h i n t h e o t h e r two m e a s u r e s . Furthermore, s i n c e t h e extremely h i g h frequency words i n E n g l i s h a r e m o s t l y t h r e e , f o u r , and ( t o a l e s s e r d e g r e e ) five l e t t e r s i n l e n g t h , t h e i n f l u e n c e of t h e h i g h e s t frequency words n e c e s s a r i l y d e c r e a s e s w i t h i n c r e a s i n g word l e n g t h . T h u s , we would e x p e c t a l o w e r c o r r e l a t i o n b e t w e e n b i g r a m an d t r i g r a m counts i n seven-letter s t r i n g s than i n f o u r - l e t t e r s t r i n g s . The c e n t r a l l i m i t a t i o n i n f r e q u e n c y - b a s e d s c h e m e s , e v e n when p o s i t i o n and word l e n g t h s a r e o b s e r v e d , i s t h a t t h e y c a n g e n e r a t e p s e u d o w o r d s w h i c h v i o l a t e E n g l i s h p h o n o l o g i c a l an d spelling conventions. F o r e x a m p l e , t h r s m , s t h s e , an d w h r s t a r e
ORTHOGRAPHIC STRUCTURE
29
unpronounceable b u t have relatively high summed b i g r a m p o s i t i o n a l c o u n t s . These can be c o n t r a s t e d w i t h b i p o n , s l e v y , and d u f i p , which h a v e r e l a t i v e l y low summed b i g r a m p o s i t i o n a l counts, but a r e legal from a rule-governed standpoint. V i o l a t i o n s c a n b e a v o i d e d , f o r t h e most p a r t , by u s i n g position-sensitive f o u r t h - o r d e r a p p r o x i m a t i o n s which a r e a l s o h i g h i n summed t r i g r a m p o s i t i o n a l c o u n t s . PHONOLOGICALLY-BASED DESCRIPTIONS An a l t e r n a t i v e t o s t a t i s t i c a l r e d u n d a n c y h a s been t o u s e the relationship between spelling and sound (i.e. , pronounceability) as a d e f i n i n g m e t r i c . Gibson e t a l . (1962) f o u n d t h a t l e t t e r s o f p r o n o u n c e a b l e pseudowords were more easily recalled in a f u l l r e p o r t t h a n were l e t t e r s o f u n p r o n o u n c e a b l e nonwords ( e . g . , dink v s . G ) .The a u t h o r s h y p o t h e s i z e d t h a t t h e o p e r a t i v e u n i t i n word p e r c e p t i o n was n o t t h e l e t t e r ( o r t h e whole w o r d ) , b u t a s e q u e n c e o f l e t t e r s which had an i n v a r i a n t s p e l l i n g - t o - s o u n d relationship. However, (1970) obtained the same r e s u l t s w i t h Gibson e t a l . congenitally deaf s u b j e c t s , thereby demonstrating t h a t t h e spelling-to-sound r e l a t i o n s h i p could not alone account f o r t h e response d i f f e r e n c e s . I t is l i k e l y t h a t o r t h o g r a p h i c s t r u c t u r e d i f f e r e n c e s (whether frequency-based o r rule-governed) were critical. L e t t e r - s o u n d c o r r e s p o n d e n c e s h a v e a l s o been u t i l i z e d i n word r e c o g n i t i o n models by R u b e n s t e i n , L e w i s , and R u b e n s t e i n ( 1 9 7 1 ) and by S m i t h and Spoehr ( 1 9 7 4 ) . However, b o t h t h e p a r a d i g m employed and the assumed u s e of l e t t e r - s o u n d r e l a t i o n s h i p s i n t h e l a t t e r two s t u d i e s d i f f e r e d from t h a t i n ( 1 9 7 1 ) and S m i t h Gibson e t a l . ( 1 9 6 2 ) . Both R u b e n s t e i n e t a l . and Spoehr ( 1 9 7 4 ) assumed t h a t l e t t e r r e c o g n i t i o n o c c u r s o n t h e b a s i s of l e t t e r f e a t u r e s ; t h en sounds a r e a t t a c h e d t o l e t t e r s o r l e t t e r s e q u e n L e s and l e x i c a l a c c e s s made o n t h e b a s i s o f a phonological u n i t . G i b s o n e t a l . ( 1 9 6 2 ) assumed t h a t word r e c o g n i t i o n o c c u r r e d on t h e b a s i s o f h i g h e r - o r d e r v i s u a l u n i t s which t h e r e a d e r formed t h r o u g h e x p e r i e n c e w i t h l e t t e r - s o u n d translation. The r e l i a b i l i t y o f any o f t h e s e h y p o t h e s e s , when viewed i n r e l a t i o n t o the c o m p l e x i t i e s of l e t t e r - s o u n d c o r r e s p o n d e n c e s i s q u e s t i o n a b l e ( c f . Venezky, 1 9 7 0 ) . Furthermore, some e m p i r i c a l evidence indicates that p h o n o l o g i c a l e n c o d i n g is n o t n e c e s s a r y f o r l e x i c a l a c c e s s ( K l e i m a n , 1 9 7 5 ; Levy, 1 9 7 8 ; M a s s a r o , 1 9 7 8 ; 1979b; Tzeng, Hung, & Wang, 1 9 7 7 ) . However, e v e n i f p h o n o l o g i c a l t r a n s l a t i o n w e r e shown t o p l a y a r o l e i n word r e c o g n i t i o n , pronounceability
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a l o n e would s t i l l be i n a d e q u a t e f o r d e s c r i b i n g o r t h o g r a p h i c structure. E n g l i s h s p e l l i n g i s c o n s t r a i n e d by p h o n o l o g i c a l c o n v e n t i o n s f i r s t , b u t a l s o by s c r i b a l c o n v e n t i o n s , which outlaw c e r t a i n p o s s i b l e b u t pronounceable s p e l l i n g s i n s e l e c t e d contexts.
RULE-GOVERNED
REGULARITY
Rule-governed regularity describes the predictable s t r u c t u r e of t h e o r t h o g r a p h y i n t e r m s of p h o n o l o g i c a l and scribal constraints. However, a c r i t i c a l f e a t u r e of t h i s p r e d i c t a b l e s t r u c t u r e of l e t t e r d e s c r i p t i o n is t h a t t h e o c c u r r e n c e s i s u t i l i z e d w i t h o u t a n y m e d i a t i o n of t h e s p o k e n language. I n c o n t r a s t t o t h e s p e l l i n g - t o - s o u n d d e s c r i p t i o n of Gibson e t a l . ( 1 9 6 2 ) , R u b e n s t e i n e t a l . ( 1 9 7 1 ) , and S m i t h and of orthographic structure in Spoehr (1974) , u t i l i z a t i o n p e r c e p t u a l r e c o g n i t i o n i s assumed t o o c c u r b e f o r e t h e p r i n t e d Although much o f t h e s t r u c t u r e p a t t e r n i s t r a n s l a t e d t o sound. of a w r i t t e n a l p h a b e t i c l a n g u a g e n e c e s s a r i l y f o l l o w s i t s phonology, a c c e s s t o t h e phonology i s n o t n e c e s s a r y f o r u t i l i z a t i o n of t h e o r t h o g r a p h i c s t r u c t u r e . Direct evidence f o r t h i s a s s u m p t i o n comes from t h e u t i l i z a t i o n of o r t h o g r a p h i c s t r u c t u r e by d e a f r e a d e r s ( G i b s o n e t a l . , 1 9 7 0 ) . I n a d d i t i o n , Singer ( i n p r e s s ) found t h a t a p h o n o l o g i c a l r e n d e r i n g o f words p r e s e n t e d i n a n a r t i f i c i a l a l p h a b e t was n o t n e c e s s a r y f o r l e a r n i n g and u t i l i z i n g o r t h o g r a p h i c s t r u c t u r e . I n the sections which f o l l o w , b o t h t h e p h o n o l o g i c a l and t h e s c r i b a l c o n s t r a i n t s of Engl i sh s p e l l i n g s a r e o u t l i n e d . Phonological Constraints The p r i m a r y c o n s t r a i n t s on E n g l i s h o r t h o g r a p h y d e r i v e from t h e a l l o w a b l e s e q u e n c e s o f s o u n d s i n E n g l i s h words. Thus, / s k / i s an a l l o w a b l e i n i t i a l c o n s o n a n t c l u s t e r and t h e r e f o r e E, on t h e o t h e r h a n d , spellings for it e x i s t (e.g., / t l / and / d l / d o n o t o c c u r and n e v e r d i d o c c u r i n i t i a l l y i n E n g l i s h w o r d s , and t h e r e f o r e no s p e l l i n g f o r t h e s e s e q u e n c e s o c c u r i n E n g l i s h words ( b u t t h e y d o i n T l i n g i t and s e v e r a l o t h e r l a n g u a g e s i n which i n i t i a l / t l / and / d l / are legal). C o m p l i c a t i n g t h i s r e l a t i o n s h i p between sound and s p e l l i n g , however, a r e s e v e r a l f a c t o r s , i n c l u d i n g s c r i b a l p e d a n t r y , which l e a v e u s w i t h s p e l l i n g s f o r (1) sound s e q u e n c e s which o n c e o c c u r r e d , b u t have s i n c e been d r o p p e d from t h e l a n g u a g e ( e . g . , WL-, &-, F-), o r f o r ( 2 ) sound s e q u e n c e s t h a t were presumed
e, e);
ORTHOGRAPHIC STRUCTURE
31
t o h a v e o c c u r r e d i n t h e l a n g u a g e from which a word was borrowed this (e.g., p s y c h o l o g y , p t a r m i g a n , debt). For p s y c h o l o g y , a s s u m p t i o n i s s u p p o r t a b l e ; f o r p t a r m i g a n i t is c l e a r l y b a s e d on m i s t a k e n e t y m o l o g y ; and f o r debt ( a n d v a r i o u s o t h e r s ) , i t i s o n l y p a r t i a l l y t r u e , i n t h a t /b/ and / t / o c c u r r e d i n t h e L a t i n a n c e s t o r of debt ( d e b i t u m ) , b u t n o t a s a f i n a l c l u s t e r . A f u r t h e r c o m p l i c a t i o n is t h e d e v i a t i o n i n s e r i a l o r d e r of s e v e r a l s p e l l i n g s from t h e order of s o u n d s which t h e y represent. C h i e f among t h e s e i s %, a s p e l l i n g which a t l e a s t some E n g l i s h s p e a k e r s h a v e r e t a i n e d a s /hw/, and -& a s i n b o t t l e , e t c . , which s p e l l s ( i n d e l i b e r a t e s p e e c h ) /al/ (&and -1e - a r e s c r i b a l r e v e r s a l s o f e a r l i e r k- and B u t e v e n w i t h t h e s e d e v i a t i o n s from e x p e c t e d p r a c t i c e , most E n g l i s h s o u n d s a r e r e p r e s e n t e d i n a m o d e r a t e l y r a t i o n a l f a s h i o n i n t h e o r t h o g r a p h y (Venezky, 1 9 7 0 ) . However, s i n c e E n g l i s h p o s s e s s e s more t h a n one p o t e n t i a l s p e l l i n g f o r a l m o s t e v e r y s o u n d , a s e c o n d s e t of c o n s t r a i n t s , h e r e c a l l e d s c r i b a l c o n s t r a i n t s , e n t e r i n t o rule-governed orthographic s t r u c t u r e .
-e).
Scribal Constraints To e x p l a i n t h e r u d i m e n t s of t h e s e c o n s t r a i n t s , some new terminology is h e l p f u l . Vowel s p e l l i n g s a r e c l a s s e d a s p r i m a r y ( 2 , g, i f 0 , g, y ) o r s e c o n d a r y (&, 3 , ", ", e t c . ) . Consonant s p e l l i n g s a r e e i t h e r f u n c t i o n a l l y s i m p l e (b, c, c h , d , e t c . ) o r f u n c t i o n a l l y compound (11, 3, and 3). Graphemic c o n s t r a i n t s r e g u l a t e p r i m a r i l y t h e d i s t r i b u t i o n (1) g e m i n a t e d (double) letters, (2) and (3) of y-1. F i r s t , u n l i k e S p a n i s h , E n g l i s h r e s i s t s d o u b l e d l e t t e r s i n word-initial p o s i t i o n , e s p e c i a l l y c o n s o n a n t s . Only a h a n d f u l o f e x c e p t i o n s t o t h i s e x i s t s , p r i m a r i l y i n v o l v i n g t h e form 00 (e.g., oodles, ooze). I n other p o s i t i o n s only 15 l e t t e r s can d o u b l e : t h o s e t h a t d o n ' t ( o r r a r e l y d o ) a r e 2 , h, A, i, &, g , 2 , y, 5 , y. B u t t h e r e a r e f u r t h e r r e s t r i c t i o n s . With few e x c e p t i o n s , doubled c o n s o n a n t s do n o t occur a f t e r secondary v o w e l s , and i n f i n a l p o s i t i o n o n l y ff, 11, and a r e common. F i n a l l y , t h e digraph u n i t s a r e n o t allowed t o double. For o n e , c h , a p s e u d o g e m i n a t e (3) was a d o p t e d i n e a r l y modern E n g l i s h , a t a b o u t t h e same t i m e t h a t 3 was a d o p t e d t o r e p r e s e n t d o u b l e d 9 when i t r e p r e s e n t e d / j / . S i m i l a r l y , & was i n v e n t e d f o r d o u b l e k which now o c c u r s o n l y i n i n f l e c t e d f o r m s o f trek (e.g. , t r e k k i n g ) . A s e c o n d s e t of graphemic c o n s t r a i n t s r e g u l a t e t h e d i s t r i b u t i o n of 2-y-w and 4-y. From t h e Middle E n g l i s h p e r i o d
=, *, u-v-w,
w,
32
CHAPTER 3
v
up t o a b o u t t h e m i d d l e of t h e 1 7 t h c e n t u r y , y and were used i n d i s c r i m i n a t e l y t o r e p r e s e n t / u / and / v / , a l t h o u g h v t e n d e d t o (According t o P y l e s ( 1 9 6 4 ) , be used i n i t i a l l y and 3 e l s e w h e r e . v was a l s o p r e f e r r e d i n t h e v i c i n i t y o f m and n). D i g r a p h s like O ,J when w r i t t e n b e f o r e a vowel m i g h t be m i s t a k e n f o r 3 ; therefore ; was d o u b l e d , and e v e n t u a l l y w r i t t e n y. I n time, 2 i n f i n a l p o s i t i o n a s t h e second p a r t o f a s e c o n d a r y vowel s p e l l i n g was r e p l a c e d by y, g i v i n g t h e p r e s e n t - d a y a l t e r n a t i o n s au/aw, - eu/ew, and ou/ow. I n g e n e r a l , t h e variant occurs b e f o r e v o w e l s and i n f i n a l p o s i t i o n ; t h e 3 v a r i a n t o c c u r s e l s e w h e r e . Where 2 would o c c u r a s a p r i m a r y vowel s p e l l i n g i n f i n a l p o s i t i o n , a f i n a l e i s added ( e . g . , blue). For r e a s o n s n o t a l t o g e t h e r c l e a r , b u t r e l a t e d t o t h e a m b i g u i t y of 3-v s p e l l i n g s , y was a l s o e x o r c i s e d from f i n a l position. B u t s i n c e no s i m p l e r e p l a c e m e n t was a v a i l a b l e a s was f o r 2 , a n e was added a f t e r t h e l e t t e r , t h u s g i v i n g p r e s e n t - d a y s p e l l i n g s l i k e d o v e , l o v e , and have, where t h e f i n a l e d o e s n o t mark a f r e e ( l o n g ) vowel p r o n u n c i a t i o n . S i m i l a r l y , I-y now a l t e r n a t e e x a c t l y a s y and )1! d o , a s second e l e m e n t s of a d i g r a p h v o w e l , t h u s , maid/may, oil/boy, and either/-. T h r e e a d d i t i o n a l f e a t u r e s of E n g l i s h s p e l l i n g which have l i m i t e d u t i l i t y i n s o u n d - t o - s p e l l i n g r u l e s , b u t which a r e i m p o r t a n t f o r t h e r e c o g n i t i o n of r e a l w o r d s , a r e d i s c u s s e d b r i e f l y i n t h e following s e c t i o n .
w
Morphemic F e a t u r e s Morpheme I d e n t i t y . The r e t e n t i o n o f morphemic i d e n t i t y a s i n p a i r s l i k e cone/conic is a n a t u r a l consequence of c o n d i t i o n e d sound c h a n g e unaccompanied by a c o r r e s p o n d i n g s p e l l i n g c h a n g e and n o t t h e r e s u l t o f o v e r t s c r i b a l i n t e n t i o n . For t h e most p a r t , however, r e t e n t i o n o f morphemic i d e n t i t y is l i m i t e d t o vowels and t h o s e c o n s o n a n t l e t t e r s which a r e s i l e n t i n one form b u t pronounced i n a r e l a t e d o n e . In the f i r s t category a r e alternations of the form s a n e / s a n i t y and telegraph/telegraphy; in the latter are p a i r s akin t o sign/signal, bomb/bombard, and hymn/hymnal. Where no s i n g l e s p e l l i n g can s t a n d f o r a p a i r of sounds, c o n s i s t e n t s p e l l i n g of a l l o m o r p h s which d i f f e r by t h o s e s o u n d s is n o t p o s s i b l e . Thus, c o l l i d e / c o l l i s i o n m u s t u t i l i z e d i f f e r e n t s p e l l i n g s f o r /d/ and
/:/. I n bound morphemes, s i m i l a r p r o c e s s e s c a n be s e e n e x e m p l i f i e d by t h e noun p l u r a l ( a n d t h i r d - p e r s o n s i n g u l a r ) and t h e p a s t t e n s e m a r k e r , -3.
as
-2
ORTHOGRAPHIC STRUCTURE
33
P a r t l y by a c c i d e n t an d p a r t l y S e p a r a t i o n of homophones. by o v e r t attention, English spelling has tended to d i f f e r e n t i a t e homophones w h e r e v e r o r t h o g r a p h i c l i c e n s e w o u l d belong allow. P a i r s l i k e s e a / s e e , b l u e / b l e w , an d r i g h t / w r i t e t o t h e accident category, b u t foul/fowl, plain/plane, and s u n / son r e s u l t from o v e r t s c r i b a l p r a c t i c e (Vachek, 1959, 1973; on t h e o r t h o g r a p h i c d i s t i n c t i v e n e s s o f homophones, see O l s o n & Kausler, 1971). The t w o - l e t t e r word b a n . S i n c e a t l e a s t t h e time o f Noah W e b s t e r an d p r o b a b l y b e f o r e , English l e x i c o g r a p h e r s have a v o i d e d e x t e n d i n g t h e r e p e r t o i r e o f t w o - l e t t e r w o r d s b ey o n d a small g r o u p o f f u n c t i o n w o r d s ( e . g . , &, of, if). Two m ech an i s m s w e r e a d o p t e d f o r l e n g t h e n i n g t w o - l e t t e r w o r d s w h i c h d i d n ' t q u a l i f y f o r inclusion in t h i s group: doubling t h e f i n a l and or adding a f i n a l c o n s o n a n t , a s i n ebb, add, odd, -e , ( e . g . , doe, hoe, &, a n d * ) . The f o r m e r m ech an i sm h a s c r e a t e d u n i q u e f i n a l c o n s o n a n t c l u s t e r s i n t h a t b, fi, 9, a n d 1 d o n o t d o u b l e i n f i n a l p o s i t i o n i n any o t h e r E n g l i s h words. These graphemic c o n s t r a i n t s have evolved independently o f sound, f o r u n l i k e t h e o r t h o g r a p h i e s of o t h e r major languages, modern E n g l i s h s p e l l i n g p r e s e r v e s c l e a r e v i d e n c e o f n e a r l y 1,300 y e a r s of sound change, s c r i b a l tampering, partial r e f o r m s , and f o r e i g n i n t r u s i o n s . There is a n u n d e r l y i n g p a t t e r n t o t h i s o r t h o g r a p h y , a s d e s c r i b e d i n V en ezk y ( 1 9 7 0 ) , b u t t h e r e is a l s o a s u b s t a n t i a l m a r g i n a l mess w h i c h c a n o n l y i n p a r t b e o r g a n i z e d i n t o s u b p a t t e r n s o r j u s t i f i e d by a p p e a l t o s u c h p r i n c i p l e s a s t h e o r t h o g r a p h i c s e p a r a t i o n o f homophones (e.g., bell/belle). Nevertheless, permeating the entire s p e l l i n g s y s t e m f r o m o r g a n i z e d c o r e t o t h e most d i s j o i n t o u t e r f r i n g e s i s a n i n t e r a c t i o n b e t w e e n p h o n o l o g i c a l an d v i s u a l f o r c e s which r a n g e s from p r o d u c t i v e c o u n t e r p o i n t a s i n s u c h s p e l l i n g s a s c o n e / c o n i c t o t h e d i s s o n a n c e o f s u c h mots n o i r s a s women. S i n c e n o E n g l i s h l a n g u a g e academy e v e r imposed a g r a n d d e s i g n on E n g l i s h s p e l l i n g , what g e n e r a l p r i n c i p l e s t h e r e a r e r e s u l t e d from t h e c o n f l u e n c e o f v a r i o u s s c r i b a l t r a d i t i o n s w i t h t h e p e r i o d i c r a v a g e s o f s o u n d c h a n g e u nacco m p an i ed b y s p e l l i n g Y e t a p r i n c i p l e of s o r t s d o e s emerge from t h e c u r r e n t change. system, v i z . , "Accede t o a l l v i s u a l i n t e r e s t s up t o , b u t n o t beyond, t h e p o i n t where p a s s a g e from s p e l l i n g t o sound is impaired."
on,
a,
34
CHAPTER 3
P s y c h o l o g i c a l Assumptions Rule-governed descriptions of orthographic s t r u c t u r e d i f f e r from o t h e r d e f i n i t i o n s o f o r t h o g r a p h i c s t r u c t u r e i n two aspects: First, i n t h e u t i l i z a t i o n of word t y p e s r a t h e r t h a n word t o k e n s , and s e c o n d , i n c l a s s i f y i n g a s r e g u l a r c e r t a i n s p e l l i n g s which d o n o t o c c u r ( y e t ) i n E n g l i s h words and c l a s s i f y i n g a s i r r e g u l a r some t h a t d o . The f i r s t d i f f e r e n c e is n o t e s s e n t i a l t o t h e d e f i n i t i o n of o r t h o g r a p h i c s t r u c t u r e , b u t i t is probably more a reflection of the differing e p i s t e m o l o g i e s of l i n g u i s t s and p s y c h o l o g i s t s . The s e c o n d d i f f e r e n c e , however, i s c e n t r a l t o t h e c o n c e p t o f o r t h o g r a p h i c s t r u c t u r e and r e q u i r e s f u r t h e r e x p l i c a t i o n . The p r i m a r y a s s u m p t i o n b e h i n d t h e o r t h o g r a p h i c r u l e s p r e s e n t e d h e r e i s t h a t r e a d e r s a b s t r a c t from t h e i r e x p e r i e n c e s w i t h p r i n t e d words t h o s e s p e l l i n g s t h a t a r e p r o d u c t i v e i n present-day E n g l i s h and u s e t h e s e t o f a c i l i t a t e r e c o g n i t i o n . For e x a m p l e , s i l e n t i n i t i a l letters, regardless of t h e f r e q u e n c y o f o c c u r r e n c e o f t h e words i n which t h e y o c c u r , a r e c l a s s i f i e d a s i r r e g u l a r s i n c e i t is u n l i k e l y t h a t new words b r o u g h t i n t o t h e E n g l i s h l a n g u a g e would e v e r be s p e l l e d w i t h them. ( S p e l l i n g a n a l o g i e s might p r e s e n t an e x c e p t i o n t o t h i s a s s u m p t i o n and c a n n o t b e i g n o r e d . However, i t i s u n l i k e l y t h a t s i l e n t i n i t i a l s p e l l i n g s would e v e r be w i d e l y e x t e n d e d . ) and On t h e o t h e r h a n d , t h e i n i t i a l s e q u e n c e s E-and t h e f i n a l s e q u e n c e s -eng, -&, and -ofe d o n o t o c c u r i n t h e f i r s t 2 0 , 0 0 0 words i n t h e T h o r n d i k e and Lorge ( 1 9 4 4 ) l i s t , y e t t h e y a r e c l a s s i f i e d as o r t h o g r a p h i c a l l y r e g u l a r s i n c e t h e y d o n o t v i o l a t e any phonological or scribal pattern. Thus pseudowords l i k e 9, woach, t r e n g , d e r l , and s t r o f e a r e p r o n o u n c e a b l e and s t r u c t u r a l l y r e g u l a r , even though t h e y c o n t a i n t r i g r a m s t h a t d o n o t o c c u r i n E n g l i s h words. The p e r c e p t u a l r e c o g n i t i o n of such s t r i n g s r e l a t i v e t o s i m i l a r pseudowords w i t h h i g h e r summed t r i g r a m c o u n t s i s a n i s s u e t h a t r e m a i n s t o be i n v e s t i g a t e d .
e-
Dichotomy I s s u e Another issue which merits empirical investigation c o n c e r n s t h e assumed d i c h o t o m o u s d e t e r m i n a n t s of o r t h o g r a p h i c r e g u l a r i t y . Given the two different constraints on orthographic s t r u c t u r e discussed above, w e should q u e s t i o n whether o r n o t t h e s c r i b a l and p h o n o l o g i c a l e l e m e n t s a r e Are, f o r e x a m p l e , i r r e g u l a r s t r i n g s separated psychologically. like and c k l i b p r o c e s s e d d i f f e r e n t l y from a n i l l e g a l
ORTHOGRAPHIC STRUCTURE
35
s t r i n g l i k e t p r i f ? A l l a r e i l l e g a l and n o n - o c c u r r i n g , y e t t h e y d i f f e r i n type of illegality. Tprif contains an i n i t i a l c o n s o n a n t c l u s t e r t h a t is p h o n o l o g i c a l l y i l l e g a l and t h e r e f o r e scribally non-occurring. and cklib are both phonologically acceptable, but c o n t a i n s c r i b a l l y outlawed features, viz., final in and i n i t i a l & i n c k l i b . For example, d o e s t h e p r o b a b i l i t y of c o r r e c t l y i d e n t i f y i n g a t a r g e t l e t t e r depend upon w h e t h e r i t is i n a p h o n o l o g i c a l l y - i l l e g a l or a scribally-illegal t e s t string?
AN I N I T I A L ALGORITHM FOR RULE-GOVERNED
REGULARITY
The a p p r o a c h t h a t we p r o p o s e , b u t h a v e n o t y e t f u l l y the disparate patterns j u s t d e v e l o p e d , for r e p r e s e n t i n g d e s c r i b e d i s t o c o n s t r u c t a s e t o f g e n e r a t i v e r u l e s which b e g i n by s e l e c t i n g a c o n s o n a n t - v o w e l - c o n s o n a n t structure for a p h o n o l o g i c a l word. Replacement r u l e s a r e a p p l i e d t o expand l e f t t o r i g h t o f e a c h vowel and e a c h c o n s o n a n t u n i t u n t i l a p h o n o l o g i c a l l y l e g a l s t r i n g r e s u l t s . A s e c o n d s e t of r u l e s then a p p l i e s sound-to-spelling rules t o generate a l e g a l pseudoword (or w o r d ) . By r e l a x i n g r u l e s a t v a r i o u s l e v e l s o f generation, we can then generate l e t t e r s t r i n g s with c o n t r o l l e d i r r e g u l a r i t i e s . For e x a m p l e , by removing t h e p l a c e r e s t r i c t i o n on f i n a l c l u s t e r s o f t h e form NASAL + STOP, w e g e n e r a t e u n p r o n o u n c e a b l e f i n a l c l u s t e r s l i k e -9 and -g. On t h e o t h e r h a n d , a l l o w i n g f i n a l /v/ t o be r e p r e s e n t e d by 1 r a t h e r t h a n a l l o w s s c r i b a l l y i l l e g a l f o r m s l i k e mov and s l a i v . So f a r , a p r e l i m i n a r y s e t of r u l e s f o r g e n e r a t i n g l e g a l m o n o sy lla b le s h a s been d e v e l o p e d , d r a w i n g o n a v a r i e t y o f s o u r c e s ( e . g . , Whorf, 1970). A 1 9 5 6 ; K u r a t h , 1 9 6 4 ; Chomsky & H a l l e , 1 9 6 8 ; Venezky, s a m p l e d e r i v a t i o n o f a l e g a l pseudoword from t h e s e r u l e s i s shown i n T a b l e 3 . 1 . I n summary, w e h a v e p r e s e n t e d two g e n e r a l a p p r o a c h e s t o d e s c r i b i n g o r t h o g r a p h i c s t r u c t u r e : s t a t i s t i c a l r e d u n d a n c y and For t h e f o r m e r , c l a s s m e t r i c s a r e rule-governed regularity. d e r i v e d from f u n c t i o n s o n t h e f r e q u e n c i e s w i t h which v a r i o u s s i z e u n i t s o c c u r ( e . g . , summed b i g r a m c o u n t s ) . For t h e l a t t e r c l a s s we h a v e s u g g e s t e d t h a t a c o m p a r a b l e m e t r i c m i g h t b e d e v e l o p e d t h r o u g h a s e t o f g e n e r a t i v e r u l e s which c o u l d b e v i o l a t e d a t v a r i o u s l e v e l s t o p r o d u c e nonwords w i t h c o n t r o l l e d d e v i a t i o n s from r u l e - g o v e r n e d r e g u l a r i t y .
36
CHAPTER 3
Table 3.1 A.
Apply Base Generation Rules
Step
Rule -
Result
Initialize
1
w ----->
2
3 4
5 6 7 8
9 10
11 12 13 B.
Derivation of a legal pseudoword (a).
#W# # c+v+c# #CC+V+C# # SCL+V+C# #g+NASAL+V+C# #s+"+V+C # #S+"+Vf+C# #s+E+vfr+C# tg+n+i+c# #s+E+i+CS# #s+g+i+STOPg# #s+g+i-+STOPvg#
cvc
C/# -------> cc CC/# -------> SCL SCL ------ > s+NASAL 11. NASAL -----> V/else -----> Vf vfr Vf/else ----> 4 Vfr -----> C/-# ----- > cs CS/Vf-# ---- > STOPg STOPg ----- > STOPVg STOPvg -----> b
#S+"+i+b#
Apply Base-to-Spelling Rules
Step.
14 15 16 17
Rule s/else
n ----> -i/-Cs#
Result
---->
----> ------------b -
<s>
#<El>*#
<e...e#>
# < sn>i&# #<sne>b<e># # < snebe>#
---- >
(a)Terminal phonological symbols are underlined; terminal spelling symbols occur in wedges, e.g., . A rule of the form x/# ------- > Y is read "Rewrite X as Y when X occurs after juncture ( I ) .'I
4
Experimental Studies
The r e s e a r c h r e p o r t e d i n t h i s book e v o l v e d from a commonality o f i n t e r e s t s among t h e a u t h o r s . These i n t e r e s t s p r i m a r i l y c e n t e r e d around f u r t h e r i n g t h e u n d e r s t a n d i n g o f t h e perceptual processes involved in word r e c o g n i t i o n and especially delineating the r o l e t h a t orthographic s t r u c t u r e plays in these processes. An e x t e n s i o n of a n i n t e r e s t i n g s t u d y by Mason ( 1 9 7 5 ) a p p e a r e d t o be a p r o d u c t i v e way t o a t t a c k t h e p r o b l e m s o f o r t h o g r a p h i c s t r u c t u r e and p e r c e p t u a l r e c o g n i t i o n of words. Mason evaluated the c o n t r i b u t i o n o f summed single-letter p o s i t i o n a l frequency i n a t a r g e t search task. Good and p o o r r e a d e r s i n d i c a t e d w h e t h e r o r n o t a s i x - l e t t e r s t r i n g c o n t a i n e d a p r e d e t e r m i n e d t a r g e t l e t t e r . Good r e a d e r s a v e r a g e d 6 3 msec f a s t e r f o r s t r i n g s h i g h t h a n f o r s t r i n g s low We w e r e c o n c e r n e d w i t h two p r i m a r y i n p o s i t i o n a l frequency. i s s u e s w i t h r e s p e c t t o Mason's r e s u l t s . F i r s t , w e q u e s t i o n e d w h e t h e r a f r e q u e n c y m e a s u r e of o r t h o g r a p h i c s t r u c t u r e was s u f f i c i e n t t o d e s c r i b e t h e f a c i l i t a t i n g e f f e c t s of s t r u c t u r e on perceptual recognition. As discussed in Chapter 3 , a rule-governed d e s c r i p t i o n o f o r t h o g r a p h i c s t r u c t u r e may b e a more a p p r o p r i a t e r e p r e s e n t a t i o n o f t h e r e a d e r ' s knowledge. S e c o n d , Mason's r e s u l t s a p p e a r e d t o be h i g h l y v a r i a b l e and we q u e s t i o n e d whether t h e t a r g e t s e a r c h t a s k u s i n g r e a c t i o n time a s a d e p e n d e n t measure reveals l a r g e e f f e c t s of orthographic structure. T h e r e were a number of r e a s o n s t o suspect the robustness of the effect in Mason's s t u d y . S u b j e c t s had o n l y 5 p r a c t i c e t r i a l s and j u s t 7 2 experimental t r i a l s . Each s u b j e c t was t e s t e d on 2 4 w o r d s , 24 s t r i n g s h i g h i n p o s i t i o n a l f r e q u e n c y , and 2 4 s t r i n g s low i n p o s i t i o n a l f r e q u e n c y . Given 1 2 good r e a d e r s , t h e r e were 288 o b s e r v a t i o n s minus e r r o r s c o n t r i b u t i n g t o e a c h e x p e r i m e n t a l
38
CHAPTER 4
c o n d i t i o n . Mason found t h a t 1 0 0 p r a c t i c e t r i a l s i n a f o l l o w u p e x p e r i m e n t r e d u ced t h e a d v a n t a g e of p e r f o r m a n c e on s t r i n g s h i g h i n summed p o s i t i o n a l f r e q u e n c y t o a n a v e r a g e of a b o u t 2 2 msec. S i n c e p r a c t i c e t r i a l s r e d u c e d t h e a d v a n t a g e by a b o u t t w o - t h i r d s we f e l t t h a t a r e p l i c a t i o n o f Mason's s t u d y w i t h improved methodology was n e c e s s a r y t o d e t e r m i n e t h e r e l i a b i l i t y of h e r results.
MASSARO ET AL. 1979 STUDIES M a s s a r o , Venezky, and T a y l o r ( 1 9 79) r e p l i c a t e d Mason's experiment using t h e t a r g e t search t a s k with sixth-grade subjects. To o b t a i n g r e a t e r r e l i a b i l i t y , b o t h t h e number of o b s e r v a t i o n s and t h e number of t e s t s t i m u l i were i n c r e a s e d . F u r t h e r m o r e , t h e l e t t e r s t r i n g s were n o t o n l y h i g h and low i n p o s i t i o n a l f r e q u e n c y b u t a l s o were c o n t r a s t e d a l o n g a n o t h e r d i m e n si o n which we c a l l e d o r t h o g r a p h i c r e g u l a r i t y . We had n o t y e t d e v e l o p e d a s y s t e m a t i c r u l e - b a s e d d e s c r i p t i o n of E n g l i s h o r t h o g r a p h y , b u t we wer e a b l e t o c h o o s e s t r i n g s t h a t a p p e a r e d t o be r e g u l a r o r i r r e g u l a r . T h e r e f o r e , a l t h o u g h we had no s y s t e m a t i c d e s c r i p t i o n of r e g u l a r i t y , we f e l t that the d e c i s i o n s we made t o c h o o s e s t r i n g s t h a t were r e g u l a r and i r r e g u l a r would p r o v i d e a t e s t of wh ethe r t h e f a c i l i t a t i n g e f f e c t s o f o r t h o g r a p h i c s t r u c t u r e c o u l d be c o m p l e t e l y a c c o u n t e d f o r by t h e p o s i t i o n a l f r e q u e n c y h y p o t h e s i s propose d by Mason. To c r e a t e t h e t e s t s t i m u l i , Massaro e t a l . (1979) s e l e c t e d f o u r anagrams from e a c h o f 40 s i x - l e t t e r words s u c h t h a t t h e anagrams were e i t h e r h i g h or low i n s i n g l e - l e t t e r positional f r e q u e n c y and e i t h e r r e g u l a r or i r r e g u l a r . The r e s u l t i n g 2 x 2 f a c t o r i a l design provides a direct assessment of t h e c o n t r i b u t i o n s o f f r e q u e n c y and r e g u l a r i t y on l e t t e r - s t r i n g perception. Each o f t h e s i x t h g r a d e r s be ga n by t a k i n g a w r i t t e n c o m p reh en s i o n t e s t . The t a r g e t s e a r c h t a s k was t h e n i n t r o d u c e d by showing t h e s u b j e c t s t h e v i s u a l d i s p l a y and t h e r e s p o n s e p a n e l . To a c q u a i n t t h e s u b j e c t s w i t h t h e r e s p o n s e p r o c e d u r e , t h e y were f i r s t 'given 50 t r i a l s o f r e s p o n d i n g " y e s " and "no" t o t h e words YES and NO p r e s e n t e d on t h e v i s u a l display. Each s u b j e c t pushed t h e " y e s " b u t t o n w i t h h i s o r h e r p r e f e r r e d hand. Nex t , t h e s u b j e c t s r e c e i v e d 50 p r a c t i c e t r i a l s w i t h random l e t t e r s t r i n g s . The s u b j e c t s were a s k e d t o i n d i c a t e w h e t h er o r n o t a t a r g e t l e t t e r was p r e s e n t i n t h e s i x - l e t t e r s t r i n g . Each t r i a l began w i t h t h e p r e s e n t a t i o n of t h e t a r g e t l e t t e r f o l l o w e d 800 msec l a t e r by t h e t e s t l e t t e r string. The t e s t l e t t e r s t r i n g remained on u n t i l t h e s u b j e c t
EXPERIMENTS ON LETTER AND WORD PERCEPTION
39
responded. S u b j e c t s were i n s t r u c t e d t o respond " y e s " i f t h e t a r g e t l e t t e r a p p e a r e d a t l e a s t o n c e i n t h e l e t t e r s t r i n g and "no" i f i t d i d n o t a p p e a r . The t a r g e t l e t t e r a p p e a r e d i n t h e l e t t e r s t r i n g on h a l f o f t h e t r i a l s ( t a r g e t t r i a l s ) and d i d n o t a p p e a r on t h e o t h e r h a l f ( c a t c h t r i a l s ) . They were t o l d t o The s u b j e c t s were t e s t e d on respond as a c c u r a t e l y a s p o s s i b l e . e a c h o f t h e u n i q u e 1 6 0 s t i m u l i , o n c e on t a r g e t t r i a l s and o n c e on c a t c h t r i a l s , g i v i n g r o u g h l y 8 0 o b s e r v a t i o n s p e r s u b j e c t a t each of t h e four experimental c o n d i t i o n s ( l e s s e r r o r t r i a l s ) . F i g u r e 4 . 1 g i v e s t h e r e s u l t s from t h i s i n i t i a l e x p e r i m e n t . Although t h e r e a c t i o n times were a b o u t 1 2 msec f a s t e r f o r
R-L
Figure 4.1
I-H
R e a c t i o n t i m e and p e r c e n t a g e c o r r e c t f o r s i x t h g r a d e r s a s a f u n c t i o n of o r t h o g r a p h i c r e g u l a r i t y and summed s i n g l e - l e t t e r p o s i t i o n a l f r e q u e n c y f o r t a r g e t and c a t c h t r i a l s ( f r o m Massaro e t a l . , 1 9 7 9 ) (key: p = orthographically regular: I = orthographically irregular; ; = h i g h summed single-letter p o s i t i o n a l f r e q u e n c y ; & = low summed single-letter positional frequency).
CHAPTER 4
r e g u l a r t h a n f o r i r r e g u l a r s t r i n g s and a b o u t 1 2 msec f a s t e r f o r h i g h t h a n f o r low p o s i t i o n a l f r e q u e n c y , n e i t h e r r e s u l t was statistically significant. These r e s u l t s imply t h a t n e i t h e r p o s i t i o n a l frequency nor r e g u l a r i t y c o n t r i b u t e s i g n i f i c a n t l y t o p e r c e p t u a l r e c o g n i t i o n i n t h e t a r g e t s e a r c h t a s k . One r e a s o n c o u l d be t h a t our m a n i p u l a t i o n o f p o s i t i o n a l f r e q u e n c y and r e g u l a r i t y d i d n o t c a p t u r e t h e knowledge t h a t s u b j e c t s u t i l i z e i n p e r c e p t u a l r e c o g n i t i o n . A second p o s s i b i l i t y i s t h a t o u r manipulation of o r t h o g r a p h i c s t r u c t u r e d i d m i r r o r d i f f e r e n c e s i n t h e p s y c h o l o g i c a l r e a l i t y of t h e s e s t r u c t u r e s b u t t h a t t h e t a r g e t s e a r c h t a s k u s i n g r e a c t i o n times is i n s e n s i t i v e t o u t i l i z a t i o n of s t r u c t u r e . We s u s p e c t e d t h a t t h e small effects in the f i r s t e x p e r i m e n t were p r i m a r i l y due t o t h e t a r g e t s e a r c h t a s k r a t h e r t h a n t o t h e s t r i n g s u t i l i z e d i n t h e e x p e r i m e n t s . T h e r e f o r e , we c a r r i e d o u t two more e x p e r i m e n t s t o c o n t r a s t t h e t a r g e t s e a r c h t a s k u t i l i z i n g r e a c t i o n time ( R T ) a s a d e p e n d e n t measure w i t h a We t a r g e t s e a r c h t a s k u s i n g a c c u r a c y as a d e p e n d e n t measure. employed c o l l e g e s t u d e n t s r a t h e r t h a n s i x t h g r a d e r s a s s u b j e c t s s i n c e t h e y were more r e a d i l y a v a i l a b l e f o r t e s t i n g . One e x p e r i m e n t was a r e p l i c a t i o n o f our RT e x p e r i m e n t . The o t h e r , a n a c c u r a c y e x p e r i m e n t , involved a s l i g h t m o d i f i c a t i o n of a more common p a r a d i g m used to s t u d y t h e u t i l i z a t i o n of orthographic structure. In variants o f a Reicher-Wheeler p o s t c u e t a s k ( s e e C h a p t e r l ) , t h e s u b j e c t i s shown a word o r a nonword f o r a brief duration followed by a masking s t i m u l u s . Two a l t e r n a t i v e l e t t e r s a r e t h e n g i v e n and t h e s u b j e c t c h o o s e s which l e t t e r h e or s h e t h i n k s was p r e s e n t e d on that trial. I n o r d e r t o make t h i s a c c u r a c y t a s k c o m p a r a b l e t o t h e RT t a s k , we m o d i f i e d i t by p r e s e n t i n g j u s t one a l t e r n a t i v e l e t t e r a f t e r t h e masking s t i m u l u s . I n t h i s case t h e s i x - l e t t e r i t e m would b e p r e s e n t e d f o l l o w e d by a masking s t i m u l u s and t h e n t h e t a r g e t l e t t e r . The t a r g e t l e t t e r would b e p r e s e n t i n t h e t e s t item o n h a l f o f t h e t r i a l s and n o t p r e s e n t o n t h e o t h e r h a l f . The s u b j e c t s would s i m p l y i n d i c a t e w h e t h e r o r n o t t h e t a r g e t l e t t e r occurred i n t h e t e s t l e t t e r s t r i n g . Performance, i n t e r m s of r e a c t i o n time iri t h e f i r s t e x p e r i m e n t and o v e r a l l a c c u r a c y i n t h e second e x p e r i m e n t , r e f l e c t s how well t h e t e s t s t r i n g s were p e r c e i v e d . The r e s u l t s o f t h e s e two e x p e r i m e n t s a r e shown i n F i g u r e s 4.2 and 4 . 3 . I n t h e r e a c t i o n time t a s k , r e a c t i o n times averaged 16 msec faster for high than for low positional-frequency strings. R e s p o n s e s were 9 msec f a s t e r f o r r e g u l a r t h a n f o r i r r e g u l a r s t r i n g s . The a c c u r a c y t a s k showed t h a t r e s p o n s e a c c u r a c y was 5 % h i g h e r f o r r e g u l a r t h a n f o r
EXPERIMENTS ON LETTER AND WORD PERCEPTION
41
i r r e g u l a r s t r i n g s and 4 % h i g h e r f o r h i g h t h a n f o r low positional-frequency strings. A l l of these r e s u l t s were statistically significant. Therefore, although t h e magnitude o f t h e e f f e c t s on r e a c t i o n time f o r t h e a d u l t s was o f t h e same o r d e r of magnitude a s t h a t f o r t h e s i x t h g r a d e r s , lower v a r i a n c e among t h e a d u l t s made t h e e f f e c t s s t a t i s t i c a l l y significant. One l i m i t a t i o n a t t h i s s t a g e of t h e r e s e a r c h was t o know w h e t h e r o r n o t s i x t h g r a d e r s would g i v e s t a t i s t i c a l l y s i g n i f i c a n t accuracy r e s u l t s i n t h e accuracy task. However, s i n c e t h i s l a t t e r ' i n f o r m a t i o n was n o t a v a i l a b l e , w e were f a c e d w i t h t h e p r o b l e m of comparing t h e m a g n i t u d e of t h e r e a c t i o n t i m e r e s u l t w i t h t h e m a g n i t u d e of t h e a c c u r a c y r e s u l t and r e a l i z e d t h a t i t r e s e m b l e d t h a t o f comparing a p p l e s and o l i v e s . If it is accepted t h a t t h e r e a c t i o n t i m e r e s u l t is small,
750
-I
I
I
I
I
700
v)
Y
5F 2
650
600
%
550
Target
0 Catch
k
yK K
0 0
n Figure 4 . 2
100
90
nnnn R-H
R-L
I-H
I-L
R e a c t i o n time and p e r c e n t a g e c o r r e c t f o r c o l l e g e s t u d e n t s a s a f u n c t i o n of o r t h o g r a p h i c r e g u l a r i t y and summed s i n g l e - l e t t e r p o s i t i o n a l f r e q u e n c y f o r t a r g e t and c a t c h t r i a l s ( f r o m Massaro e t a l . , 1979).
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42
t h e n o n e e x p l a n a t i o n f o r t h e small e f f e c t c o u l d t a k e t h e f o l l o w i n g form. I n t h e r e a c t i o n . t i m e t a s k t h e s u b j e c t was g i v e n t h e t a r g e t l e t t e r b e f o r e t h e t e s t s t r i n g was p r e s e n t e d . S i n c e t h e s u b j e c t s i m p l y was r e q u i r e d t o i n d i c a t e w he the r or n o t t h e t a r g e t was c o n t a i n e d i n t h e t e s t s t r i n g , h e or s h e may n o t h a v e had t o r e s o l v e c o m p l e t e l y a l l o f t h e l e t t e r s i n t h e s t r i n g b e f o r e a c o r r e c t d e c i s i o n was made. For e xa m ple , s u p p o se a s u b j e c t i s l o o k i n g f o r t h e t a r g e t l e t t e r i n the l e t t e r s t r i n g s c o s e , deom, and 9 r e s p e c t i v e l y . I n a l l cases t h e a p p r o p r i a t e r e s p o n s e is n o , b u t t h e s u b j e c t may be a b l e t o d e c i d e on t h i s f a s t e r w i t h some o f t h e s t r i n g s t h a n w i t h o t h e r s . Consider t h e following ar g um e nt. The re i s some e v i d e n c e t h a t o v e r a l l l e t t e r s h a p e c a n be r e s o l v e d and made a v a i l a b l e t o l a t e r s t a g e s of p r o c e s s i n g b e f o r e t h e l e t t e r is
'oo!7--90
c---oCatch
-
50
RH
Figure 4.3
R-L
I-H
I-L
Percentage c o r r e c t f o r c o l l e g e s t u d e n t s as a f u n c t i o n of o r t h o g r a p h i c r e g u l a r i t y and summed s i n g l e - l e t t e r p o s i t i o n a l f r e q u e n c y f o r t a r g e t and c a t c h t r i a l s ( f r o m Massaro e t a l . , 1 9 7 9 ) .
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Table 4 . 1
43
The s i x s e t s of l e t t e r s b a s e d o n t h e s i m i l a r i t y r e s u l t s o f Bouma ( 1 9 7 1 ) used by Massaro e t a l . (1979).
1. 2. 3.
4. 5.
6.
it
A l t h o u g h Bouma's a n a l y s i s i n d i c a t e d t h a t t h e f i r s t s e t c o u l d b e f u r t h e r d i v i d e d i n t o two s e t s c o n s i s t i n g of m , n , u , and r , v , w , t h e s e two s e t s were combined b e c a u s e o f t h e i r r e l a t i v e s i m i l a r i t y and t o p r o v i d e more r e l i a b l e d a t a by i n c r e a s i n g t h e number of o b s e r v a t i o n s w i t h i n a s e t .
c o m p l e t e l y r e c o g n i z e d (Bouma, 1 9 7 1 ; Massaro & S c h m u l l e r , 1 9 7 5 ) . t a r g e t s e a r c h t a s k c a n be used t o s t u d y t h e f e a t u r e s necessary for recognition. N e i s s e r (1963, 1967) f o r example, showed t h a t s u b j e c t s s e a r c h e d f a s t e r f o r a n u p p e r c a s e 2 i n a l i s t o f c u r v e d l e t t e r s t h a n i n a l i s t of l i n e a r l e t t e r s . T h i s r e s u l t i n d i c a t e s t h a t t h e s u b j e c t s were a b l e t o r e j e c t t h e c u r v e d l e t t e r s a s f o i l s more q u i c k l y t h a n t h e l i n e a r l e t t e r s . Applying t h i s a n a l y s i s t o t h e p r e s e n t e x a m p l e , s l i b j e c t s s h o u l d be a b l e t o r e s p o n d "no" q u i c k l y t o t h e e x t e n t t h a t none of t h e l e t t e r s i n t h e t e s t s t r i n g h a s t h e same o v e r a l l a s c e n d e r s h a p e a s t h e t a r g e t l e t t e r b. T h e r e f o r e , i t w i l l t a k e t h e s u b j e c t l o n g e r t o r e j e c t t h e s t r i n g deih t h a n t o r e j e c t t h e s t r i n g deom. The s t r i n g should be r e j e c t e d f a s t e s t of a l l . To t h e e x t e n t t h e s u b j e c t is a b l e t o u t i l i z e t h i s f e a t u r e d e t e c t i o n s t r a t e g y l t h e c o n t r i b u t i o n of orthographic s t r u c t u r e m i g h t be a t t e n u a t e d . T h e r e f o r e , i t was o f i n t e r e s t t o s e e t h e e x t e n t t o which s u b j e c t s a p p e a r e d t o b e u s i n g t h i s s t r a t e g y i n A
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t h e r e a c t i o n time and a c c u r a c y t a s k s . We h y p o t h e s i z e d t h a t t h i s s t r a t e g y would b e u t i l i z e d i n t h e r e a c t i o n time b u t n o t the accuracy task. I n t h e accuracy t a s k , t h e s u b j e c t w i l l resolve the l e t t e r s t r i n g t o the deepest l e v e l possible. In t h e r e a c t i o n time t a s k , h a v i n g t h e t a r g e t s p e c i f i e d i n a d v a n c e and h a v i n g t h e t e s t l e t t e r s t r i n g v i s i b l e d u r i n g t h e p r o c e s s i n g i n t e r v a l w i l l a l l o w t h e s u b j e c t t o t e r m i n a t e e a r l y on some catch t r i a l s . To e v a l u a t e t h i s h y p o t h e s i s , t h e l o w e r c a s e l e t t e r s o f t h e a l p h a b e t were g r o u p e d i n t o s i x g r o u p s b a s e d o n t h e s i m i l a r i t y r e s u l t s o f Bouma ( 1 9 7 1 ) . T h i s g r o u p i n g i s g i v e n i n T a b l e 4.1. The r e l a t i o n s h i p between e a c h t a r g e t l e t t e r and t e s t s t r i n g was d e f i n e d i n t e r m s o f t h e number of n o n t a r g e t l e t t e r s i n t h e s t r i n g t h a t were members o f t h e same s e t a s t h e t a r g e t l e t t e r .
P
5501
,!
I 1
I
2
1
3
NUMBER OF SIMILAR NONTARGETS Figure 4.4
R e a c t i o n time i n t h e t a r g e t s e a r c h t a s k a s a f u n c t i o n o f t h e number of s i m i l a r n o n t a r g e t l e t t e r s i n t h e t e s t s t r i n g ( f r o m Massaro e t a l . , 1 9 7 9 ) .
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45
e x a m p l e , t h e t e s t s t r i n g l i s v e r would h a v e two l e t t e r s (1 from t h e same s e t a s t h e l e t t e r t , two and J L from same s e t a s and none from t h e same s e t a s 5. F i g u r e s 4.4 and 4.5 g i v e t h i s s i m i l a r i t y a n a l y s i s f o r r e a c t i o n time and accuracy tasks r e s p e c t i v e l y . The results show highly s i g n i f i c a n t e f f e c t s on c a t c h t r i a l s i n t h e r e a c t i o n time t a s k , s u p p o r t i n g t h e i d e a of a f e a t u r e d e t e c t i o n s t r a t e g y i n t h e r e a c t ion t i m e task. The number o f l e t t e r s i n t h e t e s t s t r i n g h a v i n g t h e same o v e r a l l s h a p e a s t h e t a r g e t s h o u l d n o t be i m p o r t a n t on t a r g e t t r i a l s i n t h e r e a c t i o n time t a s k s . The t a r g e t l e t t e r m u s t b e c o m p l e t e l y r e s o l v e d b e f o r e a " y e s " r e s p o n s e c a n be made. If t h e s u b j e c t s s i m p l y r e s p o n d e d " y e s " whenever t h e o v e r a l l s h a p e of t h e t a r g e t was p e r c e i v e d , r e c o g n i t i o n e r r o r s would be h i g h l y For and the
i-)
(v
u,
I
1
1
2
I
3
NUMBER OF SIMILAR NONTARGETS F i g u r e 4.5
Percentage c o r r e c t i n t h e t a r g e t search task a s a f u n c t i o n of t h e number of s i m i l a r n o n t a r g e t l e t t e r s i n t h e t e s t s t r i n g ( f r o m Massaro e t a l . , 1 9 7 9 ) .
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p r o b a b l e . S i n c e a h i g h a c c u r a c y c r i t e r i o n was e n f o r c e d , we would n o t e x p e c t t h e number o f s i m i l a r l y s h a p e d l e t t e r s t o be a c r i t i c a l v a r i a b l e on t a r g e t t r i a l s . A s c a n be s e e n i n F i g u r e 4.4, t h e s i m i l a r i t y v a r i a b l e had no s i g n i f i c a n t e f f e c t o n t a r g e t t r i a l s i n t h e r e a c t i o n time e x p e r i m e n t . I n t h e a c c u r a c y t a s k , p e r f o r m a n c e on c a t c h t r i a l s t e n d e d t o d e c r e a s e w i t h i n c r e a s e s i n t h e number o f s i m i l a r n o n t a r g e t l e t t e r s . I n c o n t r a s t , p e r f o r m a n c e improved somewhat o n t a r g e t t r i a l s w i t h i n c r e a s e s i n t h e number o f s i m i l a r n o n t a r g e t letters. Although t h e s e results were n o t s t a t i s t i c a l l y s i g n i f i c a n t , t h e y show t h a t s i m i l a r i t y may a l s o p l a y a r o l e i n the accuracy t a s k . Although it i s d i f f i c u l t t o compare d i r e c t l y t h e m a g n i t u d e o f t h e e f f e c t s of a c c u r a c y w i t h t h o s e o f r e a c t i o n time, t h e s i m i l a r i t y a n a l y s i s makes s u c h a c o m p a r i s o n more m e a n i n g f u l . The r e a c t i o n time s t u d y i n d i c a t e d s m a l l e f f e c t s of o r t h o g r a p h i c s t r u c t u r e r e l a t i v e t o t h e e f f e c t s of s i m i l a r i t y . The a c c u r a c y study revealed l a r g e e f f e c t s of orthographic s t r u c t u r e r e l a t i v e t o small e f f e c t s of similarity. Contrasting t h e s e two v a r i a b l e s i n e a c h t a s k m i g h t a l l o w a more r e l i a b l e a s s e s s m e n t o f t h e c o n t r i b u t i o n of o r t h o g r a p h i c s t r u c t u r e . From t h i s a n a l y s i s it a p p e a r s t h a t o r t h o g r a p h i c s t r u c t u r e p l a y s a l a r g e r r o l e i n t h e a c c u r a c y s t u d y t h a n i t d o e s i n t h e r e a c t i o n time s t u d y . One o f t h e p r i m a r y m o t i v a t i o n s o f t h e p r e s e n t s e t o f e x p e r i m e n t s was t o e x p l o r e t h e d i f f e r e n c e s b e t w e e n t h e s e two t a s k s . Of c o u r s e , i t i s n o t t h e t a s k s t h e m s e l v e s t h a t a r e i n t e r e s t i n g b u t r a t h e r , what t h e y r e v e a l a b o u t t h e p e r c e p t u a l r e c o g n i t i o n of l e t t e r s t r i n g s . The f o l l o w i n g s e t o f e x p e r i m e n t s was a l s o deemed n e c e s s a r y b e c a u s e o f t h e l i m i t a t i o n s i n t h e m a n i p u l a t i o n of o r t h o g r a p h i c s t r u c t u r e i n our p r e v i o u s s t u d i e s . Although w e a t t e m p t e d t o c h o o s e r e g u l a r and i r r e g u l a r s t r i n g s f o r e a c h l e v e l o f h i g h o r low p o s i t i o n a l f r e q u e n c y , we were n o t c o n f i d e n t t h a t w e had It was d i f f i c u l t t o select been c o m p l e t e l y s u c c e s s f u l . regular-low positional-frequency items and i r r e g u l a r - h i g h items. T h i s f o l l o w e d from t h e f a c t t h a t positional-frequency p o s i t i o n a l frequency and our intuitive impression of orthographic regularity might have been highly c o r r e l a t e d . T h e r e f o r e , we may have i n a d v e r t e n t l y c o n f o u n d e d r e g u l a r i t y with p o s i t i o n a l frequency in t h a t t h e high positional-frequency items were more r e g u l a r t h a n t h e low p o s i t i o n a l - f r e q u e n c y items. I t remained a p o s s i b i l i t y t h a t t h e e f f e c t o f p o s i t i o n a l f r e q u e n c y would be e l i m i n a t e d i f w e c o u l d r e g u l a r f o r h i g h and low f i n d items t h a t were e q u a l l y p o s i t i o n a l f r e q u e n c i e s . T h e r e f o r e , we r e f i n e d our d e s c r i p t i o n
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o f o r t h o g r a p h i c r e g u l a r i t y and c h o s e a new s e t o f items o n t h e b a s i s o f t h e s e r u l e s f o r t h e p r e s e n t e x p e r i m e n t s . The r u l e s a r e p r e s e n t e d i n Appendix 4 . 1 A . I n a d d i t i o n t o s e l e c t i n g new items w e a l s o employed word s t i m u l i i n t h e e x p e r i m e n t s . Krueger (1979) s p e c u l a t e d t h a t a much l a r g e r f a c i l i t a t i o n i n t h e t a r g e t s e a r c h t a s k would be found w i t h words t h a n w i t h pseudowords. By i n c l u d i n g w i t h o u r f o u r c a t e g o r i e s o f m e a n i n g l e s s anagrams t h e words from which t h e y were d e r i v e d , w e c o u l d p r o v i d e a d i r e c t e v a l u a t i o n of t h e f a c i l i t a t i n g e f f e c t s o f word s t r u c t u r e r e l a t i v e t o p o s i t i o n a l f r e q u e n c y and r e g u l a r i t y . W e a l s o saw t h e p o t e n t i a l f o r t e s t i n g a w i d e r r a n g e of f o r m a l d e s c r i p t i o n s o f o r t h o g r a p h i c s t r u c t u r e i n t h e present experiments. A s indicated e a r l i e r , t h e q u a l i t a t i v e t e s t p r o v i d e d by t h e f a c t o r i a l d e s i g n is l i m i t e d . A good d e s c r i p t i o n of o r t h o g r a p h i c s t r u c t u r e m u s t also describe performance for individual letter strings. T h e r e f o r e , we p l a n n e d t o a n a l y z e p e r f o r m a n c e a s a f u n c t i o n of i n d i v i d u a l l e t t e r s t r i n g s i n t h e p r e s e n t s t u d i e s . These a n a l y s e s would go s i g n i f i c a n t l y beyond t h e q u a l i t a t i v e c o m p a r i s o n s between word, pseudoword, and nonword items o f p r e v i o u s s t u d i e s . A s e c o n d m o t i v a t i o n f o r i n c l u d i n g word items was t h a t a n y d e s c r i p t i o n o f o r t h o g r a p h i c s t r u c t u r e m u s t n o t b e l i m i t e d t o nonword items b u t m u s t a l s o be f u n c t i o n a l f o r word items. If i n some manner l e x i c a l ( i . e . , word) identity o v e r r u l e s o r t h o g r a p h i c s t r u c t u r e , t h e n t h e l a t t e r would n o t b e psychologically relevant i n reading. T h e r e f o r e t h e f i r s t two e x p e r i m e n t s of t h e p r e s e n t s e t o f e x p e r i m e n t s c a n be c o n s i d e r e d t o be a d i r e c t r e p l i c a t i o n of t h e Massaro e t a l . (1979) experiments which h a v e j u s t b e e n d e s c r i b e d . However, t h e p r e s e n t e x p e r i m e n t s i n c l u d e d a new s e t o f items a l o n g w i t h t h e c o r r e s p o n d i n g word s t i m u l i . In t h i s sense, t h e e x p e r i m e n t s conform t o t h e e x p e r i m e n t a l framework g i v e n by Sidman ( 1 9 6 0 ) i n t h a t we a r e b o t h r e p l i c a t i n g and e x t e n d i n g p r e v i o u s e x p e r i m e n t s . F i g u r e 4.6 illustrates the f i v e t y p e s o f i t e m s used i n a l l o f t h e c u r r e n t e x p e r i m e n t s .
STUDY 1:
I N I T I A L REPLICATION
Procedure Two e x p e r i m e n t s were c a r r i e d o u t w i t h 1 4 s u b j e c t s i n e a c h experiment. F i g u r e 4.7 g i v e s a s c h e m a t i c r e p r e s e n t a t i o n of t h e procedures f o r t h e accuracy and RT e x p e r i m e n t s . I n t h e a c c u r a c y e x p e r i m e n t t h e t e s t l e t t e r s t r i n g was p r e s e n t e d f o r a
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s h o r t d u r a t i o n f o l l o w e d i m m e d i a t e l y by a masking s t i m u l u s . The d u r a t i o n o f t h e t e s t item was a d j u s t e d f o r e a c h s u b j e c t i n o r d e r t o o b t a i n a n a v e r a g e of 75% c o r r e c t a c r o s s a l l c o n d i t i o n s i n t h e t a s k . The t a r g e t l e t t e r f o l l o w e d t h e 208 msec masking s t i m u l u s . The s u b j e c t ' s t a s k was t o i n d i c a t e by p r e s s i n g t h e a p p r o p r i a t e b u t t o n w h e t h e r o r n o t t h e t a r g e t l e t t e r was contained i n t h e test l e t t e r s t r i n g . I n t h e RT e x p e r i m e n t t h e t a r g e t l e t t e r was p r e s e n t e d f o r 500 msec f o l l o w e d by a 1 sec b l a n k p e r i o d . The t e s t s t r i n g was t h e n p r e s e n t e d and r e m a i n e d on u n t i l t h e s u b j e c t r e s p o n d e d " y e s " o r "no" w i t h r e s p e c t t o whether or n o t t h e t a r g e t l e t t e r o c c u r r e d i n t h e t e s t s t r i n g . A r e a s o n a b l e amount o f p r a c t i c e was g i v e n on b o t h t a s k s . The t e s t items were s i x - l e t t e r s t r i n g s c o n s i s t i n g o f 4 0 words and 160 anagrams c r e a t e d by t h e f a c t o r i a l c o m b i n a t i o n o f h i g h or low positional-frequency and regular or irregular
I words
I I
winter charge turned (1293)
Regular
Positional Frequency High
Low
triwen chager drunet (1438)
trewin greach tredun (540)
wrntei ahcger rdnuet (1421)
rntewi hreagc edtrnu (526)
Orthographic Regularity
I
Figure 4.6
I
The f i v e t y p e s o f i t e m s and e x a m p l e s of e a c h t y p e used i n t h e e x p e r i m e n t s . The number i n e a c h c e l l i s t h e a v e r a g e summed s i n g l e - l e t t e r positional f r e q u e n c y f o r t h a t item t y p e ( b a s e d on t h e Mayzner & T r e s s e l t , 1965, c o u n t s ) .
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s t r u c t u r e . On a n y t r i a l , any o f t h e f i v e t y p e s of s t r i n g s The t e s t c o u l d be p r e s e n t e d a s e i t h e r a c a t c h o r t a r g e t t r i a l . s t r i n g s a r e p r e s e n t e d i n Appendix 4 . 1 B . The d e t a i l s o f t h e method, p r o c e d u r e , and r e s u l t s o f t h e two t a s k s a r e p r e s e n t e d i n Appendix 4 . 1 . Orthographic S t r u c t u r e F i g u r e s 4.8 and 4.9 p r e s e n t t h e r e s u l t s from t h e a c c u r a c y RT t a s k s a s a function of t h e f i v e classes o f items. P e r f o r m a n c e i n t h e a c c u r a c y t a s k depended g r e a t l y on t h e s t r u c t u r e o f t h e t e s t s t r i n g . Words were r e c o g n i z e d 1 2 % more o f t e n t h a n t h e b e s t r e g u l a r h i g h items. The r e g u l a r s t r i n g s w e r e j u d g e d 8 % more a c c u r a t e l y t h a n t h e i r r e g u l a r strings. A c c u r a c y was 5 % h i g h e r f o r h i g h p o s i t i o n a l - f r e q u e n c y and
PRECUE RT Target Letter
+- : I-
500
Test Display
II 1000
POSTCUE ACCURACY Test
Figure 4.7
Mask
Target Letter
Schematic r e p r e s e n t a t i o n s of t h e p r e c u e time and p o s t c u e a c c u r a c y e x p e r i m e n t s .
reaction
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s t r i n g s t h a n f o r low p o s i t i o n a l - f r e q u e n c y s t r i n g s . A l l of t h e s e r e s u l t s were s t a t i s t i c a l l y s i g n i f i c a n t . The d e t a i l e d r e s u l t s and t h e s t a t i s t i c a l a n a l y s e s a r e p r e s e n t e d i n Appendix 4.1. I n t h e RT t a s k , r e a c t i o n times t o words were o n l y 7 msec f a s t e r t h a n r e a c t i o n times t o r e g u l a r - h i g h anagrams. R e g u l a r items were j u d g e d 2 3 msec f a s t e r t h a n i r r e g u l a r items, w h e r e a s h i g h p o s i t i o n a l - f r e q u e n c y items were r e s p o n d e d t o o n l y 4 msec f a s t e r t h a n low p o s i t i o n a l - f r e q u e n c y items. Only t h e e f f e c t o f r e g u l a r i t y was s t a t i s t i c a l l y s i g n i f i c a n t . The d e t a i l e d r e s u l t s and s t a t i s t i c a l a n a l y s e s a r e p r e s e n t e d i n Appendix 4.1. The h i g h l y s i g n i f i c a n t e f f e c t s o f o r t h o g r a p h i c s t r u c t u r e on r e s p o n s e a c c u r a c y and t h e r e l a t i v e l y m i n o r , and f o r t h e m o s t p a r t , n o n s i g n i f i c a n t e f f e c t s of o r t h o g r a p h i c s t r u c t u r e on r e a c t i o n time p r o v i d e a d i r e c t r e p l i c a t i o n o f o u r p r e v i o u s
1
I
I
I
R-H
R-L
I-H
I-L
50
WORD
Figure 4.8
P e r c e n t a g e c o r r e c t a s a f u n c t i o n of d i s p l a y t y p e f o r t a r g e t and c a t c h t r i a l s i n t h e p o s t c u e a c c u r a c y t a s k of S t u d y 1.
EXPERIMENTS ON LETTER AND WORD PERCEPTION
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work. These r e s u l t s u n d e r s c o r e the reliability of t h e r e g u l a r i t y and p o s i t i o n a l - f r e q u e n c y e f f e c t s on a c c u r a c y by d e m o n s t r a t i n g a g e n e r a l i z a t i o n t o b o t h a new s a m p l e o f s u b j e c t s and a new s a m p l e of s t i m u l u s items ( C l a r k , 1 9 7 3 ) . N e i t h e r r e g u l a r i t y nor p o s i t i o n a l f r e q u e n c y , however, a p p e a r s t o b e s u f f i c i e n t t o a c c o u n t f o r t h e s t r o n g a c c u r a c y a d v a n t a g e found f o r words. The i s s u e o f w h e t h e r or n o t o r t h o g r a p h i c s t r u c t u r e r a t h e r t h a n l e x i c a l i d e n t i t y c a n a c c o u n t for t h e word a d v a n t a g e w i l l b e d e l a y e d u n t i l a more d e t a i l e d d i s c u s s i o n and e v a l u a t i o n of o r t h o g r a p h i c s t r u c t u r e is p r e s e n t e d . Similarity Effects To t e s t f o r t h e e f f e c t s o f s i m i l a r i t y between t h e t a r g e t l e t t e r s o u g h t i n a d i s p l a y and t h e l e t t e r s a c t u a l l y o c c u r r i n g
Y
I
w
E 600 I-
5
P
Figure 4.9
550-
R e a c t i o n time and p e r c e n t a g e c o r r e c t a s a f u n c t i o n of d i s p l a y t y p e for t a r g e t and c a t c h t r i a l s i n t h e p r e c u e r e a c t i o n t i m e t a s k o f S t u d y 1.
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Table 4.2
Target a
For e a c h o f t h e 26 l e t t e r s i s l i s t e d t h e o t h e r l e t t e r s i n t h e a l p h a b e t t h a t were e r r o n e o u s l y i d e n t i f i e d a s t h a t l e t t e r more t h a n 5% o f t h e t i m e ( f r o m Bouma, 1 9 7 1 ) .
Similar Nontarget L e t t e r s c , e l m , n, 0 , s, x , z
Target n
Similar Nontarget L e t t e r s a, e l s, u, x
C
0
P
4
i.
1, t
V
W
j
1
W
V
k
t, x
X
Y
V
i n t h e d i s p l a y , t h e d a t a were p o o l e d a c r o s s a l l f i v e d i s p l a y t y p e s and r e p a r t i t i o n e d . The b a s i s f o r t h i s r e p a r t i t i o n i n g was t h e c l a s s i f i c a t i o n of each t r i a l ' s t a r g e t l e t t e r according t o which l e t t e r s a r e l i k e l y t o b e s e e n a s v e r y s i m i l a r t o t h e target. The c l a s s i f i c a t i o n was d e r i v e d from t h e l o w e r c a s e single-letter c o n f u s a b i l i t y s t u d y o f Bouma ( 1 9 7 1 ) shown i n We c o u n t e d a n o n t a r g e t l e t t e r a s s i m i l a r t o t h e table 2.4. target l e t t e r if the nontarget l e t t e r was e r r o n e o u s l y i d e n t i f i e d a s t h e t a r g e t more t h a n 5% o f t h e t i m e i n Bouma's s t u d y . T a b l e 4.2 presents the similarity classification a c c o r d i n g t o t h i s a n a l y s i s . For e x a m p l e , g i v e n t h e t a r g e t
EXPERIMENTS ON LETTER AND WORD PERCEPTION
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l e t t e r &, t h e s i m i l a r n o n t a r g e t l e t t e r s a r e k, E, a n d u. T h i s m ean s t h a t t h e s t i m u l u s l e t t e r s k t k, p , a n d 2 were i d e n t i f i e d a s b m o r e t h a n 5 % o f t h e t i m e i n Bouma's s t u d y . Each u n i q u e t r i a l i n o u r t a r g e t s e a r c h t a s k w as t h e n d e s c r i b e d b y t h e number o f n o n t a r g e t l e t t e r s i n t h e d i s p l a y t h a t were similar to the target according to this classification. Roughly 46, 33, 1 3 , and 7 % of e a c h s u b j e c t ' s t r i a l s f e l l i n t o t h e c a t e g o r i e s z e r o , one, two, and t h r e e similar letters (other than the target letter i t s e l f ) , respectively. F i g u r e s 4.10 and 4 . 1 1 p r e s e n t t h e a c c u r a c y an d r e a c t i o n t i m e r e s u l t s a s a f u n c t i o n o f t h e number o f s i m i l a r n o n t a r g e t l e t t e r s i n t h e d i s p l a y . T a r g e t v e r s u s c a t c h t r i a l s is t h e curve parameter i n t h e figures. In t h e accuracy t a s k , accuracy i n c r e a s e d w i t h i n c r e a s e s i n t h e number o f s i m i l a r n o n t a r g e t
100
I
1
I
I
90
k
Ya
8 0
B
80
70
I2k 60
50
1
I
1
0
1
2
L
3
NUMBER OF SIMILARNONTARGETS F i g u r e 4.10
P e r c e n t a g e c o r r e c t a s a f u n c t i o n o f t h e number o f similar nontarget letters in the test s t r i n g s i n t h e a c c u r a c y e x p e r i m e n t o f S t u d y 1.
54
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l e t t e r s o n t a r g e t t r i a l s and d e c r e a s e d o n c a t c h t r i a l s . The l a r g e s i m i l a r i t y e f f e c t s i n t h e accuracy t a s k c o n t r a s t with t h e The s m a l l e r e f f e c t s o f Massaro e t a l . shown i n F i g u r e 4 . 5 . p r e s e n t a n a l y s i s may h a v e p r o v i d e d a more s e n s i t i v e t e s t o f s i m i l a r i t y t h a n t h e Massaro e t a l . a n a l y s i s s i n c e t h e c o n f u s i o n s e t s were computed i n a more p r e c i s e manner. In p a r t i c u l a r , the present analysis allows for asymmetric is considered t o be a s i m i l a r nontarget c o n f u s i o n s . Although l e t t e r g i v e n t h e t a r g e t l e t t e r d, 9, o r 2 , t h e o n l y s i m i l a r is t h e l e t t e r 0. In nontarget l e t t e r for the t a r g e t l e t t e r t h e r e a c t i o n t i m e t a s k , r e a c t i o n time i n c r e a s e d w i t h i n c r e a s e s i n t h e number o f s i m i l a r t a r g e t l e t t e r s o n c a t c h t r i a l s b u t d i d n o t c h a n g e much o n t a r g e t t r i a l s . T h i s r e s u l t p r o v i d e s a d i r e c t r e p l i c a t i o n o f t h e s i m i l a r i t y a n a l y s i s i n t h e Massaro e t a l . s t u d y shown i n F i g u r e 4.4.
c
e,
700r---
650
th rEl +--+Target
500
450
1
2
3
NUMBER OF SIMILAR NONTARGETS F i g u r e 4.11
R e a c t i o n time a s a f u n c t i o n o f t h e number similar nontarget l e t t e r s i n the t e s t s t r i n g t h e r e a c t i o n t i m e e x p e r i m e n t o f S t u d y 1.
of in
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Target-Catch Differences Accuracy was 1 2 % h i g h e r f o r c a t c h t r i a l s t h a n f o r t a r g e t t r i a l s and t h i s e f f e c t i n t e r a c t e d w i t h d i s p l a y t y p e s ( c f . Figure 4.8). R e a c t i o n times were 47 msec s l o w e r f o r c a t c h t r i a l s than f o r t a r g e t t r i a l s ( c f . Figure 4.9). The r e s u l t s show t h a t s u b j e c t s i n a n a c c u r a c y t a s k t e n d t o be more a c c u r a t e on c a t c h t r i a l s t h a n on t a r g e t t r i a l s w h e r e a s t h e y t e n d t o t a k e l o n g e r on c a t c h t r i a l s i n t h e r e a c t i o n time e x p e r i m e n t . Given t h a t t h e s e r e s u l t s d o n o t come from t h e same e x p e r i m e n t , t h e y c a n n o t be i n t e r p r e t e d i n t e r m s o f a s p e e d a c c u r a c y t r a d e - o f f . RT task was a l s o However, r e s p o n s e a c c u r a c y in the s i g n i f i c a n t l y higher f o r catch than f o r t a r g e t t r i a l s (Figure 4.9) and t h i s r e s u l t m i g h t a c c o u n t f o r t h e l o n g e r r e a c t i o n times on c a t c h t r i a l s i n t h e r e a c t i o n t i m e t a s k . A central q u e s t i o n r a i s e d by t h i s s t u d y c o n c e r n s t h e n a t u r e o f t h e s i m i l a r i t i e s and t h e d i f f e r e n c e s between a c c u r a c y paradigms. Results from a c c u r a c y and and r e a c t i o n time r e a c t i o n time s t u d i e s a r e f r e q u e n t l y r e g a r d e d a s c o n v e r g e n t i n d i c a t i o n s of common perceptual processing. Systematic d i f f e r e n c e s between t h e a c c u r a c y and RT e f f e c t s would s u g g e s t t h a t p e r c e p t u a l p r o c e s s e s may n o t be t h e same i n b o t h c a s e s . Thus, two i m p o r t a n t q u e s t i o n s a r e w h e t h e r o r n o t a c c u r a c y and r e a c t i o n time r e s u l t s c a n be p r e d i c t e d from a common p r o c e s s i n g model, and i f s o , how t h e d i f f e r e n t s t i m u l u s e n v i r o n m e n t s o f t h e a c c u r a c y and r e a c t i o n time t a s k s c a u s e t h e o b s e r v e d d i f f e r e n c e s i n t h e m a g n i t u d e of t h e e f f e c t s . The a c c u r a c y and t h e r e a c t i o n time t a s k s w i l l be e v a l u a t e d i n t h e framework o f t h e information processing model. In order to better u n d e r s t a n d t h e e f f e c t s o f t a r g e t and c a t c h t r i a l s and t o b e t t e r e x p l i c a t e o u r i n t e r p r e t a t i o n of t h e p r o c e s s e s i n t h e a c c u r a c y and r e a c t i o n t i m e t a s k s , we w i l l p r e s e n t a n i n f o r m a t i o n p r o c e s s i n g a n a l y s i s o f p e r f o r m a n c e i n t h e a c c u r a c y and r e a c t i o n time t a s k s .
INFORMATION PROCESSING MODEL
With t h e r e g i s t r a t i o n of a l e t t e r s t r i n g a s a n image upon the retina, sensory transduction begins. Features are extracted simultaneously ( i n parallel) from e a c h l e t t e r p o s i t i o n i n t h e d i s p l a y and a r e e n t e r e d i n t o p r e p e r c e p t u a l visual storage. Feature e x t r a c t i o n i s a temporally extended p r o c e s s so t h a t t h e c o n t e n t s of p r e p e r c e p t u a l v i s u a l s t o r a g e
CHAPTER 4
b u i l d up o v e r t i m e . C o n c u r r e n t w i t h t h e e s t a b l i s h m e n t o f t h e new c o n t e n t s o f p r e p e r c e p t u a l v i s u a l s t o r a g e , t h e p r i m a r y recognition process transforms the current c o n t e n t s of p r e p e r c e p t u a l v i s u a l s t o r a g e i n t o s y n t h e s i z e d v i s u a l memory. The c o n t e n t s o f s y n t h e s i z e d v i s u a l memory a r e c o n t i n u a l l y m o n i t o r e d by a d e c i s i o n p r o c e s s w h i c h , i n t h e case o f t h e p r e c u e t a r g e t s e a r c h t a s k , e n d e a v o r s t o match t h e t a r g e t w i t h t h e f r e s h l y r e s o l v e d and c o n t i n u o u s l y u p d a t e d l e t t e r s t r i n g i n synthesized visual memory, as in Turvey's (1973) c o n c u r r e n t - c o n t i n g e n t model. it is To d e r i v e s p e c i f i c p r e d i c t i o n s from t h e model, n e c e s s a r y t o make a few assumptions about t h e primary r e c o g n i t i o n p r o c e s s and t h e d e c i s i o n p r o c e s s . Experimental s u p p o r t f o r t h e s e a s s u m p t i o n s p r e v i o u s l y h a s been d e m o n s t r a t e d ( M a s s a r o , 1 9 7 9 a ) . The f i r s t a s s u m p t i o n i s t h a t knowledge of orthographic s t r u c t u r e c o n t r i b u t e s an independent source of knowledge a b o u t t h e l e t t e r s t r i n g . A c c o r d i n g l y , e x p e r i e n c e d r e a d e r s w i l l be b i a s e d t o i n t e r p r e t t h e l e t t e r s t r i n g a s o n e t h a t is o r t h o g r a p h i c a l l y s t r u c t u r e d . T h e r e f o r e , t o t h e e x t e n t t h a t t h e l e t t e r s b e i n g r e s o l v e d from p r e p e r c e p t u a l v i s u a l s t o r a g e form w e l l - s t r u c t u r e d l e t t e r s e q u e n c e s , t h e y may b e r e s o l v e d w i t h fewer f e a t u r e s o r b e f o r e a l l f e a t u r e s h a v e been extracted. In contrast, a poorly-structured string w i l l r e q u i r e n e a r l y complete f e a t u r a l information f o r r e c o g n i t i o n b e c a u s e o r t h o g r a p h i c knowledge w i l l p r o v i d e no a d d i t i o n a l a s s i s t a n c e . T h u s , t h e c o n t e n t s o f s y n t h e s i z e d v i s u a l memory a r e e s t a b l i s h e d by p r i m a r y r e c o g n i t i o n more q u i c k l y and accurately for well-structured than f o r poorly-structured strings. The s e c o n d a s s u m p t i o n is r e l a t e d t o t h e d e c i s i o n a l g o r i t h m i n t h e t a r g e t s e a r c h t a s k . When t h e t a r g e t l e t t e r is known i n advance, t h e d e c i s i o n process monitors t h e continuously emerging c o n t e n t s o f s y n t h e s i z e d v i s u a l memory s e e k i n g a match All letter positions are monitored t o the target. i n d e p e n d e n t l y and i n p a r a l l e l . The d e c i s i o n p r o c e s s m a i n t a i n s two c r i t e r i a o r d e c i s i o n a x e s , a n a l o g o u s t o t h e model o f memory s e a r c h d e v e l o p e d by A t k i n s o n and J u o l a ( 1 9 7 4 ) . Whenever a l e t t e r p o s i t i o n exceeds t h e f i r s t c r i t e r i o n i n resemblance t o t h e t a r g e t , a match is assumed t o h a v e been f o u n d , p r o c e s s i n g t e r m i n a t e s , and a p o s i t i v e r e s p o n s e is e x e c u t e d . Whenever a l e t t e r p o s i t i o n is s u f f i c i e n t l y d i s s i m i l a r t o t h e t a r g e t t o e x c e e d t h e second c r i t e r i o n , t h e l e t t e r i s c l a s s i f i e d a s a n o t y e t been r e s o l v e d f o i l . Letter p o s i t i o n s t h a t have s u f f i c i e n t l y t o be c l a s s i f i e d a s t a r g e t o r f o i l c o n t i n u e t o be r e s o l v e d u n t i l t h e y c a n be c l a s s i f i e d or u n t i l f u r t h e r
EXPERIMENTS ON LETTER AND WORD PERCEPTION
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When a l l l e t t e r p o s i t i o n s h a v e r e s o l u t i o n is n o t p o s s i b l e . been c l a s s i f i e d a s f o i l s , a n e g a t i v e r e s p o n s e i s e x e c u t e d . I f t h e v i s u a l s t i m u l u s i s impoverished s o t h a t f u l l r e s o l u t i o n o f a l l l e t t e r p o s i t i o n s is n o t p o s s i b l e , a d e c i s i o n i s f o r c e d when no f u r t h e r r e s o l u t i o n is p o s s i b l e . Given t h a t the f u l l y resolved or c l e a r l y " s e e n " l e t t e r s h a v e been c l a s s i f i e d as f o i l s , a g u e s s r e s p o n s e m u s t be e x e c u t e d based upon the remaining "unseen" letters. The observer's p r o b a b i l i t y o f g u e s s i n g t h a t one of t h e u n r e s o l v e d l e t t e r s is a t a r g e t i s a j o i n t f u n c t i o n of a p r i o r i e x p e c t a t i o n s t h a t any g i v e n l e t t e r w i l l be a t a r g e t and t h e number of u n r e s o l v e d letters. T h e s e e x p e c t a t i o n s a r e d e r i v e d from i n s t r u c t i o n s and past experience. For t h e p r e c u e RT t a s k , t h e f o l l o w i n g p r e d i c t i o n s a l s o f o l l o w d i r e c t l y from t h e model. D e c i s i o n time i s a d i r e c t f u n c t i o n of t h e r e s o l u t i o n t i m e of t h e s t i m u l u s s t r i n g and t h e r e f o r e i s i n f l u e n c e d by t h e o r t h o g r a p h i c r e d u n d a n c i e s t h a t can be e x p l o i t e d i n t h e stimulus. The t i m e t o c o r r e c t l y i d e n t i f y a t a r g e t i n t h e l e t t e r s t r i n g is a f u n c t i o n s o l e l y of on t h e t h e time r e q u i r e d t o r e s o l v e t h e t a r g e t and w i l l , a v e r a g e , be s h o r t e r t h a n t h e time r e q u i r e d t o e x h a u s t i v e l y c l a s s i f y a l l l e t t e r s a s f o i l s on a c a t c h t r i a l . Identification time f o r t h e t a r g e t l e t t e r i s i n f l u e n c e d by t h e o r t h o g r a p h i c c o n s t r a i n t s among t h e l e t t e r s i n t h e c a t c h s t r i n g . The e m p h a s i s o n a c c u r a c y i n t h e RT t a s k d i s p o s e s t h e o b s e r v e r t o m a i n t a i n s t r i c t c r i t e r i a w h i c h , f o r t h e most p a r t , p r e c l u d e errors. I n a p o s t c u e t a s k , r e c o g n i t i o n and d e c i s i o n p r o c e s s e s a n a l o g o u s t o t h o s e f o r t h e p r e c u e t a s k a r e assumed t o o p e r a t e , e x c e p t t h a t t h e c o n t e n t s of s y n t h e s i z e d v i s u a l memory m u s t b e m a i n t a i n e d a w a i t i n g t h e a r r i v a l and r e c o g n i t i o n o f t h e t a r g e t l e t t e r . The s t i m u l u s l e t t e r s t r i n g i s r e s o l v e d a s f u l l y a s t h e combined v i s u a l i n f o r m a t i o n and o r t h o g r a p h i c s t r u c t u r e a l l o w and i s r e t a i n e d a w a i t i n g p r e s e n t a t i o n of t h e t a r g e t . Once t h e t a r g e t is i d e n t i f i e d , i t is compared w i t h however much o f t h e l e t t e r s t r i n g was r e s o l v e d . I f a match i s f o u n d , a p o s i t i v e r e s p o n s e i s e x e c u t e d . F o l l o w i n g t h e a r g u m e n t of Thompson and assumed t h a t the exact f e a t u r a l Massaro (1973), it is s i m i l a r i t y of t h e unresolved l e t t e r s t o t h e t a r g e t l e t t e r is n o t d i r e c t l y a v a i l a b l e t o t h e d e c i s i o n p r o c e s s and d o e s n o t influence the guess probability. Orthographic structure i n f l u e n c e s a c c u r a c y f o r b o t h t a r g e t and c a t c h t r i a l s b e c a u s e i t i n f l u e n c e s t h e number of l e t t e r s t h a t a r e a c c u r a t e l y p e r c e i v e d . I t may seem s u r p r i s i n g t h a t t h e Thompson and Massaro ( 1 9 7 3 ) and t h e Massaro e t a l . ( 1 9 7 9 ) s t u d i e s r e v e a l e d no
CHAPTER 4
s i g n i f i c a n t e f f e c t s of l e t t e r s i m i l a r i t y . Even i f f e a t u r a l i n f o r m a t i o n i s n o t t r a n s m i t t e d t o s y n t h e s i z e d v i s u a l memory we would e x p e c t i n c o r r e c t s y n t h e s e s t o be s i m i l a r t o t h e t e s t l e t t e r . For e x a m p l e , g i v e n t h e t e s t l e t t e r 0, we would e x p e c t t h a t r e c o g n i t i o n e r r o r s w i l l b e more l i k e l y t o c o n s i s t o f c and e t h a n I and 2. One f a c t o r t h a t may work a g a i n s t o b s e r v a t i o n of t h i s phenomenon may be t h a t t h e t e s t d i s p l a y was f o l l o w e d by a masking s t i m u l u s i n t h e a c c u r a c y t a s k and t h e r e is now some e v i d e n c e t h a t f e a t u r e s o f t h e mask c o n t r i b u t e t o p e r c e p t u a l memory o f t h e t e s t (Kallman & Massaro, 1 9 7 9 ; S m i t h , H a v i l a n d , R e d e r , B r o w n e l l , & Adams, 1 9 7 6 ) . G i v e n t h e c o n t r i b u t i o n o f t h e mask, i n c o r r e c t r e s p o n s e s m i g h t be more e a s i l y p r e d i c t e d by t h e f e a t u r e s o f t h e mask t h a n t h e f e a t u r e s o f t h e t e s t . A s e c o n d reason f o r observing small s i m i l a r i t y e f f e c t s i n t h e accuracy s t u d i e s is t h a t t h e a c c u r a c y s t u d i e s w i t h l e t t e r s t r i n g s employ a f o r c e d - c h o i c e r e s p o n s e s i t u a t i o n s o t h a t t h o s e few t r i a l s t h a t involve i n c o r r e c t perceptual syntheses a r e u n l i k e l y t o agree with t h e i n c o r r e c t response a l t e r n a t i v e . The s y s t e m a t i c l e t t e r confusions u s u a l l y found i n s i n g l e - l e t t e r recognition s t u d i e s c o u l d depend on a n open-ended s e t o f l e t t e r r e s p o n s e also possible t o observe a l t e r n a t i v e s . However, i t is s i g n i f i c a n t s i m i l a r i t y e f f e c t s a s i n t h e present accuracy study ( c f . Figure 4.18). The p a t t e r n of t h e s e r e s u l t s i s c o n s i s t e n t w i t h t h e i d e a t h a t s i m i l a r l e t t e r s may b e m i s t a k e n l y i d e n t i f i e d a s t h e t a r g e t . Hence, a c c u r a c y on t a r g e t t r i a l s i n c r e a s e s w i t h t h e number of s i m i l a r l e t t e r s t o t h e t a r g e t i n t h e t e s t s t r i n g , b u t a c c u r a c y o n c a t c h t r i a l s d e c r e a s e s a s t h e number of s i m i l a r l e t t e r s t o t h e t a r g e t is i n c r e a s e d . I t i s p o s s i b l e t o q u a n t i f y t h e p r o c e s s i n g model i n o r d e r t o d e s c r i b e t h e q u a n t i t a t i v e r e s u l t s of t h e t a r g e t s e a r c h t a s k . I n a n a c c u r a c y t a s k , i t i s assumed t h a t t h e l e t t e r s t r i n g i s perceived ( i . e . , resolved) a s f u l l y a s possible. R e s o l u t i o n of the display is a d i r e c t f u n c t i o n of b o t h t h e f e a t u r a l i n f o r m a t i o n a v a i l a b l e and t h e o r t h o g r a p h i c s t r u c t u r e o f t h e t e s t s t r i n g . S i n c e e a c h o f t h e f o u r t y p e s of m e a n i n g l e s s l e t t e r s t r i n g s was composed by making anagrams of a s i x - l e t t e r word, t h e same l e t t e r s were p r e s e n t a c r o s s t h e f i v e d i s p l a y . t y p e s . The f i v e d i s p l a y t y p e s were a l s o p r e s e n t e d a t t h e same i n t e n s i t y and d u r a t i o n s . Therefore, t h e featural information may be assumed to be constant across the display t y p e s . However, t h e d i s p l a y t y p e s d i f f e r w i t h r e s p e c t t o o r t h o g r a p h i c s t r u c t u r e and t h e s e d i f f e r e n c e s c a n a c c o u n t f o r t h e performance d i f f e r e n c e s a c r o s s t h e f i v e d i s p l a y t y p e s . T h e r e f o r e , t h e number o f l e t t e r s r e s o l v e d , R , w i l l depend on the d i s p l a y type.
EXPERIMENTS ON LETTER AND WORD PERCEPTION
59
I t is necessary t o describe a decision r u l e t h a t allows t h e s u b j e c t t o s e l e c t a " y e s " o r "no" r e s p o n s e . I t i s assumed t h a t i f one of t h e r e s o l v e d l e t t e r s is i d e n t i c a l t o t h e t a r g e t , a " y e s " r e s p o n s e is e x e c u t e d . I f t h e t a r g e t l e t t e r is n o t c o n t a i n e d i n t h e s e t of r e s o l v e d l e t t e r s , a " y e s " r e s p o n s e i s a f u n c t i o n o f t h e number o f u n r e s o l v e d l e t t e r s and t h e r e a d e r ' s E , t h a t some l e t t e r i n t h e s i x - l e t t e r s t r i n g w i l l expectation, be i d e n t i c a l t o t h e t a r g e t . Since E is the expectation for a whole s i x - l e t t e r t e s t s t r i n g c o n t a i n i n g t h e t a r g e t , t h e n E/6 i s t h e e x p e c t a t i o n t h a t any s i n g l e l e t t e r i n t h e t e s t s t r i n g is identical t o the target. The e x p e c t a t i o n v a l u e E would be some f u n c t i o n o f i n s t r u c t i o n s , f e e d b a c k , and how o f t e n t h e t a r g e t Therefore, the l e t t e r is a c t u a l l y s e e n i n t h e t e s t s t r i n g . p r o b a b i l i t y o f a " y e s " r e s p o n s e t o t h e t a r g e t t r i a l i s g i v e n by Equation 1 f o r l e t t e r s t r i n g s of l e n g t h 6.
The l e f t - h a n d t e r m of E q u a t i o n 1 i n d i c a t e s t h a t R - s i x t h s o f t h e time one o f t h e r e s o l v e d l e t t e r s w i l l be i d e n t i c a l t o t h e t a r g e t and t h e o b s e r v e r w i l l r e s p o n d " y e s " w i t h p r o b a b i l i t y o n e . On t h e r e m a i n i n g t r i a l s , 1 - R/6, t h e t a r g e t was n o t r e s o l v e d and t h e o b s e r v e r g u e s s e s w i t h p r o b a b i l i t y E / 6 w e i g h t e d by t h e number o f u n r e s o l v e d l e t t e r s ( 6 - R ) . For c a t c h t r i a l s , t h e o b s e r v e r w i l l n e v e r f i n d t h e t a r g e t a n d , t h e r e f o r e , i s i n a n i m p e r f e c t knowledge s t a t e u n l e s s h e o r s h e r e s o l v e s a l l o f t h e l e t t e r s . T h e r e f o r e , t h e l i k e l i h o o d of a " y e s " r e s p o n s e is s i m p l y t h e o b s e r v e r ' s e x p e c t a t i o n t h a t a g i v e n t e s t l e t t e r i s a t a r g e t l e t t e r , E/6, w e i g h t e d by t h e number of u n r e s o l v e d t a r g e t l e t t e r s , 6 - R: P(YeslCatch) = (6
-
R) x
(E/6)
Of c o u r s e , t h e l i k e l i h o o d o f b e i n g c o r r e c t o n c a t c h t r i a l s t h e complement o f E q u a t i o n ( 2 ) : P(No1Catch) = 1
-
[(6
-
R) x
(E/6)]
(2)
is
(3)
The model was a p p l i e d t o t h e r e s u l t s o f t h e a c c u r a c y experiment. The model was f i t t o t h e 1 0 a v e r a g e r e s p o n s e a c c u r a c i e s ( t h e f i v e d i s p l a y t y p e s on t a r g e t p r e s e n t t r i a l s and t h e f i v e d i s p l a y t y p e s o n c a t c h o r t a r g e t a b s e n t t r i a l s ) . The f i t was o b t a i n e d u s i n g a l e a s t - s q u a r e s parameter e s t i m a t i o n r o u t i n e ( C h a n d l e r , 1 9 6 9 ) . S i x p a r a m e t e r s w e r e e s t i m a t e d from t h e d a t a : one e x p e c t a t i o n p a r a m e t e r , E , and a n e s t i m a t e o f t h e
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number o f l e t t e r s f u l l y r e s o l v e d , R , f o r e a c h o f t h e f i v e display types. The o b t a i n e d f i t was q u i t e good; t h e r o o t mean s q u a r e d d e v i a t i o n was o n l y 1 . 3 % . A l t h o u g h i t is d i f f i c u l t t o a p p r e c i a t e t h e q u a n t i t a t i v e g o o d n e s s - o f - f i t f o r s u c h a model estimating s i x parameters f o r 10 d a t a p o i n t s , t h e obtained parameter v a l u e s nonetheless a r e revealing. The s u b j e c t s were c l e a r l y i n f o r m e d of t h e e q u a l number o f t a r g e t and c a t c h t r i a l s i n t h e e x p e r i m e n t and t h e r e f o r e , t h e y s h o u l d have a d o p t e d a n .5. However, t h e o b s e r v e d g r e a t e r a c c u r a c y f o r E-value of c a t c h t r i a l s would a p p e a r t o s u g g e s t a b i a s t o w a r d "no" r e s p o n s e s o r a n a p p a r e n t E-value r a t h e r c l o s e t o z e r o . In f a c t , t h e e s t i m a t e d E-value was . 4 6 s u g g e s t i n g t h a t t h e s u b j e c t s p o s s e s s e d a t most a v e r y s l i g h t b i a s . The s t r o n g i m b a l a n c e between c a t c h a c c u r a c y and t a r g e t a c c u r a c y i s a l o g i c a l c o n s e q u e n c e of t h e model even when l i t t l e o r no b i a s is present. A l t h o u g h t h e r e a r e no a p r i o r i v a l u e s o f t h e R p a r a m e t e r s t o which t h e e s t i m a t e s may b e c o m p a r e d , t h e o b t a i n e d estimates f o r R provide a reasonable s c a l i n g f o r the f i v e types o f items. T h e s e v a l u e s a r e shown i n T a b l e 4.3 a s Postcue (Study 1 ) . While t h e s p e c i f i c a t i o n o f a q u a n t i t a t i v e model p r e d i c t i n g r e a c t i o n times is c o n s i d e r a b l y more complex, it nonetheless s t e m s d i r e c t l y from t h e a b o v e i n f o r m a t i o n p r o c e s s i n g a n a l y s i s . The r e a c t i o n t i m e on a t a r g e t t r i a l i s t h e s u m o f t h e t i m e needed t o r e s o l v e t h e t a r g e t l e t t e r i n t h e l e t t e r s t r i n g p l u s t h e time needed t o i n i t i a t e and e x e c u t e t h e c o r r e c t r e s p o n s e . The r e s o l u t i o n time f o r t h e t a r g e t l e t t e r i s a f u n c t i o n o f i t s v i s u a l p r o p e r t i e s and o f t h e o r t h o g r a p h i c s t r u c t u r e o f t h e l e t t e r s t r i n g i n which t h e t a r g e t o c c u r s . Since orthographic s t r u c t u r e a f f e c t s t h e t i m e needed t o r e s o l v e t h e l e t t e r s t r i n g , o r t h o g r a p h i c s t r u c t u r e is a p a r a m e t e r o f t h e d i s t r i b u t i o n o f the reaction times. The e x p e c t e d v a l u e o f t h i s d i s t r i b u t i o n (Response p l u s a c o n s t a n t g i v e s a v e r a g e RT f o r t a r g e t t r i a l s . i n i t i a t i o n and e x e c u t i o n t i m e is assumed t o b e c o n s t a n t o r a t l e a s t d i s t r i b u t e d independently of t h e e f f e c t of primary interest.) For c a t c h t r i a l s , t h e RT i s t h e s u m o f a c o n s t a n t time f o r r e s p o n s e e x e c u t i o n p l u s t h e maximum time needed t o c l a s s i f y a l l l e t t e r s a s f o i l s . C l a s s i f i c a t i o n t i m e i s b a s e d upon t h e j o i n t d i s t r i b u t i o n o f completion t i m e s f o r e a c h o f t h e f o i l s on t h e n o n t a r g e t t r i a l s . These d i s t r i b u t i o n s have a s p a r a m e t e r s t h e similarity of the f o i l t o the t a r g e t , other visual properties which a f f e c t t h e o v e r a l l e a s e of r e s o l v i n g the f o i l , the i n f l u e n c e o f o r t h o g r a p h i c s t r u c t u r e , and f i n a l l y t h e s u b j e c t ' s c r i t e r i o n f o r a v o i d i n g f a l s e a l a r m s . Having o u t l i n e d t h e model
EXPERIMENTS ON LETTER AND WORD PERCEPTION
T a b l e 4.3
61
E s t i m a t e s o f p e r c e p t u a l r e s o l u t i o n ( R ) and a p r i o r i expectation (E) of t h e occurrence of a t a r g e t t r i a l a n d t h e r o o t mean s q u a r e d (RMS) d e r i v a t i o n s f o r t h e a c c u r a c y t a s k s i n S t u d i e s 1 a n d 2.
R
Task
E
RMS ( i n %)
Word
R-H
R-L
I-H
I-L
( S t u d y 1)
5.20
4.40
3.72
3.40
2.98
.459
1.27
( S t u d y 2)
5.22
4.38
3.56
3.26
2.86
.550
1.70
( S t u d y 2)
4.87
4.29
3.84
3.85
3.42
.880
1.67
Combined D a t a
5.08
4.33
3.68
3.51
3.08
Postcue
Precue
Postcue Precue
2.54 .514 .823
t o t h i s l e v e l o f d e t a i l , w e w i l l p r o c e e d no f u r t h e r . U n l i k e t h e a c c u r a c y m o d e l w h e r e t h e f i t o f t h e model was e n l i g h t e n i n g a b o u t p r es u m ed s u b j e c t b i a s i n t h e t a s k , the qualitative f e a t u r e s o f t h e RT d a t a f o l l o w r a t h e r d i r e c t l y f r o m t h e q u a l i t a t i v e d e s c r i p t i o n o f t h i s model. The c o m p l e t i o n o f the q u a n t i f i c a t i o n o f t h i s model might prove an i n t e r e s t i n g e x e r c i s e b u t would b e u n l i k e l y t o b e e x t r e m e l y r e v e a l i n g , p a r t i c u l a r l y s i n c e t h e e f f e c t s o f o r t h o g r a p h i c s t r u c t u r e were very small.
STUDY 2:
PRECUE VERSUS POSTCUE
W h er eas i t i s n o t p o s s i b l e t o c o m p a r e d i r e c t l y t h e m a g n i t u d e o f a c c u r a c y a n d RT e f f e c t s , t h e d i f f e r e n c e s i n a c c u r a c y betwe en words and i r r e g u l a r - l o w anagrams i n t h e
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a c c u r a c y t a s k was 2 1 % . The d i f f e r e n c e b e t w e e n t h e s e same c o n d i t i o n s i n t h e RT t a s k w a s o n l y 34 msec o r 5 .8 % o f t h e a v e r a g e RT o f 581 msec. 3 o e s t h i s r e p r e s e n t a r e a l d i f f e r e n c e i n t h e u t i l i z a t i o n o f o r t h o g r a p h i c s t r u c t u r e i n t h e two t a s k s ? the t a s k s a l l o w more o f a I f s o , wh at p r o p e r t i e s o f contribution of orthographic s t r u c t u r e i n one t a s k than i n t h e other? The o b s e r v a t i o n o f s i g n i f i c a n t a d v a n t a g e s f o r w o r d s an d pseudowords o v e r nonwords and s i n g l e l e t t e r s i n t h e p o s t c u e R e i c h e r t a s k ( B a r o n & T h u r s t o n , 1 9 7 3 ; R e i c h e r , 1969; Thompson & M a s s a r o , 1 9 7 3 ; W h e e l e r , 1 9 7 0 ) and t h e a b s e n c e o f t h e s e e f f e c t s i n p r e c u e d e t e c t i o n t a s k s ( B j o r k & Estes, 1973; E s t e s , B j o r k , & S k a a r , 1 9 7 4 ; M a s s a r o , 1 9 7 3 ; Thompson & M a s s a r o , 1 9 7 3 ) h a s l e d t o t h e s u g g e s t i o n t h a t precuing p r e c l u d e s t h e c o n t r i b u t i o n of o r t h o g r a p h i c s t r u c t u r e . The subject in a precue t a s k p r e s u m a b l y m a t c h e s t h e f e a t u r e s o f t h e remembered t a r g e t l e t t e r d i r e c t l y t o t h e f e a t u r e s o f t h e i n c o m i ng v i s u a l d i s p l a y . This s t r a t e g y precludes using orthographic structure t o assist i n resolution of t h e display. Thus, o n e h y p o t h e s i s is t h a t precuing promotes s m a l l e r advantages f o r s t r u c t u r e d d i s p l a y s . Study 2 t e s t s whether a precue, p e r se, a c c o u n t s f o r diminished e f f e c t s o f o r t h o g r a p h i c s t r u c t u r e . The p o s t c u e a c c u r a c y t a s k o f t h e S t u d y 1 was r e p l i c a t e d i n o n e c o n d i t i o n w h i l e a comparable precue accuracy t a s k was used i n t h e o t h e r condition. I f p r e c u i n g a l w a y s a l l o w s m a t c h e s t o b e made a t a feature detection level, then the e f f e c t s of orthographic structure should be severely attenuated i n t h e precue accuracy task. On t h e o t h e r h a n d , i f t h e d i s p l a y i n t h e a c c u r a c y t a s k i s r e s o l v e d t o t h e f u l l e s t e x t e n t p o s s i b l e an d o r t h o g r a p h i c structure contributes t o resolution, then the results for p r e c u e and p o s t c u e a c c u r a c y s h o u l d b e c o m p a r a b l e e x c e p t , perhaps, f o r d i f f e r e n t i a l memory l o a d s i n t h e two c o n d i t i o n s . The t e s t s t r i n g s , a p p a r a t u s , a n d d i s p l a y s e q u e n c e s were i d e n t i c a l t o t h o s e o f t h e a c c u r a c y e x p e r i m e n t i n S t u d y 1. One half of t h e s u b j e c t s received the precue t a s k on t h e f i r s t day and t h e p o s t c u e t a s k o n t h e s e c o n d d a y ; f o r t h e remaining s u b j e c t s t h i s o r d e r was r e v e r s e d . The p r e c u e t a s k i n v o l v e d t h e p r e s e n t a t i o n o f t h e t a r g e t l e t t e r f o r 5 0 0 msec f o l l o w e d b y t h e l e t t e r s t r i n g 1 sec l a t e r . The l e t t e r s t r i n g was p r e s e n t e d before t h e t a r g e t i n t h e postcue task. I n both t a s k s t h e l e t t e r s t r i n g was e x p o s e d f o r a s h o r t d u r a t i o n and masked t o g i v e a n a v e r a g e p erfo rman ce o f 75% c o r r e c t . Eighteen s u b j e c t s wer e t e s t e d i n t h e e x p e r i m e n t . The d e t a i l s o f t h e m e t h o d , p r o c e d u r e , a n d r e s u l t s a r e p r e s e n t e d i n A p p en d i x 4 . 2
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Or t h o g r a p h i c S t r u c t u r e Figure 4.12 presents percentage correct target identifications a s a function of the five levels of orthographic structure. The p r e c u e t a s k v e r s u s t h e p o s t c u e A s c a n be s e e n i n t h e figure, t a s k is t h e curve parameter. l a r g e e f f e c t s o f o r t h o g r a p h i c s t r u c t u r e were f o u n d i n b o t h t h e p r e c u e a n d p o s t c u e t a s k s , a l t h o u g h s l i g h t l y l a r g e r e f f e c t s were f o u n d i n t h e p o s t c u e t a s k . The p o s t c u e e x p e r i m e n t r e p l i c a t e s t h e previous study. The p r e c u e r e s u l t s a r e v e r y s i m i l a r t o t h e postcue r e s u l t s , although t h e a t t e n t u a t i o n of t h e orthographic s t r u c t u r e e f f e c t s i n t h e precue t a s k over t h e postcue t a s k is statistically significant. The p r i m a r y f o c u s o f t h i s e x p e r i m e n t was t o d e t e r m i n e t h e r e l a t i o n s h i p o f precue accuracy performance t o postcue accuracy
I
w n 60
-
-
Postcue Precue
50
F i g u r e 4.12
WORD
R-H
R-L
I-H
I-L
Percentage c o r r e c t a s a function of d i s p l a y type i n t h e p r e c u e a n d p o s t c u e c o n d i t i o n s o f S t u d y 2.
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performance. Although t h e i n t e r a c t i o n o f t a s k w i t h d i s p l a y conditions suggests a smaller i n f l u e n c e of o r t h o g r a p h i c s t r u c t u r e i n t h e precue than postcue t a s k , t h e results a r e s u f f i c i e n t t o r e j e c t t h e h y p o t h e s i s t h a t p r e c u i n g promotes a d r a s t i c r e d u c t i o n i n t h e u s e of o r t h o g r a p h i c s t r u c t u r e . The e f f e c t s o f s t r u c t u r e were v e r y s t r o n g f o r b o t h p r e c u e and p o s t c u e , and t h e d i f f e r e n c e between t h e two t a s k s was s m a l l by comparison. The o b s e r v e d i n t e r a c t i o n o f t a s k w i t h d i s p l a y c o n d i t i o n s p r o b a b l y r e f l e c t s d i f f e r e n t memory r e q u i r e m e n t s f o r t h e two I t is r e a s o n a b l e t o e x p e c t t h a t p e r f o r m a n c e m i g h t be tasks. p o o r e r i n a p o s t c u e t a s k b e c a u s e t h e n e c e s s i t y of r e t a i n i n g t h e d i s p l a y u n t i l t h e t a r g e t l e t t e r is p r o c e s s e d c o u l d l e a d t o memory l o s s . I t might f u r t h e r be expected t h a t f o r g e t t i n g would b e g r e a t e r f o r t h e more p o o r l y - s t r u c t u r e d displays ( B a d d e l e y , 1964). Any d i f f e r e n c e s i n o v e r a l l a c c u r a c y b e t w e e n t h e postcue than i n precue tasks a r e n o t meaningful because t h e a d a p t i v e a l g o r i t h m endeavored t o m a i n t a i n o v e r a l l a c c u r a c y a t 75%. I n f a c t , s u b j e c t s required s i g n i f i c a n t l y longer exposures i n t h e postcue than t h e precue task. The l o n g e r d u r a t i o n s f o r the. postcue t a s k a r e c o n s i s t e n t with t h e idea t h a t f o r g e t t i n g occurred t o a g r e a t e r degree i n t h e postcue than i n t h e precue task. Similarity Effects Figure 4.13 gives the percentage of correct i d e n t i f i c a t i o n s of t h e t a r g e t l e t t e r a s a f u n c t i o n of t h e Similar number of s i m i l a r n o n t a r g e t s i n t h e t e s t d i s p l a y . r e s u l t s were o b s e r v e d i n both the p r e c u e and p o s t c u e tasks. The o v e r a l l a c c u r a c y d i f f e r e n c e s o n t a r g e t and c a t c h t r i a l s f o r both tasks a r e discussed i n t h e next s e c t i o n . Accuracy d e c r e a s e d w i t h i n c r e a s e s i n t h e number o f s i m i l a r n o n t a r g e t s on c a t c h t r i a l s b u t remained r e l a t i v e l y c o n s t a n t on t a r g e t t r i a l s . Although t h e s i m i l a r i t y e f f e c t s a r e s m a l l e r i n magnitude, t h e c a t c h t r i a l s b u t n o t t h e t a r g e t t r i a l s r e p l i c a t e t h e r e s u l t s o f t h e a c c u r a c y t a s k i n S t u d y 1. The d e c r e a s e i n a c c u r a c y on c a t c h t r i a l s w i t h i n c r e a s e s i n t h e number o f s i m i l a r l e t t e r s a p p e a r s t o be a r e l a t i v e l y r e l i a b l e r e s u l t . In c o n t r a s t , a n y e f f e c t o f s i m i l a r n o n t a r g e t s on t a r g e t t r i a l s a p p e a r s t o be s m a l l e r i n m a g n i t u d e and l e s s r e l i a b l e .
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Target Versus Catch T r i a l s F i g u r e 4 . 1 4 p r e s e n t s t h e p e r c e n t a g e of c o r r e c t t a r g e t i d e n t i f i c a t i o n s f o r t a r g e t and c a t c h t r i a l s i n t h e p r e c u e and postcue accuracy tasks. Replicating t h e r e s u l t s of t h e p r e v i o u s s t u d y , o v e r a l l a c c u r a c y was much g r e a t e r on c a t c h t r i a l s t han on t a r g e t t r i a l s i n t h e p o s t c u e t a s k . I n c o n t r a s t , p e r f o r m a n c e on t a r g e t t r i a l s was more a c c u r a t e t h a n on c a t c h t r i a l s i n t h e p r e c u e a c c u r a c y t a s k . The se e f f e c t s c a n be d e s c r i b e d by t h e d e c i s i o n r u l e i n t h e model. For a c c u r a c y t a s k s i t i s assumed t h a t t h e l e t t e r s t r i n g i s r e s o l v e d a s f u l l y as p o s s i b l e w i t h t h e a s s i s t a n c e of o r t h o g r a p h i c s t r u c t u r e . I f none o f t h e r e s o l v e d l e t t e r s is t h e t a r g e t , a " y e s " r e s p o n s e is a f u n c t i o n of t h e o b s e r v e r ' s a p r i o r i e x p e c t a t i o n p r o b a b i l i t y t h a t a n u n r e s o l v e d l e t t e r i s a t a r g e t and t h e number of
Precue
J l -
m L
50
0
1
2
3
NUMBER OF SIMILAR NONTARGETS
F i g u r e 4.13 '
P e r c e n t a g e c o r r e c t f o r t a r g e t and c a t c h t r i a l s i n t h e p r e c u e and p o s t c u e c o n d i t i o n s of S t u d y 2 a s a f u n c t i o n o f t h e number of s i m i l a r n o n t a r g e t l e t t e r s in the test string.
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unresolved l e t t e r s . I n t e r m s of t h e p r e s e n t model, the e x p e c t a t i o n p a r a m e t e r E/6 must have d i f f e r e d f o r t h e p r e c u e and postcue tasks. I n f o r m a t i o n P r o c e s s i n q Model The model was t e s t e d by f i t t i n g i t t o t h e d a t a o f t h e p r e s e n t experiment. S i x p a r a m e t e r s were e s t i m a t e d f o r e a c h s e t of 10 means: one E - v a l u e , and a s e p a r a t e R-value f o r e a c h o f t h e five display conditions, e.g. , word, r e g u l a r - h i g h , e t c . The p a r a m e t e r e s t i m a t e s and t h e i r a s s o c i a t e d root mean s q u a r e d d e v i a t i o n s a r e shown i n T a b l e 4.3 a s P o s t c u e ( S t u d y 2 ) and P r e c u e ( S t u d y 2 ) . The model p r o v i d e s a good d e s c r i p t i o n of t h e r e s u l t s of both t a s k s .
100
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Observed (Obs) and p r e d i c t e d (Pre) percentage c o r r e c t f o r t a r g e t and c a t c h t r i a l s f o r t h e p r e c u e and p o s t c u e c o n d i t i o n s o f S t u d y 2 a s a f u n c t i o n of d i s p l a y type.
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Not o n l y d o e s t h e f i t of t h e model p r o v i d e s u p p o r t f o r o u r c o n c e p t u a l i z a t i o n o f t h e d e c i s i o n mechanism, b u t t h e p a r a m e t e r v a l u e s a r e meaningful. I t is i n t e r e s t i n g t o n o t e t h a t t h e a p p a r e n t b i a s toward "no" r e s p o n s e s i n t h e p o s t c u e t a s k a c t u a l l y r e f l e c t s a n a c c u r a t e and u n b i a s e d a s s e s s m e n t o f t h e e q u a l p r o b a b i l i t y o f t a r g e t and c a t c h t r i a l s . The s u b j e c t s i n t h e p r e c u e t a s k , however, d o e x h i b i t a marked b i a s t o w a r d e x p e c t i n g t h e p r e s e n c e of a t a r g e t . Smith e t a l . ( 1 9 7 6 ) have reported s i m i l a r f i n d i n g s i n a precued t a r g e t r e c o g n i t i o n task and s u g g e s t t h a t o b s e r v e r s i n p r e c u e t a s k s may e r r o n e o u s l y i n c o r p o r a t e mask f e a t u r e s i n making t h e i r j u d g m e n t s and t h u s t e n d t o see t h e t a r g e t i n t h e mask more o f t e n t h a n m i g h t b e e x p e c t e d . By m a n i p u l a t i n g t h e n a t u r e o f t h e m a s k which f o l l o w s t h e d i s p l a y t h e y found a more p r o n o u n c e d e f f e c t when t h e d i s p l a y and mask s h a r e d f e a t u r e s t h a n when t h e y d i d n o t . P e r h a p s e v e n more i n t e r e s t i n g t h a n t h e E - p a r a m e t e r s were t h e R-values which c o r r e s p o n d t o t h e number of l e t t e r s a c t u a l l y resolved f o r each d i s p l a y type. The p a r a m e t e r v a l u e s f o r R a s a f u n c t i o n of display type change s y s t e m a t i c a l l y w i t h o r t h o g r a p h i c s t r u c t u r e a c r o s s b o t h t h e p r e c u e and t h e p o s t c u e experiments. The l a r g e r e f f e c t o f d i s p l a y t y p e f o r t h e p o s t c u e t h a n f o r t h e p r e c u e t a s k i s r e f l e c t e d by t h e l a r g e r s p r e a d of t h e R-values f o r t h e p o s t c u e t a s k . A l t h o u g h t h e i n t e r a c t i o n of d i s p l a y c o n d i t i o n s w i t h t a s k i n t h e p r e s e n t e x p e r i m e n t i m p l i e s t h a t R - v a l u e s were somewhat d i f f e r e n t i n t h e p r e c u e and p o s t c u e t a s k s , a l l 2 0 d a t a p o i n t s were a l s o f i t w i t h s e v e n p a r a m e t e r s by a s s u m i n g t h a t a s i n g l e s e t o f f i v e R - v a l u e s and two E - v a l u e s , one f o r p r e c u e and one f o r t h e p o s t c u e , would b e s u f f i c i e n t . These p a r a m e t e r s and t h e i r a s s o c i a t e d r o o t mean s q u a r e d d e v i a t i o n s a r e a l s o g i v e n i n T a b l e 4 . 3 a s Combined Data. The p r e d i c t e d r e s u l t s o f t h e s e v e n - p a r a m e t e r model a r e shown a l o n g w i t h t h e o b s e r v e d r e s u l t s The r e a s o n a b l y good d e s c r i p t i o n of t h e r e s u l t i n F i g u r e 4.14. shows t h a t t h e combined f i t o f t h e two t a s k s i s q u i t e acceptable. I n a d d i t i o n , r e d u c i n g t h e number of p a r a m e t e r s from 1 2 t o 7 i n c r e a s e d t h e t o t a l r o o t mean s q u a r e d d e v i a t i o n by less t han one p e r c e n t (from 1 . 6 % t o 2 . 5 % ) .
STUDY 3 :
MIXED-CASE
The r e s u l t s o f t h e c o m p a r i s o n between p r e c u e and p o s t c u e t a s k s i n d i c a t e s t h a t precuing a l o n e is n o t a s u f f i c i e n t condition t o cause a d r a s t i c reduction i n t h e u s e of
CHAPTER
A
orthographic s t r u c t u r e , a t l e a s t i n accuracy tasks. It still m i g h t b e t h e c a s e , however, t h a t p r e c u i n g i n t h e RT t a s k i n which u n l i m i t e d v i e w i n g time i n s u r e s t h a t a l l o f t h e f e a t u r e s o f t h e d i s p l a y c a n be e x t r a c t e d p r o m o t e s a f e a t u r e d e t e c t i o n strategy. The n e x t e x p e r i m e n t a d d r e s s e s t h e i s s u e o f w h e t h e r o r n o t d i s c o u r a g i n g a f e a t u r e d e t e c t i o n s t r a t e g y w i l l promote t h e u t i l i z a t i o n of o r t h o g r a p h i c s t r u c t u r e i n t h e r e s o l u t i o n o f the test s t r i n g Much o f t h e i n t u i t i v e a p p e a l o f t h e f e a t u r e d e t e c t i o n s t r a t e g y is t h e i d e a t h a t r e c o g n i t i o n o f t h e t a r g e t l e t t e r c o u l d O C C U K o n t h e b a s i s o f o n l y a few f e a t u r e s and w i t h o u t t h e The n e c e s s i t y of f u l l y r e s o l v i n g a l l f e a t u r e s o f t h e l e t t e r . e f f e c t i v e n e s s o f t h i s s t r a t e g y would be r e d u c e d i f t h e s p e c i f i c v i s u a l c o n f i g u r a t i o n o f t h e t a r g e t , and t h u s t h e e x a c t form o f t h e c r i t i c a l f e a t u r e s , could n o t be p r e d i c t e d . One p r o c e d u r e would be t o h a v e t h e l e t t e r s t r i n g a p p e a r i n s e v e r a l d i f f e r e n t f o n t s w i t h t h e f o n t o f t h e t a r g e t a p p e a r i n g on a g i v e n t e s t t r i a l being unpredictable. The p r e s e n t e x p e r i m e n t a p p r o x i m a t e d t h i s method by p r e s e n t i n g t h e displays printed half i n u p p e r c a s e l e t t e r s and h a l f i n l o w e r c a s e . Thus, t h e l e t t e r c a s e of t h e t a r g e t l e t t e r was n o t c o m p l e t e l y p r e d i c t a b l e . Whereas i t m i g h t s t i l l be p o s s i b l e t o d e t e c t f e a t u r e s f o r u p p e r c a s e and lowercase l e t t e r s simultaneously, t h e e x t r a e f f o r t should reduce the effectiveness of the feature detection s t r a t e g y . T h e r e f o r e , i t is p r e d i c t e d t h a t i f t h e f e a t u r e d e t e c t i o n s t r a t e g y i s t h e cause o f t h e small e f f e c t o f orthographic structure i n a precue RT task, then a significantly larger effect should be observed i n t h e mixed-case c o n d i t i o n , where t h e e f f e c t i v e n e s s of t h e f e a t u r e d e t e c t i o n s t r a t e g y w i l l be d i m i n i s h e d . T a y l o r , M i l l e r , and J u o l a ( 1 9 7 7 ) h a v e r e p o r t e d t h a t m i x i n g c a s e s d i s r u p t s t h e u t i l i z a t i o n of o r t h o g r a p h i c s t r u c t u r e i n word p e r c e p t i o n . The amount o f d i s r u p t i o n was found t o b e a m o n o t o n i c a l l y i n c r e a s i n g f u n c t i o n o f t h e number of t r a n s i t i o n s between c a s e s i n t h e s t r i n g t o be p e r c e i v e d . To m i n i m i z e t h e d i s r u p t i v e i n f l u e n c e o f c a s e t r a n s i t i o n s on t h e u t i l i z a t i o n o f o r t h o g r a p h i c S t K U C t U K e , o n l y a s i n g l e t r a n s i t i o n between t h e t h i r d and f o u r t h l e t t e r s was used i n t h i s e x p e r i m e n t . The p r o c e d u r e was t h e same a s t h e e a r l i e r r e a c t i o n t i m e experiment with t h e following modifications. The t a r g e t l e t t e r was p r e s e n t e d a t t h e b e g i n n i n g o f e a c h t r i a l i n b o t h i t s u p p e r c a s e and l o w e r c a s e f o r m s . On e a c h t r i a l , t h e t e s t s t r i n g was p r e s e n t e d s o t h a t e i t h e r t h e f i r s t t h r e e l e t t e r s were i n u p p e r c a s e and t h e l a s t t h r e e l e t t e r s i n l o w e r c a s e or t h e
.
EXPERIMENTS ON LETTER AND WORD PERCEPTION
o p p o s i t e OCCUKKed. The d e t a i l s of t h e method, p r o c e d u r e , r e s u l t s a r e p r e s e n t e d i n Appendix 4.3.
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Orthographic S t r u c t u r e F i g u r e 4.15 p r e s e n t s t h e mean r e a c t i o n times i n t h e t a s k a s a f u n c t i o n o f o r t h o g r a p h i c s t r u c t u r e . T h e r e was o n l y a 7 msec a d v a n t a g e of words o v e r r e g u l a r - h i g h pseudowords. The 30 msec a d v a n t a g e o f regular over irregular s t r i n g s was s i g n i f i c a n t a s was t h e 1 4 msec a d v a n t a g e of s t r i n g s h i g h i n p o s i t i o n a l f r e q u e n c y r e l a t i v e t o s t r i n g s low i n p o s i t i o n a l frequency. By m i x i n g t h e c a s e s o f t h e l e t t e r s i n t h e p r e s e n t s t u d y , t h e o v e r a l l e f f e c t of o r t h o g r a p h i c s t r u c t u r e i n c r e a s e d from 34 msec i n t h e r e a c t i o n t i m e e x p e r i m e n t o f S t u d y 1 t o 5 1 msec i n
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R e a c t i o n time and p e r c e n t a g e c o r r e c t a s a f u n c t i o n o f d i s p l a y t y p e i n S t u d y 3: Nixed-Case
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t h e p r e s e n t mixed-case r e a c t i o n t i m e s t u d y . Mixing t h e c a s e s I t is, i n c r e a s e d t h e o v e r a l l r e a c t i o n t i m e by a b o u t 120 msec. t h e r e f o r e , n e c e s s a r y t o a s k w h e t h e r t h e 17 msec i n c r e a s e f o r t h e e f f e c t o f o r t h o g r a p h i c s t r u c t u r e is m e a n i n g f u l . I f we can assume t h a t t h e 120 msec i n c r e a s e i n RTs t o mixed-case d i s p l a y s represents the additional visual processing required, then the 17 msec i n c r e a s e i n o r t h o g r a p h i c s t r u c t u r e e f f e c t s may p r o v i d e a meaningful e v a l u a t i o n of t h e i n f l u e n c e of o r t h o g r a p h i c s t r u c t u r e i n t h e RT t a s k . The i n c r e a s e i n t h e e f f e c t o f orthographic structure r e l a t i v e t o the additional visual is 1 4 % . Even 1 4 % , however, may b e a n processing required underestimate of t h e s i z e of t h e e f f e c t o f o r t h o g r a p h i c s t r u c t u r e s i n c e t h e a d d i t i o n a l 120 msec o f p r o c e s s i n g r e q u i r e d s t i m u l i may i n c l u d e a d d i t i o n a l t i m e needed f o r by mixed-case t h e c o m p a r i s o n p r o c e s s when t h e t a r g e t c a n o c c u r i n e i t h e r uppercase o r lowercase. Similarity Effects I f mixing t h e c a s e s a t t e n u a t e d t h e f e a t u r e d e t e c t i o n s t r a t e g y t h e n w e would e x p e c t a d e c r e a s e i n t h e e f f e c t s o f t h e number o f s i m i l a r n o n t a r g e t l e t t e r s i n t h e d i s p l a y o n c a t c h t r i a l s . The s i m i l a r i t y a n a l y s e s a r e c o m p l i c a t e d by t h e m i x t u r e o f upper- and l o w e r c a s e s i n t h e s t r i n g . Because t h e c o n f u s i o n s e t s were d e r i v e d from confusions o f lowercase l e t t e r s , a p p l i c a t i o n of these c o n f u s i o n s e t s t o t h e d a t a w i t h o u t re g a rd t o l e t t e r c a s e s would n o t be a p p r o p r i a t e . Therefore, a r e s t r i c t e d s i m i l a r i t y a n a l y s i s was d o n e by e x a m i n i n g o n l y t h e lowercase l e t t e r s i n t h e d i s p l a y s t r i n g s . When t h i s was d o n e , t h e r e were o n l y two v i a b l e s i m i l a r i t y c a t e g o r i e s : z e r o and one s i m i l a r l e t t e r s . For t a r g e t t r i a l s t h e means were 658 and 658 msec f o r t h e z e r o and one c a t e g o r i e s r e s p e c t i v e l y . For c a t c h t r i a l s t h e s e means were 7 3 1 and 756 msec. T h e s e r e s u l t s r e p l i c a t e t h e RT t a s k i n S t u d y 1; RTs f o r c a t c h t r i a l s b u t n o t t a r g e t t r i a l s i n c r e a s e w i t h t h e number o f s i m i l a r n o n t a r g e t s i n the test string. Based on t h e s i m i l a r i t y a n a l y s e s , m i x i n g t h e c a s e s d i d not appear t o a t t e n t u a t e t h e f e a t u r e d e t e c t i o n s t r a t e g y . The e x p e r i m e n t p r o v i d e s mixed e v i d e n c e f o r t h e hypothesis t h a t a f e a t u r e d e t e c t i o n s t r a t e g y o c c u r s i n precue RT t a s k s . The e f f e c t o f o r t h o g r a p h i c s t r u c t u r e was i n c r e a s e d somewhat by mixing t h e c a s e s and i t m i g h t h a v e been c o n c l u d e d t h a t u s e o f a f e a t u r e d e t e c t i o n s t r a t e g y was p r e c l u d e d and more use made o f o r t h o g r a p h i c c o n t e x t . However, t h e f a i l u r e t o a t t e n u a t e s i m i l a r i t y e f f e c t s p r e c l u d e s any firm conclusion about t h e f e a t u r e d e t e c t i o n s t r a t e g y . Either the subjects
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p e r s i s t e d i n t h e now more d i f f i c u l t t a s k o f l o o k i n g f o r f e a t u r e m a t c h e s i n t w o - l e t t e r cases o r f e a t u r e d e t e c t i o n is n o t t h e c o r r e c t e x p l a n a t i o n f o r t h e r e s u l t s o f e i t h e r o f t h e two experiments.
STUDY 4 :
L I M I T E D V I E W I N G TIME
In another attempt t o discourage t h e f e a t u r e d e t e c t i o n s t r a t e g y , s u b j e c t s were not g i v e n u n l i m i t e d v i e w i n g t i m e i n t h e r e a c t i o n time t a s k of t h e p r e s e n t e x p e r i m e n t . I n t h e RT t a s k ( S t u d i e s 1 and 3 ) , t h e s u b j e c t s were g i v e n u n l i m i t e d time and hence a l l of t h e v i s u a l i n f o r mat i o n n e c e s s a r y f o r d e t a i l e d stimulus displays. In the perceptual r e s o l u t i o n of t h e a c c u r a c y t a s k ( S t u d i e s 1 and 2 ) , v i e w i n g time was s h o r t e n e d s o t h a t v i s u a l i n f o r m a t i o n was i n a d e q u a t e t o c l e a r l y r e s o l v e a l l of t h e d i s p l a y . D e c i s i o n s a t a f e a t u r e d e t e c t i o n l e v e l may depend on t h e c e r t a i n t y t h a t a l l t h e v i s u a l i n f o r m a t i o n w i l l be resolved. I f s o , l i m i t i n g v i e w i n g time i n t h e RT t a s k s h o u l d i n c r e a s e t h e s i z e of o r t h o g r a p h i c s t r u c t u r e e f f e c t s . S t u d y 4 t e s t e d t h i s h y p o t h e s i s by g i v i n g t h e s u b j e c t s t h e d i s p l a y f o r a However, i t was n o t p o s s i b l e t o l i m i t v i e w i n g l i m i t e d time. time a s s e v e r e l y a s i n t h e p r e v i o u s a c c u r a c y t a s k s and s t i l l maintain e r r o r r a t e s low enough to permit meaningful S t u d y 4 was a h y b r i d ; v i e w i n g time was i n t e r p r e t a t i o n of RTs. s h o r t e n e d and e r r o r r a t e s a l l o w e d t o r i s e b u t n e i t h e r was t a k e n t o extremes. The s t i m u l i and a p p a r a t u s were t h e same a s i n t h e r e a c t i o n time e x p e r i m e n t o f S t u d y 1. Rather than l e a v i n g t h e s t i m u l u s d i s p l a y on u n t i l t h e s u b j e c t r e s p o n d e d , t h e d i s p l a y was p r e s e n t e d f o r o n l y 2 0 0 msec and f o l l o w e d i m m e d i a t e l y by a masking s t i m u l u s . On t h e b a s i s of t h e p i l o t work, t h i s d u r a t i o n was c h o s e n b e c a u s e i t n o t o n l y l i m i t e d v i e w i n g time b u t a l s o gave t h e s u b j e c t s u f f i c i e n t v i s u a l information t o respond r e a s o n a b l y a c c u r a t e l y . S i x t e e n s u b j e c t s were c h o s e n from t h e same p o p u l a t i o n a s t h e e a r l i e r s t u d i e s . A l l o t h e r d e t a i l s a r e g i v e n i n Appendix 4 . 4 .
Or t h o g r a p h i c S t r u c t u r e F i g u r e 4.16 p r e s e n t s t h e r e a c t i o n time f o r c o r r e c t r e s p o n s e s as a f u n c t i o n o f o r t h o g r a p h i c s t r u c t u r e . A s c a n b e seen i n t h e f i g u r e , no e f f e c t s o f o r t h o g r a p h i c s t r u c t u r e were observed. Although o r t h o g r a p h i c s t r u c t u r e d i d n o t have a time, it did affect significant effect on reaction
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a c c u r a c y . The small d i f f e r e n c e s i n a c c u r a c y a s a f u n c t i o n of orthographic structure were found to be s t a t i s t i c a l l y s i g n i f i c a n t . By l i m i t i n g t h e d i s p l a y d u r a t i o n , i t a p p e a r s t h a t t h e experiment begins t o approximate an accuracy experiment, and t h e s m a l l e r e f f e c t s o f o r t h o g r a p h i c s t r u c t u r e c a n s i m p l y be a t t r i b u t e d t o t h e o v e r a l l high l e v e l of performance. Similarity Effects Although accu r acy v a r i e d s l i g h t l y w i t h d i f f e r e n c e s i n o r t h o g r a p h i c s t r u c t u r e , t h e r e were no s i g n i f i c a n t c h a n g e s i n a c c u r a c y a s a f u n c t i o n of t h e number o f s i m i l a r n o n t a r g e t s i n t h e t e s t d i s p l a y . I n c o n t r a s t , t h e RTs c o n t i n u e d t o r e v e a l t h e c o n s i s t e n t f i n d i n g t h a t RTs on c a t c h t r i a l s i n c r e a s e d w i t h i n c r e a s e s i n t h e number of s i m i l a r n o n t a r g e t s w he re a s RTs on t a r g e t t r i a l s showed no e f f e c t . A c c o r d i n g l y , t h e r e s u l t s show
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R e a c t i o n t i m e and p e r c e n t a g e c o r r e c t a s a f u n c t i o n of d i s p l a y t y p e i n S t u d y 4 : L i m i t e d Viewing Time.
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t h a t a n o r t h o g r a p h i c s t r u c t u r e e f f e c t i n terms of r e s p o n s e a c c u r a c y c a n c o e x i s t w i t h a s i m i l a r i t y e f f e c t on RT. This r e s u l t r e v e a l s t h a t a f e a t u r a l d e t e c t i o n s t r a t e g y a s i n d e x e d by s i g n i f i c a n t s i m i l a r i t y e f f e c t s does not preclude a s i g n i f i c a n t It appears t h a t c o n t r i b u t i o n of o r t h o g r a p h i c s t r u c t u r e . o r t h o g r a p h i c s t r u c t u r e e f f e c t s c a n be found i n b o t h a c c u r a c y and RT m e a s u r e s , b u t t h a t RT e f f e c t s a r e n o t a s r e l i a b l e o r s e n s i t i v e a s accuracy e f f e c t s . Target Versus Catch T r i a l s ( 5 6 3 msec) w e r e r e s p o n d e d t o more q u i c k l y Target t r i a l s t h a n c a t c h t r i a l s ( 6 3 5 msec) w h e r e a s t h e r e was no s i g n i f i c a n t d i f f e r e n c e between t h e two k i n d s o f t r i a l s i n t e r m s o f r e s p o n s e accuracy.
Discussion The r e s u l t s d i s c o n f i r m t h e hypothesis t h a t limiting v i e w i n g time m i g h t i n c r e a s e t h e i n f l u e n c e of o r t h o g r a p h i c s t r u c t u r e on RT. R e a c t i o n times were found t o be u n i f o r m o v e r conditions. However, t h e p a t t e r n o f e r r o r r a t e s r e f l e c t e d t h e i n f l u e n c e of s t r u c t u r e . Limiting v i s u a l information c l e a r l y h a s a n i n f l u e n c e on a c c u r a c y , and t h i s i n f l u e n c e is m o d u l a t e d structure. A s for the by t h e p r e s e n c e of orthographic u n u s u a l l y u n i f o r m RTs, t h e y m i g h t r e f l e c t t h e s u b j e c t s h a v i n g established and maintained a self-imposed response d e a d l i n e . T h e r e f o r e , any e f f e c t o f o r t h o g r a p h i c s t r u c t u r e would be r e f l e c t e d o n l y o n p e r f o r m a n c e a c c u r a c y .
STUDY 5 :
SPEEDED RT TASK WITH GOOD VISUAL INFORMATION
S t u d y 5 t e s t s between two h y p o t h e s e s o f t h e d i f f e r e n c e s i n t h e s e n s i t i v i t y o f t h e a c c u r a c y and RT t a s k s t o o r t h o g r a p h i c s t r u c t u r e . According t o t h e f i r s t h y p o t h e s i s , t h e d i f f e r e n c e between t h e a c c u r a c y and RT t a s k s c o u l d be d u e t o a t r a d e - o f f between t h e contribution of stimulus information and o r t h o g r a p h i c s t r u c t u r e i n t h e t a s k . T h e r e is a b u n d a n t s t i m u l u s i n f o r m a t i o n i n t h e RT t a s k , and t h e r e f o r e , t h e r e may be v e r y l i t t l e o p p o r t u n i t y f o r knowledge a b o u t o r t h o g r a p h i c s t r u c t u r e I n t h e a c c u r a c y t a s k , on t h e t o c o n t r i b u t e t o performance. o t h e r hand, t h e s t i m u l u s information i s i n a d e q u a t e and consequently, there is considerable opportunity for
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o r t h o g r a p h i c knowledge t o e x e r t a n i n f l u e n c e . This explanation i s c l e a r l y d i f f e r e n t from t h e f e a t u r e d e t e c t i o n s t r a t e g y a feature detection discussed e a r l i e r . In the case of s t r a t e g y , t h e r e is an o p p o r t u n i t y f o r orthographic s t r u c t u r e t o e x e r t an i n f l u e n c e b u t a d e c i s i o n ab o ut t h e l e t t e r s t r i n g is made w i t h o u t u t i l i z i n g t h e s t r u c t u r e . By c o n t r a s t , i n t h e c a s e of a t r a d e - o f f between v i s u a l i n f o r m a t i o n and o r t h o g r a p h i c s t r u c t u r e , t h e complete visual information precludes a c o n t r i b u t i o n of o r t h o g r a p h i c s t r u c t u r e . Evidence f o r t h e t r a d e - o f f between t h e c o n t r i b u t i o n s of s t i m u l u s i n f o r m a t i o n and knowledge comes from a number o f RT e x p e r i m e n t s t h a t have i n d e p e n d e n t l y v a r i e d s t i m u l u s q u a l i t y and knowledge ( c . f . , Meyer, S c h v a n e v e l d t , & Ruddy, 1 9 7 5 ) . M a S S a K O , J o n e s , Lipscomb, and S c h o l z ( 1 9 7 8 ) , f o r e x a m p l e , had s u b j e c t s name a word a s q u i c k l y a s p o s s i b l e . The word was e i t h e r p r e s e n t e d u p r i g h t or was r o t a t e d 1 8 0 d e g r e e s i n t h e p i c t u r e p l a n e . The word was p r e c e d e d by a word " b l a n k " or by a c a t e g o r y p r i m e , which was t h e s u p e r o r d i n a t e c a t e g o r y name o f t h e t e s t word. P r i m i n g w i t h t h e c a t e g o r y name i s t h e a d v a n c e knowledge i n t h e t a s k and i t m i g h t b e e x p e c t e d t o f a c i l i t a t e p r o c e s s i n g o f t h e t e s t word. T h e r e f o r e , R T s s h o u l d b e f a s t e r on primed t h a n unprimed t r i a l s . Of c o u r s e , r o t a t i n g t h e t e s t words s h o u l d slow down t h e naming r e s p o n s e s i n c e t h e s t i m u l u s i n f o r m a t i o n i s d e g r a d e d ; we a r e n o t used t o s e e i n g and r e a d i n g rotated text. The r e s u l t s showed that priming had a n o n s i g n i f i c a n t 7 msec f a c i l i t a t i o n when t h e words were p r e s e n t e d u p r i g h t b u t a s i g n i f i c a n t 1 2 1 msec e f f e c t when words were r o t a t e d 1 8 0 d e g r e e s . S i m i l a r r e s u l t s were f o u n d i n a lexical decision task. With a good q u a l i t y t e s t d i s p l a y , p r i m i n g had e s s e n t i a l l y no e f f e c t : g i v e n a poor q u a l i t y d i s p l a y , a d v a n c e knowledge f a c i l i t a t e d p e r f o r m a n c e . In the p r e s e n t e x p e r i m e n t s , g i v e n a good q u a l i t y d i s p l a y i n t h e RT t a s k , o r t h o g r a p h i c s t r u c t u r e had a small e f f e c t ; w i t h a poor q u a l i t y d i s p l a y i n t h e accuracy t a s k , orthographic s t r u c t u r e had a l a r g e e f f e c t . that t h e c o n t r i b u t i o n of The s e c o n d h y p o t h e s i s is o r t h o g r a p h i c s t r u c t u r e i s s i m i l a r i n t h e a c c u r a c y and RT t a s k s b u t t h e a c c u r a c y t a s k a l l o w s a more d i r e c t m e a s u r e o f t h e s i z e of t h i s c o n t r i b u t i o n . I n t h e RT t a s k where t h e v i s u a l d i s p l a y i s c l e a r l y v i s i b l e and v i e w i n g time u n l i m i t e d , t h e l e t t e r s t r i n g is r e s o l v e d v e r y q u i c k l y and t h e time t o r e s o l v e t h e l e t t e r s may be s m a l l r e l a t i v e t o t h e times f o r t h e r e m a i n i n g processes of s e a r c h , comparison, d e c i s i o n , and r e s p o n s e s e l e c t i o n . Thus, t h e f a c i l i t a t i n g e f f e c t of orthographic s t r u c t u r e m i g h t be l a r g e i n terms o f t h e time s a v i n g s f o r
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v i s u a l r e s o l u t i o n , b u t s m a l l r e l a t i v e t o t h e o v e r a l l RT. For e x a m p l e , a 20 msec e f f e c t o f s t r u c t u r e when v i s u a l r e s o l u t i o n t a k e s 100 msec w i t h o u t any c o n t r i b u t i o n o f s t r u c t u r e would expand a 500 msec RT by o n l y 4 % . Even though t h i s 20% e f f e c t on v i s u a l r e s o l u t i o n is i m p o r t a n t , i t would a p p e a r s m a l l RT. By contrast, the visual relative t o the overall i n f o r m a t i o n i n t h e a c c u r a c y t a s k i s l i m i t e d and e r r o r s a r e a d i r e c t consequence of limitations in visual resolution. Accordingly, a f a c i l i t a t i o n of v i s u a l r e s o l u t i o n w i l l be more directly reflected in an improvement in task acc u r a c y . According t o t h i s h y p o t h e s i s , even though o r t h o g r a p h i c s t r u c t u r e c o n t r i b u t e s r o u g h l y t h e same a d d i t i o n a l i n f o r m a t i o n i n b o t h t h e RT and a c c u r a c y t a s k s , t h e s i z e o f RT e f f e c t w i l l appear small r e l a t i v e t o t h e accuracy e f f e c t . t h e s e two h y p o t h e s e s , a n I n o r d e r t o t e s t between e x p e r i m e n t was c a r r i e d o u t i n which t h e r e a d e r would h a v e good q u a l i t y v i s u a l i n f o r m a t i o n b u t a c c u r a c y r a t h e r t h a n RT would be t h e primary dependent v a r i a b l e . ~f t h e c o n t r i b u t i o n of o r t h o g r a p h i c s t r u c t u r e is i n v e r s e l y r e l a t e d t o t h e q u a l i t y o f t h e v i s u a l information as predicted by the trade-off hypothesis, t h e n a v e r y s m a l l e f f e c t of s t r u c t u r e s h o u l d be a p p a r e n t o n a c c u r a c y . However, if the c o n t r i b u t i o n of the q u a l i t y of t h e v i s u a l s t r u c t u r e i s i n d e p e n d e n t of i n f o r m a t i o n and a c c u r a c y i s s i m p l y a more d i r e c t m e a s u r e , t h e n t h e t y p i c a l l a r g e e f f e c t s o f s t r u c t u r e on a c c u r a c y s h o u l d be o b s e r v e d . Given t h a t a c c u r a c y i s now t i e d t o 75% c o r r e c t , it s h o u l d be a more d i r e c t i n d e x of t h e c o n t r i b u t i o n o f s t r u c t u r e . T h e r e f o r e , t h e p r e s e n t e x p e r i m e n t p r o v i d e s a t e s t between t h e two h y p o t h e s e s w i t h o u t h a v i n g t o compare a c c u r a c y e f f e c t s t o RT e f f e c t s . A m o d i f i c a t i o n of a speed-accuracy t r a d e - o f f paradigm which r e q u i r e s a s p e e d e d r e a c t i o n i n s y n c h r o n i z a t i o n w i t h a s i g n a l e v e n t ( R e e d , 1 9 7 3 ) was used t o keep a v e r a g e p e r f o r m a n c e a t 75% c o r r e c t . The s u b j e c t s were g i v e n t h e t a r g e t l e t t e r f o l l o w e d by t h e d i s p l a y and w e r e r e q u i r e d t o r e s p o n d a s n e a r l y i n s y n c h r o n y w i t h t h e o f f s e t of t h e d i s p l a y a s p o s s i b l e . Using a n a d a p t i v e a l g o r i t h m , a d i s p l a y d u r a t i o n was c a l c u l a t e d t o keep t h e s u b j e c t ' s o v e r a l l a c c u r a c y a t 7 5 % . B e c a u s e t h e d u r a t i o n of t h e d i s p l a y a v e r a g e d a r o u n d 500 msec, i t seems S a f e h a v e good q u a l i t y s t i m u l u s t o assume t h a t t h e s u b j e c t s information. T h e r e f o r e , t h e t r a d e - o f f h y p o t h e s i s p r e d i c t s no e f f e c t of s t r u c t u r e whereas t h e h y p o t h e s i s t h a t a c c u r a c y i s a more d i r e c t m e a s u r e t h a n RT p r e d i c t s a l a r g e e f f e c t O f
structure.
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Procedure E l e v e n s t u d e n t s , s e l e c t e d from t h e same p o p u l a t i o n a s t h o s e i n t h e e a r l i e r e x p e r i m e n t s , were t e s t e d o n a s i n g l e d a y . A t a r g e t l e t t e r was p r e s e n t e d f o r 5 0 0 msec and f o l l o w e d by t h e t e s t d i s p l a y a f t e r a n i n t e r v a l o f 2 5 0 msec. The t e s t d i s p l a y d u r a t i o n was m o d i f i e d e v e r y 2 0 t r i a l s t h r o u g h o u t t h e e x p e r i m e n t S u b j e c t s were t o k e e p o v e r a l l p e r f o r m a n c e a t 75% c o r r e c t . i n s t r u c t e d t o respond as c l o s e t o t h e s t i m u l u s o f f s e t as p o s s i b l e and t h e y were g i v e n f e e d b a c k on t h i s t a s k a f t e r e a c h block of 20 t r i a l s . E s s e n t i a l l y , s u b j e c t s simply l e a r n e d t o m a i n t a i n a p a r t i c u l a r r e s p o n s e time, n o t t o r e s p o n d t o t h e o f f s e t of t h e d i s p l a y i t s e l f . None o f t h e s u b j e c t s had a n y d i f f i c u l t y w i t h t h i s t a s k . D e t a i l s o f t h e method, p r o c e d u r e , and r e s u l t s a r e g i v e n i n Appendix 4.5.
550
-
500
-
450
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kB0lh
0 Catch
8 0 F i g u r e 4.17
~
70
WORD
R-H
R-L
I-H
I-L
R e a c t i o n time and p e r c e n t a g e c o r r e c t a s a f u n c t i o n o f d i s p l a y t y p e i n S t u d y 5: Speeded RT Task w i t h Good V i s u a l I n f o r m a t i o n .
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Orthographic S t r u c t u r e F i g u r e 4.17 p r e s e n t s t h e c o r r e c t r e a c t i o n times and response accuracy a s a f u n c t i o n of o r t h o g r a p h i c s t r u c t u r e ; t a r g e t and c a t c h t r i a l s a r e p l o t t e d s e p a r a t e l y . T h e r e was a 1 5 msec e f f e c t o f o r t h o g r a p h i c s t r u c t u r e o n c o r r e c t r e a c t i o n times and a 1 . 9 % e f f e c t o n a c c u r a c y . T h e r e f o r e , no s t r o n g e f f e c t o f orthographic s t r u c t u r e on either RT or a c c u r a c y was consistent with the trade-off present. T h i s r e s u l t is h y p o t h e s i s whereby t h e c o n t r i b u t i o n o f o r t h o g r a p h i c s t r u c t u r e is i n v e r s e l y r e l a t e d t o t h e q u a l i t y of t h e v i s u a l i n f o r m a t i o n in the test string.
STUDY 6:
SPEEDED RT TASK WITH POOR VISUAL INFORMATION
The s p e e d e d RT t a s k i n S t u d y 5 p r o v i d e d e v i d e n c e t h a t t h e a c c u r a c y t a s k may g i v e l a r g e r e f f e c t s t h a n d o e s t h e RT t a s k because of t h e p o o r er q u a l i t y o f t h e v i s u a l i n f o r m a t i o n i n t h e a c c u r a c y t a s k . A c c o r d i n g l y , g i v i n g good q u a l i t y i n f o r m a t i o n i n t h e s p e e d e d RT t a s k shows no e f f e c t o f o r t h o g r a p h i c s t r u c t u r e on r e s p o n s e a c c u r a c y . B e f o r e a c c e p t i n g t h i s c o n c l u s i o n , i t i s i m p o r t a n t t o v e r i f y whether t h e speed-accuracy paradigm t h a t It was u s e d i s i t s e l f s e n s i t i v e t o o r t h o g r a p h i c s t r u c t u r e . c o u l d be t h e c a s e t h a t t h e p e r c e p t u a l s t a g e g o e s t o c o m p l e t i o n i n a l l c o n d i t i o n s and t h a t e r r o r s a r e s i m p l y a f u n c t i o n o f l a t e r s t a g e s s u c h a s r e s p o n s e s e l e c t i o n . Any small d i f f e r e n c e s i n c o m p l e t i o n times o f t h e p e r c e p t u a l s t a g e a s a f u n c t i o n o f o r t h o g r a p h i c s t r u c t u r e may n o t s i g n i f i c a n t l y i n f l u e n c e t h e a c c u r a c y o f l a t e r s t a g e s o f p r o c e s s i n g , and t h e r e f o r e , t h e d i f f e r e n c e s i n t h e p e r c e p t u a l s t a g e would n o t be r e f l e c t e d in To t e s t t h e e i t h e r response accuracy o r reaction t i m e . s s n s i t i v i t y o f t h e speeded RT t a s k , i t is n e c e s s a r y t o r e p l i c a t e t h e t a s k w i t h poor q u a l i t y i n f o r m a t i o n . I f the task i s s e n s i t i v e and t h e e f f e c t o f s t r u c t u r e is i n v e r s e l y r e l a t e d t o s t i m u l u s q u a l i t y , t h e n s i g n i f i c a n t e f f e c t s s h o u l d be found. I f t h e t a s k i s i n s e n s i t i v e t o t h e p e r c e p t u a l s t a g e , however, n o e f f e c t o f o r t h o g r a p h i c s t r u c t u r e s h o u l d be o b s e r v e d . A s d i s c u s s e d p r e v i o u s l y , MaSSaL-0 e t a l . ( 1 9 7 8 ) d e g r a d e d t h e q u a l i t y o f t e s t s t r i n g s by r o t a t i n g them 1 8 0 d e g r e e s i n t h e p i c t u r e plane. F o l l o w i n g t h i s a p p r o a c h , t h e s p e e d e d RT t a s k was r e p l i c a t e d w i t h t h e t e s t s t r i n g s r o t a t e d i n t h e same manner. Given t h a t r o t a t i o n l o w e r s t h e q u a l i t y o f t h e v i s u a l
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i n f o r m a t i o n , a n e f f e c t o f o r t h o g r a p h i c s t r u c t u r e s h o u l d be o b s e r v e d i f t h e s p e e d e d RT t a s k i s s e n s i t i v e t o p e r c e p t u a l d i f f e r e n c e s due t o t h e o r t h o g r a p h i c s t r u c t u r e . I f t h e task itself i s i n s e n s i t i v e t h e n no e f f e c t s o f s t r u c t u r e s h o u l d be observed. Procedure The s p e e d e d RT t a s k i n S t u d y 5 was r e p l i c a t e d e x a c t l y w i t h a new g r o u p o f s t u d e n t s e x c e p t t h a t t h e t e s t s t r i n g s were r o t a t e d 18B d e g r e e s i n t h e p i c t u r e p l a n e r a t h e r t h a n p r e s e n t e d upright. The t a r g e t l e t t e r was s t i l l p r e s e n t e d u p r i g h t . The d e t a i l s o f t h e method, p r o c e d u r e , and r e s u l t s a r e p r e s e n t e d i n Appendix 4.6.
-
Or t h o g r a p h i c S t r u c t u r e
F i g u r e 4.18 p r e s e n t s t h e c o r r e c t r e a c t i o n times and accuracy performance. T h e r e was a 7 msec e f f e c t o f s t r u c t u r e 700
Catch *------*Target
650
a\.\.
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-m
,-”
---
600
550
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0 Catch
O m 8 WORD F i g u r e 4.18
R-H
R-L
I-H
I-L
R e a c t i o n time and p e r c e n t a g e c o r r e c t a s a f u n c t i o n Speeded RT Task w i t h of d i s p l a y type i n Study 6: Poor V i s u a l I n f o r m a t i o n .
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on c o r r e c t r e a c t i o n times and a 1 . 7 % e f f e c t on r e s p o n s e a c c u r a c y . The r e s u l t s o f t h i s experiment are a direct r e p l i c a t i o n o f t h o s e i n t h e p r e v i o u s s p e e d e d RT t a s k and t h e r e f o r e provide s t r o n g evidence f o r t h e idea t h a t t h e speeded RT t a s k is i n s e n s i t i v e t o p e r c e p t u a l d i f f e r e n c e s due t o t h e orthographic structure. B e f o r e t h i s c o n c l u s i o n is a c c e p t e d , i t w i l l be n e c e s s a r y t o v e r i f y t h a t o r t h o g r a p h i c however, s t r u c t u r e e f f e c t s do occur with r o t a t e d t e s t s t r i n g s i n o t h e r tasks. I n o r d e r t o have a d i r e c t l y a n a l o g o u s s i t u a t i o n t o t h e s p e e d e d RT t a s k s , t h e t a s k m u s t keep t h e t e s t s t r i n g i n v i e w during the processing period. Therefore, high accuracy is t o be e x p e c t e d and RT m u s t be t h e d e p e n d e n t m e a s u r e .
STUDY 7 :
HIGH-ACCURACY
RT TASK WITH POOR VISUAL INFORMATION
Procedure To v e r i f y t h a t o r t h o g r a p h i c s t r u c t u r e e f f e c t s d o o c c u r with rotated t e s t s t r i n g s , t h e high-accuracy reaction t i m e e x p e r i m e n t o f S t u d i e s 1 and 3 was r e p l i c a t e d b u t u s i n g r o t a t e d An u p r i g h t t a r g e t l e t t e r was r a t h e r than upright test s t r i n g s . p r e s e n t e d f o l l o w e d by a r o t a t e d t e s t s t r i n g which remained in view u n t i l t h e l a s t o f up t o f o u r s u b j e c t s r e s p o n d e d . Subjects performed a s q u i c k l y a s p o s s i b l e while maintaining high a c c u r a c y . The d e t a i l s o f t h e method, p r o c e d u r e , and r e s u l t s a r e p r e s e n t e d i n Appendix 4 . 7 . Orthographic S t r u c t u r e R e a c t i o n t i m e s g e n e r a l l y i n c r e a s e d from words t o t h e irregular-low strings. F i g u r e 4.19 shows t h a t o v e r a l l e f f e c t was 3 2 msec, which i s h i g h l y s i m i l a r t o t h e e f f e c t s o f s t r u c t u r e on n o r m a l l y p r e s e n t e d s t r i n g s ( c f . F i g u r e 4 . 9 ) . This r e s u l t shows t h a t s t r u c t u r e e f f e c t s d o o c c u r w i t h r o t a t e d s t i m u l i but t h a t they a r e not larger than the s t r u c t u r e e f f e c t s o b s e r v e d w i t h u p r i g h t s t i m u l i . The i d e a t h a t a t r a d e - o f f e x i s t s between s t i m u l u s q u a l i t y and o r t h o g r a p h i c s t r u c t u r e is n o t s u p p o r t e d by t h e s e r e s u l t s . I t appears t h a t both accuracy RT t a s k s c a n r e v e a l o r t h o g r a p h i c t a s k s and h i g h - a c c u r a c y s t r u c t u r e e f f e c t s b u t t h a t t h e s p e e d e d RT t a s k d o e s n o t .
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SUMMARY OF ACCURACY AND REACTION TIME EXPERIMENTS
These exper i men t s t en d t o s u p p o r t t h e i d e a t h a t p e r c e p t u a l r e s o l u t i o n of a l e t t e r s t r i n g i s f a c i l i t a t e d t o t h e d e g r e e t h e letters i n the s t r i n g a r e well-structured. Both a c c u r a c y t a s k s w i t h l i m i t e d s t i m u l u s i n f o r m a t i o n and h i g h a c c u r a c y RT t a s k s w i t h c o m p l e t e s t i m u l u s i n f o r m a t i o n a p p e a r t o be s e n s i t i v e t o t h e e f f e c t s o f o r t h o g r a p h i c s t r u c t u r e . However, t h e m a g n i t u d e of t h e RT e f f e c t a p p e a r s s m a l l e r b e c a u s e of t h e r e l a t i v e l y l a r g e o v e r a l l RT d u e t o t h e p r o c e s s i n g time r e q u i r e d f o r o t h e r t h a n v i s u a l p r o c e s s i n g s t a g e s i n t h e RT t a s k . In contrast, a v e r a g e p e r f o r m a n c e i n t h e a c c u r a c y t a s k i s t i t r a t e d t o re m a in a t 7 5 % c o r r e c t and t h i s p e r c e n t a g e meas ure is i n f l u e n c e d a l m o s t c o m p l e t e l y by t h e v i s u a l p r o c e s s i n g s t a g e s . The p o s t h o c e v a l u a t i o n of v a r i o u s measures of o r t h o g r a p h i c s t r u c t u r e i n
E-I
H
F i g u r e 4.19
R e a c t i o n time and p e r c e n t a g e c o r r e c t a s a f u n c t i o n o f d i s p l a y t y p e i n S t u d y 7 : H igh-a c c ura c y RT Task w i t h Poor V i s u a l I n f o r m a t i o n .
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Chapter 5 w i l l allow a more d i r e c t assessment of t h e s e n s i t i v i t y o f p e r f o r m a n c e i n t h e RT and a c c u r a c y t a s k s . A second i m p o r t a n t c o n t r i b u t i o n t o p e r f o r m a n c e is t h e featural information contained in the visual display. P e r f o r m a n c e i n b o t h t h e a c c u r a c y and RT t a s k is s e n s i t i v e t o t h e v i s u a l s i m i l a r i t y of t h e test letters t o t h e t a r g e t l e t t e r . P e r f o r m a n c e on c a t c h t r i a l s is d i s r u p t e d t o t h e e x t e n t t h a t t h e test d i s p l a y contains nontarget l e t t e r s t h a t are s i m i l a r t o t h e target letter. P er f o r man ce on target trials is n o t significantly affected since processing is primarily a function o f t a r g e t l e t t e r p r o c e s s i n g time. However, t h e r e was some h i n t t h a t s i m i l a r n o n t a r g e t s may b e i n c o r r e c t l y c o n f u s e d f o r t h e t a r g e t on t a r g e t t r i a l s an d , t h e r e f o r e , l e a d t o a c o r r e c t r e s p o n s e e v e n t h o u g h t h e t a r g e t i t s e l f was n o t r e c o g n i z e d on that t r i a l I n c o n c l u s i o n , b o t h t h e a c c u r a c y and h i g h a c c u r a c y RT t a s k s a p p e a r t o o f f e r good m e a s u r e s o f t h e u t i l i z a t i o n of o r t h o g r a p h i c s t r u c t u r e i n v i s u a l p r o c e s s i n g . The s p e e d e d RT t a s k does n o t r e v e a l e f f e c t s of o r t h o g r a p h i c s t r u c t u r e . Be fo re evaluating s p e c i f i c d e s c r i p t i o n s of orthographic s t r u c t u r e , some r a t i n g e x p e r i m e n t s were c a r r i e d o u t t o a s s e s s t o w ha t e x t e n t knowledge of o r t h o g r a p h i c s t r u c t u r e is c o n s c i o u s l y a v a i l a b l e and c a n b e r e p o r t e d .
.
OVERT JUDGMENTS Whereas t h e a c c u r a c y and RT e x p e r i m e n t s imply t h a t v i s u a l r e c o g n i t i o n i s s e n s i t i v e t o t h e p r e s e n c e of o r t h o g r a p h i c s t r u c t u r e , i t i s a l s o of i n t e r e s t t o d e t e r m i n e t o what e x t e n t s u b j e c t s a r e awar e o f t h i s knowledge. For t h i s p u r p o s e , s e v e r a l o v e r t judgment e x p e r i m e n t s were c o n d u c t e d . The same 2 0 0 s t i m u l u s items i n Appendix 4 . 1 B we re p r e s e n t e d t o n a t i v e E n g l i s h s p e a k i n g c o l l e g e s t u d e n t s and judgm e nts i n t h e form of r a t i n g s and p a i r e d j u d g men t s were o b t a i n e d . Answers t o t h e f o l l o w i n g q u e s t i o n s were s o u g h t . Could t h e r a t e r s r e l i a b l y a s s i g n r a t i n g s o f o r t h o g r a p h i c s t r u c t u r e t o t h e i t e m s ? Would t h e d i m e n s i o n s u t i l i z e d by t h e r a t e r s d i s c r i m i n a t e t h e items a l o n g o u r r e g u l a r i t y d i m e n s i o n , by p o s i t i o n a l f r e q u e n c y , or b o t h ? Would t h e r a t i n g s a s s i g n e d t o t h e items show a n y meaningful r e l a t i o n s h i p t o t h e i r p e r c e p t u a l a c c u r a c y and r e a c t i o n time r e s u l t s f o u n d i n t h e p r e v i o u s e x p e r i m e n t s ?
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STUDY 8:
CHAPTER 4
T Y P I C A L I T Y RATINGS
T h r e e s e t s o f r a t i n g s were o b t a i n e d . I n t h e f i r s t one o n l y t h e 160 m e a n i n g l e s s anagrams were r a t e d . In t h e second, t h e words were t r a n s f o r m e d i n t o t h e most r e g u l a r pseudowords p o s s i b l e by t h e s u b s t i t u t i o n of a s i n g l e l e t t e r and t h e s e pseudowords were r a t e d a l o n g w i t h t h e anagrams. In the third, the words themselves were included along with the anagrams. T h e s e t h r e e p r o c e d u r e s w e r e used t o o b t a i n t h e m o s t r e l i a b l e r a t i n g s p o s s i b l e and t o d e t e r m i n e how a l t e r a t i o n s i n t h e t o t a l s e t of items r a t e d a f f e c t e d t h e r a t i n g s o f t h e All three ratings were o b t a i n e d u n d e r n e a r l y anagrams. i d e n t i c a l i n s t r u c t i o n s which a s k e d t h e r a t e r s t o b a s e t h e i r j u d g m e n t s on t h e s i m i l a r i t y o f t h e items t o E n g l i s h words where was defined as typicality of English similarity s p e l l i n g . Beyond t h e s e g e n e r a l i n s t r u c t i o n s , no s p e c i f i c a t t e m p t s were made t o i l l u s t r a t e e i t h e r s p e c i f i c r e g u l a r i t y rules or positional-frequency constraints. S u b j e c t s were a s k e d t o r a t e how much t h e l e t t e r s t r i n g s The r a t i n g s c a l e went from "most l i k e l o o k l i k e E n g l i s h words. E n g l i s h " t o " l e a s t l i k e E n g l i s h " on a s c a l e from 1 0 t o 1. C o l l e g e s t u d e n t s r a t e d t h e items in one o f t h r e e c o n d i t i o n s . Seventy subjects rated only the 160 anagrams. S i x t y - f i v e s u b j e c t s r a t e d t h e 160 anagrams p l u s 40 pseudowords which were d e r i v e d by m i s s p e l l i n g one l e t t e r i n e a c h o f t h e 40 word s t i m u l i . S i x t y - t h r e e s u b j e c t s r a t e d t h e 160 anagrams and t h e 40 words. S u b j e c t s were u r g e d n o t t o a d o p t s t r a t e g i e s o f t r y i n g t o see t h e items a s s i m i l a r t o s p e c i f i c words. Those s u b j e c t s t h a t r e c e i v e d a c t u a l words were t o l d t o d i s r e g a r d t h e s e m a n t i c c o n t e n t o f t h e words and s i m p l y j u d g e them on t h e b a s i s o f t h e i r s i m i l a r i t y t o E n g l i s h s p e l l i n g . The method, p r o c e d u r e , and d e t a i l e d r e s u l t s a r e p r e s e n t e d i n Appendix 4.8. F i g u r e 4.20 shows t h e a v e r a g e r a t i n g s f o r t h e items f o r each of t h e t h r e e g r o u p s of s u b j e c t s . The r a t i n g s a s s i g n e d t o t h e 160 anagrams were v e r y s t a b l e a c r o s s t h e t h r e e r a t i n g contexts. The s i x c o r r e l a t i o n s between a l l p o s s i b l e p a i r s o f r a t i n g s a c r o s s t h e t h r e e c o n t e x t s were a l l .97. T h i s r e s u l t demonstrates t h a t t h e r a t i n g s of t h e anagrams w e r e n o t i n f l u e n c e d by t h e p r e s e n c e o f a c t u a l words i n t h e s a m p l e o f items t o be r a t e d . The f i g u r e a l s o shows t h a t t h e r a t i n g s were p r i m a r i l y d e t e r m i n e d by t h e r e g u l a r i t y o f t h e items r a t h e r t h a n by p o s i t i o n a l f r e q u e n c y . Although t h e e f f e c t of p o s i t i o n a l f r e q u e n c y was s t a t i s t i c a l l y s i g n i f i c a n t , t h e r e s u l t s show t h a t
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83
r e g u l a r i t y produced a b o u t seven times the effect that p o s i t i o n a l frequency did. The r e s u l t s i n d i c a t e t h a t when s u b j e c t s a r e a s k e d t o r a t e items on t h e b a s i s o f t h e s i m i l a r i t y t o E n g l i s h s p e l l i n g , t h e y t e n d t o e v a l u a t e t h e items i n terms o f n o t i o n s o f r e g u l a r i t y r a t h e r t h a n i n t e r m s o f t h e p o s i t i o n a l f r e q u e n c y o f t h e items. As c a n b e s e e n i n t h e f i g u r e , t h e words were r a t e d a s more t y p i c a l t h a n even the regular-high anagrams. Even t h e pseudowords c r e a t e d by m i s s p e l l i n g t h e words by a s i n g l e l e t t e r p r o d u c e d h i g h e r r a t i n g s t h a n t h e r e g u l a r anagrams. This r e s u l t means t h a t t h e word s t i m u l i and t h e i r m i s s p e l l i n g s w e r e e i t h e r more t y p i c a l a c c o r d i n g t o t h e s u b j e c t ' s n o t i o n of E n g l i s h s p e l l i n g or t h a t t h e l e x i c a l c o n t e n t o f t h e words and p o s s i b l y t h e i r m i s s p e l l i n g s c o u l d n o t be i g n o r e d i n making t h e j u d g m e n t . If t h e r a t i n g s and t h e t a r g e t s e a r c h e x p e r i m e n t s a r e m e a s u r i n g t h e same knowledge o f o r t h o g r a p h i c s t r u c t u r e , t h e n a
WORD
Figure 4.20
R-H
R-L
I-H
I-L
R a t i n g s from 1 0 ( m o s t l i k e E n g l i s h ) t o 1 ( l e a s t l i k e E n g l i s h ) a s a f u n c t i o n of d i s p l a y t y p e i n Study 8: T y p i c a l i t y Ratings.
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CHAPTER 4
c l o s e r e l a t i o n s h i p between t h e r a t i n g s and t h e RT and a c c u r a c y m e a su r e s of the previous experiments should be o b s e r v e d . A c c o r d i n g l y , we examined t h e r e l a t i o n s h i p between t h e s e r a t i n g s and t h e p e r c e p t u a l p e r f o r m a n c e d a t a c o l l e c t e d i n S t u d i e s 1, 2 , and 3. Average RTs were o b t a i n e d f o r e a c h o f t h e 280 s t i m u l u s i t e m s by a v e r a g i n g t h e c o r r e c t r e s p o n s e RTs f o r t a r g e t and c a t c h t r i a l s from t h e r e a c t i o n time e x p e r i m e n t of S t u d y 1 and t h e mixed-case e x p e r i m e n t o f S t u d y 3. T h i s p r o v i d e d a n a v e r a g e RT f o r e a c h i t e m b ase d on a p p r o x i m a t e l y 204 o b s e r v a t i o n s . S i m i l a r l y , a n a v e r a g e a c c u r a c y was found f o r e a c h item b a se d on t h e t a r g e t and c a t c h t r i a l s f o r t h e s u b j e c t s i n t h e a c c u r a c y e x p e r i m e n t o f S t u d y 1 and t h e p r e c u e v e r s u s p o s t c u e e x p e r i m e n t o f S t u d y 2. The a v e r a g e a c c u r a c y o f e a c h item was b a s e d on 1 5 0 o b s e r v a t i o n s . C o r r e l a t i o n s b et ween t h e t h r e e r a t i n g s , a v e r a g e RT, and a v e r a g e a c c u r a c y a r e shown i n T a b l e 4 . 4 . Two t h i n g s may be observed i n Table 4 . 4 . F i r s t , t h e c o r r e l a t i o n be tw e e n t h e a c c u r a c i e s and RTs of a l l items was .56. Therefore, despite t h e m a g n i t u d e of t h e o b s e r v e d d i f f e r e n c e s between RT and a c c u r a c y measures, b o t h e x p e r i m e n t a l p r o c e d u r e s a p p e a r t o r e v e a l a common p r o c e s s i n g component. T h i s w i l l become e v e n more e v i d e n t i n t h e - c o r r e l a t i o n a l a n a l y s e s ( t o be d i s c u s s e d i n C h a p t e r 5 ) which d e m o n s t r a t e t h a t b o t h item a c c u r a c y and RT t e n d t o show s i m i l a r c o r r e l a t i o n s w i t h v a r i o u s m e a s u r e s o f orthographic structure. The c o r r e l a t i o n s between item a c c u r a c y , RT, and t h e ratings are illuminating. Correlations between t h e two p e r c e p t u a l m eas u r es and t h e r a t i n g s a r e q u i t e h i g h . The p e r c e p t u a l m eas u r es and t h e r a t i n g s s h a r e 31% t o 53% common v a r i a n c e . Whereas t h e knowledge s t r u c t u r e s ta ppe d by t h e r a t i n g p r o c e d u r e s need n o t n e c e s s a r i l y r e l a t e t o t h e knowledge s t r u c t u r e i n f e r r e d from t h e p e r c e p t u a l t a s k s , i t i s e n c o u r a g i n g t o observe t h a t there does appear to be a lawful I t would ap p ear t h a t what one knows a b o u t correspondence. orthographic structure not only influences perception but a l s o i s amenable t o i n t e r r o g a t i o n by c o n s c i o u s p r o c e s s e s . A se c ond e n c o u r a g i n g a s p e c t o f t h i s o b s e r v a t i o n i s t h a t r a t i n g t a s k s and p e r c e p t u a l t a s k s may be r e g a r d e d a s c o n v e r g i n g m e a s u r e s o f o r t h o g r a p h i c s t r u c t u r e . I f b o t h t a p a common d a t a base of o r t h o g r a p h i c s t r u c t u r e knowledge, t h e n w e c a n r e f i n e o u r u n d e r s t a n d i n g o f t h i s knowledge s o u r c e by means of r a t i n g t a s k s a s well a s p e r c e p t u a l t a s k s . For t h e c o r r e l a t i o n a l a n a l y s e s i n C h a p t e r 5 , i t e m a c c u r a c i e s , R T s , and r a t i n g s a r e e a c h r e g a r d e d
EXPERIMENTS ON LETTER AND WORD PERCEPTION
Table 4 . 4
85
C o r r e l a t i o n s among a v e r a g e a c c u r a c y , a v e r a g e RT, and t h e t h r e e r e g u l a r i t y r a t i n g s f o r t h e 200 s t i m u l u s i tems
.
(1) (1) Average a c c u r a c y
(2)
(3)
(4)
---
(2)
Average RT
(3)
R a t i n g w i t h o u t words
.58*
-.56*
--
(4)
R a t i n g w i t h pseudowords
.72
-.61
.97
--
(5)
R a t i n g w i t h words
.73
-.60
.97
.97
*
(5)
-.56
C o r r e l a t i o n based on t h e 1 6 0 anagrams o n l y , c o r r e l a t i o n s b a s e d on a l l 200 s t i m u l u s items.
--
all
other
as
r e l a t e d c o l l a t e r a l dependent measures p o t e n t i a l l y r e v e a l i n g a common o r t h o g r a p h i c s t r u c t u r e component.
STUDY 9:
POSITIONAL-FREQUENCY RATINGS
The r a t i n g s o f S t u d y 8 i n d i c a t e t h a t s u b j e c t s , when g i v e n r e l a t i v e l y n e u t r a l i n s t r u c t i o n s , b a s e t h e i r r a t i n g s more on r e g u l a r i t y than on positional f r e q u e n c y . B e f o r e we c a n conclude t h a t the r e a d e r ' s conscious knowledge is b e s t r e p r e s e n t e d by r e g u l a r i t y , i t i s n e c e s s a r y t o d e t e r m i n e w h e t h e r r e s p o n d on t h e b a s i s o f s u b j e c t s c a n be i n s t r u c t e d t o positional-frequency information. Accordingly, the rating e x p e r i m e n t w i t h o n l y 160 anagrams was r e p l i c a t e d b u t now t h e s u b j e c t s were g i v e n s p e c i f i c p o s i t i o n a l - f r e q u e n c y i n s t r u c t i o n s . The i n s t r u c t i o n s e x p l a i n e d t h e c o n c e p t o f p o s i t i o n a l f r e q u e n c y a l o n g w i t h r e l e v a n t e x a m p l e s and t o l d t h e s u b j e c t s t o r a t e t h e i t e m s e x p l i c i t l y on t h i s basis. The e x a c t i n s t r u c t i o n s ,
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method, and p r o c e d u r e a r e g i v e n i n t h e Appendix 4 . 9 . Except f o r t h e i n s t r u c t i o n s , t h e procedure r e p l i c a t e d t h e previous r a t i n g experiment t h a t gave i n s t r u c t i o n s with r e s p e c t t o t y p i c a l i t y o f E n g l i s h s p e l l i n g . The r e s u l t s and d e t a i l e d a n a l y s e s a r e g i v e n i n Appendix 4 . 9 . Figure 4 . 2 1 g i v e s t h e r e s u l t s of t h i s experiment s t r e s s i n g p o s i t i o n a l f r e q u e n c i e s a l o n g w i t h t h e r e s u l t s of t h e p r e v i o u s e x p e r i m e n t s t r e s s i n g t y p i c a l i t y . The r e s u l t s show t h a t t h e similar with both sets of r a t i n g r e s p o n s e s were v e r y i n s t r u c t i o n s . However, p o s i t i o n a l f r e q u e n c y d i d m a k e more of a contribution with positional-frequency i n s t r u c t i o n s than with t y p i c a l i t y i n s t r u c t i o n s . O v e r a l l , s u b j e c t s tended t o rate high positional-frequency items a s slightly higher t h a n low positional-frequency items to a greater degree with positional-frequency instructions than with typicality i n s t r u c t i o n s . A l s o , t h e e f f e c t of r e g u l a r i t y on t h e judgm e nts
9-
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Figure 4.21
TLPblfiY Poeltlonal Frequency
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R a t i n g s from 1 0 ( mo s t l i k e E n g l i s h ) t o l i k e E n g l i s h ) a s a f u n c t i o n of d i s p l a y typicality instructions (Study positional-frequency i n s t r u c t i o n s (Study
1 (least type for 8) and 9).
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was s l i g h t l y a t t e n t u a t e d w i t h p o s i t i o n a l - f r e q u e n c y i n s t r u c t i o n s relative t o typicality instructions. The r a t i n g experiments indicate that orthographic s t r u c t u r e i n terms o f r e g u l a r i t y a p p e a r s t o b e more c o n s c i o u s l y of positional available than structure in terms f r e q u e n c y . S u b j e c t s t e n d t o r a t e r e g u l a r items a s most l i k e E n g l i s h and i r r e g u l a r items a s l e a s t l i k e E n g l i s h r e g a r d l e s s o f w h e t h e r t h e y were g i v e n t y p i c a l i t y i n s t r u c t i o n s O K p o s i t i o n a l frequency i n s t r u c t i o n s . One limitation in the rating e x p e r i m e n t s may b e t h a t s u b j e c t s t e n d t o r a t e t h e items on t h e b a s i s of r e g u l a r i t y r e g a r d l e s s of t h e i n s t r u c t i o n s t h a t a r e g i v e n . T h e r e f o r e , a more d i r e c t i n d e x of t h e p s y c h o l o g i c a l r e a l i t y o f t h e s e two c o n c e p t s a s d e s c r i p t i o n s o f o r t h o g r a p h i c S t r u c t u r e should be obtained.
STUDY
la:
REGULARITY VERSUS POSITIONAL-FREQUENCY JUDGMENTS
I n o r d e r t o o b t a i n a more d i r e c t i n d e x of o r t h o g r a p h i c S t r u c t u r e , p r e c i s e r e g u l a r i t y i n s t r u c t i o n s were c o n t r a s t e d w i t h precise positional-frequency instructions. I t e m s from e a c h o f t h e f o u r t y p e s o f 1 6 0 anagrams w e r e p a i r e d w i t h e a c h o t h e r s u c h t h a t items o f one t y p e w e r e p a i r e d w i t h items o f t h e same t y p e o r w i t h items o f t h e o t h e r t y p e s . Some s u b j e c t s were g i v e n p a i r s o f items and a s k e d t o p i c k t h e i t e m from e a c h p a i r t h a t was most r e g u l a r . O t h e r s u b j e c t s were g i v e n t h e same p a i r s and a s k e d t o p i c k t h e i t e m t h a t was h i g h e s t i n t e r m s o f p o s i t i o n a l f r e q u e n c y . The i n s t r u c t i o n s , method, pKOCedUKe, and r e s u l t s a r e g i v e n i n Appendix 4 . 1 0 . T h i s experiment allowed a d i r e c t a s s e s s m e n t o f t h e r e l a t i v e w e i g h t c a r r i e d by o r t h o g r a p h i c r e g u l a r i t y and p o s i t i o n a l f r e q u e n c y i n t h e r e a d e r ' s e v a l u a t i o n o f o r t h o g r a p h i c s t r u c t u r e . The j u d g m e n t s o f t h e s e two g r o u p s o f s u b j e c t s were t a b u l a t e d a s t h e p r o p o r t i o n of times t h e y c h o s e a n item from one c a t e g o r y when i t was p a i r e d w i t h a n item from a n o t h e r c a t e g o r y . These r e s u l t s a r e p r e s e n t e d a s T a b l e 4.5 where t h e c e l l s o f t h e t a b l e g i v e t h e p r o p o r t i o n of times a n i t e m from t h e column c a t e g o r y was s e l e c t e d when p a i r e d w i t h a n item from t h e T O W c a t e g o r y . B e f o r e d i s c u s s i n g t h e a c t u a l r e s u l t s i n T a b l e 4 . 5 , i t is i n s t r u c t i v e t o h y p o t h e s i z e how t h i s t a b l e s h o u l d h a v e t u r n e d o u t i f t h e s u b j e c t s i n t h e two c o n d i t i o n s had a c o m p l e t e knowledge o f r e g u l a r i t y and p o s i t i o n a l f r e q u e n c y and had a p p l i e d t h i s knowledge i n a c c o r d a n c e w i t h t h e i n s t r u c t i o n s . Whenever t h e two items d i f f e r e d on t h e d i m e n s i o n r e l e v a n t f o r
CHAPTER 4
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Table 4.5
Paired-judgment preferences for the 200 stimuli under regularity and positional-frequency instructions. Cells represent proportion of times the column item was chosen over the row item. The numbers in parentheses give the hypothetical outcomes assuming that the subject had knowledge of both dimensions and followed instructions. Regularity Instructions R- H
R- H
R- L
I-H
I-L
.475 (.5)
R- L
(.5)
,693
.445 C.5)
I-H
.910 (1.0)
.a77 (1.0)
.523 (.5)
I-L
.938 11.0)
.908 (1.0)
(.5)
.509
.518 (.5)
Positional Frequency Instructions R- H
R-H
.527 (.5)
R-L
.704 (1.0)
I-H
.866 (-5)
I-L
.953 (1.0)
R- L
I-H
I-L
.488 (.5)
.740 (.0) .a95 (.5)
.525 (.5)
.687 (1.0)
.494 (.5)
EXPERIMENTS ON LETTER AND WORD PERCEPTION
T a b l e 4.6
89
Chi-square f o r t h e two p r e d i c t e d o u t c o m e s a g a i n s t t h e observed outcomes f o r t h e two i n s t r u c t i o n c o n d i t i o n s i n study 10. P r e d i c t e d Outcome
Instructions
Regularity
Positional Frequency
Regularity
93.63
1561.26
P o s i t i o n a l Frequency
258.90
1367.50
t h e judgment, t h e s u b j e c t s s h o u l d have always chosen t h e " c o r r e c t item," o n t h a t d i m e n s i o n , i . e . , t h e one t h a t was more the one that was higher in positional r e g u l a r or frequency. Whenever t h e two items were a t e q u i v a l e n t l e v e l s o n t h e r e l e v a n t dimension, the s u b j e c t s s h o u l d have chosen i n d i f f e r e n t l y between them. T h e s e "perfect" hypothetical outcomes a r e a l s o shown i n T a b l e 4.5. Comparing t h e two p a n e l s o f T a b l e 4.5 we o b s e r v e t h a t f o r instructions, subjects made c h o i c e s more both sets of c o n s i s t e n t w i t h t h e a p p l i c a t i o n of r e g u l a r i t y t h a n w i t h t h e a p p l i c a t i o n o f p o s i t i o n a l f r e q u e n c y . I n o r d e r t o assess how w e l l t h e r e s u l t s conformed t o what would be e x p e c t e d from p e r f e c t knowledge and u t i l i z a t i o n o f r e g u l a r i t y o r p o s i t i o n a l f r e q u e n c y , t h e two p r e d i c t e d o u t c o m e s were compared w i t h t h e a c t u a l outcomes under b o t h i n s t r u c t i o n c o n d i t i o n s . T a b l e 4.6 g i v e s t h e Chi-square values for c o m p a r i s o n s o f t h e two p r e d i c t e d outcomes a g a i n s t t h e observed outcomes f o r b o t h instruction conditions. The v a l u e ' s s u p p o r t t h e i n t e r p r e t a t i o n t h a t t h e s u b j e c t s ' p e r f o r m a n c e is more a d e q u a t e l y d e s c r i b e d by r e g u l a r i t y than p o s i t i o n a l frequency. However, t h o u g h s u b j e c t s a p p e a r t o be u s i n g m o s t l y r e g u l a r i t y a s a b a s i s o f t h e i r ratings, i n neither case did t h e ratings indicate t h a t only r e g u l a r i t y was u s e d . I f we compare t h e two p a n e l s o f T a b l e 4.5 t o e a c h o t h e r , we s e e t h a t t h e r e was a n a d d i t i o n a l c o n t r i b u t i o n of p o s i t i o n a l frequency when subjects were e x p l i c i t l y i n s t r u c t e d t o b a s e t h e i r judgments on f r e q u e n c y . E v i d e n t l y , s u b j e c t s c a n modify t h e i r j u d g m e n t s s l i g h t l y when g i v e n e x p l i c i t i n s t r u c t i o n s t o attend t o p o s i t i o n a l frequency.
CHAPTER 4
SUMMARY OF OVERT JUDGMENT EXPERIMENTS The e x p e r i m e n t s s u p p o r t t h e i d e a t h a t knowledge of o r t h o g r a p h i c s t r u c t u r e is c o n s c i o u s l y a v a i l a b l e and c a p a b l e of report. S u b j e c t s a r e r e l a t i v e l y good a t a s s i g n i n g r a t i n g s on t h e b a s i s of r u l e - g o v e r n e d r e g u l a r i t y b u t r e l a t i v e l y poor a t rating items on the basis of statistical redund a n c y . S i m i l a r l y , c h o o s i n g which of a p a i r of items i s more r e g u l a r is r e l a t i v e l y e a s y wh er eas c h o o s i n g which is more f r e q u e n t is n e a r l y i m p o s s i b l e . The p o s t hoc c o r r e l a t i o n s i n C h a p t e r 5 w i l l a l l o w a more d i r e c t and b r o a d e r a s s e s s m e n t of t h e n a t u r e of t h e knowledge u t i l i z e d i n o v e r t judgm e nts of letter strings.
APPENDIX 4 . 1
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Appendix 4 . 1 D e t a i l s o f Method, P r o c e d u r e , and R e s u l t s o f S t u d y 1: I n i t i a l R e p l i c a t i o n
Method S u b j e c t s . One g r o u p of 14 I n t r o d u c t o r y Psyc hology s t u d e n t s p a r t i c i p a t e d i n t h e p o s t c u e a c c u r a c y t a s k f o r an t,t,>-, a d a y on e a c h o f 2 c o n s e c u t i v e d a y s . The d a t a from t h r c a d d i t i o n a l s u b j e c t s were l o s t d u e t o computer s y s t e m f , i i l u r S i x o t h e r s u b j e c t s were t e s t e d b u t t h e i r d a t a were n o t i n c l i r l e d b e c a u s e o f i n a d m i s s i b l e o v e r a l l a c c u r a c y . Another g r o u p o f 14 IntKOdUCtOKy P s y ch o l o g y s t u d e n t s p a r t i c i p a t e d f o r a n hour e a c h d a y on 2 c o n s e c u t i v e d a y s i n t h e p r e c u e RT t a s k . A l l s u b j e c t s i n both t a s k s passed a p r e l i m i n a r y v i s i o n t e s t e s t a b l i s h i n g a t l e a s t 20/40 a c u i t y f o r b o t h e y e s . A l l s u b j e c t s w e re awarded r e s e a r c h p a r t i c i p a t i o n c r e d i t t o war d t h e i r p s y c h o l o g y g r a d e . S t i m u l i . A l i s t i n g of t h e 100 h i g h e s t and 108 l o w e s t summed single-letter positional-frequency anagrams w e re o b t a i n e d f o r s e v e r a l hundred common s i x - l e t t e r words s e l e c t e d from t h e Kucera and F r a n c i s ( 1 9 6 7 ) word l i s t . The l i s t i n g s o f t h e anagrams were p r o d u ced by a computer program which g e n e r a t e d a l l 720 p o s s i b l e p e r m u t a t i o n s f o r e a c h s i x - l e t t e r word. The p o s i t i o n a l f r e q u e n c y f o r e a c h p e r m u t a t i o n was computed from t h e Mayzner and T r e s s e l t ( 1 9 6 5 ) s i n g l e - l e t t e r c o u n t s f o r s i x - l e t t e r words by summing t h e p o s i t i o n - d e p e n d e n t f r e q u e n c y for e a c h l e t t e r . Words w i t h r e p e a t e d l e t t e r s w e re n o t u se d . From t h e 720 anagrams f o r e a c h s i x - l e t t e r word, two were c h o s e n w i t h h i g h - p o s i t i o n a l f r e q u e n c i e s and two w e re chosen with low-positional f r e q u e n c i e s . Within each frequency p a i r , o n e member was o r t h o g r a p h i c a l l y r e g u l a r ahd t h e o t h e r o r t h o g r a p h i c a l l y i r r e g u l a r . The rules used f o r judging r e g u l a r i t y a r e l i s t e d i n Appendix 4 . 1 A . L i s t e d i n Appendix 4.18 a r e t h e 200 s t i m u l u s i t e m s - - t h e 40 words and t h e 4 anagrams o f e a c h word. One-hundred t w e n t y p r a c t i c e s t i m u l i were g e n e r a t e d from 2 4 a d d i t i o n a l words. The se i t e m s w e re n o t a s e v e n l y matched f o r r e g u l a r i t y and p o s i t i o n a l f r e q u e n c y a s t h e e x p e r i m e n t a l i t e m s and a few c o n t a i n e d r e p e a t e d l e t t e r s . Two o c c u r r e n c e s o f e a c h o f t h e 1 2 0 p r a c t i c e s t i m u l i were randomized f o r e a c h s u b j e c t ' s p r a c t i c e s e q u e n c e and two o c c u r r e n c e s o f e a c h of t h e 200 e x p e r i m e n t a l s t i m u l i were randomized f o r e a c h s u b j e c t ' s e x p e r i m e n t a l s e q u e n c e . One o c c u r r e n c e was t e s t e d a s a t a r g e t t r i a l and one a s a c a t c h
.
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t r i a l . On t a r g e t t r i a l s . t h e l e t t e r was s e l e c t e d randomly w i t h r e p l a c e m e n t from t h e s i x l e t t e r s i n t h e t e s t s t r i n g . For c a t c h t r i a l s , a t a r g e t was s e l e c t e d randomly from t h e s e t o f 26 l e t t e r s w e i g h t e d by t h e i r p r o b a b i l i t y o f o c c u r r e n c e i n t h e s t i m u l u s s e t . If t h e s e l e c t e d l e t t e r was p r e s e n t i n t h e d i s p l a y s t r i n g , a d d i t i o n a l d r a w i n g s w i t h r e p l a c e m e n t w e r e made u n t i l a n a p p r o p r i a t e t a r g e t l e t t e r was s e l e c t e d . The l e t t e r s 1, k, 9, 5 , and 2 d i d n o t o c c u r i n t h e e x p e r i m e n t a l s t i m u l u s s t r i n g s and t h e r e f o r e were n e v e r t e s t e d . The d i s p l a y s were p r e s e n t e d on a B e e h i v e model %paratus. v i d e o computer t e r m i n a l u n d e r t h e c o n t r o l o f a H a r r i s DC6024/5 t h e terminal's c o m p u t e r . Hardware m o d i f i c a t i o n s p e r m i t t e d v i d e o t o b e t u r n e d on and o f f w i t h p r o g r a m - g e n e r a t e d control s i g n a l s . The d i s p l a y s t r i n g s were l o a d e d i n t o t h e memory b u f f e r o f t h e t e r m i n a l w i t h t h e v i d e o o f f and t h e n t h e v i d e o was t u r n e d on f o r t h e a p p r o p r i a t e e x p o s u r e d u r a t i o n . The Beehive employs a P4, b l u e - w h i t e phosphor which d e c a y s t o . l % o f maximum l u m i n a n c e w i t h i n 32 msec. The e x p e r i m e n t was c o n d u c t e d i n a p a r t i a l l y d a r k e n e d room t o e n h a n c e image contrast. A l l s i n g l e - l e t t e r t a r g e t and l e t t e r - s t r i n g t e s t d i s p l a y s were p r e s e n t e d i n l o w e r c a s e l e t t e r s . The B e e h i v e u s e s a 5 x 7 d o t m a t r i x , 2.5 mm w i d e x 5 mm h i g h , A t t h e a v e r a g e s u b j e c t ' s v i e w i n g d i s t a n c e of a p p r o x i m a t e l y 38 cm, t h e s i x - l e t t e r s t r i n g s s u b t e n d e d a h o r i z o n t a l v i s u a l a n g l e o f 2.25 d e g r e e s and a v e r t i c a l v i s u a l a n g l e of . 7 5 d e g r e e . The d i s p l a y s were p r e s e n t e d i n t h e upper c e n t e r o f t h e s c r e e n . The s i n g l e - l e t t e r t a r g e t was p o s i t i o n e d t o a p p e a r t h r e e c h a r a c t e r p o s i t i o n s t o t h e l e f t of t h e s t r i n g d i s p l a y , a h o r i z o n t a l v i s u a l a n g l e s e p a r a t i o n of .75 d e g r e e . To a c h i e v e a r a p i d and c o n t r o l l e d p r e s e n t a t i o n r a t e , t h e e n t i r e d i s p l a y s e q u e n c e f o r a n item was d i s p l a y e d b e n e a t h a c a r d b o a r d mask a f f i x e d t o t h e f a c e o f t h e c a t h o d e r a y t u b e ( C R T ) . A r e c t a n g u l a r window i n t h e mask s e r v e d a s a f i x a t i o n box and p e r m i t t e d o n l y t h e d e s i r e d p o r t i o n o f t h e d i s p l a y t o be o b s e r v e d . -___ Procedure. The s u b j e c t s i n the a c c u r a c y t a s k were informed t h a t t h e e x p o s u r e d u r a t i o n would b e b r i e f and would b e a d j u s t e d d u r i n g t h e s e s s i o n t o m a i n t a i n a n a c c u r a c y o f 75%. A t r i a l began w i t h t h e p r e s e n t a t i o n o f t h e s i x - l e t t e r stimulus string for a brief duration. After t h e appropriate exposure duration, t h e d i s p l a y was s c r o l l e d upward o n t h e CRT r e p l a c i n g t h e s t r i n g w i t h a masking s t i m u l u s c o n s i s t i n g o f s i x u p p e r c a s e -Xs. The masking s t i m u l u s was p r e s e n t e d f o r 208 msec t h e n scrolled again t o present the t a r g e t l e t t e r . The t a r g e t l e t t e r remained i n v i e w u n t i l t h e s u b j e c t r e s p o n d e d , a t which t i m e t h e
APPENDIX 4 . 1
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d i s p l a y was t e r m i n a t e d and a 500 msec i n t e r t r i a l i n t e r v a l begun. The e x p o s u r e d u r a t i o n o f t h e t e s t s t r i n g was i n d i v i d u a l l y determined for each subject during the practice t r i a l s . Because o f t h e 60 Hz r e f r e s h r a t e o f t h e CRT o n e r e f r e s h c y c l e ( 1 6 . 7 msec) was c h o s e n a s t h e b a s i c t i m e unit. The number of c y c l e s needed t o a c h i e v e a n o v e r a l l a c c u r a c y l e v e l o f 75% was d e t e r m i n e d o n - l i n e u s i n g a v e r s i o n of the adaptive PEST algorithm (Taylor & Creelman, 1 9 6 7 ) . Exposure d u r a t i o n was not changed during the e x p e r i m e n t a l t r i a l s . The i n i t i a l e x p o s u r e d u r a t i o n was 20 c y c l e s ( 3 3 4 msec) f o r a l l s u b j e c t s . The r a n g e o f e x p o s u r e s needed by t h e 1 4 s u b j e c t s f o r 75% a c c u r a c y was 1 t o 1 2 c y c l e s w i t h a median e x p o s u r e d u r a t i o n o f 3 c y c l e s ( 5 0 msec). The s u b j e c t s i n t h e RT t a s k were i n s t r u c t e d t o r e s p o n d a s A l l s u b j e c t s were a l s o r a p i d l y and a s a c c u r a t e l y a s p o s s i b l e . t o l d t h a t o n e - h a l f o f t h e t r i a l s would be t a r g e t t r i a l s and one-half would b e c a t c h t r i a l s . The d i s p l a y s e q u e n c e was A t r i a l began w i t h the a l t e r e d t o accommodate t h e p r e c u i n g . p r e s e n t a t i o n of t h e t a r g e t l e t t e r a t t h e l e f t of t h e f i x a t i o n window f o r 500 msec. The t a r g e t l e t t e r was t h e n t e r m i n a t e d and 1 s e c l a t e r t h e s t i m u l u s s t r i n g was d i s p l a y e d . The s t i m u l u s remained i n view u n t i l t h e s u b j e c t r e s p o n d e d , a t which time t h e A d i s p l a y was t e r m i n a t e d and a 500 msec i n t e r v a l begun. masking f i e l d was n o t u s e d . To a c q u a i n t s u b j e c t s i n b o t h t h e a c c u r a c y and RT t a s k s w i t h t h e r e s p o n s e p r o c e d u r e and v i s u a l d i s p l a y , e a c h d a y ' s s e s s i o n began w i t h 10 t r i a l s c o n s i s t i n g o f o n l y t h e word YES o r NO i n s t e a d o f t h e d i s p l a y s t r i n g . No t a r g e t l e t t e r was presented. The s u b j e c t s p r e s s e d t h e c o r r e s p o n d i n g l y l a b e l e d response buttons. The YES r e s p o n s e was a s s i g n e d t o e a c h s u b j e c t ' s p r e f e r r e d hand ( r i g h t hand f o r 9 o f t h e 1 4 s u b j e c t s i n t h e a c c u r a c y t a s k ; 1 3 o f t h e 1 4 s u b j e c t s i n t h e RT t a s k ) . The "yes-no" t r i a l s were f o l l o w e d by t h e 240 p r a c t i c e t r i a l s and t h e 400 e x p e r i m e n t a l t r i a l s . The p r a c t i c e t r i a l s were d i v i d e d i n t o f o u r 60 t r i a l b l o c k s and t h e e x p e r i m e n t a l t r i a l s w e r e d i v i d e d i n t o f i v e 8 0 - t r i a l b l o c k s . A t t h e end o f e a c h b l o c k t h e s u b j e c t was g i v e n a n o p p o r t u n i t y t o r e s t and r e c e i v e d f e e d b a c k i n t h e form o f a p e r c e n t c o r r e c t s c o r e o r RT and e r r o r r a t e , a s a p p r o p r i a t e , for t h e p r e c e d i n g b l o c k . A l l s u b j e c t s were t e s t e d i n two s u c h s e s s i o n s s c h e d u l e d on consecutive days.
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O r t h o g r a p h i c s t r u c t u r e . Analyses o f v a r i a n c e were c a r r i e d o u t on t h e a v e r a g e p e r c e n t a g e c o r r e c t f o r e a c h s u b j e c t f o r e a c h of t h e 5 d i s p l a y t y p e s and t a r g e t v e r s u s c a t c h t r i a l s . For t h e a c c u r a c y t a s k , t h e main e f f e c t o f d i s p l a y t y p e was s i g n i f i c a n t , F (4, 52) = 8 2 . 5 6 , E < . 0 0 1 , and t h e d i f f e r e n c e s among t h e s e c o n d i t i o n s were t e s t e d w i t h s p e c i f i c c o n t r a s t s . A c c u r a c y f o r words was 1 2 % g r e a t e r t h a n f o r t h e b e s t pseudoword items ( r e g u l a r - h i g h ) , E (1, 52) = 40.54, E < .001. Three o r t h o g o n a l c o n t r a s t s analogous t o a 2 x 2 a n a l y s i s of v a r i a n c e f o r t h e f o u r nonword d i s p l a y t y p e s r e v e a l e d t h a t t h e r e g u l a r s t r i n g s were j u d g e d 8 % more a c c u r a t e l y t h a n i r r e g u l a r s t r i n g s , E (1, 52) = 7 . 0 5 , E < .01. High p o s i t i o n a l - f r e q u e n c y s t r i n g s were judged 5 % more accurately t h a n low p o s i t i o n a l - f r e q u e n c y s t r i n g s , E (1, 5 2 ) = 7.05, E < .01. The i n t e r a c t i o n o f p o s i t i o n a l f r e q u e n c y and r e g u l a r i t y was n o t s i g n i f i c a n t , 2 (1, 52) = 3 . 2 0 , p > .05. For t h e RT a n a l y s i s , RTs f o r i n c o r r e c t t r i a l s and c o r r e c t t r i a l R T s which e x c e e d e d 2 sec ( l e s s t h a n .2% o f t h e d a t a ) w e r e e x c l u d e d from t h e a n a l y s e s l e a v i n g a p p r o x i m a t e l y 76 o f 8 0 p o s s i b l e o b s e r v a t i o n s p e r c e l l . For t h e RT d a t a , t h e r e was a l s o a s i g n i f i c a n t main e f f e c t of d i s p l a y t y p e , 1 ( 4 , 5 2 ) = 17.16, E < .001. T h i s main e f f e c t was examined w i t h t h e same s e t o f s p e c i f i c c o n t r a s t s . The 7 msec a d v a n t a g e f o r words o v e r r e g u l a r - h i g h pseudowords was n o t s i g n i f i c a n t , E (1, 52) = 2 . 0 1 , E > .10. R e g u l a r items were j u d g e d 23 msec f a s t e r t h a n i r r e g u l a r items, a s i g n i f i c a n t d i f f e r e n c e , E (1, 52) = 9 . 5 4 , E < .005. N e i t h e r t h e 4 msec d i f f e r e n c e b e t w e e n h i g h and low p o s i t i o n a l f r e q u e n c y n o r t h e i n t e r a c t i o n o f r e g u l a r i t y and p o s i t i o n a l f r e q u e n c y were s i g n i f i c a n t , b o t h Es < 1. Error The main p e r c e n t a g e s were a n a l y z e d s i m i l a r l y t o t h e RTs. e f f e c t o f d i s p l a y t y p e was n o t s i g n i f i c a n t , E ( 4 , 5 2 ) = 1 . 1 3 . test for the e f f e c t s of S i m i l a r i t y a n a l y s e s . To s i m i l a r i t y between t h e t a r g e t l e t t e r and t h e l e t t e r s i n t h e d i s p l a y , t h e d a t a were f i r s t pooled a c r o s s d i s p l a y t y p e s . Each t r i a l ' s t a r g e t l e t t e r was c l a s s i f i e d a c c o r d i n g t o which l e t t e r s i n t h e d i s p l a y were l i k e l y t o be s e e n a s v e r y s i m i l a r t o t h e t a r g e t . The c l a s s i f i c a t i o n was d e r i v e d from t h e l o w e r c a s e s i n g l e - l e t t e r c o n f u s a b i l i t y s t u d y p u b l i s h e d by Bouma ( 1 9 7 1 ) . A l e t t e r was c o u n t e d a s s i m i l a r t o t h e t a r g e t l e t t e r i f t h e l e t t e r was e r r o n e o u s l y i d e n t i f i e d a s t h e t a r g e t more t h a n 5 % o f t h e time. T a b l e 4 . 2 p r e s e n t s t h e c l a s s i f i c a t i o n a c c o r d i n g t o t h i s a n a l y s i s . Each t r i a l was t h e n c l a s s i f i e d by t h e number o f n o n t a r g e t l e t t e r s i n t h e d i s p l a y t h a t were s i m i l a r t o t h e
APPENDIX 4 . 1
95
t a r g e t a c c o r d i n g t o t h i s c r i t e r i o n . Roughly 4 6 , 3 3 , 1 3 , and 1 % of each s u b j e c t ' s t r i a l s f e l l i n t o t h e c a t e g o r i e s z e r o , o n e , two, and t h r e e s i m i l a r l e t t e r s ( o t h e r t h a n t h e t a r g e t l e t t e r i t s e l f ) , respectively. For t h e a c c u r a c y t a s k d a t a , t h e e f f e c t of number s i m i l a r l e t t e r s was s i g n i f i c a n t . ( 3 , 39) = 7 . 1 4 , p < .001. Accuracy on t a r g e t t r i a l s i n c r e a s e d some w i t h i n c r e a s e s i n t h e number o f s i m i l a r l e t t e r s , w h e r e a s a c c u r a c y on c a t c h t r i a l s d e c r e a s e d s i g n i f i c a n t l y w i t h i n c r e a s e s i n t h e number o f s i m i l a r l e t t e r s , -F ( 3 , 3 9 ) = 22.28, p < .001. For t h e RT t a s k , i n c r e a s i n g t h e number of s i m i l a r l e t t e r s p r o d u c e d a s i g n i f i c a n t i n c r e a s e i n RT, E ( 3 , 39) = 4.41 < .01. The i n c r e a s e was c l e a r l y l a r g e r on c a t c h t r i a l s t h a n t a r g e t t r i a l s , E ( 3 , 39) = 3 . 1 3 , p < . 0 5 . T a r g e t - c a t c h d i f f e r e n c e s . For t h e a c c u r a c y t a s k , a c c u r a c y was g r e a t e r f o r c a t c h t r i a l s ( 8 4 % ) t h a n f o r t a r g e t t r i a l s ( 7 2 % ) . E (1, 1 3 ) = 1 9 . 6 5 , p < .001, and t h i s e f f e c t i n t e r a c t e d ( 4 , 52) = 8.14, < .001. O r t h o g r a p h i c with d i s p l a y types, s t r u c t u r e had a g r e a t e r e f f e c t on t a r g e t t h a n c a t c h t r i a l s . For t h e RT t a s k , t h e r e was a d i f f e r e n c e between t a r g e t and c a t c h t r i a l s . C a t c h t r i a l s w e r e 47 msec s l o w e r t h a n t a r g e t However, t h i s e f f e c t d i d t r i a l s , E (1, 1 3 ) = 4 2 . 5 5 , p < .001. Target-catch n o t i n t e r a c t w i t h d i s p l a y t y p e , 1( 4 , 52) = 1.49. d i f f e r e n c e s were a l s o r e f l e c t e d i n t h e e r r o r r a t e s i n t h e RT t a s k . T a r g e t t r i a l s e x p e r i e n c e d more e r r o r s ( 6 . 8 % ) t h a n d i d T h e r e was c a t c h t r i a l s ( 3 . 3 % ) , E (1, 1 3 ) = 29.88, p < .0001. no i n t e r a c t i o n w i t h d i s p l a y t y p e , E ( 4 , 52) = 1 . 2 4 .
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Appendix 4 . 1 A R u l e s f o r t h e S e l e c t i o n of O r t h o g r a p h i c a l l y R e g u l a r and I r r e g u l a r S t r i n g s T h e s e r u l e s were d e r i v e d by e x t e n d i n g t h e r u l e s g i v e n i n Venezky ( 1 9 7 0 ) , Venezky and Massaro ( 1 9 7 9 ) , and Massaro e t a l . ( 1 9 7 9 ) . Among a l l p o s s i b l e anagrams of a word, a l e t t e r s t r i n g was r e g a r d e d a s o r t h o g r a p h i c a l l y i r r e g u l a r i f i t c o n t a i n e d a t l e a s t one o f t h e f o l l o w i n g s p e l l i n g s : a. p h o n o l o g i c a l l y i l l e g a l ( i n E n g l i s h ) i n i t i a l or f i n a l c l u s t e r (e.g. , tlfies, i a s G ) . b. o r t h o g r a p h i c a l l y i l l e g a l s p e l l i n g for a n i n i t i a l or f i n a l c o n s o n a n t or c o n s o n a n t c l u s t e r ( e . g . , keagc, tlerav) c . a n i l l e g a l vowel s p e l l i n g ( e . g . , p r s a e d , n m t E ) . d . a p h o n o l o g i c a l l y i l l e g a l m e d i a l c l u s t e r ( e . g . , ilmpes, iGsa) L e t t e r s t r i n g s were r e g a r d e d a s r e g u l a r i f t h e y were p h o n o l o g i c a l l y l e g a l and c o n t a i n e d common vowel and c o n s o n a n t spellings.
.
.
APPENDIX 4 . 1 8
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Appendix 4 . 1 B The 200 S t i m u l u s Items Used i n S t u d i e s 1 - 1 0 The items l i s t e d a r e i n columns a c c o r d i n g t o t y p e , where W word; R-H = r e g u l a r - l o w ; I-H = i r r e g u l a r - h i g h ; R-L = r e g u l a r - l o w ; and I - L = i r r e g u l a r - l o w . Each row c o n t a i n s a word and t h e f o u r anagrams g e n e r a t e d from i t .
=
Word
R- H -
a c tion amount answer barely belong breath bridge charge double famous finger garden gather glance hardly itself lawyer longer master modern
cainot mauton swaner blayer goblen thaber begr i d chager bodule foamus f er i n g nagred thager caleng hyr a l d siflet weraly logren tamer dormen
R-L
onicat otanum erswan bye K a1 glenob therab gredib greach edolub osafum gref i n gredan greath glecan hydra1 flesit l y e r aw gleron steram drenom
I-H aiocnt auotnm wnraes lbraey lnboeg bhrtea ierbgd ahcge r leoubd uaomf s rfnieg arnged hrtaeg lcnaeg yr ahld t l f ies rwlaey glnoer mr t a e s oermnd
I-L
icntoa nmtaou rnwesa r bleya ebgnlo rtbeha ebrgdi hreagc obdeul ofmsua efngr i ednrga grheta eclnga rdlhya eflsti e y r lwa egnrlo emr t s a rmedno
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APPENDIX 4 . 1 8 (COnt.)
Word
R- H -
R- L -
I-H -
I-L -
mother namely nearly permit player poetry purely reason remain result shared simple single spread stared stream travel trials turned winter
thomer manely lareny p r ime t rapley petory yulper sarone r amine surtel shread pimsel snigel p r ased sarted trames vartle s a r t il drunet t r iwen
therom lyeman nyelar trepim lyerap tyerop ryelup erosan amer i n tresul dreash ems1 i p glesin dresap dresat tresam treval t r isal tredun trewin
m rote h lmnaey lrnaey tmr i e p p l r aey yptoer lpyuer snaoer mr a i e n lrtues srdaeh ilmpes ilgnes p r saed srtaed mtraes avrlet iastlr rdnuet wrntei
hre tm o emnyla enyr l a rtpei m epylra erytpo erplyu rnseoa rnie m a elsrtu hsreda lsepmi nglesi dsepr a dtsera esrtma tlerav irltsa edtrnu rntewi
APPENDIX 4.2
99
Appendix 4.2 D e t a i l s o f Method, P r o c e d u r e , a n d R e s u l t s o f S t u d y 2 : Precue versus Postcue
Method Subjects. Eighteen I n t r o d u c t o r y Psychology s t u d e n t s , 8 m a l e and 1 0 f e m a l e , p a r t i c i p a t e d f o r a n h o u r e a c h d a y o n 2 c o n s e c u t i v e d a y s and r e c e i v e d r e s e a r c h p a r t i c i p a t i o n c r e d i t t o w a r d t h e i r p s y c h o l o g y g r a d e . The d a t a f r o m a n a d d i t i o n a l 1 2 s t u d e n t s was l o s t d u e t o m a c h i n e m a l f u n c t i o n s an d i n a d m i s s i b l e A l l s u b j e c t s passed a preliminary v i s i o n o v e r a l l accuracy. t e s t e s t a b l i s h i n g a t l e a s t 20/40 a c u i t y f o r b o t h e y e s . None o f t h e s u b j e c t s had s e r v e d i n a n y o f o u r p r e v i o u s e x p e r i m e n t s . ~S t i m u l i a n d a p p a r a t u s . The stimuli, a p p a r a t u s , and d i s p l a y s e q u e n c e f o r t h e p o s t c u e t a s k were i d e n t i c a l t o t h o s e For o f t h e a c c u r a c y t a s k o f S t u d y 1 d e s c r i b e d i n A p p en d i x 4 . 1 . t h e precue t a s k , a t r i a l began w i t h t h e p r e s e n t a t i o n o f t h e t a r g e t l e t t e r a t t h e l e f t o f t h e f i x a t i o n window f o r 5 0 0 msec. The t a r g e t l e t t e r was t h e n t e r m i n a t e d and 1 s e c l a t e r t h e was displayed for the appropriate exposure string duration. A f t e r d i s p l a y i n g t h e s t i m u l u s s t r i n g , t h e masking s t i m u l u s was s c r o l l e d i n t o v i e w a n d r e m a i n e d o n t h e s c r e e n u n t i l t h e s u b j e c t responded. The r a n g e o f e x p o s u r e d u r a t i o n s us ed f o r t h e p r e c u e t a s k was 1 t o 8 c y c l e s w i t h a m e d i a n o f 2 cycles. F o r t h e p o s t c u e t a s k t h e r a n g e was 2 t o 11 c y c l e s w i t h a median of 3 c y c l e s . Procedure. Half t h e s u b j e c t s r e c e i v e d t h e precue t a s k t h e f i r s t day and t h e p o s t c u e t a s k t h e second day. For t h e r e m a i n i n g s u b j e c t s t h i s o r d e r was r e v e r s e d . Each d a y t h e a p p r o p r i a t e t a s k w a s e x p l a i n e d t o t h e s u b j e c t and p e r f o r m a n c e a c c u r a c y was s t r e s s e d . S u b j e c t s were t o l d t h a t o n e - h a l f o f t h e t r i a l s would b e t a r g e t a n d o n e - h a l f would b e c a t c h t r i a l s . A s i n S t u d y 1, t h e t e s t s e q u e n c e c o n s i s t e d o f 1 0 "y es- n o " t r i a l s , 4 6 0 - t r i a l p r a c t i c e b l o c k s d u r i n g w h i c h e x p o s u r e w as a d j u s t e d w i t h t h e a d a p t i v e a l g o r i t h m , a n d ,5 8 0 - t r i a l e x p e r i m e n t a l b l o c k s A l l subjects d u r i n g which t h e e x p o s u r e remained c o n s t a n t . r e s p o n d e d " y e s " t o t a r g e t t r i a l s w i t h t h e i r p r e f e r r e d h an d ( r i g h t hand f o r 1 7 o f t h e 1 8 s u b j e c t s ) .
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Re s u l t s Orthographic s t r u c t u r e . An a n a l y s i s o f v a r i a n c e was c o m p u t e d from t h e s u b j e c t s ' mean a c c u r a c i e s f o r t h e 2 x 2 x 5 combinations of type of task (precue versus postcue) , t r i a l (word, type ( t a r g e t v e r s u s c a t c h ) , and d i s p l a y c o n d i t i o n regular-high, regular-low, i r r e g u l a r - h i g h , and irregular-low) The m a i n e f f e c t o f d i s p l a y t y p e was s i g n i f i c a n t , E ( 4 , 6 8 ) = 63.57, E < . 0 0 1 , a n d p l a n n e d c o m p a r i s o n s were p e r f o r m e d a s i n S t u d y 1. Words were j u d g e d 8 % m o r e a c c u r a t e l y t h a n t h e regular-high p o s i t i o n a l - f r e q u e n c y n o n w o r d s , E (1, 6 8 ) = 3 4 . 8 8 , E < .001. F o r t h e a n a g r a m d i s p l a y t y p e s , r e g u l a r s t r i n g s were j u d g e d 6 % more a c c u r a t e l y t h a n i r r e g u l a r s t r i n g s , (1, 6 8 ) = 4 2 . 0 1 , E < .001. H i g h p o s i t i o n a l - f r e q u e n c y s t r i n g s were j p d g e d 5 % more a c c u r a t e l y t h a n l o w p o s i t i o n a l - f r e q u e n c y s t r i n g s , E (1, 6 8 ) = 3 0 . 6 3 , E < .001. R e g u l a r i t y and p o s i t i o n a l f r e q u e n c y d i d The i n t e r a c t i o n o f n o t i n t e r a c t , E (1, 6 8 ) = 1 . 7 1 , p > .15. t y p e o f t a s k w i t h d i s p l a y c o n d i t i o n was s i g n i f i c a n t , E ( 4 , 6 8 ) = 2.99, p < .024. T h e o v e r a l l e f f e c t s o f s t r u c t u r e were g r e a t e r i n t h e postcue than t h e precue task. Although accuracy f o r i r r e g u l a r - l o w p o s i t i o n a l f r e q u e n c y was e q u i v a l e n t i n t h e two t a s k s , the trends diverged s t e a d i l y with increasing s t r u c t u r e s o t h a t a c c u r a c y f o r w o r d s was 6 % g r e a t e r in the postcue than t h e precue task. No o t h e r i n t e r a c t i o n s a p p r o a c h e d significance. S i m i l a r i t y a n a l y s e s . A p o s t h o c s i m i l a r i t y a n a l y s i s was performed a s i n t h e p r e v i o u s experiment. The a n a l y s i s o f variance included a s f a c t o r s t h e type of t a s k , t h e type of t r i a l ( t a r g e t v e r s u s c a t c h ) , a n d t h e number o f s i m i l a r l e t t e r s . T h e r e was a m a i n e f f e c t o f t h e number o f s i m i l a r l e t t e r s , (3, 51) = 2.86, E < . 0 5 , and a s i g n i f i c a n t i n t e r a c t i o n w i t h c a t c h and t a r g e t t r i a l s , 1 ( 3 , 5 1 ) = 3 . 5 8 , p < . 0 2 5 . Relative t o the p r e v i o u s a c c u r a c y e x p e r i m e n t shown i n F i g u r e 4 . 1 0 , t h e p r e s e n t r e s u l t s shown i n F i g u r e 4 . 1 3 r e v e a l e d much s m a l l e r d e c r e a s e s o n c a t c h t r i a l s and l i t t l e c h a n g e on t a r g e t t r i a l s w i t h i n c r e a s e s The same r e s u l t s were i n t h e number o f s i m i l a r l e t t e r s . o b s e r v e d i n t h e p r e c u e and p o s t c u e t a s k s . N e i t h e r t h e main e f f e c t o f Target versus catch trials. type of task (precue versus postcue) nor t r i a l type (target their v e r s u s c a t c h ) was s i g n i f i c a n t ( b o t h E s < 1 ) ; h o w e v e r , (1,17) = 8 . 6 3 , E < . 0 0 9 . It is i n t e r a c t i o n was s i g n i f i c a n t , apparent from F i g u r e 4 . 1 4 t h a t s u b j e c t s were more a c c u r a t e o n t a r g e t than catch t r i a l s i n the precue condition, whereas t h i s b i a s was r e v e r s e d i n t h e p o s t c u e t a s k .
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Appendix 4.3 D e t a i l s of t h e Method, P r o c e d u r e , and R e s u l t s o f S t u d y 3: Mixed-Case
Method Subjects. E i g h t e e n I n t r o d u c t o r y Psychology s t u d e n t s , 3 m a l e and 1 5 f e m a l e s , p a r t i c i p a t e d f o r a n hour e a c h d a y on 2 consecutive days and received research participation c r e d i t . One a d d i t i o n a l s u b j e c t was l o s t for f a i l u r e t o complete t h e ex p er i men t . A l l s u b j e c t s passed a p r e l i m i n a r y v i s i o n t e s t w i t h a t l e a s t 20/40 a c u i t y f o r b o t h e y e s and no s u b j e c t had s e r v e d i n p r e v i o u s e x p e r i m e n t s . Stimuli, apparatus, p r o c e d u r e . The p r o c e d u r e and a p p a r a t u s were t h e same a s i n t h e RT t a s k o f S t u d y 1 w i t h t h e following modifications. The t a r g e t l e t t e r p r e s e n t e d a t t h e b e g i n n i n g of e a c h t r i a l was d i s p l a y e d i n b o t h i t s u p p e r c a s e and l o w e r c a s e f o r m s t o remind t h e s u b j e c t t h a t e i t h e r form m i g h t be T h e s e two l e t t e r s were shown present in the s t i m u l u s display. f o r 500 msec f o l l o w e d by a 1 s e c b l a n k i n t e r v a l and w e r e c e n t e r e d a t what would be s e r i a l p o s i t i o n s 3 and 4 i n t h e s t i m u l u s d i s p l a y . The l e t t e r s t r i n g was t h e n d i s p l a y e d u n t i l t h e s u b j e c t responded. For a randomly s e l e c t e d o n e - h a l f of a l l t r i a l s , t h e f i r s t t h r e e l e t t e r s of t h e s t i m u l u s s t r i n g were p r e s e n t e d i n u p p e r c a s e and t h e l a s t t h r e e l e t t e r s i n l o w e r c a s e . For t h e r e m a i n i n g t r i a l s t h i s o r d e r of c a s e s was r e v e r s e d . A s i n t h e p r e v i o u s e x p e r i m e n t s , t h e s u b j e c t s s e r v e d i n two 1-hour s e s s i o n s on c o n s e c u t i v e d a y s . Each s e s s i o n c o n s i s t e d of 1 0 "yes-no" warm-up t r i a l s , 240 p r a c t i c e t r i a l s , and 400 e x p e r i m e n t a l t r i a l s . The instructions to the subjects e m p h a s i z e d s p e e d and a c c u r a c y o f r e s p o n d i n g and e n c o u r a g e d s u b j e c t s t o t r y t o " r e a d " e a c h d i s p l a y a s a whole a s t h e most e f f e c t i v e means of making f a s t and a c c u r a t e j u d g m e n t s ( J o h n s t o n & McClelland, 1 9 7 4 ) . Results
Orthographic s t r u c t u r e . The s u b j e c t s ' mean RTs f o r t h e 10 c o m b i n a t i o n s o f t y p e of t r i a l ( t a r g e t and c a t c h ) and d i s p l a y type (word, r e g u l a r - h i g h , regular-low, irregular-high, and irregular-low) were a n a l y z e d . I n c o r r e c t t r i a l RTs and c o r r e c t t r i a l R T s e x c e e d i n g 2 sec were e x c l u d e d . The e r r o r r a t e s v a r i e d between 1 . 0 % and 8 . 9 % . To d e t e r m i n e i f t h i s v a r i a b i l i t y i n
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e r r o r r a t e was a f f e c t i n g RT t r e n d s , t h e s u b j e c t s were r a n k e d on e r r o r r a t e and d i v i d e d i n t o two g r o u p s ; t h e n i n e s u b j e c t s w i t h t h e l o w e s t e r r o r r a t e s formed one g r o u p and t h e r e m a i n i n g subjects the other. The a v e r a g e RT f o r t h e s u b j e c t s w i t h l o w e r e r r o r r a t e s was 647 msec, w h e r e a s f o r t h e h i g h e r e r r o r r a t e s u b j e c t s , t h e mean RT was 756 msec, E (1, 16) = 3.47, p < .078. Grouping d i d n o t i n t e r a c t w i t h a n y o t h e r f a c t o r i n t h e analysis. The s i g n i f i c a n t main e f f e c t f o r d i s p l a y t y p e , E ( 4 , 6 4 ) = 6 5 . 2 3 , p < .001, was a n a l y z e d i n t e r m s o f t h e same c o m p a r i s o n s examined i n t h e p r e v i o u s e x p e r i m e n t s . The 7 msec d i f f e r e n c e between words and r e g u l a r - h i g h pseudowords was n o t s i g n i f i c a n t , -F < 1. The c o m p a r i s o n s among t h e anagrams r e v e a l e d t h a t t h e 30 msec d i f f e r e n c e b e t w e e n r e g u l a r and i r r e g u l a r a n a g r a m s was significant, ( 1, 6 4 ) = 3 3 . 5 0 , < .001. A l s o t h e 1 4 msec d i f f e r e n c e between h i g h and low p o s i t i o n a l - f r e q u e n c y items was < .006. The i n t e r a c t i o n o f s i g n i f i c a n t , E (1, 6 4 ) = 8 . 0 9 , r e g u l a r i t y w i t h p o s i t i o n a l f r e q u e n c y was n o t s i g n i f i c a n t , E < 1. An a n a l y s i s o f v a r i a n c e was c a l c u l a t e d on e r r o r r a t e s . T h e d i s p l a y t y p e main e f f e c t , E ( 4 , 6 8 ) = 2 . 8 6 , p < . 0 3 0 , and t h e i n t e r a c t i o n of d i s p l a y type w i t h t r i a l ( t a r g e t versus catch), E (4,68) = 2.98, p < .025, were both seem t o be s i g n i f i c a n t . Although t h e t r e n d does not p a r t i c u l a r l y m e a n i n g f u l , t h e s o u r c e o f t h e s e two e f f e c t s i s t h e somewhat g r e a t e r e r r o r r a t e f o r t h e i r r e g u l a r i t e m s o n t a r g e t trials. S i m i l a r i t y a n a l y s e s . A r e s t r i c t e d s i m i l a r i t y a n a l y s i s was done on only the lowercase letters in the display strings. R e a c t i o n times i n c r e a s e d 2 4 msec on c a t c h t r i a l s and d i d n o t c h a n g e on t a r g e t t r i a l s w i t h i n c r e a s e s from z e r o t o one s i m i l a r l e t t e r s , E (1, 1 7 ) = 5 . 8 4 , p < .05. T a r g e t v e r s u s c a t c h t r i a l s . A s i n t h e p r e v i o u s RT t a s k , t a r g e t t r i a l s were j u d g e d more q u i c k l y ( 6 6 0 msec) t h a n w e r e c a t c h t r i a l s ( 7 4 3 m s e c ) , E (1, 1 6 ) = 65.23, p < .001. Type o f t r i a l d i d n o t i n t e r a c t w i t h t y p e of l e t t e r s t r i n g . For t h e error data, catch trials (97.1%) were s i g n i f i c a n t l y more a c c u r a t e t h a n t a r g e t t r i a l s ( 9 3 . 8 % ) a s i n t h e RT d a t a o f S t u d y 1, 1 (1, 1 7 ) = 3 3 . 8 1 , p < .001. However, t r i a l t y p e d i d i n t e r a c t w i t h d i s p l a y t y p e a s noted above.
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Appendix 4 . 4 D e t a i l s o f Method, P r o c e d u r e , and R e s u l t s o f S t u d y 4 : L i m i t e d Viewing T i m e
Subjects. S i x t e e n I n t r o d u c t o r y Psychology s t u d e n t s , 8 m a l e s and 8 f e m a l e s , were t e s t e d f o r a s i n g l e 90-minute s e s s i o n and r e c e i v e d r e s e a r c h p a r t i c i p a t i o n c r e d i t . A s i n t h e p r e v i o u s e x p e r i m e n t s , a l l s u b j e c t s were t e s t e d f o r v i s u a l a c u i t y o f a t l e a s t 20/40, a l l r e s p o n d e d w i t h t h e i r p r e f e r r e d hand (right hand f o r 1 5 of t h e 1 6 ) , and no s u b j e c t had p a r t i c i p a t e d i n t h e e a r l i e r experiments. Procedure. The s t i m u l i and a p p a r a t u s were t h e same a s t h e p r e v i o u s e x p e r i m e n t s . An e x p e r i m e n t a l t r i a l began w i t h t h e p r e s e n t a t i o n of t h e lowercase t a r g e t l e t t e r p o s i t i o n e d w i t h i n t h e v i e w i n g r e c t a n g l e a t d i s p l a y s e r i a l p o s i t i o n 4 f o r 500 msec. A 1 sec b l a n k i n t e r v a l f o l l o w e d and t h e n t h e s t i m u l u s s t r i n g i n l o w e r c a s e was p r e s e n t e d f o r 200 msec. The s t i m u l u s was s c r o l l e d upward and r e p l a c e d by s i x u p p e r c a s e Xs which s e r v e d a s a mask and r e m a i n e d i n v i e w u n t i l t h e s u b j e c t responded. F o l l o w i n g t h e s u b j e c t ' s r e s p o n s e t h e r e was a 500 msec i n t e r t r i a l i n t e r v a l . The t e s t i n g s e s s i o n f o r e a c h s u b j e c t c o n s i s t e d of 1 0 "yes-no" warm-up t r i a l s , 240 p r a c t i c e t r i a l s , and 2 4 0 0 - t r i a l experimental sessions. A s i n a l l previous experiments, t r i a l s were g r o u p e d i n t o 80 t r i a l b l o c k s . Between b l o c k s s u b j e c t s were g i v e n a m i n u t e o r two o f r e s t and f e e d b a c k i n t h e form of a mean RT e r r o r p e r c e n t a g e f o r t h e b l o c k . A 5 m i n u t e r e s t was g i v e n between t h e two e x p e r i m e n t a l s e s s i o n s . The s u b j e c t s were t o l d t h a t h a l f t h e t r i a l s would be t a r g e t t r i a l s and h a l f would be c a t c h t r i a l s . They were a l s o i n f o r m e d t h a t t h e s t i m u l u s d i s p l a y would be b r i e f and t h a t t h e y would h a v e t o r e a d i t c a r e f u l l y . Speed and a c c u r a c y o f r e s p o n d i n g were e m p h a s i z e d .
O r t h o g r a p h i c s t r u c t u r e . A s i n t h e p r e v i o u s RT s t u d i e s , t h e s u b j e c t s ' mean RT f o r e a c h c e l l o f t h e d e s i g n , e x c l u d i n g i n c o r r e c t t r i a l RTs and c o r r e c t RTs e x c e e d i n g 2 s e c , were a n a l y z e d . The s u b j e c t s ' e r r o r r a t e s v a r i e d between 4.5% and 1 1 . 9 % , which i s h i g h e r t h a n n o r m a l l y d e s i r e d f o r RT t a s k s . For
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t h i s r e a s o n , s u b j e c t s were a g a i n r a n k e d b y e r r o r r a t e an d divided i n t o lo w a n d h i g h e r r o r r a t e g r o u p s . An a n a l y s i s o f v a r i a n c e i n d i c a t e d no e f f e c t o f g r o u p i n g t h e s u b j e c t s by e r r o r r a t e ( a l l F s < 1 ) . T h e a n a l y s e s o f t h e RT d a t a i n d i c a t e d no Only t h e d i s p l a y e f f e c t of d i s p l a y t y p e , E ( 4 , 56) = 1.27. t y p e b y t r i a l t y p e i n t e r a c t i o n was s i g n i f i c a n t . The n a t u r e o f t h i s i n t e r a c t i o n may b e s e e n i n F i g u r e 4 .1 6 . T a r g e t an d c a t c h RTs a p p e a r t o t r a d e - o f f a c r o s s d i s p l a y t y p e s . This p a t t e r n is i n d i c a t i v e of a s h i f t i n b i a s , o r a t l e a s t confidence, across A s s u b j e c t s become m o r e r e l u c t a n t ( s l o w e r ) the d i s p l a y types. t o r e s p o n d " y e s " t h e y become m o r e w i l l i n g ( f a s t e r ) t o r e s p o n d "no." For t h e most p a r t , t h i s p a t t e r n o f d e c r e a s i n g c o n f i d e n c e c o i n c i d e s w i t h t h e d e c l i n e i n o r t h o g r a p h i c s t r u c t u r e w h i c h is a r e a s o n a b l e r e a c t i o n t o d i s p l a y s t h a t a r e more d i f f i c u l t t o resolve. An a n a l y s i s o f t h e e r r o r d a t a r e v e a l e d o n l y a m a i n e f f e c t This display type o f d i s p l a y t y p e , E ( 4 , 6 0 ) = 6 . 7 9 , E < .001. Th e m ai n e f f e c t was e x a m in e d w i t h t h e u s u a l s e t o f c o n t r a s t s . d i f f e r e n c e i n e r r o r r a t e b e t w e e n w o r d s an d r e g u l a r - h i g h items was t o o s m a l l t o b e s i g n i f i c a n t , b u t t h e 1.8% d i f f e r e n c e b e t w e e n w o r d s and t h e a v e r a g e o f t h e r e g u l a r items was The e r r o r r a t e was significant, (1.60) = 6.42, p < -013. 1. 7 % s m a l l e r f o r r e g u l a r t h a n i r r e g u l a r items, (1,60) = 8.59, E < .005. N e i t h e r t h e p o s i t i o n a l - f r e q u e n c y e f f e c t ( e r r o r r a t e d i f f e r e n c e of o n l y 0.4%, 1 < 1) nor t h e i n t e r a c t i o n of r e g u l a r i t y w i t h t h e p o s i t i o n a l f r e q u e n c y were s i g n i f i c a n t , (1, 6 0 ) = 1 . 3 0 . Similarity analyses. F o r r e s p o n s e a c c u r a c y , t h e number o f s i m i l a r n o n t a r g e t l e t t e r s had no e f f e c t o n e i t h e r t a r g e t o r c a t c h t r i a l s , 2 ' s > .1. F o r RTs, t h e e f f e c t o f t h e number o f s i m i l a r n o n t a r g e t l e t t e r s had no e f f e c t o n t a r g e t t r i a l s an d a RTs l a r g e e f f e c t o n c a t c h t r i a l s , 1 ( 3 , 4 5 ) = 1 4 . 2 4 , E < .0 0 1 . i n c r e a s e d o n l y 1 msec o n t a r g e t t r i a l s an d 67 msec o n c a t c h t r i a l s w i t h i n c r e a s e s from z e r o t o t h r e e s i m i l a r l e t t e r s . Target-catch differences. A s i n t h e p r e v i o u s p o s t c u e RT e x p e r i m e n t s t h e r e was a m a i n e f f e c t o f t r i a l t y p e , E (1, 1 4 ) = 2 6 . 6 2 , E < . 0 0 1 , w i t h t a r g e t t r i a l s ( 5 6 3 msec) b e i n g r e s p o n d e d t o more q u i c k l y t h a n c a t c h t r i a l s ( 6 3 5 msec). T h e r e was a l s o the i n t e r a c t i o n of t r i a l type with d i s p l a y type discussed a b o v e. F o r t h e e r r o r d a t a , t h e r e was n e i t h e r a s i g n i f i c a n t m ai n e f f e c t o f t r i a l t y p e , E (1, 1 5 ) = 1 . 9 5 , n o r a s i g n i f i c a n t i n t e r a c t i o n w i t h d i s p l a y t y p e , E < 1.
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Appendix 4.5 D e t a i l s of Method, P r o c e d u r e , and R e s u l t s o f S t u d y 5: Speeded RT Task w i t h Good V i s u a l I n f o r m a t i o n
Method Subjects. Eleven I n t r o d u c t o r y Psychology s t u d e n t s , 10 f e m a l e and 1 m a l e , were t e s t e d f o r a s i n g l e 1-hour s e s s i o n and received research participation credit. S u b j e c t s were t e s t e d i n f o u r g r o u p s ; t h r e e g r o u p s w i t h t h r e e p a r t i c i p a n t s and o n e w i t h two. A l l s u b j e c t s r e s p o n d e d w i t h t h e i r p r e f e r r e d hand in ( r i g h t hand f o r 9 of t h e 11). No s u b j e c t had p a r t i c i p a t e d an e a r l i e r e x p e r i m e n t . A p p a r a t u s 4 s t i m u l i . The s t i m u l i were t h e same a s i n t h e p r e v i o u s e x p e r i m e n t s . The v i s u a l d i s p l a y s were g e n e r a t e d by a DEC LSI-11 computer under s o f t w a r e c o n t r o l and p r e s e n t e d & on T e k t r o n i x Monitor 604 o s c i l l o s c o p e s ( T a y l o r , K l i t z k e , MaSSaKO, 1 9 7 8 ) . T h e s e m o n i t o r s employ a P31 phosphor w i t h a d e c a y t o . l % o f s t i m u l a t e d l u m i n a n c e w i t h i n 3 2 msec. The a l p h a b e t c o n s i s t e d of l o w e r c a s e n o n s e r i f e d l e t t e r s r e s e m b l i n g t h e t y p e f o n t U n i v e r s 55. For a n o b s e r v e r s e a t e d c o m f o r t a b l y a t an experimental s t a t i o n , t h e s i x - l e t t e r d i s p l a y s subtended a b o u t 1 . 9 d e g r e e o f v i s u a l a n g l e h o r i z o n t a l l y and t h e d i s t a n c e from t h e t o p o f a n a s c e n d e r t o t h e b o t t o m o f a d e s c e n d e r was degree. This computerized laboratory f a c i l i t y about .4 p e r m i t t e d t h e t e s t i n g of up t o f o u r s u b j e c t s i n p a r a l l e l . Each s u b j e c t r e c e i v e d t h e same v i s u a l d i s p l a y on h i s o r h e r d i s p l a y m o n i t o r , and t h e computer collected individual s u b j e c t ' s responses. Procedure. The experimental procedure was a response-signal method ( R e e d , 1 9 7 3 ) i n which t h e s u b j e c t e n d e a v o r s t o respond i n synchrony w i t h a s i g n a l which, i n t h i s c a s e , was t h e o f f s e t of t h e s t i m u l u s d i s p l a y s t r i n g . The e x a c t p r o c e d u r e was a s f o l l o w s . A t r i a l began w i t h t h e p r e s e n t a t i o n o f a s i n g l e f i x a t i o n p o i n t i n t h e c e n t e r of t h e s c r e e n . After 250 msec t h e f i x a t i o n p o i n t was r e p l a c e d by t h e t e s t l e t t e r f o r 500 msec. The f i x a t i o n p o i n t r e t u r n e d f o r 250 msec f o l l o w e d by t h e d i s p l a y s t r i n g . The d i s p l a y was i n i t i a l l y p r e s e n t e d f o r 550 msec w i t h t h i s v a l u e r e v i s e d e v e r y 2 0 t h t r i a l t o a c h i e v e a n o v e r a l l a c c u r a c y o f 75% f o r t h e g r o u p o f s u b j e c t s b e i n g t e s t e d . The t r i a l t e r m i n a t e d when a l l s u b j e c t s r e s p o n d e d o r , in the e v e n t t h a t a s u b j e c t f a i l e d t o r e s p o n d , a t t h e end of 4 s e c . A 500 msec i n t e r t r i a l i n t e r v a l was g i v e n . A t t h e end o f e v e r y 20
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t r i a l s , e a c h s u b j e c t was g i v e n f e e d b a c k a b o u t h i s o r h e r A t t r i a l termination the p e r f o r m a n c e i n t h e f o l l o w i n g manne'r. word FEEDBACK was p r e s e n t e d a t t h e c e n t e r o f t h e s c r e e n f o r 1 sec. One-half second l a t e r two columns o f numbers a p p e a r e d on t h e s c r e e n , a s u b j e c t number and t h e s u b j e c t ' s a v e r a g e d e v i a t i o n from t h e d i s p l a y s t r i n g o f f s e t t o t h e r e s p o n s e i n msec. A n e g a t i v e d e v i a t i o n i n d i c a t e d a n a v e r a g e r e s p o n s e p r i o r t o the display offset: a positive deviation indicated t h a t the a v e r a g e r e s p o n s e f e l l a f t e r t h e d i s p l a y o f f s e t . Each s u b j e c t ' s number was C l e a r l y p o s t e d a t h i s o r h e r s u b j e c t s t a t i o n t o was facilitate remembering which feedback score a p p r o p r i a t e . The f e e d b a c k s c o r e s were v i s i b l e f o r 2.5 s e c a f t e r which came the normal half second intertrial i n t e r v a l . The s u b j e c t s ' i n s t r u c t i o n s a c q u a i n t e d them w i t h t h e t a s k and t h e g e n e r a l t y p e s o f s t i m u l u s i t e m s . I t was s t r e s s e d t h a t t h e s u b j e c t s were t o be a s a c c u r a t e a s p o s s i b l e and y e t respond a s nearly in synchrony with the signal as possible. They were t o l d how t h e y would r e c e i v e f e e d b a c k and a g a i n i t was s t r e s s e d t h a t t h e y s h o u l d e n d e a v o r t o m a i n t a i n a z e r o f e e d b a c k s c o r e . A l l s u b j e c t s r e c e i v e d 120 p r a c t i c e t r i a l s f o l l o w e d by two e x p e r i m e n t a l s e s s i o n s o f 400 t r i a l s each. A s h o r t r e s t b r e a k was g i v e n between t h e two e x p e r i m e n t a l sessions. All s u b j e c t s became a d e p t a t t h e t a s k by t h e end o f t h e p r a c t i c e t r i a l s or e a r l y i n the f i r s t experimental s e s s i o n so t h a t t h e d i s p l a y o f f s e t t i m e s were r e a s o n a b l y s t a b l e t h r o u g h o u t t h e two s e s s i o n s . Average d i s p l a y o f f s e t times f o r t h e f o u r g r o u p s o f s u b j e c t s were a s f o l l o w s : 4 1 2 , 634, 485, and 505 msec.
Results S e p a r a t e a n a l y s e s were made of t h e mean a c c u r a c i e s and t h e mean R T s f o r b o t h c o r r e c t and i n c o r r e c t t r i a l s . For t h e a c c u r a c y d a t a t h e r e were n o s i g n i f i c a n t e f f e c t s ( a l l Fs < 1 ) . The a n a l y s i s o f v a r i a n c e f o r t h e R T s i n c l u d e d t r i a l t y p e , d i s p l a y c o n d i t i o n , and c o r r e c t n e s s o f t h e r e s p o n s e a s f a c t o r s . (1, 10) = T h e r e were s i g n i f i c a n t e f f e c t s of t y p e o f t r i a l , 8.04, < .017; c o r r e c t n e s s of r e s p o n s e , (1, 1 0 ) = 1 9 . 9 9 , < .001; and t h e i n t e r a c t i o n of t h e s e two f a c t o r s , (1, 1 0 34.32, < .001. T h e s e e f f e c t s w e r e a r e s u l t of t h e s i g n i f i c a n t l y s l o w e r c o r r e c t c a t c h t r i a l r e s p o n s e s seen i n F i g u r e 4.17. A l t h o u g h we o b s e r v e d t h e normal RT a d v a n t a g e f o r c o r r e c t t a r g e t t r i a l s over c o r r e c t c a t c h t r i a l s , t h e incor e c t t a r g e t and i n c o r r e c t c a t c h t r i a l s n e a r l y c o i n c i d e d w i t h t h e
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correct type, display ( 4 , 40) from 477
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t a r g e t t r i a l responses. The main e f f e c t o f d i s p l a y ( 4 , 40) = 3 . 1 7 , p < . 0 2 3 , and t h e i n t e r a c t i o n of t y p e w i t h c o r r e c t n e s s o f r e s p o n s e and t y p e of t r i a l , = 3.25, < . 0 2 1 , were s i g n i f i c a n t . Mean RT i n c r e a s e d msec f o r words t o 492 msec f o r i r r e g u l a r - l o w nonwords.
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Appendix 4.6 D e t a i l s o f Method, P r o c e d u r e , and R e s u l t s of S t u d y 6: Speeded RT T a s k w i t h Poor V i s u a l I n f o r m a t i o n Method Subjects. Thirteen Introductory Psychology student v o l u n t e e r s p a r t i c i p a t e d a s s u b j e c t s ; t h e d a t a o f two w e r e l o s t due t o a computer m a l f u n c t i o n . All s u b j e c t s were n a t i v e E n g l i s h s p e a k e r s , had normal o r c o r r e c t e d - t o - n o r m a l v i s i o n , had not participated i n any o f t h e o t h e r e x p e r i m e n t s , were right-handed, and r e c e i v e d some c r e d i t t o w a r d t h e i r c o u r s e grade for p a r t i c i p a t i n g . Materials, apparatus, procedure. The s t i m u l i and in a p p a r a t u s were t h e same a s i n S t u d y 5 and a r e d e s c r i b e d Appendix 4.5. The i m p o r t a n t difference in the present e x p e r i m e n t i s t h a t t h e c o m p l e t e t e s t l e t t e r s t r i n g was r o t a t e d 180 d e g r e e s i n t h e p i c t u r e p l a n e . Rotating t h e complete t e s t s t r i n g r a t h e r than t h e individual l e t t e r s s e p a r a t e l y c r e a t e s a d i s p l a y much e a s i e r t o r e a d ( K o l e r s , 1 9 7 0 ) . The i n i t i a l d i s p l a y d u r a t i o n was l e n g t h e n e d t o 700 msec. The t a r g e t l e t t e r was s t i l l p r e s e n t e d u p r i g h t . S u b j e c t s responded " y e s " w i t h t h e i r d o m i n a n t hand.
Results The means among l e t t e r - s t r i n g t y p e s i n d i c a t e d a 1.1% a d v a n t a g e o f words o v e r t h e b e s t pseudowords ( r e g u l a r - h i g h ) and a 1 . 6 % a d v a n t a g e of words o v e r a l l t y p e s o f nonwords. Accuracy f o r r e g u l a r nonwords was 0.2% b e t t e r t h a n f o r i r r e g u l a r nonwords. Nonwords o f h i g h p o s i t i o n a l f r e q u e n c y had a 0 . 5 % a d v a n t a g e o v e r nonwords o f low p o s i t i o n a l f r e q u e n c y . A s m i g h t b e e x p e c t e d from d i f f e r e n c e s t h i s s m a l l , t h e a n a l y s i s o f v a r i a n c e i n d i c a t e d no e f f e c t of l e t t e r - s t r i n g types, E < 1. F u r t h e r m o r e , t h e r e was n o d i f f e r e n c e between t a r g e t and < 1. c a t c h t r i a l s , E < 1, and no i n t e r a c t i o n , The a c c u r a c y r e s u l t s o f t h e p r e s e n t e x p e r i m e n t c a n be compared t o t h o s e o f S t u d y 5 w i t h u p r i g h t l e t t e r s t r i n g s . This a n a l y s i s i n d i c a t e d no d i f f e r e n c e s o f any k i n d between t h e two (1, 2 1 ) = 0.14; for experiments ( f o r upright-rotated, target-catch, (1, 2 1 ) = 1 . 1 8 ; f o r t h e u p r i g h t - r o t a t e d x target-catch i n t e r a c t i o n , 1 (1, 21) = 0.07; for the l e t t e r - s t r i n g t y p e s , E ( 4 , 84) = 0.92; f o r t h e u p r i g h t - r o t a t e d x letter-string interaction, (4, 84) = 0.09; for the
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target-catch x l e t t e r - s t r i n g i n t e r a c t i o n , 1 ( 4 , 8 4 ) = 1.27; and f o r t h e three-way i n t e r a c t i o n , ( 4 , 84) = 0.23). An e x a m i n a t i o n o f t h e r e a c t i o n t i m e s i n t h e r o t a t e d experiment revealed r e s u l t s s i m i l a r t o those of t h e accuracy data. Means were c a l c u l a t e d o n c o r r e c t r e a c t i o n t i m e s t h a t d i d Words were a c t u a l l y n o t e x c e e d 2 , 0 0 0 msec ( 0 . 2 5 % e x c e e d e d ) . slower than regular-high nonwords. r e s p o n d e d t o 9 msec R e a c t i o n t i m e s were 9 msec l o n g e r f o r i r r e g u l a r n o n w o r d s t h a n low f o r r e g u l a r n o n w o r d s a n d 8 msec l o n g e r f o r n o n w o r d s o f r a t h e r than of high p o s i t i o n a l frequency. The a n a l y s i s o f v a r i a n c e i n d i c a t e d s i g n i f i c a n t l y l o n g e r r e a c t i o n times f o r c a t c h t r i a l s a s compared t o t a r g e t t r i a l s , -F (1, 11) = 4 6 . 7 3 , p < - 0 0 1 , b u t no e f f e c t o f 1e t t e r - s t r i ng t y p e s , 2 ( 4 , 4 4 ) = 2 . 4 3 , p < . 0 5 , a n d no i n t e r a c t o n , 1 ( 4 , 4 4 ) = 1 . 6 0 , p < .l. The r e a c t i o n times f o r t h e r o t a t e d l e t t e r s t r i n g s a l s o were c o m p a r e d t o t h o s e f o r t h e u p r i g h t l e t t e r s t r i n g s . The a v e r a g e r e a c t i o n t i m e f o r r o t a t e d l e t t e r s t r i n g s was 1 0 4 msec l o n g e r t h a n f o r u p r i g h t l e t t e r s t r i n g s , F (1, 2 1 = 2 6 . 9 4 , p < .001. C a t c h t r i a l s t o o k 66 msec l o n g e r t h a n t a r g e t t r i a l s , 1 (1, 2 1 ) = 7 5 . 8 4 , p < . 0 0 1 , b u t t h i s d i d n o t i n t e r a c t w i t h rotated, (1, 2 1 ) = w h e t h e r t h e l e t t e r s t r i n g s were 1.26. T h e r e was a n o v e r a l l d i f f e r e n c e o f l e t t e r - s t r i n g t y p e s , F (4, 8 4 ) = 5 . 7 7 , p < .001. Letter-string types did not interact with the other factors: with rotation, (4, 84) = 0.49; w i t h t a r g e t - c a t c h t r i a l s , 1 ( 4 , 84) = 1.18; and f o r t h e three-way i n t e r a c t i o n , E ( 4 , 84) = 1.18. To e x a m i n e d i f f e r e n c e s among display durations, the d i s p l a y d u r a t i o n s f o r e a c h o f t h e 40 s e t s o f 20 t r i a l s were grouped i n t o 4 b l o c k s o f 10 s e t s each. Each o f t h e c o n s e c u t i v e 4 blocks t h u s represented 10 d i s p l a y d u r a t i o n s f o r 10 sets of 20 t r i a l s . An a n a l y s i s o f v a r i a n c e i n d i c a t e d no d i f f e r e n c e s among b l o c k s , ( 3 , 33) = 0.67, b u t d i d i n d i c a t e a d i f f e r e n c e among t h e 1 0 s e t s w i t h i n a b l o c k , E ( 9 , 9 9 ) = 4 . 2 5 , 2 < . 0 0 1 , and a b l o c k b y s e t i n t e r a c t i o n , E ( 2 7 , 2 9 7 ) = 2 . 2 1 , E < . 0 0 5 . T h e s e e f f e c t s r e f l e c t t h e o p e r a t i o n o f b o t h p r a c t i c e and fatigue. Initially the display durations decreased with e x p e r i e n c e , b u t t h e n i n c r e a s e d t o w a r d t h e end o f t h e f i r s t 200 trials. Following a break between h a l v e s of t h e experiment, d i s p l a y times a g a i n decreased u n t i l l a t e i n t h e second h a l f o f t h e experiment.
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The d i s p l a y d u r a t i o n s a l s o were compared between t h e u p r i g h t and r o t a t e d e x p e r i m e n t s . A l t h o u g h t h e a v e r a g e d i s p l a y d u r a t i o n was 498 msec f o r u p r i g h t p r e s e n t a t i o n and 556 msec f o r r o t a t e d p r e s e n t a t i o n , t h e e f f e c t was n o t s i g n i f i c a n t , (1, 2 1 ) = 2.64, n o r was t h e r e a n e f f e c t o f t h e b l o c k s of 1 0 d i s p l a y d u r a t i o n s , E ( 3 , 6 3 ) = 1 . 5 6 , and t h e two f a c t o r s a l s o d i d n o t T h e r e w e r e , however, d i f f e r e n c e s i n t e r a c t , E ( 3 , 6 3 ) = 2.53. among i n d i v i d u a l d i s p l a y d u r a t i o n s , ( 9 , 189) = 2.05, E < .05, and d i s p l a y d u r a t i o n s i n t e r a c t e d w i t h e v e r y t h i n g e l s e : w i t h upright-rotated l e t t e r s t r i n g s , E ( 9 , 1 8 9 ) = 4.65, E < . 0 0 1 ; w i t h b l o c k s , F ( 2 7 , 567) = 1 . 6 3 , p < . 0 5 ; and i n a t h r e e - w a y interaction, ( 2 7 , 567) = 1 . 6 9 , E < .05. These i n t e r a c t i o n s r e f l e c t t h e s l i g h t f a t i g u e f a c t o r in t h e r o t a t e d e x p e r i m e n t and t h e a b s e n c e o f s u c h i n t h e u p r i g h t e x p e r i m e n t . For t h e u p r i g h t s t i m u l i , t h e d i s p l a y d u r a t i o n s continued t o decrease throughout the experiment.
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Appendix 4.7 D e t a i l s o f Method, P r o c e d u r e , and R e s u l t s o f S t u d y 7: High-Accuracy RT Task w i t h Poor V i s u a l I n f o r m a t i o n
Twelve s u b j e c t s were used and met t h e same c o n s t r a i n t s a s The same i n t h e s p e e d e d RT t a s k i n S t u d y 6 (Appendix 4 . 6 ) . r o t a t e d s t i m u l i a l s o were used w i t h t h e f o l l o w i n g p r o c e d u r a l d i f f e r e n c e s . A t r i a l c o n s i s t e d o f a 250 msec f i x a t i o n p o i n t f o l l o w e d by a n u p r i g h t l e t t e r which was p r e s e n t e d f o r 5 0 0 msec a t t h e f i x a t i o n p o i n t and t h e n t h e r o t a t e d l e t t e r s t r i n g . The l e t t e r s t r i n g remained on t h e s c r e e n u n t i l t h e l a s t s u b j e c t ( u p t o f o u r a t a time) r e s p o n d e d . Results Means were c a l c u l a t e d f o r c o r r e c t r e a c t i o n times t h a t d i d msec (1.4% e x c e e d e d ) . R e a c t i o n times n o t e x c e e d 2,000 g e n e r a l l y i n c r e a s e d from words t o t h e i r r e g u l a r - l o w nonwords, F ( 4 , 4 4 ) = 6 . 4 7 , E < .081. R e g u l a r - h i g h nonwords a v e r a g e d 6 msec l o n g e r t h a n w o r d s , i r r e g u l a r nonwords r e s u l t e d i n r e a c t i o n times t h a t were 1 6 msec l o n g e r t h a n r e g u l a r nonwords, and nonwords o f low p o s i t i o n a l f r e q u e n c y r e s u l t e d i n r e a c t i o n times t h a t were 18 msec l o n g e r t h a t nonwords of h i g h p o s i t i o n a l f r e q u e n c y . The a v e r a g e r e a c t i o n times f o r c a t c h t r i a l s was 110 msec l o n g e r t h a n f o r t a r g e t t r i a l s , F (1, 11) = 1610.10, p < .001, b u t t h i s d i d n o t i n t e r a c t w i t h l e t t e r - s t r i n g t y p e s , 1 ( 4 , 4 4 ) = 0.79.
D i f f e r e n c e s between l e t t e r s t r i n g s were f u r t h e r examined by o r t h o g o n a l c o n t r a s t s . The d i f f e r e n c e between words and a l l nonwords was s i g n i f i c a n t , t ( 4 4 ) = 3 . 1 8 , p < .005, a s was t h e d i f f e r e n c e between r e g u l a r and i r r e g u l a r nonwords, t ( 4 4 ) = 1.683, p = .05. However, t h e d i f f e r e n c e between nonwords o f h i g h and low p o s i t i o n a l f r e q u e n c y was n o t s i g n i f i c a n t , t ( 4 4 ) = 0.94. S i m i l a r l y , a Newman-Kuels t e s t i n d i c a t e d t h a t t h e 6 msec difference between words and the best pseudowords ( r e g u l a r - h i g h ) was n o t s i g n i f i c a n t , p > .10. A c o m p a r i s o n of r e a c t i o n times between t h e i n i t i a l r e p l i c a t i o n e x p e r i m e n t u s i n g u p r i g h t s t i m u l i and t h e p r e s e n t times f o r r o t a t e d s t i m u l i study indicated t h a t reaction a v e r a g e d 2 7 9 msec l o n g e r t h a n f o r u p r i g h t s t i m u l i , (1, 2 4 ) = 42.35, 2 < .0Ol. The d i f f e r e n c e between c a t c h and t a r g e t
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was s i g n i f i c a n t , F (1, 24) = 1 5 3 . 4 4 , p < . 0 0 1 , a s was the t r i a l type x rotated-upright interaction, (1, 2 4 ) = 23 . 6 8 , 2 < - 0 0 1 . D i f f e r e n c e s b e t w e e n l e t t e r s t r i n g s were s i g n i f i c a n t , E ( 4 , 9 6 ) = 20.12, 2 < .001, b u t l e t t e r s t r i n g s d i d not i n t e r a c t with anything: with rotated-upright, ( 4 , 96) = 0.53; with target-catch, E ( 4 , 96) = 0.53; and f o r t h e three-way i n t e r a c t i o n , ( 4 , 9 6 ) = 1.60.
trials
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Appendix 4.8 D e t a i l s o f Method, P r o c e d u r e , and R e s u l t s o f S t u d y 8 : T y p i c a l i t y Ratings
The subjects
o v e r t judgment experiments c o n s i s t e d of a s k i n g to make conscious judgments about the test items. T h r e e s e t s o f r a t i n g j u d g m e n t s were o b t a i n e d u n d e r s i m i l a r i n s t r u c t i o n s and a r e d e s c r i b e d h e r e a s " T y p i c a l i t y Ratings." A f o u r t h r a t i n g was o b t a i n e d i n S t u d y 9 u n d e r e x p l i c i t i n s t r u c t i o n s a s t o t h e n a t u r e of p o s i t i o n a l f r e q u e n c y and is d e s c r i b e d a s " P o s i t i o n a l - F r e q u e n c y R a t i n g s . " A f i n a l s e t o f j u d g m e n t s i n S t u d y 1 0 were o b t a i n e d by a " P a i r e d - J u d g m e n t " procedure. Method R a t i n g Forms. T h r e e r a t i n g f o r m s were p r e p a r e d . The f i r s t form employed t h e 1 6 0 a n a g r a m s ; t h e s e c o n d form employed t h e 1 6 0 anagrams p l u s 40 pseudowords d e r i v e d from t h e o r i g i n a l words by t h e s u b s t i t u t i o n of a s i n g l e l e t t e r ; and t h e t h i r d form used t h e e n t i r e 200 s t i m u l u s s t r i n g s i n c l u d i n g t h e o r i g i n a l words. ( S e e Appendix 4 . 1 8 f o r t h e 40 words and t h e i r 160 a n a g r a m s ; see Appendix 4.8A f o r t h e o n e - l e t t e r s u b s t i t u t i o n p s e u d o w o r d s ) . Each l i s t was randomized and p r i n t e d w i t h 20 l e t t e r s t r i n g s p e r p a g e . The s t r i n g s were t y p e d i n l o w e r c a s e w i t h f i v e u n d e r s c o r e s t y p e d t o t h e r i g h t of e a c h s t r i n g a s a space f o r w r i t i n g t h e s t r i n g ' s r a t i n g . The r a t i n g s c a l e t o be used was r e p r o d u c e d a t t h e t o p o f e a c h p a g e a s f o l l o w s : "Most l i k e E n g l i s h 1 0 9 8 7 6 5 4 3 2 1 L e a s t l i k e E n g l i s h . " The f o u r or f i v e p a g e s c o m p r i s i n g e a c h l i s t were a s s e m b l e d i n random o r d e r i n t o b o o k l e t s . Each b o o k l e t was p r e p a r e d w i t h a n a p p r o p r i a t e s h e e t of i n s t r u c t i o n s . These i n s t r u c t i o n s a r e r e p r o d u c e d i n Appendix 4.8B, and 4.8C. Introductory S u b j e c t s . One hundred ninety-e ight P s y c h o l o g y s t u d e n t s f i l l e d o u t one of t h r e e r a t i n g f o r m s . The r a t e r s p a r t i c i p a t e d i n g r o u p s o f 8 t o 1 2 p e r s o n s and r e c e i v e d r e s e a r c h p a r t i c i p a t i o n c r e d i t . The f i r s t 70 s u b j e c t s r a t e d t h e f i r s t form which c o n t a i n e d o n l y t h e 1 6 0 anagrams. The n e x t 65 s u b j e c t s f i l l e d o u t t h e s e c o n d form which i n c l u d e d t h e 160 anagrams and t h e o n e - l e t t e r s u b s t i t u t i o n pseudowords made from t h e words. The f i n a l 63 s u b j e c t s r a t e d t h e t h i r d form which
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c o n t a i n e d t h e o r i g i n a l s e t o f 200 s t i m u l u s items ( i . e . , t h e 1 6 0 a n a g r a m s an d t h e 40 w o r d s ) . Each s u b j e c t worked a t h i s o r h e r own s p e e d , an d o n t h e a v e r a g e , t o o k 1 5 t o 2 5 m i n u t e s t o r a t e t h e items. -P r o cedure. Each s e s s i o n b e g a n with t h e experimenter reading t h e i n s t r u c t i o n s while the s u b j e c t followed along. The f o r m a l i n s t r u c t i o n s were s u p p l e m e n t e d w i t h v e r b a l i n s t r u c t i o n s s t r e s s i n g " s i m i l a r i t y t o English s p e l l i n g " a s the primary rating criterion. S u b j e c t s were u r g e d n o t t o a d o p t s t r a t e g i e s of r a t i n g r e g u l a r i t y on t h e b a s i s of being a b l e t o transform a s t r i n g i n t o a word through l e t t e r a d d i t i o n s , d e l e t i o n s , s u b s t i t u t i o n s , o r by m a k in g a n a g r a m s . The r a t e r s who r e c e i v e d t h e l i s t c o n t a i n i n g a c t u a l w o r d s were a l s o a s k e d t o d i s r e g a r d t h e s e m a n t i c c o n t e n t o f t h e words t o t h e f u l l e s t e x t e n t possible. F i n a l l y , t h e r e l a t i v e n a t u r e o f t h e s c a l e was stressed. I t was i n d i c a t e d t h a t t h e p s y c h o l o g i c a l s c a l e s h o u l d s p a n t h e p r e s e n t e d s e t o f i t e m s and a l l 1 0 s c a l e v a l u e s s h o u l d be used. Results A v e r a g e r a t i n g s were t a b u l a t e d b o t h w i t h i n s u b j e c t s an d across subjects. For t h e w i t h i n s u b j e c t t a b u l a t i o n s , t h e s u b j e c t ' s r a t i n g s f o r t h e 40 s t i m u l i i n e a c h c a t e g o r y were averaged. F o r t h e item a n a l y s e s , a n a v e r a g e f o r e a c h item w as o b t a i n e d by averaging the ratings assigned by each subject. These d a t a permitted a n a l y s e s t o determine i f t h e ratings' r e l i a b i l i t y r e f l e c t e d d i f f e r e n c e s i n mean r a t i n g s f o r analyses of t h e 4 o r 5 c a t e g o r i e s o f s t i m u l i . S i x one-way v a r i a n c e w e r e c o m p u te d f o r a l l p a i r w i s e c o m p a r i s o n s among t h e three instruction conditions; t h r e e a n a l y s e s were b a s e d o n s u b j e c t s a s t h e s a m p l i n g v a r i a b l e a n d t h r e e were b a s e d o n items a s t h e s a m p l i n g v a r i a b l e . The mean r a t i n g s w e r e s o r e l i a b l e t h a t e r r o r v a r i a n c e s were u n i f o r m l y s m a l l i n a l l s i x a n a l y s e s ( s t a n d a r d e r r o r o f e s t i m a t e is t h e r a n g e o f .0 4 t o .68 s c a l e u n i t s f o r a l l s i x a n a l y s e s ) . W it h s u c h s m a l l e r r o r v a r i a n c e s , a l l p a i r w i s e d i f f e r e n c e s b e t w e e n c a t e g o r y m ean s were r e l i a b l e a t t h e .05 l e v e l .
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A P P E N D I X 4.8A
Appendix 4.8A The Pseudowords used i n S t u d y 8 .
Word action amount answer barely belong breath bridge charge double famous finger garden gather glance hardly itself 1awye r longer master modern
Pseudoword aption amaunt onswer parely belang breeth bradge churge gouble vamous vinger gurden gither glunce herdly itsolf rawyer ronger moster madern
Word mother namely nearly perm i t player poetry purely reason remain result shared s imp1 e single spread stared stream travel trials turned winter
Pseudoword mather nomely mearly permat plader boetry burely leason remoin resilt sharet sumple f ingle spreed stured streem trove1 treals tarned wunter
11 6
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A p p e n d ix 4.88 D i r e c t i o n s f o r T y p i c a l i t y R a t i n g s W i t h o u t Words an d f o r T y p i c a l i t y R a t i n g s W it h P s e u d o w o r d s
On t h e p a g e s w h i c h f o l l o w a r e l e t t e r s t r i n g s made u p t o None o f t h e s t r i n g s , h o w e v e r , i s a n look l i k e E n g l i s h words. E n g l i s h word. Your t a s k i s t o r a t e e a c h o n e o n a s c a l e o f 1 t o 1 0 a c c o r d i n g t o how much i t l o o k s l i k e a r e a l E n g l i s h word. S t r i n g s wh i ch a r e e x t r e m e l y c l o s e s h o u l d b e g i v e n h i g h r a t i n g s , w h i l e s t r i n g s which a r e n o t v e r y c l o s e s h o u l d b e g i v e n low ratings. S i n c e no r e a l w o r d s a r e included, the highest p o s s i b l e r a t i n g (10) s h o u l d b e g i v e n t o s t r i n g s w h i c h you f e e l a r e most l i k e E n g l i s h words. Similarly, a r a t i n g of 1 should b e g i v e n t o t h e s t r i n g w h i c h a r e l e a s t l i k e E n g l i s h w o r d s. The s t r i n g s have been s e l e c t e d t o r e p r e s e n t a l l p o s s i b l e l e v e l s o f s i m i l a r i t y t o E n g l i s h w i t h r o u g h l y e q u a l n u m b er s a t e a c h l e v e l . Skim o v e r t h e s t r i n g s o n t h e f i r s t p a g e b e f o r e you b e g i n There r a t i n g s o you h a v e a n i d e a o f t h e i r r a n g e o f v a r i a t i o n . a r e 160(200) s t r i n g s i n a l l , d i v i d e d r a n d o m l y a c r o s s 4 ( 5 ) pages, s o e a c h p a g e s h o u l d h a v e r o u g h l y t h e same v a r i a t i o n a s any .other. You s h o u l d work a t a f a i r l y q u i c k and e v e n p a c e a l t h o u g h t h e r e is n o t i m e l i m i t .
APPENDIX 4 . 8 C
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Appendix 4.8C D i r e c t i o n s f o r T y p i c a l i t y R a t i n g s w i t h Words
On t h e p a g e s which f o l l o w a r e l e t t e r s t r i n g s made up t o be Some of t h e s t r i n g s a r e , i n f a c t , s p e l l e d l i k e E n g l i s h words. E n g l i s h words, whereas other strings are not English words. I n d e p e n d e n t o f t h e meaning o f t h e w o r d s , however, y o u r t a s k i s t o r a t e e a c h one o n a s c a l e of 1 t o 1 0 a c c o r d i n g t o how much i t is s p e l l e d l i k e t y p i c a l E n g l i s h s p e l l i n g . S t r i n g s which a r e e x t r e m e l y c l o s e s h o u l d be g i v e n h i g h r a t i n g s , w h i l e s t r i n g s which a r e n o t v e r y c l o s e s h o u l d be g i v e n low r a t i n g s . The h i g h e s t p o s s i b l e r a t i n g ( 1 0 ) s h o u l d be g i v e n t o s t r i n g s Similarly, a which you f e e l a r e s p e l l e d most l i k e E n g l i s h . r a t i n g o f 1 s h o u l d be g i v e n t o t h e s t r i n g s which a r e s p e l l e d The s t r i n g s h a e been s e l e c t e d t o r e p r e s e n t l e a s t l i k e English. a l l p o s s i b l e l e v e l s of s i m i l a r i t y t o En g lish s p e l l i n g w i t h r o u g h l y e q u a l numbers a t e a c h l e v e l . Skim o v e r t h e s t r i n g s on t h e f i r s t p a g e s b e f o r e you b e g i n There r a t i n g s o you h a v e a n i d e a of t h e i r r a n g e of v a r i a t i o n . so a r e 200 s t r i n g s i n a l l , d i v i d e d randomly a c r o s s 5 p a g e s , e a c h page s h o u l d h a v e r o u g h l y t h e same v a r i a t i o n a s a n y o t h e r . You s h o u l d work a t a f a i r l y q u i c k and e v e n p a c e a l t h o u g h t h e r e is no time l i m i t .
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Appendix 4 . 9 The Method, P r o c e d u r e , and R e s u l t s o f S t u d y 9 : Positional-Frequency Ratings
Method R a t i n g forms were c o n s t r u c t e d by g e n e r a t i n g f r e s h c o p i e s of t h e form from S t u d y 8 employing t h e 160 anagrams. Explicit p o s i t i o n a l - f r e q u e n c y i n s t r u c t i o n s ( r e p r o d u c e d i n Appendix 4.9A) were s u b s t i t u t e d for t h e p r e v i o u s i n s t r u c t i o n s and t h e s c a l e a t t h e t o p o f e a c h p a g e was m o d i f i e d t o r e a d : "Most f r e q u e n t 1 0 9 8 7 6 5 4 3 2 1 L e a s t f r e q u e n t . " s u b j e c t s were t e s t e d i n small g r o u p s of 8 t o 1 0 ; t h e f o r m a l i n s t r u c t i o n s were r e a d f o l l o w e d by v e r b a l e m p h a s i s o f t h e s a l i e n t p o i n t s o f t h e i n s t r u c t i o n s ; and s u b j e c t s were g i v e n u n l i m i t e d time a l t h o u g h t h e y u s u a l l y c o m p l e t e d t h e form i n 1 5 t o 25 m i n u t e s . F o r t y - n i n e I n t r o d u c t o r y Psychology s t u d e n t s r a t e d t h i s form.
As before,
Results As i n S t u d y 8 , a v e r a g e r a t i n g s were t a b u l a t e d by l e t t e r s t r i n g t y p e f o r e a c h s u b j e c t and f o r e a c h s t i m u l u s item a c r o s s subjects. Two a n a l y s e s o f v a r i a n c e w e r e computed on t h e s e d a t a and, a s i n t h e p r e v i o u s ratings, a l l possible pairwise c o m p a r i s o n s o f t h e f o u r anagram c a t e g o r i e s were s i g n i f i c a n t .
APPENDIX 4.9A
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Appendix 4.9A Directions f o r Positional-Frequency Ratings
It is a r e l a t i v e l y s i m p l e matter to determine t h e f r e q u e n c y w i t h which t h e d i f f e r e n t l e t t e r s of t h e a l p h a b e t a r e I t is another m a t t e r to used a t v a r i o u s l o c a t i o n s i n words. d e t e r m i n e i f p e o p l e a r e aware o f t h i s " p o s i t i o n a l f r e q u e n c y . " On t h e p a g e s which f o l l o w a r e l e t t e r s t r i n g s d e r i v e d by anagramming common E n g l i s h s i x - l e t t e r words. I n some i n s t a n c e s t h e l e t t e r s h a v e b e e n moved t o t h e p o s i t i o n s t h e y most commonly occupy i n s i x - l e t t e r words ( h i g h f r e q u e n c y p o s i t i o n s ) and i n some i n s t a n c e s t h e y h a v e been moved t o l o c a t i o n s t h a t t h e y v e r y i n f r e q u e n t l y occupy i n six-letter words (low frequency p o s i t i o n s ) . Your t a s k i s t o r a t e e a c h s t r i n g on a s c a l e o f 1 t o 1 0 a c c o r d i n g t o how much you b e l i e v e t h a t t h e l e t t e r s i n t h e s t r i n g occupy t h e i r most f r e q u e n t p o s i t i o n s . The h i g h e s t possible rating ( 1 0 ) s h o u l d b e g i v e n t o t h e s t r i n g s whose l e t t e r s a r e i n t h e i r most f r e q u e n t p o s i t i o n s . The l o w e s t rating (1) s h o u l d be g i v e n t o s t r i n g s whose l e t t e r s a r e i n their l e a s t frequent p o s i t i o n s . The strings have been c o n s t r u c t e d s o t h a t some s t r i n g s h a v e a l l t h e i r l e t t e r s i n t h e i r most f r e q u e n t p o s i t i o n s , some s t r i n g s h a v e t h e i r l e t t e r s i n t h e i r l e a s t f r e q u e n t p o s i t i o n s , and t h e r e m a i n i n g s t r i n g s have l e t t e r s a t a l l v a r i o u s p o s i t i o n s of g r e a t e r o r l e s s e r f r e q u e n c y . Thus you s h o u l d f i n d s t r i n g s a p p r o p r i a t e t o a l l 10 l e v e l s o f t h e s c a l e w i t h r o u g h l y e q u a l numbers a t e a c h l e v e l . Skim o v e r t h e s t r i n g s on t h e f i r s t page b e f o r e you b e g i n r a t i n g s o you h a v e a n i d e a o f t h e i r r a n g e of v a r i a t i o n . T h e r e a r e 160 s t r i n g s i n a l l , d i v i d e d randomly a c r o s s f o u r p a g e s , s o e a c h page s h o u l d h a v e r o u g h l y t h e same v a r i a t i o n a s a n y o t h e r . You s h o u l d work a t a f a i r l y q u i c k and e v e n p a c e e v e n t h o u g h t h e r e is no time l i m i t .
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Appendix 4.10 D e t a i l s o f Method, P r o c e d u r e , and R e s u l t s o f S t u d y 1 0 : R e g u l a r i t y v e r s u s Positional-Frequency Paired-Judgments
Method Response forms. The p a i r e d - j u d g m e n t f o r m s were p r e p a r e d by f i r s t p a r t i t i o n i n g e a c h o f t h e f o u r c a t e g o r i e s o f a n a g r a m s i n t o f o u r randomly s e l e c t e d s u b s e t s o f 1 0 items e a c h . E i g h t y p a i r s were p r o d u c e d by p a i r i n g t h e 1 6 0 anagrams a s f o l l o w s : One 1 0 - i t e m s u b s e t from e a c h c a t e g o r y was matched t o a 1 0 - i t e m s u b s e t from a n o t h e r c a t e g o r y and t h e members of t h e s u b s e t p a i r e d o f f p r o d u c i n g between c a t e g o r y p a i r s . T h i s l e f t one 1 0 - i t e m s u b s e t w i t h i n e a c h c a t e g o r y whose members were p a i r e d w i t h e a c h o t h e r t o form f i v e w i t h i n c a t e g o r y p a i r s . A t o t a l l i s t o f 320 p a i r s was formed by p e r f o r m i n g t h i s matching p r o c e d u r e f o u r times, r o t a t i n g t h e m a t i n g o f t h e s u b s e t s w i t h i n each c a t e g o r y t o a c h i e v e a co mp l et el y c o u n te rb a la n c e d l i s t where e v e r y i t e m was p a i r e d o n c e w i t h a member of e v e r y o t h e r c a t e g o r y and o n c e w i t h a member of i t s own c a t e g o r y . Eight such t o t a l l y d i f f e r e n t l i s t s were c o n s t r u c t e d and item b a l a n c i n g ( r i g h t - h a n d p a i r member v e r s u s l e f t - h a n d p a i r member) was randomized. The t o t a l e f f e c t was t o e n s u r e t h a t e v e r y item had a n e q u a l o p p o r t u n i t y t o be p a i r e d w i t h a n y o t h e r item. Once c o n s t r u c t e d , t h e l i s t s were p r i n t e d w i t h 80 p a i r s p e r page. Each b o o k l e t was p r e f a c e d w i t h a s e t o f i n s t r u c t i o n s which e i t h e r g a v e a d e t a i l e d d e s c r i p t i o n of r e g u l a r i t y o r p o s i t i o n a l f r e q u e n c y . I n b o t h c a s e s , a p p r o p r i a t e e x a m p l e s were i n c l u d e d . The " r e g u l a r i t y " i n s t r u c t i o n s g r o u p c h o s e t h e m o s t r e g u l a r of e a c h pair whereas t h e " p o s i t i o n a l - f r e q u e n c y ' ' i n s t r u c t i o n s g r o u p c h o s e t h e member w i t h t h e h i g h e s t p o s i t i o n a l frequency. Subjects. Forty-eight I n t r o d u c t o r y Psychology s t u d e n t s 22 completed t h e paired-judgment t a s k . Of these r a t e r s , received "regularity" instructions and 26 received All subjects received "positional-frequency" instructions. r e s e a r c h p a r t i c i p a t i o n c r e d i t a s recompense. A s in the previous rating studies, subjects Procedure. were t e s t e d i n g r o u p s o f 1 0 t o 1 5 and g i v e n u n l i m i t e d time t o t h e somewhat l e n g t h i e r f o r m , c o m p l e t e t h e form. D u e t o s u b j e c t s t o o k 20 t o 30 minutes t o c o m p l e t e t h e form. Approximately one-half of the groups received e x p l i c i t r e g u l a r i t y i n s t r u c t o n s ( s e e Appendix 4.10A) , which d e s c r i b e d
APPENDIX 4.10
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l e t t e r s e q u e n c e r e g u l a r i t y , and r e q u i r e d t h a t t h e more r e g u l a r member of e a c h p a i r be c h o s e n . The r e m a i n i n g g r o u p s r e c e i v e d e x p l i c i t p o s i t i o n a l - f r e q u e n c y i n s t r u c t i o n s ( s e e Appendix 4 . 1 0 B ) which d e s c r i b e d s i n g l e - l e t t e r p o s i t i o n a l f r e q u e n c y and r e q u i r e d t h a t t h e member of e a c h p a i r w i t h t h e h i g h e r o v e r a l l p o s i t i o n a l frequency be chosen. A l l s u b j e c t s w i t h i n a group received t h e same i n s t r u c t i o n s .
Results The p r o p o r t i o n s o f times t h a t i t e m s from a n anagram c a t e g o r y were c h o s e n o v e r items from t h e same c a t e g o r y o r d i f f e r e n t c a t e g o r i e s a r e shown i n T a b l e 4.5. Table 4.5 g i v e s t h e p r o p o r t i o n o f times an i t e m from t h e column c a t e g o r y was selected when paired with an item from the row c a t e g o r y . Comparing t h e two p a n e l s o f T a b l e 4.5 w e o b s e r v e t h a t s u b j e c t s i n b o t h i n s t r u c t e d c o n d i t i o n s made c h o i c e s more c o n s i s t e n t w i t h t h e a p p l i c a t i o n of r e g u l a r i t y t h a n w i t h t h e a p p l i c a t i o n of p o s i t i o n a l f r eq u en cy alth o u g h both observed tables differ from the hypothesized "perfect" outcome. Comparing t h e two p a n e l s of T a b l e 4 . 5 t o e a c h o t h e r , we see e v i d e n c e a g a i n t h a t s u b j e c t s c a n modify t h e i r j u d g m e n t s s l i g h t l y when g i v e n e x p l i c i t instructions t o attend t o p o s i t i o n a l frequency.
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Appendix 4.10A R e g u l a r i t y I n s t r u c t i o n s f o r Paired-Judgments
Our r e s e a r c h is d i r e c t e d a t d i s c o v e r i n g what i t i s we know a b o u t E n g l i s h words t h a t a l l o w s u s t o l o o k a t m e a n i n g l e s s s t r i n g s of l e t t e r s and j u d g e how much t h e y r e s e m b l e words. In t r y i n g t o u n d e r s t a n d t h e s t r u c t u r e p r e s e n t i n words, we h a v e f o c u s e d on a n i m p o r t a n t component p r o p e r t y - - r e g u l a r i t y of For e x a m p l e , t h e r e a r e many c o n s o n a n t l e t t e r sequencing. th, etc.) s e q u e n c e s which b e g i n words ( e . g . , @, and which end words ( e . g . , 9, e l e t c . ) . There a r e common vowel s e q u e n c e s a s w e l l ( e . g . , 00, 9 , G , sf e t c . ) . F i n a l l y , . t h e r e i s r e g u l a r i t y i n how t h e s e c o n s o n a n t s and vowel g r o u p i n g s a r e t h e m s e l v e s s e q u e n c e d w i t h i n words. On t h e p a g e s which f o l l o w a r e 320 p a i r s o f m e a n i n g l e s s six-letter s t r i n g s which h a v e been c o n s t r u c t e d t o v a r y a l o n g t h i s d i m e n s i o n of l e t t e r s e q u e n c e r e g u l a r i t y . T h a t i s , some s t r i n g s p r e s e r v e normal l e t t e r s e q u e n c i n g w h i l e o t h e r s v i o l a t e normal s e q u e n c i n g t o a l e s s e r or g r e a t e r d e g r e e . The o b j e c t o f t h i s e x p e r i m e n t is t o d e t e r m i n e t h e e x t e n t o f your knowledge by h a v i n g you s e l e c t t h e more r e g u l a r s t r i n g i n e a c h p a i r . You a r e t o e v a l u a t e b o t h members o f e a c h p a i r and c h o o s e t h e one t h a t is more p e r m i s s i b l e i n t e r m s o f r e g u l a r i t y o f l e t t e r sequencing. B e f o r e you b e g i n , s k i m o v e r t h e p a i r s o n t h e f i r s t p a g e t o g e t a f e e l f o r t h e t a s k . Once you b e g i n , t r y t o work a t a f a i r l y s t e a d y p a c e and n o t d w e l l t o o l o n g on t h e p a i r s you f i n d d i f f i c u l t . You m u s t make a c h o i c e f o r e a c h p a i r , g u e s s i n g i f necessary. Have you any q u e s t i o n s ?
=,a, *,e,
e,
APPENDIX 4.10B
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Appendix 4.10B Positional-Frequency I n s t r u c t i o n s f o r Paired-Judgments
Our r e s e a r c h i s d i r e c t e d a t d i s c o v e r i n g what i t is we know a b o u t E n g l i s h words t h a t a l l o w s u s t o l o o k a t m e a n i n g l e s s s t r i n g s o f l e t t e r s and j u d g e how much t h e y r e s e m b l e words. In t r y i n g t o u n d e r s t a n d t h e s t r u c t u r e p r e s e n t i n words, w e have f o c u s e d on a n i m p o r t a n t component p r o p e r t y - - l e t t e r frequency. I n d i v i d u a l l e t t e r s and g r o u p s o f l e t t e r s o c c u r w i t h v a r y i n g f r e q u e n c y a t d i f f e r e n t p o s i t i o n s w i t h i n words. For e x a m p l e , you c a n p r o b a b l y t h i n k o f words t h a t end i n fi and words t h a t end i n y, b u t fi i s 1 0 t i m e s more f r e q u e n t t h a n y i n f i n a l L i k e w i s e , 9 and & b o t h o c c u r a t t h e b e g i n n i n g of position. words, b u t i s 50 times a s f r e q u e n t i n i n i t i a l p o s i t i o n . In g e n e r a l , c o n s o n a n t s a r e more f r e q u e n t t h a n vowels a t word i n i t i a l and word f i n a l p o s i t i o n s w i t h t h e e x c e p t i o n o f f i n a l e , and s o on. On t h e p a g e s which f o l l o w a r e 320 p a i r s of m e a n i n g l e s s six-letter s t r i n g s which h a v e b e e n c o n s t r u c t e d t o v a r y a l o n g t h e d i m e n s i o n of l e t t e r f r e q u e n c y by p o s i t i o n . T h a t i s , some s t r i n g s h a v e been c r e a t e d by p l a c i n g e a c h l e t t e r i n i t s m o s t f r e q u e n t p o s i t i o n i n s i x - l e t t e r E n g l i s h words. O t h e r s have t h e i r l e t t e r s p l a c e d i n l e s s f r e q u e n t p o s i t i o n s and s t i l l o t h e r s have t h e i r l e t t e r s i n t h e i r l e a s t f r e q u e n t p o s i t i o n s . The o b j e c t of t h i s e x p e r i m e n t is t o d e t e r m i n e how w e l l you can judge when letters are in their most f r e q u e n t positions. You a r e t o e v a l u a t e b o t h members o f e a c h p a i r and c h o o s e t h e more " f r e q u e n t " o f t h e two, e . g . , t h e s t r i n g which a p p e a r s t o h a v e more o f i t s l e t t e r s i n t h e i r more f r e q u e n t positions. B e f o r e you b e g i n , s k i m o v e r t h e p a i r s on t h e f i r s t p a g e t o g e t a f e e l f o r t h e t a s k . Once you b e g i n , t r y t o work a t a f a i r l y s t e a d y p a c e and n o t t o d w e l l t o o l o n g on t h e p a i r s you find d i f f i c u l t . You m u s t make a c h o i c e f o r e a c h p a i r , g u e s s i n g i f necessary. Have you any q u e s t i o n s ?
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5
Structural Descriptions
To p r o v i d e a more d e t a i l e d a n a l y s i s o f o r t h o g r a p h i c s t r u c t u r e e f f e c t s , we c o n d u c t e d p o s t h o c c o r r e l a t i o n a l a n a l y s e s o f t h e p e r c e p t u a l r e c o g n i t i o n and o v e r t judgment d a t a r e p o r t e d The i n d e p e n d e n t v a r i a b l e s w e r e b a s e d upon i n Chapter 4. v a r i o u s f r e q u e n c y and r e g u l a r i t y m e a s u r e s . Even t h o u g h f i r m c o n c l u s i o n s m i g h t n o t b e r e a c h e d , we f e l t t h a t o u r s a m p l e of items was s u f f i c i e n t l y l a r g e and s u f f i c i e n t l y r e p r e s e n t a t i v e t h a t these correlational analyses could provide valid i n d i c a t i o n s o f which m e a s u r e s m i g h t w a r r a n t f u r t h e r t h e o r e t i c a l and e m p i r i c a l e x a m i n a t i o n . T h r e e d e p e n d e n t m e a s u r e s were d e r i v e d from t h e e x p e r i m e n t s r e p o r t e d i n C h a p t e r 4 f o r e a c h o f t h e 200 s t i m u l u s items, i . e . , The f i r s t m e a s u r e was t h e t h e 40 words and t h e i r 4 anagrams. mean a c c u r a c y f o r e a c h item averaged a c r o s s a l l t r i a l occurrences i n the postcue a c c u r a c y experiment of Study 1: I n i t i a l R e p l i c a t i o n and t h e p r e c u e and p o s t c u e e x p e r i m e n t s o f S t u d y 2: P r e c u e v e r s u s P o s t c u e . A c o r r e s p o n d i n g r e a c t i o n time ( R T ) m e a s u r e was d e r i v e d by a v e r a g i n g t h e RTs f o r a l l t r i a l o c c u r r e n c e s o f e a c h item i n t h e r e a c t i o n time e x p e r i m e n t s o f S t u d y 1: I n i t i a l R e p l i c a t i o n and S t u d y 3 : Mixed-Case. The t h i r d m e a s u r e was t h e a v e r a g e r a t i n g s from one of t h e r a t i n g e x p e r i m e n t s i n S t u d y 8 : T y p i c a l i t y R a t i n g s . The e x p e r i m e n t was t h e one i n which t h e words t h e m s e l v e s w e r e r a t e d a l o n g w i t h t h e 160 anagrams. Each o f t h e 200 s t i m u l u s items a l o n g w i t h i t s r e s p e c t i v e a c c u r a c y , r e a c t i o n t i m e , and r a t i n g i s p r e s e n t e d i n Appendix 5.1. As d i s c u s s e d i n C h a p t e r 3 , a l a r g e number o f m e a s u r e s o f o r t h o g r a p h i c s t r u c t u r e b a s e d upon c o u n t s o f l e t t e r , “-gram, and word f r e q u e n c i e s may be computed. Q u a n t i t a t i v e m e a s u r e s b a s e d upon o r t h o g r a p h i c r u l e s a r e less r e a d i l y c o n s t r u c t e d . A l t h o u g h
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we d e v i s e d and t e s t e d one m e a s u r e o f r e g u l a r i t y b a s e d upon t h e r u l e s o u t l i n e d i n C h a p t e r 3 , w e c o n c e n t r a t e d upon f r e q u e n c y m e a s u r e s and q u e s t i o n s r e l a t e d t o t h e i r c o n s t r u c t i o n . The s p e c i f i c i s s u e s were a s f o l l o w s . Should f r e q u e n c y c o u n t s be based upon c o u n t s o f word t y p e s o r word t o k e n s ? What f r e q u e n c y s c a l e g i v e s t h e most p r e d i c t i v e i n d e x o f p e r f o r m a n c e , raw f r e q u e n c y o r some t r a n s f o r m e d f r e q u e n c y s c a l e s u c h a s l o g f r e q u e n c y ? Is p o s i t i o n a l d e p e n d e n c y , i . e . , w h e t h e r t h e c o u n t s p r e s e r v e p o s i t i o n o f t h e "-gram i n t h e sampled word, a n i m p o r t a n t f a c t o r ? What "-gram u n i t g i v e s t h e most p o w e r f u l measure: s i n g l e - l e t t e r , b i g r a m , o r t r i g r a m c o u n t s ? What i s t h e c o n t r i b u t i o n o f l e x i c a l s t a t u s and word f r e q u e n c y t o p e r f o r m a n c e ? And f i n a l l y , what method o f combining t h e f r e q u e n c i e s o f t h e components of a l e t t e r s t r i n g p r o v i d e t h e b e s t o v e r a l l i n d e x of i t s s t r u c t u r e ? T h e s e q u e s t i o n s w i l l be discussed i n t h e following s e c t i o n s .
DESCRIPTIVE MEASURES
The s o u r c e of a l l o u r f r e q u e n c y m e a s u r e s i s a word c o r p u s sampled by Kucera and F r a n c i s ( 1 9 6 7 ) . T h i s c o r p u s c o n s i s t e d o f 500 s a m p l e s o f a p p r o x i m a t e l y 2,000 words e a c h s e l e c t e d from 1 5 categories. A d e s c r i p t i o n of t h e c o r p u s , i t s s e l e c t i o n , and i t s processing are presented by K u c e r a and F r a n c i s . We o b t a i n e d a m a g n e t i c t a p e of t h e word c o u n t produced from t h e t h e "Rank L i s t " i n t h e K u c e r a and F r a n c i s corpus ( i . e . , monograph). The words were s o r t e d i n t o 1 0 l i s t s c o n s i s t i n g o f 1- t o 1 0 - l e t t e r words r e s p e c t i v e l y . Words l o n g e r t h a n 1 0 c h a r a c t e r s were d e l e t e d a s were items c o n t a i n i n g numbers, punctuation , o r s p e c i a l codings f o r c a p i t a l i z a t i o n s , foreign This a l p h a b e t s , and u n u s u a l g r a p h i c f e a t u r e s o r symbols. resulted i n 10 l i s t s of words, one f o r each l e t t e r length. T h e s e word l i s t s formed t h e b a s i s f o r c o u n t s o f s i n g l e l e t t e r s , b i g r a m s , and t r i g r a m s . T a b l e s were p r e p a r e d by c o u n t i n g t h e o c c u r r e n c e of e a c h -n-gram a t t h e p o s i t i o n i t o c c u r r e d i n words o f a g i v e n l e n g t h . Two c o u n t s were o t a i n e d . One was a t y p e c o u n t b a s e d upon t h e number of word t y p e s t h a t c o n t a i n e d a g i v e n E-gram, and t h e o t h e r was a t o k e n c o u n t b a s e d upon t h e t o t a l number o f A occurrences of the word containing the "-gram. position-insensitive c o u n t ( b u t s t i l l word l e n g t h d e p e n d e n t ) was a l s o o b t a i n e d f o r e a c h "-gram by summing a c r o s s t h e
ORTHOGRAPHIC STRUCTURE AND R E C O G N I T I O N
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position-dependent c o u n t s . Because Kucera and Francis maintained a f a i t h f u l count o f t h e a c t u a l graphic p a t t e r n s fo u n d i n t h e c o r p u s , their list c o n t a i n s r a r e words, t y p o g r a p h i c e r r o r s , f o r e i g n p e r s o n and p l a c e n am es, a n d o t h e r i d e o s y n c r a t i c i t e m s . To l i m i t t h e i m p a c t o f s u c h items o n o u r l i m i t s were e s t a b l i s h e d f o r b o t h word t a b u l a t i o n s , cut-off f r e q u e n c y a n d number o f s a m p l e s . The c u t - o f f s were a minimum c o u n t o f a t l e a s t o n e o c c u r r e n c e i n t h r e e o f t h e 500 s a m p l e s . T h u s , u n u s u a l w o r d s and u s a g e s , r e g a r d l e s s o f t h e i r f r e q u e n c y , were i g n o r e d u n l e s s t h e y o c c u r r e d i n t h r e e o r m o r e s e p a r a t e s a m p l e s . I n t h i s way, w o r d s w i t h t h e minimum f r e q u e n c y o f t h r e e were c o u n t e d o n l y i f t h e y o c c u r r e d o n c e i n e a c h o f t h r e e s a m p l e s . A l t h o u g h t h i s l i m i t was a r b i t r a r y , i n s p e c t i o n o f t h e word l i s t i n t h e l o w f r e q u e n c y r a n g e i n d i c a t e d t h a t t h e s e were reasonable cut-offs. The s i n g l e - l e t t e r t o k e n c o u n t s f o r word l e n g t h s 3 t h r o u g h 7 a n d t h e b i g r a m t o k e n c o u n t s f o r word l e n g t h s 3 t h r o u g h 7 a r e p r e s e n t e d a s A p p e n d i c e s 5 .2 an d 5 . 3 , r e s p e c t i v e 1y All o f t h e f r e q u e n c y m e a s u r e s t h a t w i l l b e d i s c u s s e d were d e r i v e d f r o m t h e s e t a b l e s w i t h two e x c e p t i o n s , word f r e q u e n c y and E n g l i s h n e s s . The f r e q u e n c i e s o f t h e 40 w o r d s were t a k e n d i r e c t l y f r o m t h e K u c e r a and F r a n c i s c o u n t . E n g l i s h n e s s is a m e a s u r e p r o p o s e d b y T r a v e r s and O l i v i e r ( 1 9 7 8 ) and w as co m p u t ed from t a b l e s s u p p l i e d t o u s b y t h e a u t h o r s . E n g l i s h n e s s is a c o n t i n u e d p r o d u c t o f ;-gram probabilities estimated t o the l e v e l of third-order t r a n s i t i o n a l p r o b a b i l i t i e s . Th e f o r m u l a f o r s i x - l e t t e r words o r l e t t e r s t r i n g s i s a s f o l l o w s :
.
E n g l i s h n e s s (#LlL2L3L4L5L6#) = - l o g [P(L11#)*P(L2l#Ll)*P(L3lLlL2)* P(L41L2L3)*P(L51L3L4)*P(L61L4L5)1
(4)
w h e r e # r e p r e s e n t s a s p a c e and L i i s t h e l e t t e r a t p o s i t i o n i . The term P ( L k l L ( k - Z ) L ( k - l ) ) i s e s t i m a t e d by t h e r a t i o o f t h e t r i g r a m frequency o f L(k-Z)L(k-l)Lk t o t h e bigram frequency L(k-Z)L(k-l). I t should be noted that these frequency e s t i m a t e s a r e n o t p o s i t i o n s e n s i t i v e e x c e p t i n a s much a s t h e y the initial a r e tied t o i n i t i a l position occurrences, i.e., t r i g r a m # L 1 L 2 and i n i t i a l b ig ram # L 1 . The c o u n t s a r e a l s o n o t word-length specific. The i n i t i a l term P ( L i l # ) i n t h e f o r m u l a is a c t u a l l y t h e f r e q u e n c y o f t h e i n i t i a l l e t t e r a s i t o c c u r s i n t h e f i r s t p o s i t i o n i n words o f any l e n g t h . Th e r a t i o n a l e f o r e x a m i n i n g t h i s measure is t o p r o v i d e a c o m p a r i s o n t o t h e o t h e r f r e q u e n c y m e a s u r e s we w i l l e x a m i n e . T r a v e r s an d O l i v i e r ( 1 9 7 8 ) p r o v i d e d some e v i d e n c e t h a t t h e m e a s u r e had success i n
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d e s c r i b i n g performance i n a f u l l r e p o r t o f s h o r t p r e s e n t a t i o n s of l e t t e r s t r i n g s . Our r e g u l a r i t y m e a s u r e c o n s i s t e d o f a c o u n t of t h e number of i r r e g u l a r i t i e s c o n t a i n e d i n e a c h o f t h e 2 0 0 s t i m u l u s items. The e x a c t r u l e s f o r t h e i r r e g u l a r i t y count a r e given i n Table 5.1. An i r r e g u l a r i t y was c o u n t e d f o r e a c h v i o l a t i o n o f c e r t a i n s c r i b a l c o n s t r a i n t s , f o r e a c h i m p e r m i s s i b l e vowel c l u s t e r and f o r e a c h i m p o s s i b l e c o n s o n a n t c l u s t e r when c o n s i d e r e d a s p a r t of a m o n o s y l l a b l e . The items were t r e a t e d a s m o n o s y l l a b l e s b e c a u s e a n a p p r o p r i a t e s y l l a b i c a t i o n i s d i f f i c u l t t o impose on n o n s e n s e s t r i n g s . W i t h o u t r i g i d c r i t e r i a , j u d g m e n t s f o r some anagrams would be u n r e a s o n a b l y a r b i t r a r y . Thus, we c h o s e t o t r e a t a l l s t r i n g s a s monosyllabic even though t h i s r e q u i r e d c l a s s i f i c a t i o n of some two s y l l a b l e words a s c o n t a i n i n g irregularities at syllable b o u n d a r i e s . The counts of i r r e g u l a r i t i e s f o r e a c h o f t h e items o f e a c h o f t h e f i v e s t i m u l u s c a t e g o r i e s a r e shown i n Appendix 5 . 1 .
TYPE VERSUS TOKEN COUNTS
The f i r s t g e n e r a l i s s u e i n d e r i v i n g a f r e q u e n c y m e a s u r e i s whether type counts or token counts are most appropriate. C e r t a i n l y , t h e two methods o f c o u n t i n g w i l l produce frequency measures that have some d e g r e e of c o r r e l a t i o n . Even t h o u g h i t i s p r o b a b l y p o s s i b l e t o f i n d o c c u r r i n g i n o n l y a small number o f o c c u r r e n c e s o f “-grams e x t r e m e l y f r e q u e n t words and o t h e r E-grams o c c u r r i n g i n many i n f r e q u e n t word t y p e s , o n t h e a v e r a g e t h e g r e a t e r t h e t y p e count t h e g r e a t e r the token c o u n t . Only by e x a m i n i n g s i t u a t i o n s where t h e two m e a s u r e s a r e r e l a t i v e l y u n c o r r e l a t e d Thus, i f c a n t h e i m p o r t a n c e o f t h e two a p p r o a c h e s be measured. and our items e x h i b i t a s t r o n g c o r r e l a t i o n between t y p e t o k e n - b a s e d m e a s u r e s l i t t l e c a n be d e t e r m i n e d from o u r d a t a t o A t t h e same time, i f o u r s a m p l e is s u p p o r t one o v e r t h e o t h e r . r e p r e s e n t a t i v e of a w i d e r a n g e of l e t t e r s t r i n g s and t h e two a p p r o a c h e s a r e h i g h l y c o r r e l a t e d , t h e q u e s t i o n may b e o f no practical significance. I n any s i t u a t i o n where s u c h a m e a s u r e would be u s e f u l , e i t h e r m i g h t be used w i t h e s s e n t i a l l y identical effect. We found t h a t t h e c o r r e l a t i o n s between c o m p a r a b l e t y p e m e a s u r e s and t o k e n m e a s u r e s for our s a m p l e were v e r y h i g h . Measures b a s e d on s i n g l e l e t t e r s , b i g r a m s , and t r i g r a m s ,
ORTHOGRAPHIC STRUCTURE AND RECOGNITION
Table 5.1
The r u l e s f o r t h e i r r e g u l a r i t y c o u n t of stimulus items
129
the
200
1.
Segment s t r i n g i n t o vowel and c o n s o n a n t s u b s t r i n g s . Treat f i n a l -& a s i f i t w e r e -9. T r e a t between v o w e l s a s a ( l e g a l ) consonant.
2.
For e a c h c o n s o n a n t s t r i n g , d e t e r m i n e minimal number o f inserted t o make t h e s t r i n g vowels which m u s t b e pronounceable. I n i t i a l consonant c l u s t e r s m u s t be l e g a l in i n i t i a l position. F i n a l consonant c l u s t e r s m u s t be l e g a l i n f i n a l p o s i t i o n , i n c l u d i n g t h o s e f o l l o w e d by f i n a l -e . Medial c o n s o n a n t c l u s t e r s m u s t b e l e g a l i n i n i t i a l position.
3.
Rate each resulting consonant substring for p o s i t i o n - s e n s i t i v e s c r i b a l r e g u l a r i t y ( c o u n t one f o r e a c h irregular substring).
4.
For e a c h vowel s u b s t r i n g , d e t e r m i n e minimal number of c o n s o n a n t s which m u s t b e i n s e r t e d t o c r e a t e s c r i b a l l y r e g u l a r sequences. Mark a s i r r e g u l a r i l l e g a l i n i t i a l and f i n a l vowel s u b s t r i n g s .
5.
Count number of i n s e r t e d vowels and c o n s o n a n t s , p l u s number of s c r i b a l l y irregular consonant and vowel s u b s t r i n g s . T h i s y i e l d s an i r r e g u l a r i t y i n d e x .
6.
(among more o b v i o u s The vowel s t r i n g s ", E , s, and c a s e s ) would be i l l e g a l vowel s t r i n g s . y would be i l l e g a l a s a vowel i n i n i t i a l p o s i t i o n and i, 2 , a, E, and 9 would b e i l l e g a l i n f i n a l p o s t i o n . is l e g a l a s is y a s a s i n g l e , n o n - i n i t i a l vowel.
7.
h i s n o t a l l o w e d i n f i n a l p o s i t i o n u n l e s s p r e c e d e d by 9, Or S .
8.
y and y between v o w e l s a r e t o be c o u n t e d a s c o n s o n a n t s .
c,
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b o t h p o s i t i o n s e n s i t i v e and p o s i t i o n i n s e n s i t i v e , c o r r e l a t e d between . 8 4 and .99. With s u c h h i g h c o r r e l a t i o n s no m e a n i n g f u l d i s c r i m i n a t i o n c a n be made between t h e two a p p r o a c h e s . Figure 5 . 1 shows some 5-gram c o r r e l a t i o n s b a s e d on t y p e and t o k e n counts: t h e two sets of counts give highly similar correlations. For t h i s r e a s o n , u n l e s s o t h e r w i s e s t a t e d , we w i l l d i s c u s s o n l y m e a s u r e s based on t o k e n c o u n t s i n t h e remainder of t h i s c h a p t e r .
SCALE OF FREQUENCY
T h i s a n a l y s i s c o n c e r n s t h e f r e q u e n c y s c a l e t o be c h o s e n i n computing f r e q u e n c y m e a s u r e s . While t h e e f f e c t s o f f r e q u e n c y
Accuracy 0
B
LINEAR
Bigram Trigram
I
I
I
LOG
LINEAR
LOC
TYPE Figure 5.1
TOKEN
C o r r e l a t i o n s o f a c c u r a c y and r e a c t i o n times a s a f u n c t i o n o f l i n e a r o r l o g and t y p e o r t o k e n position-sensitive single-letter, bigram, and trigram counts.
ORTHOGRAPHIC STRUCTURE A N D RECOGNITION
131
seem t o b e p s y c h o l o g i c a l l y r e a l , i t i s n o t n e c e s s a r y t h a t t h e mental representations of frequency directly reflect the frequency o f o b j e c t i v e counts. One a l t e r n a t i v e s c a l e t h a t h a s b e e n s u c c e s s f u l i n o t h e r r e s e a r c h i s a l o g a r i t h m i c ( b a s e 10) scale. Not o n l y a r e t h e r e some d a t a t o s u g g e s t t h e p o s s i b i l i t y 1952; o f a l o g a r i t h m i c r e p r e s e n t a t i o n ( S o l o m o n 6, P o s t m a n , T a y l o r , 1977; T r a v e r s & O l i v i e r , 1978) , b u t a l s o a l o g a r i t h m i c representation i s c o n s i s t e n t w i t h r e c e n t s t u d i e s o f number representation (Shepard, 1978) and with many other psychological scales. T h e r e f o r e , w e computed a l l of our f r e q u e n c y m e a s u r e s b a s e d upon b o t h r e g u l a r l i n e a r frequencies and l o g f r e q u e n c i e s . For t h e s e measures, and a l l t r a n s f o r m e d tables for the scales ( t o be discussed) , linear-frequency position-dependent "-grams were n o t r e s c a l e d b e f o r e m e a s u r e s T h e r e f o r e , t h e two s e t s o f were computed f o r a n y item. m e a s u r e s b e i n g c o r r e l a t e d were s u m s o f p o s i t i o n - d e p e n d e n t single letters, bigrams, and t r i g r a m s d e r i v e d from e i t h e r linear-frequency o r log-frequency tables. In nearly every i n s t a n c e t h e l o g - f r e q u e n c y m e a s u r e was m o r e h i g h l y c o r r e l a t e d w i t h t h e p e r f o r m a n c e m e a s u r e t h a n was l i n e a r f r e q u e n c y ( s e e , f o r example, F i g u r e 5 . 1 ) . Although log f r e q u e n c i e s , f o r purposes o f d e s c r i b i n g t h e e f f e c t s of o r t h o g r a p h i c s t r u c t u r e on r e c o g n i t i o n performance, were b e t t e r t h a n l i n e a r f r e q u e n c i e s , w e were a l s o i n t e r e s t e d i n comparing t h e l o g s c a l e w i t h o t h e r transformations of the linear freqencies. For t h i s i n v e s t i g a t i o n , w e c h o s e o u r b e s t f r e q u e n c y m e a s u r e , summed t o k e n p o s i t i o n - s e n s i t i v e b i g r a m s , a n d a p p l i e d a r a n g e o f t r a n s f o r m a t i o n s t o i t . A power f u n c t i o n o f t h e form X
y = a
(5)
gave v a r i o u s s c a l e s depending on t h e v a l u e of t h e exponent x. The E x p o n e n t s o f 0 . 8 , 0 . 7 , 0 . 5 , 0 . 2 , a n d 0 . 1 were s e l e c t e d . 0.2 exponent approximates t h e log function very c l o s e l y i n t h e range of f r e q u e n c y v a l u e s r e p r e s e n t e d by o u r s t i m l u i . The l a r g e r exponents y i e l d e d v a l u e s i n t e r m e d i a t e between t h o s e of log s c a l e s w h i l e t h e 0 . 1 exponent produced t h e l i n e a r and v a l u e s more e x t r e m e t h a n t h e l o g function. The c o r r e l a t i o n between t h e s e b i g ram m e a s u r e s and t h r e e per f or m ance m e a s u r e s g r e w m o n o t o n i c a l l y f r o m t h e l i n e a r s c a l e m e a s u r e t o t h e l o g and 0.2 e x p o n e n t power f u n c t i o n w h e r e c o r r e l a t i o n s p e a k e d and t h e n f e l l f o r ' t h e m o r e e x t r e m e 0 . 1 e x p o n e n t power function. The c o r r e l a t i o n s between a v e r a g e a c c u r a c y and t h e s e bigram measures were . 6 3 f o r t h e l i n e a r s c a l e ; . 7 7 f o r t h e l o g s c a l e ; a n d .68,
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. 7 0 , . 7 4 , . 7 7 , .75 f o r e x p o n e n t s of 0 . 8 , 0 . 7 , 0 . 5 , 0 . 2 , and 0 . 1 respectively. These d a t a i n d i c a t e t h a t i f f r e q u e n c y m e a s u r e s a r e u t i l i z e d by t h e r e a d e r , t h e y a p p e a r t o be computed o n l o g f r e q u e n c i e s , and s o o n l y log-frequency m e a s u r e s w i l l be discussed further.
POSITION-SENSITIVE VERSUS POSITION-INSENSITIVE COUNTS
T h e r e have been many a t t e m p t s t o d e r i v e a m e a s u r e o f p e r c e p t a b i l i t y b a s e d upon p o s i t i o n - i n s e n s i t i v e f r e q u e n c y c o u n t s 1954; (Gibson 1 9 6 4 ; G i b s o n , e t a l . , 1970; Postman & Conger, Spoehr & S m i t h , 1 9 7 5 ) . T h e s e a t t e m p t s h a v e t y p i c a l l y shown t h a t counts t h a t accumulate frequencies without regard t o p o s i t i o n give inadequate m e a s u r e s . On the o t h e r hand, p o s i t i o n - s e n s i t i v e m e a s u r e s h a v e r e c e i v e d some s u p p o r t a s y i e l d i n g b e t t e r m e a s u r e s ( G i b s o n e t a l . , 1 9 7 0 ; Mason, 1 9 7 5 , McClelland & J o h n s t o n , 1 9 7 7 ) . We compared t h e two t y p e s o f measures a g a i n s t our d a t a . T a b l e 5 . 2 shows t h e c o r r e l a t i o n s between t h e t h r e e p e r f o r m a n c e m e a s u r e s w i t h s i n g l e - l e t t e r , b i g r a m , and t r i g r a m c o u n t s d e r i v e d from b o t h p o s i t i o n - s e n s i t i v e and p o s i t i o n - i n s e n s i t i v e c o u n t s . The s t r i k i n g d i f f e r e n c e i n t h i s t a b l e is between t h e two d i f f e r e n t s i n g l e - l e t t e r m e a s u r e s . A s n o t e d by e a r l i e r r e s e a r c h e r s ( e . g . , Postman & Conger, 1 9 5 4 ) , o v e r a l l l e t t e r frequency without regard t o p o s i t i o n is not a very powerful predictor of r e c o g n i t i o n performance. By c o n t r a s t , a p o s i t i o n - d e p e n d e n t s i n g l e - l e t t e r m e a s u r e is a l m o s t a s p o w e r f u l a s p o s i t i o n - i n s e n s i t i v e b i g r a m s and t r i g r a m s f o r RT. It should be noted t h a t d e s c r i b i n g a c c u r a c y and position-insensitive c o u n t s d o b e t t e r a s t h e =-gram's length increases. For "-grams of a g i v e n l e n g t h , p o s i t i o n d e p e n d e n c e seems t o l e a d t o a b e t t e r i n d e x of s t r u c t u r e a l t h o u g h t h e a d v a n t a g e is e s s e n t i a l l y e l i m i n a t e d f o r t r i g r a m c o u n t s . The apparent s u p e r i o r i t y of position-sensitive bigrams over For t h e position-sensitive t r i g r a m s w i l l be d i s c u s s e d n e x t . r e m a i n d e r of t h e s e a n a l y s e s , p o s i t i o n - s e n s i t i v e c o u n t s w i l l be used.
ORTHOGRAPHIC STRUCTURE A N D RECOGNITION
T a b l e 5.2
!&pe
133
C o r r e l a t i o n s between t h e t h r e e dependent an d summed l o g f r e q u e n c y c o u n t s , b o t h d e p e n d e n t and p o s i t i o n i n d e p e n d e n t .
o f Frequen cy Measure
measures position
Dependent Measures
Accuracy
RT -
Rat inq
P o s i t i o n Independent Single Letter
.20
-.36
.04
B i g r am
.59
-.55
.73
Trigram
.68
-.57
.84
Single Letter
.62
-.48
.45
B i g r am
.77
-.64
.83
T r i g r am
.75
-.54
.80
P o s i t i o n Dependent
THE MOST EFFECTIVE FREQUENCY MEASURE
We h a v e n o t e d t h a t summed p o s i t i o n - s e n s i t i v e l o g b i g r a m f r e q u e n c i e s had t h e h i g h e s t c o r r e l a t i o n s w i t h our t h r e e p e r f o r m a n c e m e a s u r e s . T h i s measure, i n f a c t , h ad t h e h i g h e s t frequency c o r r e l a t i o n s o f any of t h e a l m o s t 5 0 forms o f measures t h a t w e examined. For example, p o s i t i o n - s e n s i t i v e s i n g l e l e t t e r s account f o r an average of 29% of the variance in our t h r e e performance measures, while position-sensitive b i g r a m s a c c o u n t f o r 57%. Although it m i g h t b e e x p e c t e d t h a t l a r g e r !-grams s h o u l d n a t u r a l l y c a p t u r e more o r t h o g r a p h i c structure than smaller E-grams, we observed that position-sensitive bigram c o u n t s of s e v e r a l kinds (discussed below) were b e t t e r t h a n comparable f r e q u e n c y measures based
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upon t r i g r a m s . I t is p o s s i b l e t o h y p o t h e s i z e s e v e r a l r e a s o n s why t h i s s h o u l d be t h e c a s e . F i r s t , t h e sampling e r r o r i n t h e t r i g r a m t a b l e s may be l a r g e enough r e l a t i v e t o t h e s a m p l i n g e r r o r i n t h e b i g r a m t a b l e s t o a c c o u n t f o r t h e e f f e c t . The rough equivalence between p o s i t ion- i n d e p e n d e n t and position-dependent t r i g r a m c o u n t s m i g h t h a v e r e s u l t e d from a t r a d e - o f f between t h e a d v a n t a g e of p o s i t i o n s e n s i t i v i t y and t h e larger error variance for position-sensitive c o u n t s . Second, t r i g r a m s s i m p l y may h a v e r e a c h e d a p o i n t o f d i m i n i s h i n g returns. With b i g r a m s a c c o u n t i n g f o r 5 7 % o f t h e v a r i a n c e , t h e r e s i m p l y may b e no room f o r n o t i c e a b l e improvements w i t h l a r g e r "-gram measures. Finally, i t c o u l d be t h a t b i g r a m c o u n t s a r e more r e p r e s e n t a t i v e of t h e r e a d e r ' s knowledge and u t i l i z a t i o n o f o r t h o g r a p h i c s t r u c t u r e . We w i l l r e t u r n t o t h i s q u e s t i o n i n a l a t e r s e c t i o n of t h i s c h a p t e r . The m e a s u r e s t h a t have been d i s c u s s e d w e r e b a s e d upon t h e s u m o f t h e f r e q u e n c i e s f o r t h e component "-grams i n a l e t t e r string. E n g l i s h n e s s was d e s c r i b e d a s a p r o d u c t of f r e q u e n c y r a t i o s and would a p p e a r t o p r o v i d e a n i n t e r e s t i n g c o m p a r i s o n i n t e r m s o f how a f r e q u e n c y m e a s u r e s h o u l d be computed from component "-gram frequencies. The observation t h a t log f r e q u e n c y i s a b e t t e r s c a l e n a r r o w s t h e d i s t a n c e between E n g l i s h n e s s and summed "-gram m e a s u r e s s i n c e E n g l i s h n e s s is computed a s t h e s u m o f t h e l o g a r i t h m s o f f r e q u e n c y r a t i o s . In a c t u a l c o m p a r i s o n , E n g l i s h n e s s p r o v e d t o be a l e s s p o w e r f u l It measure t h a n the position-dependent bigram m e a s u r e . c o r r e l a t e d - . 6 5 w i t h a v e r a g e a c c u r a c y , . 4 7 w i t h a v e r a g e RT, and -.a2 with the ratings. I t o c c u r r e d t o u s t h a t t h e n o r m a l i z a t i o n p r o c e s s of d i v i d i n g a t r i g r a m f r e q u e n c y by t h e t o t a l f r e q u e n c y o f a l l r e l a t e d t r i g r a m s might have t h e p o t e n t i a l f o r producing an is essentially what extremely powerful measure. That Englishness does except that it is based upon p o s i t i o n - i n s e n s i t i v e c o u n t s . T h i s would make p a r t i c u l a r l y good t h e o r e t i c a l s e n s e i n t h e case where p a r t i a l v i s u a l i n f o r m a t i o n was a v a i l a b l e and was used t o r e s o l v e O K e s t i m a t e unknown letters. For e x a m p l e , i f some t r i g r a m xyz i s c o n s i d e r e d a t some p o i n t i n a l e t t e r s t r i n g , t h e p r e d i c t a b i l i t y o f z g i v e n t h e p r e c e e d i n g l e t t e r s xy i s a f u n c t i o n of t h e f r e q u e n c y o f xyz r e l a t i v e t o t h e t o t a l f r e q u e n c y of a l l t r i g r a m s xy-, where t h e f i n a l l e t t e r r a n g e s o v e r t h e e n t i r e a l p h a b e t and t a k e s on a l l a c t u a l l y o c c u r r i n g v a l u e s . Of c o u r s e , c o n s t r a i n t s need n o t work o n l y f o r w a r d , t h e r a t i o s xyz/x-z and xyz/-yz a r e a l s o o f interest. Analogously, r a t i o s o f p a r t i c u l a r b i g r a m s xy t o t h e g e n e r a l b i g r a m s u m s x- and -y c a n be computed.
ORTHOGRAPHIC STRUCTURE AND R E C O G N I T I O N
T a b l e 5.3
C o r r e l a t i o n s between t h e p e r f o r m a n c e m e a s u r e s and summed b i g r a m , E n g l i s h n e s s , and c o n s t r a i n t - r a t i o m e a s u r e s a l l based on l o g word-token f r e q u e n c i e s .
F r e q u e n c y Measure
P e r f o r m a n c e Measure Accuracy
Summed Bigrams Englishness
135
.77 -.65
RT -
-.64 .47
Rating .85 -.82
XYd X Y -
.75
-.55
.81
X Y z/x-z
.74
-.5 6
.82
XY4
.74
-.54
.80
XY/X-
.76
-.64
.86
XY1-Y
.75
-.64
.85
-Y
These f i v e c o n s t r a i n t r a t i o s s u g g e s t f i v e p o t e n t i a l l y i n t e r e s t i n g m e a s u r e s d e r i v e d by summing t h e f o u r t r i g r a m c o n s t r a i n t r a t i o s o r f i v e bigram c o n s t r a i n t r a t i o s f o r our six-letter s t r i n g s . Again, t h e m e a s u r e s were computed a s r a t i o s o f l i n e a r f r e q u e n c i e s and a s r a t i o s o f l o g f r e q u e n c i e s . The c o u n t s c o u l d be based on word-type frequencies or word-token frequencies. In t h i s case, y e t another type frequency. Letter-type frequency is p o s s i b l e , l e t t e r - t y p e f r e q u e n c y i s s i m p l y t h e number of l e t t e r s t h a t a c t u a l l y o c c u r in the f r e e variable position. Thus, a t r i g r a m of t h e form s-r m i g h t c o n s i s t of a f a m i l y o f e i g h t o r n i n e t r i g r a m s w h i l e q-i h a s o n l y a s i n g l e p o s s i b l e member. L e t t e r - t y p e f r e q u e n c y was t a k e n a s t h e r e c i p r o c a l number of t r i g r a m s i n a f a m i l y o r z e r o i f t h e f a m i l y h a s no n a t u r a l l y o c c u r r i n g member, i.e., all A similar letter-type measure was illegal trigrams. constructed f o r bigrams. I n a l l , t h e r e were 3 0 measures computed from c o n s t r a i n t r a t i o s ( f i v e k i n d s of r a t i o s x two f r e q u e n c y s c a l e s x t h r e e k i n d s o f t y p e and t o k e n c o u n t s ) .
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The r e s u l t s f o r t h e s e c o n s t r a i n t - r a t i o m e a s u r e s m i r r o r e d t h e r e s u l t s f o r t h e s i m p l e summed fi-gram frequencies. Ratios of log frequencies c o n s i s t e n t l y gave higher c o r r e l a t i o n s than r a t i o s of l i n e a r frequencies. Word-token f r e q u e n c i e s and word-type f r e q u e n c i e s were n e a r l y i n d i s t i n g u i s h a b l e i n terms o f t h e i r c o r r e l a t i o n s with the performance measures; t h e s e f r e q u e n c y m e a s u r e s c o r r e l a t e d w i t h e a c h o t h e r a t .90 o r h i g h e r . Letter-type f r e q u e n c i e s c o r r e l a t e d s l i g h t l y less h i g h l y with word-type and word-token f r e q u e n c y m e a s u r e s b u t a l s o d i d n o t c o r r e l a t e a s h i g h l y w i t h t h e performance measures. Finally, t h e bigram r a t i o measures gave s l i g h t l y h i g h e r c o r r e l a t i o n s with t h e performance measures t h a n d i d t h e t r i g r a m r a t i o s . A representative s a m p l e of t h e s e m e a s u r e s i s shown i n T a b l e 5 . 3 . C o r r e l a t i o n s among t h e f r e q u e n c y m e a s u r e s were q u i t e h i g h . The t h r e e t r i g r a m m e a s u r e s shown i n T a b l e 5 . 3 c o r r e l a t e d w i t h e a c h
.a
-
.4 -
.6
H Bd
.2-
.o-
K K 0 -.2 0
-
-.4
-
-.6
-
-.8
-
-1.0
I
o
x
Blgram Trlgram
I
I
I
I
I
I
1
2
3
4
5
6
SERIAL POSITION Figure 5.2
C o r r e l a t i o n s o f a c c u r a c y and r e a c t i o n t i m e s w i t h s i n g l e - l e t t e r , b i g r a m , and t r i g r a m f r e q u e n c i e s a s a f u n c t i o n of t h e i r r e s p e c t i v e s e r i a l p o s i t i o n s i n the six-letter strings.
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L i k e w i s e , t h e two b i g r a m c o n s t r a i n t - r a t i o o t h e r .98 or h i g h e r . m e a s u r e s c o r r e l a t e d . 9 9 w i t h e a c h o t h e r . Given t h e u n i f o r m l y h i g h c o r r e l a t i o n s between a l l t h e c o n s t r a i n t - r a t i o m e a s u r e s , i t i s i m p o s s i b l e t o d i s c r i m i n a t e among them. F u r t h e r m o r e , these r a t i o s do not account f o r any more v a r i a n c e t h a n t h e c o m p u t a t i o n a l l y s i m p l e r summed l o g b i g r a m m e a s u r e . For t h e s e r e a s o n s , t h e summed l o g b i g r a m m e a s u r e is t o be p r e f e r r e d o v e r the constraint ratios. Having found t h a t computing more complex m e a s u r e s was no more e f f e c t i v e t h a n summing t h e component b i g r a m s o f a l e t t e r s t r i n g , w e i n v e s t i g a t e d a s i m p l e r m e a s u r e . We examined t h e c o r r e l a t i o n s o f t h e f r e q u e n c i e s of e a c h o f t h e component -n-grams w i t h t h e p e r f o r m a n c e m e a s u r e s . Thus, t h e r e were s i x c o r r e l a t i o n s f o r s i n g l e - l e t t e r f r e q u e n c i e s , f i v e f o r bigram f r e q u e n c i e s , and f o u r f o r t r i g r a m f r e q u e n c i e s with each
.3
0
8 o”
t
-6
.2-
- 4
.l-
0
g
K 40-
- 6
30-
20 -
SERIAL POSITION Figure 5 . 3
V a r i a n c e s of s i n g l e - l e t t e r and b i g r a m o c c u r r e n c e s along with their observed c o r r e l a t i o n s with accuracy measures at the respective serial positions in the six-letter strings.
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performance measure. F i g u r e 5.2 p r e s e n t s t h e r e s u l t s o f t h i s analysis. A l t h o u g h some o f t h e i n d i v i d u a l "-grams d i d n e a r l y a s w e l l a s t h e summed m e a s u r e s , n o s i n g l e "-gram u n i t had a s h i g h a c o r r e l a t i o n a s i t s c o r r e s p o n d i n g summed m e a s u r e . I t is a p p a r e n t f r o m t h e f i g u r e t h a t t h e e n d l e t t e r p o s i t i o n s were t h e most i m p o r t a n t , b u t a s t h e 3-gram length increased the p o s i t i o n a l d i f f e r e n c e s w e re d i m i n i s h e d F i g u r e 5. 2 shows t h a t t h e d e g r e e t o which a p a r t i c u l a r n-gram p r e d i c t s p e r f o r m a n c e is c r i t i c a l l y d e p e n d e n t o n i t s s e r i a l p o s i t i o n , e s p e c i a l l y f o r t h e s i n g l e - l e t t e r an d t o some e x t e n t t h e bigram c o u n t s . I n o r d e r t o e v a l u a t e whether t h i s e f f e c t is due t o t h e i n f o r m a t i o n a l c o n s t r a i n t s i n t h e s t i m u l i themselves, we derived a measure af redundancy or p r e d i c t a b i l i t y f o r each serial position. The v a r i a n c e o f l e t t e r o c c u r r e n c e s a t e a c h s e r i a l p o s i t i o n w as co m p u t ed b a s e d on t h e t a b l e o f f r e q u e n c i e s g i v e n i n Appendix 5 . 2 a n d 5.3. H i g h v a r i a n c e s o c c u r t o t h e e x t e n t t h a t some l e t t e r s o c c u r more o f t e n t h a n o t h e r s . These v a r i a n c e measures f o r t h e As single-letter and b i g r a m c o u n t s a r e shown i n F i g u r e 5 .3 . m i g h t b e e x p e c t e d f r o m p h o n o l o g i c a l and s c r i b a l c o n s t r a i n t s , l e t t e r s a r e much m o r e p r e d i c t a b l e i n i n i t i a l and f i n a l positions than in the middle of s i x - l e t t e r w o r d s. Also presented i n Figure 5.3 are t h e corresponding c o r r e l a t i o n s with t h e accuracy measure. The v a r i a n c e a nd c o r r e l a t i o n m e a s u r e s a r e h i g h l y c o r r e l a t e d f o r s i n g l e - l e t t e r c o u n t s w h i ch m ean s t h a t s u b j e c t s e x p l o i t redundancy d i r e c t l y t o t h e degree t h a t i t is present. Although t h i s correspondence m i g h t b e e x p e c t e d t o occur necessarily, the bigram results argue the o p p o s i t e . Although t h e v a r i a n c e measures a r e roughly s i m i l a r f o r t h e f i r s t t h r e e s e r i a l p o s i t i o n s , t h e c o r r e l a t i o n s a r e much h i g h e r f o r t h e f i r s t two p o s i t i o n s t h a n f o r t h e t h i r d . In a d d i t i o n , a l t h o u g h t h e f i n a l b i g r a m i s much m o r e p r e d i c t a b l e t h a n t h e p e n u l t i m a t e b i g r a m , t h e c o r r e l a t i o n s d o n o t d i f f e r by much.
.
FREQUENCY VERSUS R E G U L A R I T Y
A major concern of t h e p r e s e n t r e s e a r c h h a s been t o c o m p ar e f r e q u e n c y w i t h r u l e - g o v e r n e d r e g u l a r i t y a s i n d i c e s o f 3 t h e form of s t r u c t u r e . We h a v e d i s c u s s e d i n C h a p t e r e x p e r i m e n t a t i o n t h a t w i l l need t o b e c o n d u c t e d t o f u r t h e r d i f f e r e n t i a t e t h e s e two i n d i c e s . We h a v e p r e s e n t e d e v i d e n c e i n
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Chapter 4 t h a t r e g u l a r i t y i s a t l e a s t a s important f o r p e r c e p t u a l r e c o g n i t i o n and more i m p o r t a n t f o r o v e r t j u d g m e n t s a s is s i n g l e - l e t t e r p o s i t i o n a l frequency. In t h e p r e s e n t c h a p t e r , w e h a v e shown t h a t s i n g l e - l e t t e r p o s i t i o n a l f r e q u e n c y is a good m e a s u r e b u t t h a t b i g r a m p o s i t i o n a l f r e q u e n c y i s a W e h a v e examined s e v e r a l d i m e n s i o n s o f the b e t t e r measure. f r e q u e n c y domain and p r e s e n t e d s e v e r a l f i n d i n g s a b o u t f r e q u e n c y measures. T h i s i n v e s t i g a t i o n of t h e q u a n t i t a t i v e a s p e c t s of f r e q u e n c y m e a s u r e s was r e l a t i v e l y d i r e c t and s t r a i g h t f o r w a r d . A comparable i n v e s t i g a t i o n i s n o t p o s s i b l e f o r r e g u l a r i t y . We h a v e made o n l y a v e r y modest s t a r t . A s a n i n i t i a l e f f o r t t o q u a n t i f y r e g u l a r i t y , w e computed a s i m p l e c o u n t of o r t h o g r a p h i c i r r e g u l a r i t i e s b a s e d upon o u r p r e l i m i n a r y a t t e m p t a t a grammar of o r t h o g r a p h y ( s e e T a b l e 5 . 1 ) . The r e s u l t d o e s r a t h e r w e l l i n c o r r e l a t i n g w i t h p e r f o r m a n c e m e a s u r e s b u t is n o t s u f f i c i e n t l y developed t o a l l o w f o r a d e c i s i v e comparison w i t h bigram f r e q u e n c y . The r e g u l a r i t y c o u n t c o r r e l a t e d . 5 7 w i t h a v e r a g e accuracy, -.53 with average RT, and .85 with the ratings. Although t h e s e c o r r e l a t i o n s w i t h t h e two r e c o g n i t i o n m e a s u r e s a r e q u i t e modest i n c o m p a r i s o n w i t h t h e f r e q u e n c y measures described i n t h i s c h a p t e r , the correlation with r a t i n g s i s c o m p a r a b l e w i t h t h e b e s t f r e q u e n c y m e a s u r e . While we h e s i t a t e t o d r a w s t r o n g c o n c l u s i o n s , i t would a p p e a r t h a t potential for developing not only refined t h e r e is rule-governed measures but a l s o q u a n t i t a t i v e l y u s e f u l s t r u c t u r e i n d i c e s b a s e d upon t h e s e r u l e s . One m a j o r p r o b l e m w i t h d i s t i n g u i s h i n g between f r e q u e n c y and r e g u l a r i t y m e a s u r e s o f o r t h o g r a p h i c s t r u c t u r e is t h a t t h e s e two m e a s u r e s a r e n a t u r a l l y c o r r e l a t e d i n t h e w r i t t e n I t is p o s s i b l e t o u n t a n g l e t h e s e m e a s u r e s a s we d i d language. i n the present studies. However, by i n d e p e n d e n t l y v a r y i n g single-letter p o s i t i o n a l f r e q u e n c y and r e g u l a r i t y , we a c t u a l l y c r e a t e d l e t t e r s t r i n g s t h a t v a r i e d s y s t e m a t i c a l l y w i t h bigram f r e q u e n c y . Our r e g u l a r s t r i n g s were h i g h e r i n b i g r a m f r e q u e n c y than the corresponding irregular strings. Therefore, r e g u l a r i t y and position-sensitive log bigram frequency i n our l i s t of 2a8 t e s t ite m s. I n f u t u r e c o r r e l a t e d .759 e x p e r i m e n t s , w e p l a n t o i n d e p e n d e n t l y v a r y t h e s e two m e a s u r e s of o r t h o g r a p h i c s t r u c t u r e i n p e r c e p t u a l r e c o g n i t i o n and o v e r t judgment e x p e r i m e n t s .
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W I T H I N CLASS ANALYSIS
All of t h e a n a l y s e s p r e s e n t e d s o f a r i n t h i s c h a p t e r have examined c o r r e l a t i o n s between m e a s u r e s computed f o r t h e items a c r o s s t h e f i v e c l a s s e s of s t i m u l u s s t r i n g s . Whereas i t i s v e r y i m p o r t a n t t o e x p l a i n t h i s between c l a s s v a r i a n c e , i t i s e q u a l l y i m p o r t a n t t o examine how w e l l s e v e r a l m e a s u r e s o f orthographic s t r u c t u r e explain t h e variance within each c l a s s . To d o t h i s , t h e c o r r e l a t i o n a l a n a l y s e s were r e p e a t e d s e p a r a t e l y for the words and the regular-high, regular-low, irregular-high, and i r r e g u l a r - l o w anagram c l a s s e s . Figure 5 . 4 presents the correlations for the three position-sensitive log
3
x
Bigram Trigram
:" '
.4
-.6
-.8 -1.0
Figure 5 . 4
c WORDS
Reaction Time
R-H
R-L
I-H
I-L
C o r r e l a t i o n s o f a c c u r a c y and r e a c t i o n times a s a f u n c t i o n of s i n g l e - l e t t e r , b i g r a m , and t r i g r a m f r e q u e n c i e s f o r each of t h e f i v e - l e t t e r s t r i n g types.
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n-gram counts with the accuracy and RT performance A s c a n be s e e n i n t h e f i g u r e , t h e m o s t s i g n i f i c a n t measures. r e s u l t is t h e r e l a t i v e l y poor c o r r e l a t i o n s o f p e r f o r m a n c e w i t h trigram frequencies. S i n g l e l e t t e r and bigram f r e q u e n c i e s d o Finally, a l l correlations for the about equally w e l l overall. This l a t t e r r e s u l t might word RT d a t a were c l o s e t o z e r o . i n d i c a t e t h a t l e x i c a l s t a t u s makes a unique c o n t r i b u t i o n i n t h e RT t a s k attenuating the contributions of orthographic s t r u c t u r e . Future research w i l l be necessary t o address t h i s issue.
WORD FREQUENCY
An a d d i t i o n a l m e a s u r e o f i n t e r e s t i s word f r e q u e n c y . Word f r e q u e n c y h a s shown t o b e a g o o d p r e d i c t o r o f word r e c o g n i t i o n ( B r o a d b e n t , 1 9 6 7 ) . Log word f r e q u e n c y c o r r e l a t e s . 6 4 w i t h a v e r a g e a c c u r a c y and .62 w i t h r a t i n g s ; however, f o r j u s t t h e word items the correlations are -.27 and -.11 respectively. T h i s means t h a t word frequency cannot be d i r e c t l y r e s p o n s i b l e f o r t h e e f f e c t s o f o r t h o g r a p h y s i n c e much higher c o r r e l a t i o n s should have been seen i n t h e c l a s s o f words. I n f a c t , a dummy v a r i a b l e a s s i g n i n g t h e v a l u e 1 t o a l l words and 0 t o a l l nonwords c o r r e l a t e s .66 w i t h a v e r a g e Log word f r e q u e n c y c o r r e l a t e s a c c u r a c y and .63 w i t h r a t i n g s . .52 a n d . 7 8 w i t h p o s i t i o n - s e n s i t i v e l o g b i g r a m a n d t r i g r a m f r e q u e n c i e s r e s p e c t i v e l y i n o u r s e t o f 200 i t e m s . T h e r e f o r e , l e x i c a l s t a t u s i t s e l f a p p e a r s t o c o n t r i b u t e v e r y l i t t l e beyond what c a n b e a c c o u n t e d f o r b y s u b l e x i c a l o r t h o g r a p h i c s t r u c t u r e .
YULTI P L E REGRESS1 ON
A s e r i e s o f m u l t i p l e r e g r e s s i o n a n a l y s e s were c a r r i e d o u t t o s e e how much o f t h e v a r i a n c e o f e a c h o f t h e d e p e n d e n t measures could be accounted f o r b y some c o m b i n a t i o n o f d e s c r i p t i v e measures. For response accuracy, l o g bigram f r e q u e n c y , l o g word f r e q u e n c y , a n d l o g s i n g l e - l e t t e r f r e q u e n c y a c c o u n t e d f o r a t o t a l o f 6 8 % o f t h e v a r i a n c e . No o t h e r d e s c r i p t i v e v a r i a b l e i m p r o v e d o n t h e 4 0 % o f t h e RT v a r i a n c e a c c o u n t e d f o r by l o g bigram f r e q u e n c y . F i n a l l y , 88% of t h e
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variance of t h e r a t i n g judgments was a c c o u n t e d f o r by r e g u l a r i t y count, log trigram frequency, a n d l o g word show that the k n o w l ed g e of frequency. These r e s u l t s o r t h o g r a p h i c s t r u c t u r e r e v e a l e d by a n o v e r t judgment t a s k d o e s n o t r e v e a l i t s e l f t o t h e same d e g r e e i n p e r c e p t u a l r e c o g n i t i o n tasks. T h i s r e s u l t is not unreasonable considering t h e additional v i s u a l processing requirements i n the perceptual recognition tasks. In addition, t h e accuracy task allows a s i g n i f i c a n t l y l a r g e r c o n t r i b u t i o n of o r t h o g r a p h i c s t r u c t u r e The r e a s o n f o r t h i s d i f f e r e n c e a p p e a r s t h a n d o e s t h e RT t a s k . t o be due t o t h e r e l a t i v e l y small c o n t r i b u t i o n of v i s u a l p r o c e s s i n g t o t h e RT m e a s u r e c o m p a r e d t o t h e r e l a t i v e l y l a r g e c o n t r i b u t i o n of v i s u a l processing t o t h e accuracy measure (see Chapter 4 ) .
SUMMARY
The p o s t h o c c o r r e l a t i o n s were r e a s o n a b l y s u c c e s s f u l in i l l u m i n a t i n g t h e r o l e o f a number o f v a r i a b l e s r e l e v a n t t o m e a s u r e s o f o r t h o g r a p h i c s t r u c t u r e . Type an d t o k e n c o u n t s were e q u a l l y good m e a s u r e s f o r o u r s t i m u l u s items, wher eas l o g c o u n t s were s i g n i f i c a n t l y b e t t e r t h a n l i n e a r c o u n t s . Position counts. s e n s i t i v i t y i s c r i t i c a l , e s p e c i a l l y f o r s m a l l e r !-gram F i n a l l y , p o s i t i o n - s e n s i t i v e l o g bigram f r e q u e n c y appeared t o be t h e m o s t e f f e c t i v e m e a s u r e , a l t h o u g h t h e r e a p p e a r s t o b e some p o t e n t i a l f o r d e v e l o p i n g a n e q u a l l y good r e g u l a r i t y m easur e.
APPENDIX 5.1
143
Appendix 5.1 S t i m u l u s Items a n d R e s u l t s E a c h o f t h e 2 0 0 s t i m u l u s items a n d i t s r e s p e c t i v e a v e r a g e p e r c e n t a g e a c c u r a c y (Acc) , a v e r a g e RT, a v e r . a g e r a t i n g , summed p o s i t i o n - s e n s i t i v e l o g s i ng le- 1e t t e r f r e q u e n c y , summed PO si t i o n - s e n s i t i v e l o g b i g ram f r e q u e n c y , summed p o s i t i o n - s e n s i t i v e log trigram f r e q u e n c y , l o g word f r e q u e n c y , a n d number o f irregularities
.
CHAPTER 5
144
WORDS
action amount answer barely belong breath bridge charge double f am o u s finger garden gather glance hardly itself lawyer longer master modern mother namely nearly permit player poetry purely reason r em ai n result shared s imp1 e single spread stared stream travel trials turned winter
Acc
RT
%
msec
81 77 89 89 89 86 94 86 92 89 92 93 89 87 89 79 86 94 93 93 93 90 89 83 95 93 92 85 85 86 93 91 91 91 95 89 85 82 85 91
644 6 56 644 635 603 629 654 642 621 639 653 619 673 637 661 637 646 627 627 616 610 662 620 590 619 642 607 605 638 636 640 622 632 611 672 616 622 623 675 621
Rating
8.8 9.3 8.2 9.3 9.5 9.3 8.9 9.4 8.9 8.9 9.5 9.7 9.4 9.3 9.4 9.2 8.7 9.6 9.7 9.5 9.5 9.4 9.3 9.6 9.6 9.2 9.1 9.1 9.5 9.7 9.4 9.4 9.2 9.2 9.4 9.5 9.6 9.2 9.3 9.7
Single Letter
Bigram T r i g r a m
22.33 21.83 22.10 23.30 22.76 21.48 21.94 22.28 22.13 22.05 22.80 22.75 22.87 21.77 22.49 21.03 21.60 22.96 23.55 22.33 23.31 22.53 22.52 22.52 21.85 22.80 23.03 22.46 22.19 23.02 23.55 22.94 23.02 22.60 23.44 21.94 21.87 22.53 23.42 23.11
15.26 14.12 14.08 15.63 15.12 13.56 13.05 14.51 13.56 13.34 15.58 14.26 15.91 13.70 14.87 13.63 12.50 15.67 16.56 14.40 16.47 14.84 14.76 14.16 14.61 12.36 15.85 15.60 14.42 14.56 15.92 15.01 14.58 13.42 16.32 14.19 13.51 12.64 15.57 16.34
10.98 9.67 8.87 9.59 7.99 8.36 8.58 9.61 7.94 8.56 9.78 9.04 10.23 8.94 9.06 10.25 6.99 10.20 10.54 9.64 11.10 8.22 9.47 9.01 9.47 8.09 9.33 10.76 9.15 9.74 9.74 10.78 9.30 8.78 10.10 9.85 8.53 7.07 10.74 10.32
Word # o f Freq. 1rr. 2.46 2.24 2.18 1.49 1.57 1.72 1.99 2.09 1.75 1.95 1.60 1.78 1.30 1.60 2.03 2.48 1.63 2.29 1.86 2.30 2.33 1.52 2.15 1.89 1.71 1.94 1.48 2.38 1.97 2.39 1.60 2.21 2.24 1.92 1.78 1.71 1.79 1.59 2.51 1.92
1 0 1 0 0 0 0 0 0 0 0 1 0 0 2 1 0 0 0 0 0 0 1 1 0 1 0 0 0 0 0 1 0 0 0 0 0 0 1 1
APPENDIX 5.1
145
REGULAR-HIGH
cainot mauton swaner blayer goblen thaber begrid chager bodule foamus fering nagred thager caleng hyrald siflet weraly loqren tasmer dormen t home K manelv lareny primet raplev petory yulper sarone ramine surtel shread pimsel snigel prased sarted trames vartle sartil drunet
triwen
ACC
RT
%
msec
82 70 81 81 81 78 78 86 77 74 83 83 72 77 69 72 81 79 77 87 87 87 79 81 88 89 74 83 82 82 79 81 81 87 91 80 79 70 81 72
645 620 615 666 638 6 37 640 673 673 670 617 659 612 659 677 640 649 604 648 625 654 639 656 629 634 645 662 635 605 610 675 641 604 639 622 582 638 672 636 672
Rating
6.5 7.5 7.6 8.0 8.6 7.6 7.8 8.3 8.0 7.3 7.7 7.0 7.7 5.6 6.6 7.7 5.7 7.4 7.3 8.2 7.3 8.4 7.2 8.0 7.7 7.3 8.0 7.8 8.2 7.3 9.2 7.7 6.8 8.4 8.4 8.3 7.2 7.3 6.8 6.6
Single Letter
Biqram T r i g r a m
22.69 22.49 22.25 21.79 21.94 22.42 22.27 22.90 22.78 21.80 23.22 22.66 22.70 22.85 21.84 23.06 22.87 22.53 22.92 22.92 22.68 22.96 23.15 22.64 22.49 23.13 21.17 23.83 23.29 23.43 23.19 22.48 22.42 23.18 24.44 22.80 22.95 22.85 22.49 21.90
13.74 13.54 13.40 13.78 13.35 14.95 12.89 15.27 13.92 10.39 15.85 13.74 15.29 15.50 9.21 12.69 13.87 12.07 13.94 14.56 15.54 15.33 14.18 13.97 11.86 14.12 10.87 14.63 14.84 14.64 13.92 11.77 12.58 15.33 16.02 14.11 15.01 12.89 13.05 11.54
4.38 2.28 5.50 8.14 3.60 5.14 3.96 7.54 2.63 0.00 9.73 4.75 6.39 6.17 3.10 5.33 3.36 3.89 3.87 6.00 8.41 8.76 5.68 4.78 2.62 5.36 5.09 6.14 8.42 5.23 7.94 2.36 1.34 6.16 6.87 7.74 8.74 3.90 2.81 1.90
Word FKeq. 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
# of IKK.
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 1 0 1 0 0 1 0 1 1 0 0
CHAPTER 5
146
REGULAR-LOW AC C
%
onicat otanum erswan byeral glenob therab gredib greach edolub osafum grefin gredan greath glecan hydra1 flesit lyeraw gleron steram drenom therom lyeman nyelar trepim lyerap tyerop ryelup erosan amerin tresul dreash emslip glesin dresap dresat tresam treval trisal tredun trewin
71 59 71 77 79 75 66 68 68 53 81 85 83 81 72 71 73 80 79 75 80 66 77 73 75 72 73 73 77 74 73' 73 71 75 87 76 84 71 72 79
RT R a t i n g msec 637 668 675 667 660 666 672 648 679 669 633 653 601 648 654 621 690 621 626 627 658 693 656 645 702 647 684 621 638 636 686 638 632 652 647 635 663 608 641 651
6.5 6.9 6.0 4.8 7.3 7.0 5.9 8.7 5.3 4.4 7.0 7.0 8.1 6.5 7.6 7.6 6.8 8.0 7.6 7.1 7.6 8.1 5.3 7.2 5.9 5.3 6.1 6.9 7.0 6.9 7.9 6.7 7.1 6.8 6.3 7.0 8.1 7.1 7.7 7.3
Single Letter
Bigram T r i q r a m
Word # o f Freq. Irr.
20.84 20.12 21.01 20.60 19.23 19.48 18.96 21.03 17.97 18.41 20.20 21.13 21.00 20.67 19.92 21.38 19.87 21.27 21.21 21.10 21.07 20.53 20.64 20.67 19.08 19.29 18.59 21.72 20.78 20.74 21.211 18.97 20.90 19.73 21.54 20.79 20.78 21.33 20.99 20.91
10.31 12.46 8.35 8.29 9.63 9.68 10.13 13.62 4.79 5.98 12.27 13.02 13.66 10.86 6.68 11.58 6.87 12.32 11.08 12.93 12.72 9.64 7.45 10.67 6.47 7.49 4.56 11.75 11.53 11.28 12.29 6.56 11.50 9.52 11.21 11.26 11.91 13.45 9.29 10.96
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.60 2.65 0.00 1.20 1.74 3.39 5.34 5.69 0.00 0.00 4.80 4.13 8.11 0.00 1.20 1.00 0.00 2.12 2.84 3.93 3.39 2.16 1.95 1.74 0.00 0.00 0.00 1.08 1.26 2.22 6.56 1.32 2.71 2.48 2.48 2.52 1.74 4.13 3.55 2.34
0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 1 1 0 1 1 1 0 0 0 0 1 0 0 0 0 0 0 0 0
APPENDIX 5.1
147
IRREGULAR-HIGH
aiocnt auotnm wnraes lbraey lnboeg bhrtea ierbgd ahcger leoubd uaomf s rfnieg arnged hrtaeg lcnaeq yrahld t l f ies rwlaey glnoer mrtaes oermnd mroteh lmnaey lrnaey tmriep plraey yptoer lpyuer snaoer mraien lrtues srdaeh ilmpes ilgnes prsaed srtaed mtraes avrlet iastlr rdnuet wrntei
Acc
RT
%
msec
63 69 70 81 65 75 66 71 76 61 70 84 70 67 61 68 73 78 76 71 82 70 69 68 84 70 68 75 75 71 67 74 68 85 86 72 74 81 75 63
656 652 666 699 692 664 728 674 691 698 656 663 663 675 681 664 688 662 657 650 660 705 648 662 573 692 671 645 612 656 680 635 658 623 675 647 656 650 712 696
Rating
3.1 3.7 2.4 3.0 2.1 1.5 2.3 3.0 2.5 2.0 2.2 3.8 2.3 2.2 2.4 2.6 2.1 2.9 2.3 2.8 2.8 2.6 2.8 2.7 2.9 2.6 3.0 4.3 3.4 2.0 2.1 3.8 4.5 3.3 2.2 2.3 4.4 2.6 2.1 2.4
Single Letter
Biqram T r i g r a m
22.36 22.07 22.93 21.76 21.87 22.22 21.96 22.64 21.38 20.03 22.21 22.98 22.50 22.06 21.14 22.89 21.52 22.42 23.27 22.62 22.84 21.74 22.70 20.72 22.96 21.13 21.70 23.41 23.27 23.34 22.36 22.08 22.00 23.25 23.75 23.20 21.71 22.67 21.74 20.67
7.20 5.49 8.58 7.90 4.07 9.43 5.31 5.86 10.15 3.61 5.60 14.28 5.98 3.46 9.17 10.79 6.14 9.15 9.56 10.37 8.68 5.91 7.39 7.81 8.90 8.56 6.44 5.96 11.40 11.26 4.32 11.74 8.80 9.44 9.92 10.13 10.12 9.07 7.91 11.47
0.00 1.49 1.18 1.18 0.60 1.59 1.32 2.73 0.00 0.00 1.83 6.08 0.00 0.00 1.34 3.30 0.00 0.00 0.00 2.30 2.53 0.00 0.00 2.31 1.18 0.70 0.00 1.56 1.97 2.42 0.00 3.47 3.72 0.00 0.00 2.82 3.63 4.33 0.00 2.76
Word # o f FKeq. i K K . 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.a0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
2 3 3 2 3 4 3 2 2 4 2 1 3 3 2 2 3 2 3 3 2 3 3 2 2 3 2 2 2 2 4 2 2 2 3 2 2 3 2 3
CHAPTER 5
148
IRREGULAR-LOW AC c
%
icntoa nmtaou rnwesa rbleya ebgnlo rtbeha ebrgd i hreagc obdeul ofmsua efnqri ednrga grheta eclnqa rdlhya eflsti eyrlwa egnrlo emrtsa rmedno hretmo emnyla enyrla rtpeim epylra ervtpo erplvu rnseoa rniema elsrtu hsreda lsepmi nglesi dsepra dtsera esrtma tlerav irltsa edtrnu
62 55 65 67 69 72 58 68 73 62 71 67 77 65 53 66 67 67 66 71 69 73 78 67 70 71 66 63 69 71 75 69 65 82 77 74 67 70 71
RT R a t i n g msec 683 707 704 728 670 736 697 646 692 710 697 698 655 7 38 743 707 707 655 629 644 633 695 677 652 670 6 59 666 648 656 664 656 672 662 665 668 681 680 655 656
2.0 2.1 2.2 2.4 2.7 2.8 2.0 2.4 4.6 2.5 2.1 2.4 3.2 2.6 1.8 2.7 2.8 2.9 2.3 3.1 2.4 4.5 3.0 2.4 3.1 3.2 2.8 2.4 2.3 2.2 2.4 2.8 2.4 3.6 2.4 3.4 2.4 2.8 2.1
Word # o f Freq. Irr.
Single Letter 20.38 19.06 20.26 18.96 19.04 19.78 18.09 20.49 19.15 18.80 18.98 19.25 20.07 20.09 18.53 18.72 18.53 19.24 20.19 19.48 19.84 19.05 20.20 20.65 19.56 19.23 18.37 21.08 20.44 19.52 19.90 18.23 18.25 19.81 21.03 20.06 17.70 20.53 19.12
6.29 2.62 6.02 2.98 5.08 3.45 4.46 7.66 8.15 6.02 6.80 6.05 9.11 5.10 0.00 7.60 4.09 6.11 4.25 3.88 5.25 4.15 8.91 4.62 3.29 5.59 3.54 5.96 8.26 4.51 7.92 4.49 5.28 5.25 10.08 7.24 6.34 3.39 4.93
0.48 0.00 1.45 0.00 0.00 0.00 0.00 2.37 0.00 0.00 1.36 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2.03 0.00 0.00 0.00 0.00 0.00 0.00 1.51 0.48 0.00 0.70 0.00 2.00 0.00 5.92 0.00 1.28 0.00 0.00
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 c1.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
3 4 3 2 4 3 3 2 1 3 3 4 2 2 4 2 4 4 4 3 3 2 2 2 2 2 2 4 2 4 3 3 2 2 3 4 2 4 3
APPENDIX 5 . 2
149
A p p e n d i x 5.2 S i n g l e - L e t t e r P o s i t i o n a l F r e q u e n c i e s (Token Counts) A c c o r d i n g t o S e r i a l P o s i t i o n and Word L e n g t h f o r Words 3 t o 7 L e t t e r s i n Length. I n s t r u c t i o n s f o r Using Frequency T a b l e s The w o r d s u s e d t o o b t a i n t h e s i n g l e - l e t t e r frequencies came from t h e K u c e r a and F r a n c i s ( 1 9 6 7 ) word c o u n t . Words wh i ch had a K u c e r a and F r a n c i s c o u n t o f a t l e a s t t h r e e an d wh i ch a p p e a r e d i n a t l e a s t t h r e e d i f f e r e n t s a m p l e d t e x t s were selected. T h ey were t h e n s e p a r a t e d f o r e a c h word l e n g t h . T h e s e c o u n t s were m u l t i p l i e d b y t h e f r e q u e n c y o f e a c h o f t h e wo r d s s o t h a t t h e s i n g l e - l e t t e r f r e q u e n c i e s o f t h e t a b l e s a r e based on t o k e n r a t h e r t h a n t y p e c o u n t s (see C h a p t e r 1 ) . This s e l e c t i o n p r o c e d u r e y i e l d e d t h e f o l l o w i n g number o f word t o k e n s f o r e a c h word l e n g t h : 2 1 0 9 9 0 , 1 5 3 3 1 5 , 1 0 2 6 9 9 , 7 6 2 9 5 , 68894 f o r 3 t h r o u g h 7 l e t t e r words, r e s p e c t i v e l y . The number o f t i m e s e a c h l e t t e r o f t h e a l p h a b e t o c c u r r e d These i n e a c h l e t t e r p o s i t i o n o f t h e w o r d s was c o u n t e d . t o t a l s , along with t h e i r sum, are presented i n t h e t a b l e s a s t h e f i r s t row o f n u m b e r s f o r e a c h l e t t e r . T h u s , f o r e x a m p l e , f o r s i x - l e t t e r words, t h e l e t t e r 5 occurred i n t h e s i x t h l e t t e r p o s i t i o n 2 3 1 t i m e s and o c c u r r e d i n a l l p o s i t i o n s a t o t a l o f 3 , 8 0 4 t i m e s . Below e a c h o f t h e f r e q u e n c i e s i s t h e b a s e 10 logarithm of the frequency count. I t s h o u l d b e n o t e d t h a t f o r some s i n g l e l e t t e r s , the f r e q u e n c y o f o c c u r r e n c e is z e r o i n some p o s i t i o n s . The l o g a r i t h m o f z e r o is u n d e f i n e d , b u t f o r t h e p u r p o s e s o f t h e t a b l e s was s e t e q u a l t o z e r o .
150
CHAPTER 5
S I N G L E L E T T E R F R E Q U E N C I E S F O R WORDS OF L E T T E R LENGTH 3 LETTER POSITION 2ND 3RD 1ST A
B C D E
F G
H I J K
L
M
39519 4.597 5902 3.771 2466 3.392 2301 3.362 760 2.881 10988 4.041 1967 3.294 21515 4.333 2009 3.303 515 2.712 182 2.260 1604 3.205 4180 3.621
28085 4.448 3 .477 379 2.579 142 2.152 11050 4.043 644 2.809 498 2.697 75511 4.878 13084 4.117 0 0.000 62 1.792 3766 3.576 15 1.176
221 2.344 364 2.561 186 2.270 37652 4.576 82860 4.918 639 2.806 790 2.898 16 1.204 7 .845 0 0.000 150 2.176 3192 3.504 3108 3.492
SUM
67825 4.831 6269 3.797 3031 3.482 40095 4.603 94670 4.976 12271 4.089 3255 3.513 97042 4.987 15100 4.179 515 2.712 394 2.595 8562 3.933 7303 3.864
A P P E N D I X 5.2 S I N G L E L E T T E R F R E Q U E N C I E S F O R WORDS O F L E T T E R L E N G T H 3 LETTER P O S I T I O N 3RD 1ST 2ND N
0 P
Q R
s T
U V W
X
Y
z
7865 3.896 8900 3.949 1227 3.089 11 1.041 864 2.937 6354 3.803 73207 4.865 592 2.772 93 1.968 14079 4.149 0 0.000 3855 3.586 35 1.544
33973 4.531 23643 4.374 27 1.431 0 0.000 5591 3.747 736 2.867 1937 3.287 9472 3.976 41 1.613 2199 3.342 6 .778 126 2.100 0 0.000
6169 3.790 4829 3.684 474 2.676 0 0.000 16036 4.205 22017 4.343 16145 4.208 3307 3.519 73 1.863 5380 3.731 671 2.827 6704 3.825 0 0.000
SUM
48007 4.681 37372 4.573 1728 3.238 11 1.041 22491 4.352 29107 4.464 91289 4.960 13371 4.126 207 2.316 21658 4.336 677 2.831 111685 4.029 35 1.544
151
152
CHAPTER 5
SINGLE LETTER FREQUENCIES FOR WORDS OF LETTER LENGTH 4 LETTER POSITION 2N D 1ST 3RD A
B C D
E
F G H I J
K L
M
3077 3.488 7266 3.861 4530 3.656 4614 3.664 3714 3.570 10556 4.023 3091 3.490 9784 3.991 2191 3.341 2051 3.312 2252 3.353 7898 3.898 10777 4.032
26766 4.428 244 2.387 90 1.954 393 2.594 20802 4.318 0 0.000 128 2.107 29988 4.477 22145 4.345 0 0.000 85 1.929 2843 3.454 50 1.699
20259 4.307 253 2.403 6697 3.826 2462 3.391 21789 4.338 1648 3.215 1169 3.068 376 2.575 9661 3.985 0 0.000 3066 3.487 11225 4.050 6902 3.839
4TH
SUM
953 2.979 301 2.479 54 1.732 10129 4.006 32881 4.517 528 2.723 1351 3.131 12322 4.091 35 1.544 0 0.000 5572 3.746 7346 3.866
51055 4.708 8064 3.907 11371 4.056 17598 4.245 79186 4.899 12724 4.105 5739 3.759 52470 4.720 34032 4.532 2051 3.312 10975 4.040 29312 4.467 26102 4.417
8373 3.923
APPENDIX 5 . 2
153
SINGLE LETTER FREQUENCIES FOR WORDS OF LETTER LENGTH 4 LETTER POSITION 1ST 2N D 3RD N
0 P
Q R S
T
2119 3.326 4261 3.630 3518 3.546 15 1.176 3075 3.488 10815 4.034 30636 4.486
U
1340 3.127
V
1308 3.117 22367 4.350 0 0.000 1996 3.300 64 1.806
W X
Y 2
4TH
SUM 30393 4.483 42273 4.626 7251 3.860 18 1.255 28522 4.455 33145 4.520 68344 4.835 11171 4.048
5753 3.760 24056 4.381 978 2.990 0 0.000 6514 3.814 742 2.870 563 2.751 7042 3.848 2843 3.454 555 2.744 62 1.792 673 2.828
8265 3.917 10798 4.033 1040 3.017 0 0.000 13598 4.133 10091 4.004 12251 4.088 2751 3.439 5723 3.758 1526 3.184 470 2.672 998 2.999
14256 4.154 3158 3.499 1 7 15 3.234 3 .477 5335 3.727 11497 4.061 24894 4.396 38 1.580 0 0.000 2163 3.335 77 1.886 10214 4.009
9874 3.994 2661 1 4.425 609 2.785 13881 4.142
0 0.000
305 2.484
120 2.079
489 2.689
154
CHAPTER 5
SINGLE LETTER FREQUENCIES FOR WORDS OF LETTER LENGTH 5
A
B C D E
F G H I
J
K L M
LETTER POSITION 2ND 1ST 3RD
4TH
5TH
SUM
12306 4.090 826 2.917 938 2.972 2681 3.428 1484 5 4.172 314 2.497 3796 3.579 1740 3.241 13572 4.133 291 2.464 1182 3.073 2801 3.447 2103 3.323
5563 3.745 4 38 2.641 8332 3.921 2860 3.456 18479 4.267 447 2.650 1475 3.169 2465 3.392 683 2 3.835 0 0.000 1242 3.094 11708 4.068 1641 3.215
523 2.719 36 1.556 582 2.765 11845 4.074 21152 4.325 493 2.693 3349 3.525 7039 3.848 75 1.875 0 0.000 2195 3.341 4948 3.694 404 2.606
36206 4.559 8715 3.940 16824 4.226 20390 4.309 66374 4.822 8386 3.924 12885 4.110 33400 4.524
7359 3.867 5264 3.721 6416 3.807 2379 3.376 2189 3.340 5614 3.749 3565 3.552 3348 3.525 917 2.962 525 2.720 618 2.791 4187 3.622 4220 3.625
10455 4.019 2151 3.333 556 2.745 625 2.796 9709 3.987 1518 3.181 700 2.845 18808 4.274 9821 3.992 0 0.000 85 1.929 4783 3.680 1357 3.133
31217 4.494 816 2.912 5322 3.726 28427 4.454 9725 3.988
APPENDIX 5 . 2
155
SINGLE LETTER FREQUENCIES F O R WORDS OF LETTER LENGTH 5 LETTER POSITION 1ST 2ND 3RD N
0
P Q R
S T U V W
X
Y 2
2336 3.368 3064 3.486 4418 3.645
4TH
5TH
SUM 23397 4.369 35303 4.548 8345 3.921 6 30 2.799 40444 4.607 37771 4 * 577 41678 4.620 17521 4.244 5852 3.767 15587 4.193 681 2.833 7370 3.867 229 2.360
4331 3.637 10612 4.026 1046 3.020 0 0.000 8523 3.931 2106 3.323 4727 3.675 9278 3.967 2979 3.474 755 2.878 364 2.561 4 57 2.660
8513 3.930 2682 3.428 879 2.944 0 0.000 9276 3.967 8108 3.909 6054 3.782
2038 3.309 938 2.972 12634 4.102 0 0.000 1547 3.189
2899 3.462 18464 4.266 1255 3.099 115 2.061 7818 3.893 959 2.982 5756 3.760 3058 3.485 687 2.837 682 2.834 151 2.179 287 2.458
3139 3.497 1239 3.093 1121 3.050 7 .845 102 2.009
5318 3.726 4 81 2.682 747 2.873 0 0.000 11791 4.072 15072 4.178 11098 4.045 8 .90 3 9 .954 395 2.597 159 2.201 4977 3.697
3 .477
0 0.000
126 2.100
97 1.987
3 .477
515 2.712 3036 3.482 11526 4.062 14043 4.147
156
CHAPTER 5
SINGLE LETTER FREQUENCIES FOR WORDS OF LETTER LENGTH 6 LETTER POSITION 2ND 3RD 1ST A
B C D E
F G H I
J K
L M
5529 3.743 5116 3.709 6237 3.795 3146 3.498 3313 3.520 3953 3 * 597 1712 3.234 2310 3.364 1668 3.222 541 2.733 225 2.352 3918 3.593 4718 3.674
11057 4.044 284 2.453 1753 3.244 294 2.468 14308 4.156 90 3 2.956 211 2.324 4498 3.653 7396 3.869 0 0.000 73 1.863 3028 3.481 548 2.739
6081 3.784 1102 3.042 3765 3.576 1648 3.217 3548 3.550 2424 3.385 1746 3.242 1292 3.111 4374 3.641 140 2.146 732 2.855 4417 3.645 3912 3.592
4TH
5TH
6TH
SUM
4226 3.626 1286 3.109 1494 3.174 2638 3.421 7619 3.882 347 2.540 2500 3.398 2784 3.445 10676 4.828 0 0.000 2002 3.301 3448 3.538 2143 3.331
3257 3.513 79 1.898 3384 3.529 1284 3.109 23111 4.364 57 1.756 2425 3.385 1096 3.040 2909 3.464
449 2.652 40 1.602 743 2.871 13473 4.129 12471 4.096 593 2.773 3784 3.578
30599 4.486 7907 3.898 17376 4.240 22483 4.352 64370 4.809 8277 3.918 12378 4.093 14511 4.162 27068 4.432 681 2.833 3804 3.580 26303 4.420 13598 4.133
B 0.000 541 2.733 8721 3.941 1297 3.113
2531 3.403 45 1.653 0 0.000 231 2.364 2771 3.443 980 2.991
APPENDIX 5 . 2
157
SINGLE LETTER FREQUENCIES FOR WORDS OF LETTER LENGTH 6
N
0
P
Q R S
T
U V W
X
Y
z
LETTER POSITION 3RD 1ST 2ND
4TH
5TH
6TH
SUM
3306 3.519 10986 4.041 1154 3.062 166 2.220 4923 3.692 862 2.936 3427 3.535 5252 3.720
4535 3.657 6715 3.827 1398 3.146 91 1.959 9119 3.960 4710 3.673 7531 3.877 2800 3.447
4451 3.648 5925 3.773 2401 3.380 64 1.806 3680 3.566 2784 3.445 7658 3.884 5928 3.773
8005 3.903 5221 3.718 786 2.895 0 0.000 6188 3.792 2717 3.434 3149 3.498 1027 3.012
5286 3.723 172 2.236 109 2.037 0 0.000 8147 3.911 10904 4.038 6979 3.844 61 1.785
27626 4.441 30417 4.483 11675 4.067 391 2.592 36333 4.560 33400 4.524 32673 4.514 16147 4.208
183 2.262
1606 3.206 1382 3.141 154 2.188 999 3.000 74 1.869
984 2.993 772 2.888 13 1.114 3 50 2.544 122 2.086
364 2.561 110 2.041 3 .477 4 94 2.694 70 1.845
0 0.000 670 2.826 31 1.491 5825 3.765 0 0.000
4210 3.624 5887 3.770 911 2.960 8473 3.928 272 2.435
2043 3.310 1398 3.146 5827 3.765 70 1.845 4276 3.631 11423 4.058 3929 3.594 1079 3.033 1073 3.031 2645 3.422 0 0.000 140 2.146 6 .778
308 2.489 710 2.851 665 2.823 0 0.000
158
CHAPTER 5
SINGLE LETTER FREQUENCIES FOR WORDS OF LETTER LENGTH 7 LETTER POSITION 1ST 2ND 3RD A
B C D E F G H
I J
K L
M
4796 3.681 4147 3.618 7268 3.861 2846 3.454 3068 3.487 3548 3.550 1982 3.297 3232 3.509 1268 3.103 471 2.673 532 2.726 1990 3.299 3649 3.562
6979 3.844 407 2.610 946 2.976 372 2.571 15655 4.195 623 2.794 663 2.822 3963 3.598 6571 3.818 0 0.000 48 1.681 2524 3.402
7353 3.866 690 2.839 3977 3.600 1168 3.067 4768 3.678 1162 3.065 1493 3.174 501 2.700 4053 3.608 167 2.223 69 1.839 3526 3.547
917 2.962
2923 3.466
4TH
5TH
6TH
7TH
SUM
4582 3.661 1357 3.133 2921 3.466 2263 3.355 6532 3.815 859 2.934 1564 3.194 2243 3.351
5253 3.720 611 2.786 1735 3.239 1202 3.080 10073 4.003 4 58 2.661 1803 3.256 2874 3.458 15115 4.179 0 0.000 524 2.719 3125 3.495
5036 3.702 85 1.929 2707 3.432 2059 3.314 16835 4.226 132 2.121 2323 3.366 1035 3.015 1735 3.239 0 0.000 137 2.137 4433 3.647
34566 4.539 7316 3.864 19909 4.299 18794 4.274 66037 4.820 7551 3.878 17043 4.232 15492 4.190
983 2.993
656 2.817
567 2.754 19 1.279 355 2.550 8884 3.949 9106 3.959 769 2.886 7215 3.858 1644 3.216 18 1.255 0 0.000 120 2.079 3830 3.583 1478 3.170
6031 3.780 2 54 2.405 1280 3.107 4545 3.658 1730 3.238
34791 4.541 892 2.950 2710 3.433 23973 4.380 12336 4.091
APPENDIX 5 . 2
159
SINGLE LETTER FREQUENCIES FOR WORDS OF LETTER LENGTH 7 LETTER POSITION 3RD 2N D 1ST N 0
e Q R
S T U V W
X Y 2
1628 3.212 1460 3.164 6067 3.783 358 2.554 3726 3.571 8092 3.908 3731 3.572 603 2.780 1043 3.018 3289 3.517 0 0.000 93 1.968 7 .845
3150 3.498 8667 3.938 1211 3.083 113 2.053 6991 3.845 558 2.747 1976 3.296 4693 3.671 386 2.587 161 2.207 954 2.980 366 2.563 0 0.000
5166 3.713 5792 3.763 2154 3.333 199 2.299 8487 3.929 4162 3.619 5538 3.743 2573 3.410 1421 3.153 764 2.883 314 2.497 392 2.593 82 1.914
4TH
5TH
6TH
7TH
SUM
3785 3.578 2962 3.472 2655 3.424 26 1.415 4046 3.607 4055 3.608 8755 3.942 3082 3.489 1442 3.159 1544 3.189 0 0.000 304 2.483 77 1.886
3401 3.532 5046 3.703 994 2.997 23 1.362 4791 3.680 1224 3.088 4215 3.625 3862 3.587 1106 3.044 269 2.430 31 1.491 116 2.064 60 1.778
11623 4.065 2700 3.431 576 2.760 0 0.000 6193 3.792 4233 3.627 3466 3.540 1840 3.265 629 2.799 2 54 2.405 38 1.580 66 1.820 103 2.013
4650 3.667 210 2.322 138 2.140 0 0.000 4948 3.694 12054 4.081 6324 3.801 3 .477 0 0.000 116 2.064 114 2.057 6332 3.802 0 0.000
33403 4.524 26837 4.429 13795 4.140 719 2.857 39182 4.593 34378 4.536 34005 4.532 16656 4.222 6027 3.780 6397 3.806 1451 3.162 7669 3.885 329 2.517
16 0
CHAPTER 5
A p p e n d ix 5 . 3 Bigram P o s i t i o n a l F r e q u e n c i e s ( T o k e n C o u n t s ) A c c o r d i n g t o S e r i a l P o s i t i o n and Word L e n g t h f o r Words 3 t o 7 Letters i n Length. I n s t r u c t i o n s f o r using frequency t a b l e s T h e s e c o u n t s were b a s e d o n t h e same word t o k e n s a s were the single-letter c o u n t s i n Appendix 5 . 2 . In t h i s case, h o w e v e r , e a c h word was b r o k e n down i n t o i t s b i g r a m c o m p o n e n t s (i.e., battle----> &, at, E, g , k)an d t h e f r e q u e n c y o f o c c u r r e n c e o f e a c h o f t h e b i g r a m s was t a b u l a t e d f o r e a c h word length. For example, f o r s i x - l e t t e r words, t h e bigram 9 o c c u r r e d a s t h e i n i t i a l bigram 1 8 5 times, a s t h e second bigram 160 times, a s t h e t h i r d bigram 148 times, e t c . N o t i c e t h a t 3 never o c c u r r e d a s t h e s i x t h bigram. Also n o t i c e t h a t t h e b i g r a m do n e v e r o c c u r r e d a t a l l . A b i g r a m w h i c h d i d n o t o c c u r a t l e a s t o n c e f o r w o r d s o f a g i v e n l e n g t h was o m i t t e d f r o m t h e listing in the tables. I t s h o u l d b e n o t e d t h a t f o r some b i g r a m s , t h e f r e q u e n c y o f The l o g a r i t h m o f z e r o i s o c c u r r e n c e is z e r o i n some p o s i t i o n s . u n d e f i n e d , b u t f o r t h e p u r p o s e s o f t h e t a b l e s was s e t e q u a l t o zero.
A P P E N D I X 5.2 BIGRAM F R E Q U E N C I E S F O R W O R D S OF LETTER L E N G T H 3 BIGRAM P O S I T I O N 1ST 2ND SUM AB
3 .477 298 2.474
12 1.079 0 0.000
15 1.176 298 2.474
AD
98 1.991
5378 3.731
5476 3.738
AF
5 .699
0 0.000
5 .699
AG
473 2.675 424 2.627
75 1.875 0 0.000
548 2.739
0 0.000
15 1.176
15 1.176
AL
3008 3.478
33 1.519
3041 3.483
AM
15 1.176
122 2.086
137 2.137
AN
30232 4.480
3316 3.521
33548 4.526
A0
0 0.000
24 1.380
24 1.380
AP
18 1.255
98 1.991
116 2.064
AR
4736 3.675
1324 3.122
6060 3.782
AS
144 2.158
12364 4.092
12508 4.097
AT
16 1.204
414 2.617
4 30 2.633
AU
25 1.398
0 0.000
25 1.398
AV
13 1.114
0 0.000
13 1.114
AW
5 .699
713 2.853
718 2.856
AX
6 .778
AY
B 0.000 348 2.542
226 2.354 3971 3.599
232 2.365 3971 3.599
' 0 0.000
348 2.542
AC
A1 AK
BA
424 2.627
161
162
CHAPTER 5
BIGRAM FREQUENCIES F O R WORDS OF LETTER LENGTH 3
B I G R A M POSITION 1ST 2ND SUM BE
BI BO
BU CA
CE
co CR CT CU
CY DA DD
DE DI DO DR
DS DU EA EB
194 2.288 492 2.692 367 2.565 4501 3.653 2108 3.324 0 0.000 73 1.863 48 1.681
0 0.000 0 0.000 0 0.000 0 0.000 60 1.778 0 0.000 0 0.000
197 2.294 492 2.692 367 2.565 4501 3.653 2108 3.324 60 1.778 13 1.863 48 1.681
0 0.000 237 2.375 0 0.000 740 2.869
307 2.487 0 0.000 12 1.079 0 0.000
3 07 2.487 2 37 2.375 12 1.079 740 2.869
0 0.000 44 1.643 1152 3.061 135 2.130 73 1.863 0 0.000
132 2.121 0 0.000 0 0.000 0 0.000 0 0.000 10 1.000 0 0.000 126 2.100 26 1.415
132 2.121 44 1.643 1152 3.061 135 2.130 73 1.863 10 1.000 157 2.196 216 2.334 26 1.415
157 2.196 90 1.954 0 0.000
.h 7 73
A P P E N D I X 5.2 B I G R A M F R E Q U E N C I E S F O R WORDS O F L E T T E R LENGTH 3 BIGRAM P O S I T I O N 1ST 2ND SUM EC
0 0.000
36 1.556
36 1.556
ED
0 0.000
513 2.710
513 2.710
EE
0 0.000
845 2.927
845 2.927
EG
25 1.398
69 1.839
94 1.973
EI
0 0.000
7 .845
7 .845
EL
3 .477
16 1.204
19 1.279
EM
0 0.000
8 ,903
8 .903
EN
410 2.613
1083 3.035
1493 3.174
EO
0 0.000
7 .845
7 .845
EP
0 0.000
13 1.114
13 1.114
ER
30 1.477
3408 3.532
3438 3.536
ES
3 .471
155 2.190
158 2.199
ET
58 1.763
2243 3.351
2301 3.362
EV
19 1.279
33 1.519
52 1.716
EW
0 0.000
2262 3.354
2262 3.354
0 0.000
97 1.987
97 1.981
EY
122 2.086
103 2.013
225 2.352
FA
505 2.703
0 0.000
505 2.703
FE
679 2.832
679 2.832
FF
0 0.000
0 0.000 639 2.805
FI
161 2.207
0 0.000
161 2.207
EX
639 2.806
163
164
CHAPTER 5
B I G R A M F R E Q U E N C I E S F O R WORDS O F L E T T E R L E N G T H 3 BIGRAM P O S I T I O N 2ND 1ST SUM
FL
51 1.708
0 0.000
51 1.708
FO
9535 3.979
0 0.000
9535 3.979
FT
0 0.000
5 .699
5 .699
FU
57 1.756
0 0.000
57 1.756
GA
154 2.188 781 2.893
0 0.000 2 27 2.356
154 2.188
GG
0 0.000
12 1.079
12 1.079
GI
27 1.431
0 0.000
27 1.431
GO
819 2.913
259 2.413
1078 3.033
GU
186 2.270
0 0.000
HA
7694 3.886
0 0.000
186 2.270 7694 3.886
HE
3078 3.488
72830 4.862
75908 4.880
HI
9747 3.989
0 0.000
9747 3.989
HO
970 2.987
2252 3.353
HU
26 1.415
0 0.000
3222 3.508 26 1.415
HY
0 0.000
429 2.632
4 29 2.632
IA
0 0.000
48 1.681
48 1.681
IC
57 1.756
8 .903
65 1.813
ID
0 0.000
1301 3.114
1301 3.114
IE
0 0.000 0 0.000
169 2.228
169 2.228
455 2.658
455 2.658
GE
IG
1008 3.003
A P P E N D I X 5.2 BIGRAM FREQUENCIES F O R W O R D S OF LETTER LENGTH 3 BIGRAM POSITION 2ND SUM 1ST IK
4 .602
0 0.000
IL
39 1.591
93 1.968
4 .602 132 2.121
IM
0 0.000
2741 3.438
2741 3.438
IN
36 1.556
168 2.225
204 2.310
I0
6 .778 0 0.000
4 .602
10 1.000
88 1.944
88 1.944
IR
0 0.000
352 2,547
352 2.547
IS
0 0.000
6997 3.845
6997 3.845
IT
1858 3.269
413 2.616
2271 3.356
IV
9 .954
0 0.000
9 .954
IX
0 0.000
247 2.393
247 2.393
JA
77 1.886
0 0.000
77 1.886
JE
63 1.799
0 0.000
63 1.799
JI
36 1.556
0 0.000
36 1.556
JO
333 2.522 6 .778
0 0.000
333 2.522
0 0.000
6 .778
KA
21 1.322
0 0.000
21 1.322
KE
100 2.000
4 .602
1fl4 2.017
KI
61 1.785
0 0.000
61 1.785
KY
0 0.000 491 2.691
58 1.763 17 1.230
58 1.763
IP
JU
LA
508 2.706
165
CHAPTER 5
166
BIGRAM F R E Q U E N C I E S F O R WORDS OF L E T T E R LENGTH 3 BIGRAM P O S I T I O N 1ST 2ND SUM LD
0 0.000
660 2.820
660 2.820
LE
618 2.791
0 0.000
618 2.791
LI
113 2.053
0 0.000
113 2.053
LL
0 0.000
3040 3.483
3040 3.483
LM
0 0.000
3 .411
3 .417
LO
377 2.576
0 0.000
377 2.576
LT
5 .699
0 0.000
5 .699
LU
0 0.000
8 .903
8 .903
LY
0 0.000
38 1.580
38 1.580
MA
2690 3.430
0 0.000
2690 3.430
ME
895 2.952
0 0.000
895 2.952
MI
13 1.114
0 0.000
13 1.114
MO
16 1.204
0 0.000
16 1.204
MR
534 2.728
0 0.000
534 2.728
MU
32 1.505
0 0.000
32 1.505
MY
0 0.000 17 1.230,
15 1.176
15 1.176
0 0.000
17 1.230
NC
0 0.000
20 1.301
20 1.301
ND
0 0.000
29265 4.466
29265 4.466
NE
1669 3.222
3292 3.517
4961 3.696
NI
3 ,477
0 0.000
3 .477
NA
APPENDIX 5.2 BIGRAM FREQUENCIES F O R W O R D S OF LETTER L E N G T H 3 BIGRAM POSITION 2ND SUM 1ST NK
0 0.000
7 .845
7 .845
NN
0 0.000
38 1.580
38 1.580
NO
6161 3.790
0 0.000
6161 3.790
NT
0 0.000
6 .778
6 .778
NU
15 1.176 0 0.000
0 0.000 1345 3.129
15 1.176
OA
15 1.176
0 0.000
15 1.176
OB
0 0.000
307 2.487
3 07 2.487
oc
24 1.380
23 1.362
47 1.672
OD
44 1.643
357 2.553
401 2.603
OE
0 0.000
81 1.908
81 1.908
OF
639 2.806
0 0.000
639 2.806
OG
0 0.000
114 2.057
114 2.057
01
93 1.968
0 0.000
93 1.968
OL
660 2.820
10 1.000
670 2.826
OM
0 0.000
ON
3292 3.517
66 1.820 306 2.486
66 1.820 3598 3.556
00
0 0.000
a44 2.926
844 2.926
OP
0 0.000 3 .477
230 2.362 9684 3.986
230 2.362 9687 3.986
0 0.000
52 1.716
52 1.716
NY
OR 0s
1345 3.129
167
CHAPTER 5
168
B I G R A M F R E Q U E N C I E S FOR WORDS OF LETTER L E N G T H 3 BIGRAM POSITION 1ST 2ND SUM OT
0 0.000
5397 3.732
3348 3.525
3299 3.518
5397 3.732 6647 3.823
0 0.000
40 1.602
40 1.602
782 2.893
2405 3.381
3187 3.503
0 0.000
101 2.004
101 2.004
OY
0 0.000
327 2.515
3 27 2.515
PA
253 2.403
0 0.000
253 2.403
PE
400 2.602
3 .477
403 2.605
PI
75 1.875
0 0.000
75 1.875
PO
40 1.602
0 0.000
40 1.602
PR
22 1.342
0 0.000
22 1.342
PT
0 0.000
15 1.176
15 1.176
PU
437 2.640
0 0.000
437 2.640
PY
0 0.000
9 .954
9 .954
QU
11 1.041
0 0.000
11 1.041
RA
212 2.326
30 1.477
242 2.384
RC
0 0.000
41 1.613
41 1.613
RE
248 2.394
4396 3.643
4644 3.667
RI
39 1.591
0 0.000
39 1.591
RM
0 0.000
94 1.973
RO
121 2.083
16 1.204
94 1.973 137 2.137
ou ov OW
ox
APPENDIX 5.2 BIGRAM FREQUENCIES FOR WORDS OF LETTER LENGTH 3 BIGRAM POSITION 1ST 2N D SUM RS
0 0.000
539 2.732
5 39 2.732
RT
0 0.000
208 2.318
208 2.318
RU
240 2.380
0 0.000
240 2.380
RY
4 .602
267 2.427
271 2.433
SA
1194 3.077
0 0.000
1194 3.077
SE
1414 3.150 2872 3.458
589 2.770
2003 3.302
11 1.041
2883 3.460
SI
439 2.642
0 0.000
439 2.642
SK
58 1.763
128 2.107
186 2.270
SL
5 .699
0 0.000
5 .699
SO
185 2.267
0 0.000
185 2.267
SP
9 .954
0 0.000
9 -954
ss
0 0.000
5 .699
5 .699
ST
0 0.000
3 .477
3 .477
SU
178 2.250
0 0.000
178 2.250
TA
241 2.382
0 0.000
241 2.382
TC
0 0.000
58 1.763
58 1.763
TD
0 0.000
5 .699
5 .699
TE
208 2.318 69983 4.845
16 1.204 0 0.000
224 2.350 69983 4.845
82 1.914
0 0.000
82 1.914
sn
TH TI
169
170
CHAPTER 5
BIGRAM F R E Q U E N C I E S F O R WORDS O F L E T T E R LENGTH 3 BIGRAM P O S I T I O N 2N D 1ST SUM TO TR TS
TU
TW UB UD UE UG UH
UM UN
uo UP
UR US
UT UY VA VE VI
1125 3.051 140 2.146 0 0.000 16 1.204 1412 3.150 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 3 .477 0 0.000 0 0.000 0 0.000 589 2.770 0 0.000 0 0 * 000 32 1.505 0 0.000 52 1.716
0 0.000 0 0.000 1858 3.269 0 0.000 0 0.000 19 1.279 41 1.613 166 2.220 65 1.813 5 ,699 74 1.869 486 2.687 11 1.041 45 1.653 1268 103 37 568 134 853 121 083 0 0.000 32 1.505 0 0.000
1125 3.051 140 2.146 1858 3.269 16 1.204 1412 3.150 19 1.279 41 1.613 166 2.220 65 1.813 5 .699 74 1.869 489 2.689 11 1.041 45 1.653 1268 3.103 626 2.797 7134 3.853 121 2.083 32 1.505 32 1.505 52 1.716
A P P E N D I X 5.2 BIGRAM FREQUENCIES F O R W O R D S OF LETTER LENGTH 3 BIGRAM P O S I T I O N 1ST 2ND SUM
vo
9 .954 0 0.000
0 0.000 9 .954
9 .954 9 .954
WA
11203 4.049
0 0.000
11203 4.049
WE
64 1.806
15 1.176
79 1.898
WH
2656 3.424 75 1.875
0 0.000 0 0.000
2656 3.424
0 0.000
772 2.888
772 2.888
76 1.881
1412 3.150
1488 3.173
WR
5 .699
0 0.000
5 .699
XE
0 0.000
6 .778
6 .778
YE
569 2.755
126 2.100
695 2.842
YO
3286 3.517
0 0.000
3286 3.517
ZE
26 1.415
0 0.000
26 1.415
9 .954
0 0.000
9 .954
VY
WI WN
wo
zo
75 1.875
171
172
CHAPTER 5
BIGRAM FREQUENCIES FOR WORDS OF LETTER LENGTH 4 BIGRAM POSITION 1ST 2ND 3RD AB AC
AD AF AG AH A1 AK AL AM
AN A0 AP AQ AR AS
AT AU AV AW AX
236 2.373 65 1.813 54 1.732 0 0.000 69 1.839 0 0.000 62 1.792 10 1.000 1127 3.052 33 1.519 98 1.991 0 0.000 4 .602 0 0.000 660 2.820 62 1.792 47 1.672 44 1.643 0 0.000 461 2.664 45 1.653
70 1.845 3085 3.489 1210 3.083 82 1.914 178 2.250 0 0.000 3156 3.499 1569 3.196 1667 3.222 1958 3.292 2519 3.401 64 1.806 124 2.093 0 0.000 2197 3.342 2345 3.370 988 2.995 51 1.708 4415 3.645 158 2.199 16 1.204
33 1.519 0 0.000 1191 3.076 28 1.447 39 1.591 31 1.491 0 0.000 55 1.740 593 2.773 231 2.364 2390 3.378 0 0.000 95 1.978 3 .477 1427 3.154 52 1.716 13013 4.114 0 0.000 0 0.000 74 1.869 0 0.000
SUM 339 2.530 3150 3.498 2455 3.390 110 2.041 286 2.456 31 1.491 3218 3.508 1634 3.213 3381 3.530 2222 3.347 5007 3.700 64 1.806 223 2.348 3 .477 4284 3.632 2459 3.391 14048 4.148 95 1.978 4415 3.645 693 2.841 61 ~1.785
A P P E N D I X 5.2 BIGRAM F R E Q U E N C I E S F O R W O R D S OF LETTER LENGTH 4 BIGRAM P O S I T I O N 2ND 1ST 3RD
SUM
AY
0 0.000
763 2.883
1004 3.002
1767 3.247
AZ
0 0.000
151 2.179
0 0.000
151 2.179
BA
1579 3.198
0 0.000
47 1.672
1626 3.211
BE
3186 3.503
28 1.447
48 1.681
3262 3.513
BI
214 2.330
0 0.000
0 0.000
214 2.330
BL
217 2.336
216 2.334
0 0.000
433 2.636
BO
1803 3.256
0 0.000
0 0.000
1803 3.256
BR
14 1.146
0 0.000
0 0.000
14 1.146
BS
0 0.000
83 1.919
83 1.919
BT
0 0.000
0 0.000 0 0.000
13 1.114
13 1.114
BU
244 2.387
0 0.000
0 0.000
244 2.387
BY
9 .954
0 0.000
62 1.792
71 1.851
CA
1837 3.264
15 1.176
0 0.000
1852 3.268
CE
223 2.348
0 0.000
1196 3.078
1419 3.152
CH
73 1.863
14 1.146
3267 3.514
CI
400 2.602
13 1.114
0 0.000
3354 3.526 413 2.616
CK
0 0.000
0 0.000
1706 3.232
1706 3.232
CL
279 2.446
0 0.000
0 0.000
279 2.446
CO
1514 3.180
0 0.000
21 1.322
1535 3.186
CR
56 1.748
9 .954
0 0.000
65 1.813
CT
0 0.000
39 1.591
4 58 2.661
497 2.696
173
174
CHAPTER 5
BIGRAM FREQUENCIES FOR WORDS OF LETTER LENGTH 4 BIGRAM POSITION 1ST 2ND 3RD CU
CY DA DD DE DG DI DL DN DO DR DS DU DY EA
EB EC ED EE EF EG
148 2.170 0 0.000 1004 3.002 0 0.000 717 2.856 0 0.000 268 2.428 0 0.000 0 0.000 2146 3.332 238 2.377 0 0.005 234 2.369 7 .845 1296 3.113 0 0.000 10 1.000 90 1.954 0 0.050 0 0.000 35 1.544
0 0.000 0 0.000 44 1.643 24 1.380 204 2.310 78 1.892 0 0.000 19 1.279 3 .477 21 1.322 0 0.000 0 0.000 0 0.050 0 0.000 3589 3.555 13 1.114 119 2.076 16 1.204 5115 3.709 487 2.688 67 1.826
0 0.000 49 1.690 0 0.000 0 0.000 1851 3.267 3 .477 0 0.000 0 0.000 0 0.000 3 .477 0 0.000 204 2.310 0 0.000 401 2.603 529 2.723 0 0.000 0 0.000 1414 3.150 371 2.569 41 1.613 0 0.000
SUM 148 2.170 49 1.690 1048 3.020 24 1.380 2772 3.443 81 1.908 268 2.428 19 1.279 3 .477 2170 3.336 238 2.377 204 2.310 234 2.369 408 2.611 5414 3.734 13 1.114 129 2.111 1520 3.182 5486 3.739 528 2.723 102 2.009
A P P E N D I X 5.2 BIGRAM F R E Q U E N C I E S F O R W O R D S OF L E T T E R L E N G T H 4 BIGRAM P O S I T I O N 1ST 2ND 3RD
SUM
EI
0 0.000
46 1.663
0 0.000
46 1.663
EK
0 0.000
EL
176 2.246
EM
10 1.000
0 0.000 2512 3.400 0 0.000
344 2.537 276 2.441 2149 3.332
344 2.537 2964 3.472 2159 3.334
EN
73 1.863
1158 3.064
8037 3.905
EO
0 0.000
19 1.279
0 0.000
9268 3.967 19 1.279
EP
18 1.255
238 2.377
534 2.728
790 2.898
ER
3 .477
5130 3.710
1646 3.216
6779 3.831
ES
0 0.000
1450 3.161
1394 3.144
2844 3.454
ET
0 0.000
186 2.270
567 2.754
7 53 2.877
EU
0 0.000 1588 3.201
0 0.000 10 1.000
5 .699 0 0.000
5 .699 1598 3.204
EW
0 0.000
159 2.201
803 2.905
962 2.983
EX
7 .845
454 2.657
34 1.531
495 2.695
EY
408 2.611
34 1.531
3645 3.562
4087 3.611
FA
1390 3.143 1233 3.091
0 0.000 0 0.000
6 .778 1021 3.009
1396 3.145 2254 3.353
0 0.000 1480 3.170
0 0.000 0 0.000
5 .699 0 0.000
5 .699 1480 3.170
FL
242 2.384
0 0.000
0 8.000
242 2.384
FO
1204 3.081
0 0.000
0 0.000
1204 3.081
EV
FE FF FI
175
CHAPTER 5
176
BIGRAM FREQUENCIES FOR WORDS OF LETTER LENGTH 4 BIGRAM POSITION 2ND 3RD 1ST FR
SUM
4662 3.669 0 0.000
0 0.000 0 0.000
0 0.000 601 2.779
4662 3.669 601 2.779
FU
345 2.538
0 0.000
0 0.000
345 2.538
FY
0 0.000
0 0.000
7 .845
7 .845
GA
583 2.766
0 0.000
13 1.114
596 2.775
GE
103 2.013
69 1.839
304 2.483
476 2.678
GG
0 0.000
35 1.544
0 0.000
35 1.544
GH
0 0.000
0 0.000
517 2.713
517 2.713
GI
647 2 811
0 0.000
0 0.000
647 2.811
GL
61 1 785
21 1.322
0 PI. 0 0 0
82 1.914
GN
0 0 000
0 0.000
94 1.973
94 1.973
GO
296 3 113
3 .477
0 0.000
1299 3.114
GR
292 2.465
0 0.000
0 0.000
292 2.465
GS
0 D.OOO
0 0.000
241 2.382
241 2.382
GU
109 2.037 5393 3.732 2247 3.352
0 0.000 14317 4.156
0 0.000 0 0.000
9 1 52 3.962
4 .602
109 2.037 19710 4.295 11403 4.057
HI
658 2.818
5500 3.740
0 0.000
6158 3.789
HN
0 0.000 1276 3.106 0 0.000
0 0.000
362 2.559
362 2.559
648 2.812 10 1.000
10 1.000
1934 3.286 10 1.000
FT
HA HE
HO
HR
0 0.000
APPENDIX 5 . 2 BI G R A M FREQUENCIES FOR WORDS OF LETTER LENGTH 4 BIGRAM POSITION
HU HY IA
IB IC
ID
IE IF IG
IK IL IM IN
I0
IP IR
IS IT
IV IZ JA
1ST
2ND
3RD
SUM
201 2.303 9 .954 0 0.000 0 0.000 0 0.000 221 2.344 0 0.000
361 2.558 0 0.000 21 1.322
562 2.750 9 .954 65 1.813 11 1.041 475 2.677 3172 3.501 433 2.636
0 0.000 3 .477 0 0.000 9 -954 0 0.000 1831 3.263 13 1.114 0 0.000 46 1.663 5 .699 59 1.771 4 .602 0 0.000 261 2.417
999 3.000 631 2.800 1426 3.154 3093 3.490 1649 3.217 2217 3.346 30 1.477 134 2.127 687 2.837 839 2.924 7847 3.895 877 2.943 138 2.140 0 0.000
0 0.008 0 0.000 44 1.643 0 0.000 28 1.447 2205 3.359 0 0.000 0 0.000 0 0.000 0 0.000 4 27 2.630 73 1.863 698 2.844 47 1.672 2 54 2.405 292 2.465 5199 3.716 309 2.490 0 0.000 5 .699 0 0.000
11 1.041 447 2.650 666 2.823 433 2.636
999 3.000 634 2.802 1426 3.154 3529 3.548 1722 3.236 4746 3.676 90 1.954 388 2.589 1025 3.011 6043 3.781 8215 3.915 881 2.945 143 2.155 261 2.417
177
CHAPTER 5
178
BIGRAM FREQUENCIES FOR WORDS OF LETTER LENGTH 4 BIGRAM POSITION JE
JI JO JU KA
KE KI
KL KN
KO
KS LA LB LD LE
LF LG
LI LK LL LM
1ST
2ND
3RD
SUM
97 1.987 7 .845 539 2.732 1147 3.060 48 1.681 528 2.723 529 2.723 0 0.000 1136 3.055 11 1.041 0 0.000 1654 3.219 0 0.000 0 0.000 1228 3.089 0 0.000 0 0.000 2835 3.453
0 0.000 0 0.000 0 0.000 0 0.000 20 1.301 0 0.000 62 1.792 3 .477 0 0.000 0 0.000 0 0.000 663 2.822 0 0.000 3 .477 118 2.072 0 0.000 6 .778 79 1.898
0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 3048 3.484 0 0.000 0 0.000 0 0.000 0 0.000 18 1.255 10 1.000 7 .845 1264 3.102 866 2.938 388 2.589 0 0.000 0 0.000
97 1.987 7 .845 539 2.732 1147 3.060
0 0.000 0 0.000 0 0.000
0 0.000 18 1.255 0 0.000
365 2.562 5379 3.731 157 2.196
365 2.562 5397 3.732 157 2.196
68 1.833 3576 3.553 591 2.772 3 .477 1136 3.055 11 1.041 18 1.255 2327 3.367 7 .845 1267 3.103 2212 3.345 388 2.589 6 .778 2914 3.464
APPENDIX 5.2 BIGRAM FREQUENCIES FOR WORDS OF LETTER LENGTH 4 BIGRAM POSITION 2N D 3RD 1ST
LO LP LS LT LU LV LY MA MB ME MI MM MN MO MP MS MU MY NA NC ND
2032 3.308 0 0.000 0 0.000 0 0.000 144 2.158 0 0.000 5 .699 3631 3.560 0 0.000 504 2.702 895 2.952 0 0.000 0 0.000 3751 3.574 0 0.000 0 0.000 1961 3.292 35 1.544 350 2.544 0 0.000 0 0.000
2 54 2.405 0 0.000 1245 3.095 4 .602 449 2.652 4 .602 0 0.000 0 0.000 0 0.000 19 1.279 14 1.146 10 1.000 0 0.000 0 0.000 0 0.000 0 0.000 7 .845 0 0.000 12 1.079 539 2.732 102 2.009
11 1.041 316 2.500 24 1.380 508 2.706 0 0.000 0 0.000 1930 3.286 54 1.732 82 1.914 6252 3.796 0 0.000 0 0.000 43 1.633 0 0.000 178 2.250 161 2.207 0 0.000 132 2.121 10 1.000 10 1.000 2140 3.330
SUM 2297 3.361 316 2.500 1269 3.103 512 2.709 593 2.773 4 .602 1935 3.287 3685 3.566 82 1.914 6775 3.831 909 2.959 10 1.000 43 1.633 3751 3.574 178 2.250 161 2.207 1968 3.294 167 2.223 372 2.571 549 2.740 2242 3.351
179
CHAPTER 5
180
BIGRAM FREQUENCIES F O R W O R D S OF LETTER L E N G T H 4 BIGRAM POSITION 2ND 1ST 3RD NE
1196 3.078
552 2.742
NG
0 0.000
NI
SUM
3449 3.538
0 0.000
1701 3.231 1245 3.095
181 2.258
113 2.053
0 0.000
294 2.468
NK
0 0.000
0 0.000
308 2.489
3 08 2.489
NL
0 0.000 0 0.000 330 2.519
1747 3.242
0 0.000
49 1.690 755 2.878
25 1.398 7 .845
1747 3.242 74 1.869
NS
0 0.000
0 0.000
304 2.483
304 2.483
NT
0 0.000
1877 3.273
1349 3.130
3226 3.509
NU
62 1.792
5 .699
67 1.826
NV
0 0.000
0 0.000 7 .845
0 0.000
.845
NY
0 0.000
0 0.808
1161 3.065
1161 3.065
OA
13 1.114
608 2.784
0 0.000
621 2.793
OB
8 .903
81 1.908
4 ,602
93 1.968
oc
0 0.000
123 2.090
133 2.124
OD
28 1.447
395 2.597
10 1.000 1053 3.022
OE
0 0.000
746 2.873
14 1.146
1476 3.169 760 2.881
OF
0 0.000
67 1.826
63 1.799
130 2.114
OG
0 0.000 38 1.580
78 1.892 362 2.559
0 0.000 0 0.000
78 1.892 400 2.602
25 1.398
189 2.276
0 0.000
214 2.330
NN NO
OH 01
1245 3.095
1092 3.038
7
A P P E N D I X 5.2 BIGRAM F R E Q U E N C I E S F O R WORDS O F L E T T E R LENGTH 4 BIGRAM P O S I T I O N 1ST 2ND 3RD OK
23 1.362
OL
SUM
6 .778
39 1.591 1363 3.134
1070 3.029 267 2.427
OM
0 0.000
2934 3.467
4952 3.695
ON
2422 3.384
1854 3.268
867 2.938
00
0 0.000 322 2.508
3703 3.569
0 0.000
330 2.519
302 2.480
5143 3.711 3703 3.569 9 54 2.980
OR
27 1.431
4755 3,677
451 2.654
5233 3.719
0s
0 0.000
2065 3.315
64 1.806
2129 3.328
OT
3 .477
993 2.997
373 2.572
1369 3.136
ou
27 1.431
1582 3.199
14 1.146
1623 3.210
OV
1251 3.097
410 2.613
0 0.000
1661 3.220
ow
58 1.763
1209 3.082
1286 3.109
2553 3.407
10 1.000
0 0.000
5 .699
15 1.176
0 0.000 1638 3.214
170 2.230 28 1.447
3 .477
173 2.238
40 1.602
1706 3.232
PE
104 2.017
332 2.521
558 2.747
994 2.997
PH
65 1.813
0 0.000
0 0.000
65 1.813
PI
269 2.430
34 1.531
0 0.000
303 2.481
PL
560 2.748 666 2.823 30 1.477
0 0.000 552 2.742
0 0.000 0 0.000 0 0.000
560 2.748 1218 3.086 30 1.477
OP
ox OY PA
PO
PR
0 0.000
1132 3.054 1636 3.214 7886 3.897
181
182
CHAPTER 5
BIGRAM FREQUENCIES FOR WORDS OF LETTER LENGTH 4 BIGRAM POSITION 1ST 2ND 3RD
PS PT PU
PY QU RA
RB RC
RD RE RF RG RI RK RL RM
RN
RO
RP RR
RS
0 0.000 0 0.000 186 2.270 0 0.000 15 1.176 561 2.749 0 0.000 0 0.000 0 0.000 706 2.849 0 0.000 0 0.000 424 2.627 0 0.000 0 0.000 0 0.000 0 0.000 1162 3.065 0 0.000 0 0.000 0 0.000
0 0.000 0 0.000 32 1.505 0 0.000 0 0.000 273 2.436 0 0.000 13 1.114 0 0.000 860 2.934 0 0.000 21 1.322 176 2.246 0 0.000 0 0.000 253 2.403 0 0.000 4586 3.661 0 0.000 0 0.000 0 0.000
164 2.215 240 2.380 0 0.000 38 1.580 0 0.000 19 1.279 27 1.431 0 0.000 747 2.873 7375 3.868 3 .477 0 0.000 6 .778 1475 3.169 283 2.452 792 2.899 555 2.744 76 1.881 13 1.114 22 1.342 280 2.459
SUM 164 2.215 240 2.380 218 2.338 38 1.580 15 1.176 853 2.931 27 1.431 13 1.114 747 2.873 8941 3.951 3 .477 21 1.322 606 2.782 1475 3.169 283 2.452 1045 3.019 555 2.744 5824 3.765 13 1.114 22 1.342 288 2.459
A P P E N D I X 5.2 BIGRAM F R E Q U E N C I E S F O R W O R D S OF LETTER L E N G T H 4 BIGRAM P O S I T I O N 1ST 2ND 3RD
SUM
RT
0 0.000
66 1.820
845 2.927
9 11 2.960
RU
222 2.346
266 2.425
14 1.146
502 2.701
RX
0 0.000
0 0.000
8 .903
8 .903
RY
0 0.000
0 0.000
1050 3.021
1050 3.021
SA
3211 3.507
0 0.000
0 0.000
3211 3.507
15 1.176
0 0.000
6 .778
21 1.322
SE
1160 3.064
675 2.829
1057 3.024
2892 3.461
SH
628 2.798
0 0.000
342 2.534
970 2.987
SI
837 2.923
44 1.643
0 0.900
881 2.945
SK
52 1.716
18 1.255
2 32 2.365
302 2.480
SL
166 2.220
5 .699
0 0.000
171 2.233
SM
7 .845
0 0.000
0 0.000
7 .845
SN
71 1.851
0 0.000
0 0.000
71 1.851
SO
2387 3.378
SP
139 2.143
0 0.000 0 0.000
1080 3.033 3 .477
3467 3.540 142 2.152
0 0.000
0 0.000
1092 3.038
1092 3.038
ST
448 2.651
0 0.000
6087 3.784
6535 3.815
SU
1665 3.221
0 0.000
0 0.000
1665 3.221
29 1.462 0 0.000 1022 3.009
0 0.000 0 0.000 159 2.201
0 0.000 192 2.283
29 1.462 192 2.283 1354 3.132
sc
ss
sw SY TA
173 2.238
183
184
CHAPTER 5
B I G R A M FREQUENCIES FOR WORDS OF LETTER LENGTH 4
B I G R A M POSITION 1ST 2ND 3RD
TC TE TH TI TO TR TS TT TU TW TY UA
UB
uc UD UE
OF UG UI
UK UL
0 0.000 693 2.841 24777 4.394 1818 3.260 1384 3.141 453 2.656 0 0.000 0 0.000 282 2.450 7 .845 200 2.301 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 21 1.322 0 0.000 0 0.000 0 0.000
5 .699 219 2.340 0 0.000 10 1.000 163 2.212 0 0.000 0 0.000 4 .602 3 ,417 0 0.000 0 0.000 28 1.447 78 1.892 2366 3.374 46 1.663 26 1.415 5 .699 75 1.875 86 1.934 14 1.146 561 2.749
0 0.000 990 2.996 8165 3.912 0 0.000 1903 3.279 0 0.000 536 2.729 12 1.079 0 0.000 0 0.000 472 2.674 0 0.000 148 2.170 0 0.000 23 1.362 389 2.590 0 0.000 64 1.806 0 0.000 3 .477 94 1.973
SUM 5 .699 1902 3.279 32942 4.518 1828 3.262 3450 3.538 4 53 2.656 536 2.729 16 1.204 285 2.455 7 .845 672 2.827 28 1.447 226 2.354 2366 3.374 69 1.839 415 2.618 5 .699 160 2.204 86 1.934 17 1.230 655 2.816
A P P E N D I X 5.2 BIGRAM F R E Q U E N C I E S F O R W O R D S OF LETTER L E N G T H 4 BIGRAM P O S I T I O N 1ST 2ND 3RD UM
0 0.000
UN
SUM
19 1.279
108 2.033
122 2.086
89 1.949 447 2.650
16 1.204
585 2.767
UP
495 2.695
14 1.146
20 1.301
529 2.723
UR
21 1.322
801 2.904
1497 3.175
2319 3.365
US
675 2.829
2147 3.332
387 2.588
3209 3.506
UT
6 .778
212 2.326
61 1.785
279 2.446
0 0.000
0 0.000
30 1.477
30 1.477
0 0.000
31 1.491
0 0.000
31 1.491
0 0.000 109 2.037 0 0.000
16 1.204 12 1.079
0 0.000 4 .602
16 1.204 125 2.097
0 0.000
4 .602
4 .602
VE
857 2.933
2759 3.441
5661 3.753
9277 3.967
VI
252 2.401
72 1.857
0 0.000
324 2.511
90 1.954
0 0.000
0 0.000
90 1.954
0 0.000 1117 3.048
0 0.000 470 2.672
54 1.732 4 .602
54 1.732 1591 3.202
WD
0 9.000
0 0.000
3 .477
3 .477
WE
5289 3.723
50 1.699
12 1.079
5351 3.728
WH
4407 3.644 10328 4.014 0 0.000
0 0.000 22 1.342 0 0.000
0 0.000 0 0.000 14 1.146
4407 3.644 10350 4.015 14 1.146
ux UY
uz VA VD
vo VY WA
WI WK
185
CHAPTER 5
186
BIGRAM FREQUENCIES FOR WORDS OF LETTER LENGTH 4
BIGRAM P O S I T I O N 1ST 2ND 3RD
WL WN WO
WR
ws XE
XI XT YA
YD
YE YM YN YO
YP YR
YS YT
YU ZE 21
0 0 000 0 0 000 214 3 084 12 1.079 0 0.000 0 0.000 0 0.000 0 0.000 69 1.839 0 0.000 694 2.841 0 0.000 0 0.000 1227 3.089 0 0.000 0 0.000 0 0.000 0 0.000 6
.I78
37 1.568 16 1.204
0 0.000 13 1.114 0 0.000 0 0.000 0 0.000 17 1.230 45 1.653 0 0.000 0 0.000 0 0.000 415 2.618 9 .954 5 .699 0 0.000 200 2.301 9 ,954 0 0.000 35 1.544 0 0.000 0 0.000 0 0.000
27 1.431 1169 3.068 0 0.000 0 0.000 297 2.473 0 0.000 16 1.204 4 54 2.657 0 0.000 5 .699 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 989 2.995 4 .602 0 0.000 163 2.212 13 1.114
SUM 27 1.431 1182 3.073 1214 3.084 12 1.079 297 2.473 17 1.230 61 1.785 454 2.657 69 1.839 5 .699 1109 3.045 9 .954 5 .699 1227 3.089 200 2.301 9 ,954 989 2.995 39 1.591 6 ,778 200 2.301 29 1.462
A P P E N D I X 5.2 BIGRAM F R E Q U E N C I E S F O R W O R D S OF LETTER LENGTH 4 BIGRAM P O S I T I O N 1ST 2ND 3RD ZO
ZY
zz
11 1.041 0 0.000 0 0.000
0 0.000 0 0.000 0 0.000
0 0.000 14 1.146 115 2.061
SUM 11 1.041 14 1.146 115 2.061
187
188
CHAPTER 5
BIGRAM F R E Q U E N C I E S FOR WORDS OF L E T T E R LENGTH 5 BIGRAM P O S I T I O N 1ST 2ND 3 RD
4TH
SUM
0 0.000
17 1.230
0 0.000
2592 3.414
AA
7 .845
0 0.000
AB
2151 3.333
438 2.641
10 1.000 3 .477
AC
109 2.037
309 2.490
1625 3.211
14 1.146
2057 3.313
AD
308 2.489
2 37 2.375
541 2.733
285 2.455
1371 3.137
AF
1070 3.029 686 2.836
5 .699 241 2.382
171 2.233
3 .477
1249 3.097
315 2.498
0 0.000
1242 3.094
AH
109 2.037
4 .602
0 0.000
26 1.415
139 2.143
A1
45 1.653
581 2.764
1088 3.037
7 .845
1721 3.236
AJ
0 0.000
0 0.000
0 0.000
247 2.393
AK
0 0.000
247 2.393 644 2.809
120 2.079
225 2.352
989 2.995
AL
875 2.942
810 2.908
1066 3.028
1616 3.208
4367 3.640
AM
396 2.598
362 2.559
305 2.484
111 2.045
1174 3.070
AN
176 2.246
994 2.997
1312 3.118
1228 3.089
3710 3.569
A0
0 0.000
0 0.000
17 1.230
0 0.000
17 1.230
AP
204 2.310
384 2.584
122 2.086
32 1.505
742 2.870
AR
410 2.613
1934 3.286
2670 3.427
394 2.595
5408 3.733
AS
489 2.689
884 2.946
1041 3.017
468 2.670
2882 3.460
AT
69 1.839
1449 3.161
1260 3.100
736 2.867
3514 3.546
AU
8 .903
274 2.438
8 .903
0 0.000
290 2.462
AV
62 1.792 185 2.267
332 2.521
416 2.619 98 1.991
0 0.000
810 2.908
15 1.176
310 2.491
AG
AW
12 1.079
APPENDIX 5.2
189
BIGRAM FREQUENCIES FOR WORDS OF LETTER LENGTH 5 BIGRAM POSITION 1ST 2ND 3RD
AX AY A2
BA BB
BE BI BL BO
BR BS BT
BU BY CA
cc CE CH CI CK CL
0 0.000 0 0.000 0 0.000 745 2.872 0 0.000 1556 3.192 269 2.430 654 2.816 668 2.825 984 2.993 0 0.000 0 0.000 372 2.571 16 1.204 731 2.864 0 0.000 121 2.083 925 2.966 161 2.207 0 0.000 1097 3.040
65 1.813 211 2.324 38 1.580 0 0.000 7 .845 0 0.000 7
.845 0 0.000 2115 3.325 0 0.000 0 0.000 b7
0.000 18 1.255 4 .602 86 1.934 43 1.633 146 2.164 3 .477 7 .845 0 0.000 0 0.000
0 0.000 74 1.869 44 1.643 61 1.785 60 1.778 144 2.158 77 1.886 287 2.458 162 2.210 3 .477 0 0.000 12 1.079 20 1.301 0 0.000 337 2.528 0 0.000 187 2.272 3 .477 12 1.079 112 2.049 81 1.908
4TH
SUM
19 1.279 384 2.584 0 0.000 0 0.000 0 0.000 161 2.207 21 1.322 0 0.d00 4 .602 0 0.000 80 1.903 114 2.057 0 0.000 58 1.763 0 0.c100 0 0.000 2712 3.433 4479 3.651 0 0.000 1000 3.000 0 0.000
84 1.924 669 2.825 82 1.914 806 2.906 67 1.826 1861 3.270 374 2.573 941 2.974 2949 3.470 987 2.994 80 1.903 126 2.100 410 2.613 78 1.892 1154 3.062 43 1.633 3166 3.501 5410 3.733 180 2.255 1112 3.046 1178 3.071
190
CHAPTER 5
BIGRAM F R E Q U E N C I E S F O R WORDS OF L E T T E R L E N G T H 5 BIGRAM P O S I T I O N 1ST 2ND 3RD
4TH
SUM
2783 3.445 457 2.660
134 2.127 82 1.914
18 1.255 0 0.000
0 0.000 0 0.000
2935 3.468
cs
0 0.000
0 0.000
0 0.000
7 .845
7 .845
CT
0 0.000
42 1.623
100 2.000
87 1.940
2 29 2.360
CU
113 2.053
13 1.114
88 1.944
0 0.000
214 2.330
CY
28 1.447
0 0.000
0 0.000
47 1.672
75 1.875
DA
412 2.615
50 1.699
321 2.507
5 .699
788 2.897
DD
0 0.000
211 2.324
34 1.531
0 0.000
245 2.389
DE
522 2.718
208 2.318
1814 3.259
5 58 2.747
3102 3.492
DG
0 0.000
44 1.643
143 2.155
0 0.000
187 2.272
DI
112 2.049
11 1.041
225 2.352
0 0.000
348 2.542
DL
0 0.000
7 .845
59 1.771
0 0.000
66 1.820
DM
0 0.000
37 1.568
0 0.000
0 0.000
37 1.568
DO
450 2.653 775 2.889
21 1.322
30 1.477
0 0.000
9 .954
11 1.041 0 0.000
512 2.709 7 84 2.894
DS
0 0.000
0 0.000
19 1.279
1736 3.240
1755 3.244
DT
0 0.000
0 0.000
14 1.146
0 0.000
14 1.146
DU
52 1.716
25 1.398
13 1.114
3 .477
DW
11 1.041 45 1.653
11 1.041 0 0.000 3865 3.587
0
0 0.000
0 0.000 547 2.738
93 1.968 22 1.342 592 2.772
2082 3.318
12 1.079
6532 3.815
CO CR
OR
DY EA
573 2.758
FI. 0 0 0
539 2.732
191
APPENDIX 5 . 2 B I G R A M FREQUENCIES FOR WORDS OF LETTER LENGTH 5
EB EC
ED EE
EF EG
EH EI
EK EL EM
EN EO
EP EQ ER
ES ET EU EV
EW
B I G R A M POSITION 3RD 1ST 2ND
4TH
SUM
0 0.000 0 0.000 89 1.949 0 0.000 0 0.000 14 1.146 0 0.000 104 2.017 0 0.000 77 1.886 64 1.806 303 2.481
44 1.643 18 1.255 41 1.613 883 2.946 27 1.431 628 2.798 5 .699 763 2.883 0 0.000 474 2.676 31 1.491 685 2.836
4 .602 261 2.417 237 2.375 930 2.968 10 1.000 18 1.255 0 0.000 2688 3.429 151 2.179 490 2.690 589 2.770 486 2.687
0 0.000 0 0.000 2825 3.451 665 2.823 210 2.322 0 0.000 0 0.000 0 0.000 95 978 752 876 19 279 686 227
48 1.681 279 2.446 3192 3.504 2478 3.394 247 2.393 660 2.820 5 .699 3555 3.551 246 2.391 1793 3.254 703 2.847 3160 3.500
0 0.000 6 .778 90 1.954 79 1.898 31 1.491
0 0.000 123 2.090 0 0.000 494 2.694 166 2.220 128 2.107 0 0.000 1088 3.031 151 2.179
0 0.000 216 2.334 0 0.000 4347 3.638 2095 3.321 178 2.250 9 .954 3 .477 51 1.708
3 .477 126 2.100 0 0.000 7346 3.866 3937 3.595 297 2.473 0 0.000 0 0.000 71 1.851
3 .477 471 2.673 90 1.954 12266 4.089 6229 3.794 614 2.788 9 . 9 54 1688 3.227 273 2.436
11 1.041 0 0.000 597 2.776 0 0.000
192
CHAPTER 5
BIGRAM FREQUENCIES FOR WORDS OF LETTER LENGTH 5
BIGRAM POSITION 1ST 2N D 3RD
151 2.179 0 0.000 628 2.798 245 2.389 0 0.000 2400 3.380 395 2.597 1171 3.069 541 2.733 0 0.000 0 0.000 234 2.369
89 1.949 6 .778 0 0.000 0 0.000 80 1.903 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 1438 3.158 0 0.000
GA
160 2.204
578 2.762
GE
3 .477 0 0.000 15 1.176 665 2.823 201 2.303 0 0.000 0 0.000 521 2.717
44 1.643 0 0.000 0 0.000
EX EY
FA FE FF FI FL FO FR FS FT FU
GG GH
GI GL GM
GN GO
4 .602 0 0.000 0 0.000 0 0.000 9 .954
0 0.000 0 0.000 0 0.000 112 2.049 0 0.000 0 0.000 63 1.799 0 0.000 El
0.000 0 0.000 122 2.086 17 1.230 4 56 2.659 290 2.462 18 1.255 2413 3.383 162 2.210 56 1.748 4 .602 68 1.833 69 1.839
4TH
SUM
93 1.968 342 2.534 0 0.000 84 1.924 189 2.276 0 0.000 0 0.000 0 0.000 0 0.000 12 1.079 162 2.210 0 0.000 0 0.000 1040 3.017 3 .477 138 2.140 0 0.000 0 0.000 0 0.000 7 .845 72 1.857
333 2.522 348 2.542 628 2.798 441 2.644 269 2.430 2400 3.380 458 2.661 1171 3.069 541 2.733 12 1.079 1722 3.236 251 2.400 1194 3.077 1377 3.139 21 1.322 2566 3.409 831 2.920 2 57 2.410 4 .602 75 1.875 671 2.827
APPENDIX 5 . 2
193
B I G R A M FREQUENCIES FOR WORDS OF LETTER LENGTH 5 B I G R A M POSITION GR
GS GU
GY HA
HE HI HN
HO HR
HS HT HU HY IA
IB
IC ID IE
IF IG
1ST
2ND
3RD
4TH
SUM
1763 3.246 0 0.000 233 2.367
51 1.708 0 0.000 0 0.000
0 0.000 192 2.283 0 0.000
4 .602 611 2.786 823 2.915 105 2.021 0 0.000 1404 3.147 0 0.000 0 0.000 0 0.000
14 1.146 924 2.966 8507 3.930 6209 3.793 0 0.000 2421 3.384 713 2.853 0 0.000 0 0.000
149 2.173 0 0.000 111 2.045 0 0.000 0 0.000 1717 3.235 4 .602 6 .778 8 .903 5 .699 0 0.000 0 0.000
1963 3.293 192 2.283 344 2.537 41 1.613 1535 3.186 11058 4.044 6323 3.801 6 .778 3837 3.584 718 2.856 28 1.447 2413 3.383
399 2.601 6 .778 0 0.000 0 0.000 0 0.000 211 2.324
27 1.431 7 ,845 87 1.940 93 1.968 19 1.279 2 57 2.410 534 2.728 180 2.255 2468 3.392
0 0.000 0 0.000 0 0.000
0 0.000 0 0.000 144 2.158 12 1.079 4245 3.628 229 2.360 594 2.774 199 2.299 26 1.415
23 1.362 0 0.000 11 1.041 5 .699 0 0.000 4 .602 0 0.000 28 1.447 2413 3.383 0 0.000 4 .602 123 2.090 0 0.000 555 2.752 333 2.522 112 2.049 27 1.431 0 0.000
426 2.629 17 1.230 3 54 2.549 105 2.021 4829 3.684 1030 3.013 1240 3.093 4 06 2.609 2494 3.397
CHAPTER 5
194
BIGRAM FREQUENCIES F O R WORDS OF LETTER L E N G T H 5
I1 IK IL IM IN I0 IP IR IS IT IV IX I2
JA JE JI JO
JU KA KE KI
BIGRAM POSITION 3RD 2N D 1ST
4TH
SUM
0 0.000 20 1.301 2279 3.358 91 1.959 3331 3.523 255 2.407 92 1.964 325 2.512 305 2.484 1217 3.085 174 2.241 0 0.000 34 1.531 0 0.000 0 0.000 0 0.000 291 2.464 0 0.000 0 0.000 1151 3.061 5 .699
4
.602 0 0.000 722 2.859 98 1.991 1090 3.037 156 2.193 34 1.531 2752 3.440 447 2.650 339 2.530 0 0.000 30 1.477 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 358 2.554 0 0.000
4 .602 102 2.009 3536 3.549 758 2.880 6050 3.782 443 2.646 152 2.182 5038 3.702 1147 3.060 1926 3.285 1244 3.095 226 2.354 58 1.763 142 2.152 86 1.934 11 1.041 446 2.649 131 2.117 27 1.431 1530 3.185 155 2.190
0 0.000 0 0.000 0 0.000 131 2.117 228 2.358 8 .903 0 0.000 47 1.672 169 2.228 106 2.025 17 1.230 0 0.000 0 0.000 142 2.152 86 1.934 11 1.041 155 2.190 131 2.117 27 1.431 21
1.322 68 1.833
0 0.000 82 1.914 535 2.728 438 2.641 1401 3.146 24 1.380 26 1.415 1914 3.282 2 26 2.354 264 2.422 1053 3.022 196 2.292 24 1.380 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 82 1.914
APPENDIX 5 . 2
195
B I G R A M FREQUENCIES FOR WORDS OF LETTER LENGTH 5
KL KN KO
KS KU KY LA LB
B I G R A M POSITION 3RD 1ST 2N D
4TH
SUM
8 .903 0 0.000 0 0.000 0 0.000 0 0.000 18 1.255 113 2.053 3 .477
0 0.000 0 0.000 0 0.000 812 2.910 0 0.000 72 1.857 28 1.447 0 0.000
8 .903 490 2.690 12 1.079 812 2.910 3 .477 90 1.954 3235 3.510 19 1.279
0 0.000 49 1.690 731 2.864 8 .903 5 .699 5 .699 232 2.365 65 1.813 789 2.897 39 1.591 405 2.607 53 1.724 38 1.580
0 0.000 5715 3.757 1837 3.264 12 1.079 0 0.000 0 0.000 0 0.000 3 .477 1806 3.257 19 1.279 10 1.000 4 .602 1006 3.003
5 .699 5872 3.769 4205 3.624 20 1.301 5 .699 5 .699 1478 3.170 68 1.833 2726 3.436 64 1.806 2754 3.440 57 1.756 1048 3.020
0 0.000 490 2.690 12 1.079 0 0.000 0 0.000 0 0.000 1119 3.049 0 0.000
LC
0 0.000
LD
0 0.000 1063 3.027 0 0.000
LE
LF LG
LH LI
LK LL LM
LO
LP LS
0 0.000 0 0.000 958 2.981 0 0.0063 10 1.000 0 0.000 878 2.943 0 0 * 000 0 0.000
0 0.000 0 0.000 0 0.000 0 0.000 3 .477 0 0.000 1975 3.296 16 1.204 5 .699 108 2.033 574 2.759 0 0.000 0 0.000 0 0.6300 288 2.459 0 0.000 121 2.083 6 -778 1461 3.165 0 0.000 4 .602
CHAPTER 5
196
BIGRAM FREQUENCIES FOR WORDS OF LETTER LENGTH 5 BIGRAM POSITION
LT LU LV
LY MA MB ME
MI ML MM MN
MO
MP YS
MU
MY NA NC
ND NE NG
1ST
2ND
3RD
4TH
SUM
0 0.000 111 2.045 0 0.000 48 1.681 978 2.990 0 0.000 650 2.813 1109 3.045
24 1.380 191 2.281 6 .778 4 .602 693 2.841 0 0.000 34 1.531 115 2.061
40 1.602 200 2.301 26 1.415 0 0.000 581 2.764 44 1.643 1162 3.065 105 2.021
213 2.328 0 0.000 0 0.000 1055 3.023 67 1.826 27 1.431 283 2.452 22 1.342
271 2.442 502 2.701 32 1.505 1107 3.044 2319 3.365 71 1.851 2129 3.328 1351 3.131
0 0.000 0 0.000 0 0.000 1236 3.092 0 0.000
0 0.000 0 0.000 0 0.000 416 2.619 96 1.982
12 1.079 46 1.663 6 .778 107 2.029
0 0.000 241 2.382 6 .778 281 2.449 0 0.000 0 0.000 1025 3.011 0 0.000
0 0.000 3 .477 0 0.000 61 1.785 62 1.792 922 2.965 144 2.158 162 2.210
0 0.000 0 0.000 0 0.000 0 0.000 27 1.431 1098 3.041 0 0.000 117 2.068 101 2.004 0 0.000 1331 3.124 607 2.783 3346 3.525
12 1.079 46 1.663 6 .778 1759 3.245 159 2.201 1098 3.041 248 2.394 123 2.090 621 2.793 1028 3.012 3004 3.478 2637 3.421 3878 3.589
36 1.556 0 0.000 4 .602 0 0.000 178 2.250 966 2.985 751 2.876 861 2.935 370 2.568
APPENDIX 5.2
197
BIGRAM FREQUENCIES F O R WORDS OF L E T T E R LENGTH 5 BIGRAM POSITION 1ST
2ND
3RD
4TH
SUM
467 2.669 0 0.000
441 2.644 44 1.643
53 1.724 0 0.000
0 0.000 0 0.000
961 2.983 44 1.643
NK
0 0.000
8 .903
113 2.053
711 2.852
832 2.920
NL
0 0.000
4 .602
0 0.000
0 0.000
4 .602
NN
0 0.000 546 2.737 0 0.000
58 1.763
113 2.053
6 .7ia
177 2.248
370 2.568
38 1.580
20 1.301
152 2.182 0 0.000
1106 3.044 20 1.301
0 0.000
0 0.000
99 1.996
0.000
99 1.996
NS
0 0.000
38 1.580
34fJ 2.531
819 2.913
1197 3.078
NT
0 0.000
565 2.752
313 2.496
1403 3.147
2281 3.358
NU
17 1.230
0 0.000
22 1.342
0 0.000
39 1.591
NX
0 0.000
0 0.000
0 0.000
9 .954
9 .9 54
NY
0 0.000
0 0.000
0 0.000
142 2.152
142 2.152
OA
3 .477
573 2.758
105 2 . fJ21
0 0.000
681 2.833
0 0.000 77 1.886
108 2.033
23 1.362
0 0.000
400 2.602
295 2.470
3 .477
131 2.117 775 2.889
OD
17 1.230
419 2.622
259 2.413
361 2.558
1056 3.024
OE
0 0.000
114 2.057
44 1.643
11 1.041
169 2.228
OF
448 2.651 0 0.000 0 0.000
5 .599 61 1.785
1.176 0 0.000
45 1.653 0 0.000
513 2.710 61 1.785
9 .954
0 0.000
0 0.000
9 .954
NI NJ
NO NP NR
OB
oc
OG OH
15
0 0.000 0
198
CHAPTER 5
BIGRAM FREQUENCIES FOR WORDS OF LETTER LENGTH 5
BIGRAM POSITION 3 RD 2ND 1ST 01
OK OL
OM ON
00 OP OR
0s OT OU
ov OW
ox OY 02
PA PE PH PI PL
3 .477 0 0.000 98 1.991 0 0.000 53 1.724 0 0.000 63 1.799 404 2.606 9 .954 1702 3.231 105 2.021 11 1.041 71 1.851 0 0.000 0 0.000 0 0.000 838 2.923 318 2.502 143 2.155 297 2.473 1117 3.048
1306 3.116 50 1.699 489 2.689 775 2.889 820 2.914 663 2.822 109 2.037 2726 3.436 279 2.446 663 2.822 7649 3.884 500 2.699 581 2.764 14 1.146 94 1.973 57 1.756 301 2.479 446 2.649 0 0.000 71 1.851 30 1.477
4TH
SUM
69 1.839 411 2.614 373 2.572 99 1.996 1475 3.169 724 2.860 129 2.111 7 59 2.880 1619 3.209 4 29 2.632 2342 3.370 449 2.652 972 2.988 7 .845 10 1.000 4 .602 52 1.716
0 0.000 63 1.799 8 .903 46 1.663 396 2.598 3 .477 25 1.398 1243 3.094 28 1.447 88 1.944 0 0.000 9 .954 309 2.490 0 0.000 44 1.643 0 0.000 5 .699
1378 3.139 524 2.719 968 2.986 920 2.964 2744 3.438 1390 3.143 326 2.513 5132 3.710 1935 3.287 2882 3.460 10096 4.004 969 2.986 1933 3.286 21 1.322 148 2.170 61 1.785 1196 3.078
501 2.700 0 0.000 72 1.857 146 2.164
134 2.127 39 1.591 0 0.000 0 0.000
1399 3.146 182 2.260 440 2.643 1293 3.112
APPENDIX 5.2
199
B I G R A M FREQUENCIES FOR WORDS OF LETTER LENGTH 5 B I G R A M POSITION
PO
1ST
2ND
3RD
4TH
SUM
1028 3.012 0 0.000 615 2.789 0 0.000 0 0.000 62 1.792 0 0.000 515 2.712
25 1.398 103 2.013 0 0.000 10 1.000 117 2.068 20 1.301 0 0.000 0 0.000 292 2.465 17 1.230 419 2.622 482 2.683 1058 3.024 0 0.000 404 2.606 0 0.000 255 2.407 199 2.299
4 .602 0 0.000 0 0.000 491 2.691 108 2.033 0 0.000 98 1.991 0 0.000 123 2.090 0 0.000 0 0.000 824 2.916 4157 3.619 7 .845 0 0.000 0 0.000 16 1.204 91 1.959
1208 3.082 240 2.380 713 2.853 515 2.712 229 2.360 85 1.929 98 1.991 630 2.799 2418 3.383 75 1.875 419 2.622 1682 3.226 7607 3.881 7 .845 488 2.688 108 2.033 2748 3.439 290 2.462
1319 3.120 408 2.611 90 1.954
12 1.079 71 1.851 116 2.064
1331 3.124 543 2.735 2 29 2.360
RK
0 0.000
151 2.179 137 2.137 98 1.991 14 1.146 4 .602 3 .477 0 0.000 115 2.061 1278 3.107 58 1.763 0 0.000 376 2.575 1906 3.280 0 0.000 84 1.924 0 0.000 1508 3.178 0 0.000
RL
0 0.000 0 0.000 0 0.000
0 0.000 64 1.806 23 1.362
PP PR PS PT PU PY
QU RA RB RC
RD RE
RF RG RH RI
RM RN
725 2.860 0 0.000 0 0.000 0 0.000 486 2.687 0 0.000 0 0.000 108 2.033 969 2.986
200
CHAPTER 5
BIGRAM FREQUENCIES FOR WORDS OF LETTER LENGTH 5 B I G R A M POSITION
1ST
2ND
3RD
4TH
SUM
548 2.739 0 0.000 0 0.000 0 0.000 0 0.000 200 2.301 0 0.000 0 0.000 375 2.574 370 2.568 943 2.975 1655 3.219
1926 3.285 0 0.000 64 1.806 0 0.000 0 0.000 512 2.709 0 0.000 19 1.279 24 1.380 9 .954 6 .778 6 .778
131 2.117 109 2.037 362 2.559 1718 3.235 1028 3.012 61 1.785 171 2.233 0 0.000 55 1.740 7 .845 519 2.715 0 0.000
115 2.061 72 1.857 0 0.000 1416 3.151 997 2.999 5 .699 0 0.000 1254 3.098 6 .778 0 0.000 4720 3.674 289 2.461
2720 3.435 181 2.258 4 26 2.629 3134 3.496 2025 3.306 778 2.891 171 2.233 1273 3.105 460 2.663 386 2.587 6188 3.792
SI
1025 3.011
SK
85 1.929 254 2.405 766 2.884 61 1.785
222 2.346 398 2.600 7 .845 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 191 2.281
700 2.845 51 1.708 6 .778 0 0.000 0 0.000 31 1.491 5 .699 0 0.000 17 1.230
0 0.000 7 .845 0 0.000 3 .477 0 0.000 7 .845 25 1.398 0 0.000 787 2.896
1947 3.289 541 2.733 267 2.427
RO RP RR RS
RT RU
RV RY SA SC SE SH
SL SM SN
SO
750 2.875
SP
896 2.952 25 1.398 0 0.000
SQ SS
1950 3.290
769 2.886 61 1.785 788 2.897 926 2.967 25 1.398 995 2.998
A P P E N D I X 5.2
201
B I G R A M F R E Q U E N C I E S F O R WORDS O F L E T T E R LENGTH 5 BIGRAM P O S I T I O N 1ST 2ND 3RD
4TH
SUM
3855 3.586 156 2.193
0 0.000 96 1.982
499 2.698 216 2.334
2236 3.349 0 0.000
6590 3.819 468 2.670
sw
306 2.486
0 0.000
0 0.000
0 0.000
306 2.486
SY
4 .602
0 0.000
0 0.000
28 1.447
32 1.505
TA
809 2.908 0 0.000 0 0.000
1551 3.191 0 0.000
362 2.559 2 68 2.428
50 1.699 0 0.000
2772 3.443 268 2.428
0 0.000
3 .477
0 0.000
3 -477
TE
624 2.795
372 2.571
3129 3.495
2104 3.323
6229 3.794
TH
9669 3.985
1713 3.234
44 1.643
2068 3.316
13494 4.130
TI
517 2.713
8 56 2.932
591 2.772
0 0.000
1964 3.293
TL
0 0.000
12 1.079
81 1.908
0 0.000
93 1.968
TO
870 2.940
764 2.883
98 1.991
36 1.556
1768 3.247
TR
1212 3.084
60 1.778
85 1.929
0 0.000
1357 3.133
TS
0 0.080
0 0.000
0 0.000
1173 3.069
1173 3.069
TT
0 0.000
29 1.462
58 1.763
29 1.462
116 2.064
TU
109 2.037
301 2.479
8 .903
0 0.000
418 2.621
TW
109 2.037
0 0.000
0 0.000
0 0.0Q0
109 2.037
TY
124 2.093
98 1.991
0 0.00B
591 2.772
813 2.910
TZ
0 0.000 0 0.000 0 0.000
0 0.000 51 1.708 62 1.792
0 0.000 211 2.324 138 2.140
3 .477
3 .477
0 0.000
262 2.418
9 .954
209 2.320
ST
su
TC TD
UA UB
202
CHAPTER 5
BIGRAM F R E Q U E N C I E S F O R WORDS OF L E T T E R LENGTH 5 BIGRAM P O S I T I O N 2N D 1ST 3RD
uc
0 0.000
UD
4TH
SUM
225 2.352
0 0.000
49 1.690 110 2.041
268 2.428
0 0.000 108 2.033
UE
0 0.000
161 2.207
66 1.820
425 2.628
274 2.438 486 2.687 652 2.814
UF
0 0.000 0 0.000
0 0.000
44 1.643
0 0.000
44 1.643
108 2.033
176 2.246
0 0.000
284 2.453
U I
0 0.000
773 2.888
129 2.111
0 0.000
902 2.955
UL
5 .699
301 2.479
4442 3.648
17 1.230
4765 3.678
UM
0 0.000
384 2.584
57 1.756
37 1.568
478 2.679
UN
1588 3.201
283 2.452
1541 3.188
51 1.708
3463 3.539
00
0 0.000
21 1.322
0 0.000
0 0.000
21 1.322
UP
86 1.934
28 1.447
0 0.000
402 2.604
516 2.713
UR
85 1.929
351 2.545
463 2.666
56 1.748
955 2.980
US
261 2.417
304 2.483
902 2.955
150 2.176
1617 3.209
UT
13 1.114
65 1.813
616 2.790
1876 3.273
2570 3.410
ux
0 0.000 0 0.000
0 0.000
8 .903 7 .845
51 1.708
8 .903 0 0.000 0 0.000
327 2.515
UG
VA
'262 2.418
0 0.000 7 .845 14 1.146
VE
70 1.845
583 2.766
2570 3.410
1125 3.051
4348 3.638
VI
294 2.468
9 .954
2 77 2.442
0 0.000
580 2.763
VO
309 2.490
81 1.908
3 .477
0 0.000
81 1.908 0 0.000
0 0.000 114 2.057
2.673 117 2.068
uz
VY
0 0.000
4ii
203
APPENDIX 5 . 2 B I G R A M FREQUENCIES FOR WORDS OF LETTER LENGTH 5 B I G R A M POSITION WA
WD
WE WF WH WI WL
WN
WO WR
ws wu
1ST
2ND
3RD
4TH
SUM
961 2.983 0 0.000 201 2.303 0 0.000 6184 3.791 207 2.316 0 0.000 0 0.000 4632 3.666 446 2.649 0 0.000 0 0.000
165 2.217 0 0.000 172 2.236 17 1.230 0 0.000 178 2.250 0 0.000 67 1.826 35 1.544 0 0.000 0 0.000 48 1.681 0 0.000 27 1.431 11 1.041 63 1.799 0 0.000 50 1.699 0 0.000 3 .477 0 0,000
0 0.000 7 .845 569 2.755 0 0.000 0 0.000 68 1.833 38 1.580 73 1.863 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 74 1.869 211 2.324 3 .477 25 1.398 51 1.708 0 0.000 78 1.892 134 2.127
0 0.000 53 1.724 0 0.000 0 0.000 0 0.000 0 0.000 15 1.176 738 2.868 0 0.000 0 0.000 311 2.493 0 0.000 4 .602
1126 3.052 60 1.778 942 2.974 17 1.230 6184 3.791 453 2.656 53 1.724 878 2.943 4667 3.669 446 2.649 311 2.493 48 1.681 7 .845
0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 7 .845 0 0.000 0 0.000
101 2.004 222 2.346 66 1.820 25 1.398 101 2.004 7 .845 149 2.173 134 2.127
WY
3 .477
XA
0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 68 1.833 0 0.000
XE
XI
xo XT XY YA
YB
204
CHAPTER 5
B I G R A M FREQUENCIES FOR WORDS OF LETTER LENGTH 5
YC
YD YE YI
YL YM
YN YO
YP YR
YS YT ZA
ZE ZI ZO
ZY ZZ
B I G R A M POSITION 1ST 2N D 3RD
4TH
SUM
21 1.322 0 0.000 35 1.544 5 .699 113 2.053 3 .477 12 1.079 38 1.580 14 1.146 0 0.000 4 .602 0 0.000 0 0.000 84 1.924 12 1.079 15 1.176 0 0.000 15 1.176
0 0.000 10 1.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 18 1.255 0 0.000 0 0.000 74 1.869 0 0.000 3 .477 48 1.681 0 0.008 0 0.000 46 1.663 0 0.000
45 1.653 10 1.000 987 2.994 118 2.012 124 2.093 9 .954 12 1.079 548 2.739 137 2.137 36 1.556 78 1.892 6 .778 3 .417 132 2.121 12 1.079 18 1.255 46 1.663 15 1.176
0 0.000 0 0.000 952 2.979 35 1.544 0 0.000 0 0.000 0 0.000 492 2.692 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 3 .477 0 0.000 0 0.000
24 1.380 0 0.000 0 0.000 18 1.892 11 1.041 6 .778 0 0.000 0 0.000 123 2.090 36 1.556 0 0.000 6 .778 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000
205
APPENDIX 5 . 2 B I G R A M FREQUENCIES FOR WORDS OF LETTER LENGTH 6
B I G R A M POSITION 3RD 2N D 1ST AA
AB AC AD
AE
AF AG AH
A1 AJ AK
AL AM AN
AP AQ AR
AS AT AU AV
0 0.000 170 2.230 967 2.985
141 2.149 8 .903 232 2.365 192 2.283 0 0.000 12 1.079 0 0.000 0 0.000 1094 3.039 202 2.305 604 2.781 185 2.267 0 0.000 906 2.957 344 2.537 253 2.403 139 2.143 49 1.690
0 0.000 122 2.086 406 2.609 131 2.117 6 .778 64 1.806 102 2.009 0 0.000 494 2.694 3 .477 470 2.672 1430 3.155
0 0.000 140 2.146 332 2.521 363 2.560 0 0.000 11 1.041 221 2.344 22 1.342 324 2.511 0 0.000 103 2.013 472 2.674
743 2.871 1377 3.139 160 2.204 0 0.000 1830 3.262 715 2.854 1950 3.290 368 2.566 388 2.589
85 1.929 895 2.952 148 2.170 6 .778 865 2.937 4 37 2,640 9 67 2.985 96 1.982 257 2.410
4TH
5TH
SUM
7 .845 0 0.000 277 2.442 167 2.223 15 1.176 0 0.000 156 2.193 0 0.000 462 2.665 0 0.000 46 1.663 270 2.431 316 2.500 491 2.691 71 1.851 0 0.000 933 2.970 151 2.179
0 0.000 0 0.000 4 .602 185 2.267 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 10 1.000 1558 3.193 83 1.919 310 2.491 4 .602 0 0.000 278 2.444 220 2.342
7 .845 432 2.635 1986 3.298
370 2.568 0 0.000 13 1.114
193 2.286 57 1.756 0 fl.000
3733 3.572 660 2.820 707 2.849
987 2.994 29 1.462 3 07 2.487 671 2.827 22 1.342 1292 3.111 3 .477 629 2.799 4824 3.683 1429 3.155 3677 3.565 568 2.754 6 .778 4812 3.682 1867 3.271
2 06
CHAPTER 5
B I G R A M FREQUENCIES FOR WORDS OF LETTER LENGTH 6 B I G R A M POSITION 2N D 3RD 1ST AW
AX AY AZ
BA BB
BE
31 1.491 0 0.000 0 0.000 0 0.000 376 2.575 0 0.000 3022 3.480
BI
121 2.083
BJ
0 0.000 101 2.004 0 0.000 535 2.728 533 2.727 0 0.000 0 0.000 425 2.628 0 0.000 3 .477 1468 3.157 0 0.000 320 2.505
BL
BM BO
BR BS
BT BU BW
BY CA
cc CE
62 1.792 9 .954 200 2.301 27 1.431 0 0.000 0 0.000 7 .845 0 0.000 68 1.833 3 .477 0 0.000 25 1.398 69 1.839 58 1.763 42 1.623 12 1.079 0 0.000 0 0.000 36 1.556 167 2.223 44 1.643
11 1.041 3 .477 282 2.450 41 1.613 53 1.724 85 1.929 155 2.190 106 2.025
0 0.000 490 2.690 18 1.255 92 1.964 33 1.519 8 .903 31 1.491 24 1.380 7 .845 0 0.000 436 2.639 0 0.000 567 2.754
4TH
5TH
SUM
3 .477 3 .477 472 2.674 3 .477 58 1.763 8 .903 755 2.884 21 1.322 0 0.000 266 2.425 0 0.000 152 2.182 0 0.000 0 0.000 16 1.204 0 0.000 0 0.000 0 0.000 115 2.064 4 .602 929 2.968
10 1.000 20 1.301 325 2.512 0 0.000 0 0.000 0 0.000 3 .477 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 16 1.204 0 0.000 0 0.000 0 0.000 60 1.778 45 1.653 0 0.000 1267 3.103
117 2.068 35 1.544 1279 3.107 71 1.851 4 87 2.688 93 1.968 3952 3.597 248 2.394 68 1.833 860 2.934 18 1.255 804 2.905 635 2.803 82 1.914 89 1.949 461 2.664 7 .845 53 1.799 2101 3.322 171 2.233 3127 3.495
APPENDIX 5.2
207
BIGRAM FREQUENCIES FOR WORDS OF LETTER LENGTH 6 BIGRAM POSITION 3RD 2N D 1ST CH CI CK CL CN CO CR
cs CT
cu CY DA DD DE DF DG DH DI DJ DL DM
1371 3.137 177 2.248 0 0.000 438 2.641 0 0.000 2059 3.314 311 2.493 0 0.000 0 0.000 83 1.919 10 1.000 329 2.517 0 0.000 1235 3.092 0 0.000 0 0.000 0 0.000 392 2.593 0 0.000 0 0.000 0 0.000
546 2.737 0 0.000 0 0.000 0 0.000 0 0.000 35 1.544 370 2.568 0 0.000 555 2.144 0 0.000 0 0.000 0 0.000 22 1.342 16 1.204 0 0.000 5 .699 4 .602 87 1.940 16 1.204 0 0.000 10 1.000
174 2.241 538 2.731 468 2.670 23 1.362 15 1.176 998 2.999 119 2.076 0 0.000 297 2.473 130 2.114 0 0.000 19 1.279 310 2.491 604 2.781 3 .477 123 2.090 0 0.000 379 2.579 0 0.000 0 0.000 3 .477
4TH
5TH
SUM
13 1.114 46 1.663 186 2.270 102 2.009 0 0.000 60 1.778 0 0.000 0 0.000 5 .699 33 1.519 0 0.000 2 54 2.405 0 0.000 1285 3.109 0 0.000 105 2.021 8 .903 101 2.004 0 0.000 469 2.671 0 0.000
779 2.892 0 0.000 167 2.223 0 0.000 0 0.000 27 1.431 0 0.000 51 1.708 761 2.881 0 0.000 287 2.458 45 1.653 0 0.000 460 2.663 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000
2883 3.460 761 2.881 821 2.914 563 2.751 15 1.176 3179 3.502 800 2.903 51 1.708 1618 3.209 246 2.391 297 2.473 647 2.811 332 2.521 3600 3.556 3 .477 233 2.367 12 1.079 959 2.982 16 1.204 469 2.671 13 1.114
CHAPTER 5
208
BIGRAM FREQUENCIES FOR WORDS OF LETTER LENGTH 6 B I G R A M POSITION DN
DO DR
DS
DT
DU DV
DW DY EA
EB EC ED
EE
EF EG EH EI
EJ EK
EL
1ST
2N D
0 0.000 293 2.467 236 2.373 0 0.000 0 0.000 649 2.812 0 0.000 12 1.079 0 0.000 231 2.364 0 0.000
0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 23 1.362 66 1.820 45 1.653 0 0.000 1875 3.273 74 1.869 1638 3.214 131 2.117 777 2.890 1180 3.072 4 28 2.631 304 2.483 196 2.292 10 1.000 0 0.000 586 2.768
15 1.176 134 2.127 0 0.000 358 2.554 0 0.000 0 0.000 344 2.537 0 0.000 0 0.000 89 1.949
3RD 20 1.301 8 .903 15 1.176 56 1.748 5 .699 a8 1.944 0 0.000 15 1.176 0 0.000 410 2.613 11 1.041 109 2.037 282 2.450 274 2.438 85 1.929 11 1.041 0 0.000 111 2.045 0 0.000 24 1.380 163 2.212
4TH
5TH
SUM
0 0.000 398 2.600 11 1.041 3 .477 0 0.000 4 .602 0 0.000 0 0.000 0 0.000 593 2.773 8 .903 743 2.871
0 0.000 0 0.000 0 0.000 535 2.728 10 1.000 0 0.000 0 0.000 0 0.000 234 2.369 6 .778 0 0.000 0 0.000
20 1.301 699 2.844 262 2.418 594 2.774 15 1.176 764 2.883 66 1.820 72 1.857 234 2.369 3115 3.493 93 1.968 2505 3.399
35 1.929 703 2.847 6 .778 3 .477 0 0.000 3 .477 0 0.000 18 1.255 1509 3.179
8585 3.934 224 2.350 130 2.114 0 0.000 0 0.000 13 1.114 0 0.000 5 .699 325 2.512
9217 3.965 1978 3.296 1759 3.245 442 2.645 304 2.483 657 2.824 10 1.000 47 1.672 2672 3.427
209
APPENDIX 5 . 2 B I G R A M FREQUENCIES FOR WORDS OF LETTER LENGTH 6 B I G R A M POSITION
EM EN
EO
EP EQ ER
ES ET EU
EV EW EX EY
EZ FA FE FF FI FL FO FR
1ST
2ND
3RD
4TH
5TH
SUM
62 1.792 886 2.947 0 0.000 0 0.000 23 1.362 73 1.863 144 2.158 32 1.505 143 2.155 126 2.100 0 0.000 649 2.812
685 2.836 936 2.971 976 2.989 343 2.535 0 0.000 1551 3.191 769 2.886 1071 3.030 9 .954 312 2.494 177 2.248 97 1.987
48 1.681 1274 3.105 3 .477 314 2.497 0 0.000 1461 3.165 601 2.779 130 2.114 32 1.505 28 1.447 24 1.380 0 0.000
4 35 2.638 1099 3.041 12 1.079 35 1.544 0 0.000 6964 3.843 3735 3.572
4 .602 0 0.000 997 2.999 165 2.217 0 0.000 803 2.905 218 2.338 926 2.967 573 2.758
183 2.262 0 0.000 0 0.000 0 0.000 791 2.898 0 0.000 10 1.000 0 0.000 102 2.009
360 2.556 803 2.905 129 2.111 76 1.881 0 0.000 2 52 2.401 82 1.914 2 53 2.403 0 0.000 63 1.799 33 1.519 10 1.000 7 .845
0 0.000 33 1.519 0 0.000 185 2.267 12 1.079 51 1.708 12 1.079 0 0.000 0 0.000
284 2.453
1590 3.201 4998 3.699 1120 3.049 768 2.885 23 1.362 10301 4.013 5331 3.727 2650 3.423 188 2.274 529 2.723 321 2.507 760 2.881 478 2.679
0 0.000 0 0.000 6 .778 9 . 9 54 0 0.000 0 0.000 0 0.000 0 0.000
33 1.519 1054 3.023 790 2.898 974 2.989 1155 3.063 271 2.433 2182 3.339 727 2.862
0 0.000 57 1.756 434 2.637 162 2.210 301 2.479 31 1.491 1256 3.099 52 1.716
1164 3.066 4 .602 0 0.000 87 1.940 4 .602
210
CHAPTER 5
B I G R A M FREQUENCIES FOR WORDS OF LETTER LENGTH 6 B I G R A M POSITION
FS FT FU FY GA
GE GG GH GI GL
GM GN GO GR
GS GT GU
GY HA HE
HI
1ST
2ND
3RD
4TH
5TH
SUM
0 0.000 0 0.000 271 2.433 0 0.000 196 2.292 322 2.508 0 0.000 16 1.204 138 2.140 88 1.944 0 0.000 0 0.000 119 2.076 661 2.820 0 0.000 0 0.000 172 2.236 0 0.000 834 2.921 493 2.693 316 2.500
0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 100 2.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 19 1.279
9 .954 99 1.996 23 1.362 0 0.000 129 2.111 124 2.093 117 2.068 544 2.736 226 2.354 11 1.041 0 0.000
0 0.000 26 1.415 61 1.785 0 0.000 86 1.934 1851 3.022 0 0.000 722 2.859 150 2.176 205 2.312 4 .602 0 0.000 33 1.519 23 1.362 0 0.000 116 2.064 110 2.041 0 0.000 29 1.462 1739 3.240 370 2.568
23 1.362 0 0.000 0 0.000 19 1.279 0 0.000 844 2.926 0 0.000 872 2.941
32 1.505 125 2.097 355 2.550 19 1.279 411 2.614 2441 3.388 117 2.068 2154 3.333 514 2.711 304 2.483 4 .602 275 2.439 191 2.281 910 2.959 462 2.665 116 2.064 583 2.766 112 2.049 1763 3.246 2976 3.474 1559 3.193
0 0.000 92 1.964 0 0.000 0 0.000 0 0.000 0 0.000 848 2.928 328 2.516 586 2.768
124 2.093 36 1.556 134 2.127 0 0.000 0 0.000 301 2.479 0 0.000 34 1.531 399 2.601 287 2.458
0 0.000 0 0.000 0 0.000 132 2.121 3 .477 0 0.000 462 2.665 0 0.000 0 0.000 112 2.049 18 1.255 17 1.230 0 0.000
APPENDIX 5.2
211
BIGRAM F R E Q U E N C I E S F O R WORDS OF LETTER L E N G T H 6 BIGRAM P O S I T I O N HL HM HN HO HR HS HT
HU HW HY IA IB IC ID IE IF IG I1 IK IL IM
1ST
2ND
3RD
4TH
5TH
SUM
0 0.000 0 0.000 0 0.000 463 2.666 0 0.000 0 0.000 0 0.000 204 2.310 0 0.000 0 0.000 0 0.000 0 0.000
0 0.000 0 0.000 0 0.000 1991 3.299 361 2.558 0 0.000 0 0.000 359 2.555 3 .477 22 1.342 56 1.748 43 1.633
0 0.000 0 0.000 43 1.633 524 2.719 5 .699 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 43 1.633 25 1.398
99 1.996 7 .845 0 0.000
0 0.000 22 1.342 0 0.000 0 0.000 0 0.000 273 2.436 703 2.847 0 0.000 0 0.000 63 1.799 99 1.996 0 0.000
99 1.996 29 1.462 43 1.633 3219 3.508 366 2.563 273 2.436 947 2.976 618 2.791 3 .477 85 1.929 733 2.865 68 1.833
3 .477 16 1.204 0 0.000 0 0.000 19 1.279 0 0.000 0 0.000 0 0.000 138 2.140
284 2.453 322 2.508 253 2.403 100 2.000 870 2.940 0 0.000
169 2.228 195 2.290 203 2.307 32 1.505 452 2.665 7 .845
739 2.869 168 2.225 46 1.663 0 0.000 8 .903 16 1.204
2255 3.353 1049 3.021 1549 3.190 167 2.223 1491 3.173 23 1.362
169 2.228 548 2.739 421 2.624
0 0.000 346 2.539 107 2.029
0 0.000 142 2.152 27 1.431
261 2.417 1606 3.206 790 2.898
241 2.382 0 0.000 0 0.000 244 2.387 55 1.740 0 0.000 0 0.000 535 2.728 0 0.000 1060 3.025 348 2.542 1047 3.020 35 1.544 132 2.121 0 0.000 92 1.964 570 2.756 97 1.987
212
CHAPTER 5
BIGRAM F R E Q U E N C I E S F O R WORDS O F L E T T E R LENGTH 6 BIGRAM P O S I T I O N 3 RD 1ST 2ND
4TH
5TH
SUM.
873 2.941 0 0.000
828 2.918 18 1.255
916 2.962 36 1.556
4190 3.622 1100 3.041
9 15 2.961 31 1.491
7722 3.888 1185 3.074
IP
0 0.000
29 1.462
5 .699
33 1.519
34 1.531
101 2.004
IQ
0 0.000
91 1.959
58 1.763
0 0.000
0 0.000
149 2.173
IR
17 1.230
IS
298 2.474
389 2.590 800 2.903
325 2.512 392 2.593
406 2.609 480 2.681
73 1.863 167 2.223
1210 3.083 2137 3.330
IT
304 2.483
1757 3.245
901 2.955
235 2.371
444 2.647
3641 3.561
IU
0 0.000
0 0.000
0 0.000
108 2.033
0 0.000
108 2.033
IV
0 0.000 0 0.000
394 2.595 21 1.322
122 2.086 0 0.000
208 2.318
724 2.860
0 0.000
0 0.000 0 0.000
I2
0 0.00Q
3 .477
30 1.477
0 0.000
0 0.000
33 1.519
JA
50 1.699
0 0.000
0 0.000
0 0.000
0 0.000
50 1.699
JE
119 2.076
0 0.000
84 1.924
0 0.000
0 0.000
203 2.307
JO
176 2.246 196 2.292 31 1.491
0 0.000 0 0.000 0 0.000
13 1.114 43 1.633 0 0.000
0 0.000 0 0.000 22 1.342
189 2.276 239 2.378
KE
6 .778
16 1.204
176 2.246
0 0.000 0 0.000 0 0.000 1927 3.285
127 2.104
2252 3.353
KI
152 2.182
57 1.756
543 2.735
12
1.079
0 0.000
764 2.883
0 0.000 25 1.398 11 1.041
0 0.000 0 0.000
7 .845 0 0.000 6 .778
42 1.623 0 0.000 7 .845
Q 0.000 0 0.000 0 0.000
49 1.690 25 1.398 24 1.380
IN I0
IX
JU KA
KL KN KO
0
0.000
21 1.322
53 1.724
213
APPENDIX 5.2 B I G R A M FREQUENCIES FOR WORDS OF LETTER LENGTH 6 B I G R A M POSITION 2ND 1ST 3RD
KS KU KY
LA LB
LD LE
LF LG LI LK LL LM LN
LO
LP LS LT LU
LV LW
0 0.000 0 0.000 0 0.000 518 2.714 0 0.000 0 0.000 718 2.856
0 0.000 0 0.000 0 0.000 914 2.961 47 1.672 28 1.447 210 2.322
0 0.000 0 0.000 0 0.000 321 2.507 0 0.000 189 2.276
0 0 * 000 0 0.000 1605 3.205 0 0.000 0 0.000
52 1.716 0 0.000 173 2.238 0 0.000 78 1.892
0 0.000
0 0.000 0 0.000 978 2.990 0 0.000
432 2.635 0 0.000 536 2.729 0 0.000
0 0.000 0 0.000 81 1.908 0 0.000 0 0.000
0 0.000 0 0.000 57 1.756 0 0.000 4 58 2.661
316 2.500
10 1.000 773 2.888 234 2.369 1471 3.168 117 2.068
11 1.041 193 2.286 79 1.898 78 1.892 144 2.158 413 2.616 68 1.833 0 0.000
4TH
5TH
SUM
0 0.000 14 1.146 0 0.000 155 2.190 0 0.000 93 1.968 1635 3.214 0 0.000 0 0.000 577 2.761 0 0.000
360 2.556 0 0.000 32 1.505 19 1.279 0 0.000 1004 3.002 3499 3.544 4 54 2.657
360 2.556 14 1.146 32 1.505 1927 3.285 47 1.672 1314 3.119 6378 3.805
0 0.000 0 0.000 0 0.000
10 1.000 3128 3.495 234 2.369
391 2.592
81 1.908
2021 3.306
0 0.000 0 0.000 342 2.534 0 0.000
0 0.000 0 0.000 13 1.114 0 0.000 500 2.699
549 2.740 11 1.041 2062 3.314 79 1.898 578 2.762 597 2.176 555 2.744 121 2.083 458 2.661
0 0.000 194 2.288 4 .602 53 1.724 0 0.000
259 2.413 0 0.000 0 0.000 0 0.000
506 2.704
214
CHAPTER 5
BIGRAM FREQUENCIES FOR WORDS OF LETTER LENGTH 6
B I G R A M POSITION ~~~
LY MA
MB ME MI
ML MM MN
MO
MP MS MT MU
MY NA
NB NC
ND
NE
NF
NG
1ST
2ND
3RD
4TH
5TH
SUM
18 1.255 1493 3.174 0 0.000 801 2.904 436 2.639 0 0.000 0 0.000 0 0.000 1637 3.214 0 0.000 0 0.000 0 0.000
43 1.633 48 1.681 12 1.079 27 1.431 85 1.929 0 0.000 5 .699 0 0.000 223 2.348 135 2.130 0 0.000 0 0.000
0 0.000 346 2.539 788 2.897 420 2.623 613 2.787 7 .845 433 2.636
4 .602 540 2.732 12 1.079 988 2.995 194 2.288 79 1.898 0 0.000
2892 3.461 28 1.447 0 0.000 1022 3.009 7 .845 0 0.000 0 0.000
2957 3.471 2455 3.390 812 2.910 3258 3.513 1335 3.125 86 1.934 4 38 2.641
105 2.021
133 2.124
0 0.000 0 0.000 120 2.079 0 0.000
2815 3.449 699 2.844 136 2.134 28 1.447
215 2.332 136 2.134 512 2.709 0 0.000 0 0.000 0 0.000 519 2.715 0 0.000
9 .954
37 1.568 0 0.000 193 2.286 0 0.000 157 2.196 717 2.856 236 2.373 6 .778 773 2.888
0 0.000 15 1.176 51 1.708 0 0.000 0 0.000 2237 3.350
268 2.428 155 2.190 935 2.971
0 0.000
4 .602 113 2.053
4 .602 216 2.334 297 2.473 128 2.107 35
1.544
107 2.029
19 1.279 7 07 2.849 532 2.726 10 1.000 0 0.000
9 .954 248 2.394 32 1.505 6 .778 28 1.447 7 .845 0 0.000 66 1.820 0 0.000 544 2.736 284 2.453 1362 3.134 0 0.000 765 2.884
447 2.650 0 0.000 3776 3.577
4 .602 917 2.962 3535 3.548 2692 3.430 41 1.613 5421 3.734
APPENDIX 5.2
215
BIGRAM FREQUENCIES FOR WORDS OF LETTER LENGTH 6 BIGRAM POSITION 1ST 2N D 3RD NI NJ NK NL NM NN NO NP NR NS
NT NU NV NW NY NZ OA
OB
oc OD OE
68 1.833 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 450 2.653 0 0.000 0 0.000 0 0.000 0 0.000 494 2.694 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 114 2.057 46 1.663 3 .477 0 0.000
673 2.828 43 1.633 10 1.000 165 2.217 0 0.000 113 2.053 430 2.633 9 .954 25 1.398 445 2.648 231 2.364 3 .477 35 1.544 12 1.079 206 2.314 6 .778 131 2.117 214 2.330 624 2.795 4 36 2.639 119 2.076
380 2.580 0 0.000 72 1.857 6 .778 3 .477 582 2.765 72 1.857 0 0.000 22 1.342 118 2.072 955 2.980 176 2.246 51 1.708 4 .602 12 1.079 0 0.000 28 1.447 7 .845 67 1.826 71 1.851 0 0.000
4TH
5TH
SUM
71 1.851 0 0.000 100 2.000 75 1.875 0 0.000 67 1.826 286 2.456 0 0.000 0 0.000 0 0.000 7 51 2.876 63 1.799 0 0.000 0 0.000 0 0.000 17 1.230 116 2.064 0 0.000 3 .477 123 2.090 32 1.505
9 .954 0 0.000
1201 3.080 43 1.633 187 2.272 246 2.391 3 .477 762 2.882 1238 3.093 9 .954 47 1.672 870 2.940 3023 3.480 736 2.867 86 1.934 16 1.204 305 2.484 23 1.362 275 2.439 335 2.525 740 2.869 1040 3.017 163 2.212
5
.699 0 0.000 0 Q.OOO 0 0.000 0 0.000 0 0.000 0 0.000 3 07 2.487 1086 3.036 0 0.000 0 0.000 0 0.000 87 1.940 0 0.000 0 0.000 0 0.000 0 0.000 4 07 2.610 12 1.079
216
CHAPTER 5
BIGRAM FREQUENCIES FOR WORDS OF LETTER LENGTH 6 BIGRAM POSITION 2ND 1ST 3 RD
OF OG
OH 01 OK OL OM ON 00
OP OR 0s
OT
ou ov OW
ox OY 02
PA PE
313 2.496 0 0.000 0 0.000 0 0.000 0 0.000 21 1.322 0 0.000 8 .903 0 0.000 197 2.294 178 2.250 0 0.000 323 2.509
125 2.097 9 .954 30 1.477 314 2.497 10 1.000 1189 3.075 781 2.893
82 1.914 8 .903 38 1.580 61 1.785 6 .778 0 0.000 849 2.929 1450 3.161
4TH
STH
SUM
0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 598 2.777 223 2.348 2267 3.355 0 0.000 22 1.342 762 2.882 35 1.544 288 2.459
466 2.668 16 1.204 30 1.477 460 2.663 580 2.763 2007 3.303 1664 3.221 4259 3.629 1311 3.118 1501 3.176 4956 3.695 1534 3.186 1643 3.216
0 0.000 0 0.000 573 2.758 3 .477 31 1.491 0 0.000 0 0.000 197 2.294
849 2.929
28 1.447 7 .845 0 0.000 116 2.064 531 2.725 114 2.057 179 2.253 105 2.021
592 2.772 104 2.017 1523 3.183 428 2.631 853 2.931
193 2.286 1007 3.003 392 2.593 268 2.428 72 1.857
0 0.000 0 0.000 0 0.000 30 1.477 39 1.591 85 1.929 481 2.682 1030 3.013 526 2.721 171 2.233 2101 3.322 803 2.905 107 2.029
1606 3.206 407 2.610 598 2.777 0 0.000 26 1.415 18 1.255 44 1.643 278 2.444
2869 3.458 130 2.114 504 2.702 0 0.000 0 0.000 27 1.431 127 2.104 511 2.708
123 2.090 62 1.792 83 1.919 0 0.000 10 1.000 0 0.000 0 0.000 639 2.806
4680 3.670 607 2.783 1796 3.254 64 1.806 73 1.863 45 1.653 1020 3.009 3075 3.488
APPENDIX 5 . 2
217
BIGRAM FREQUENCIES FOR WORDS OF LETTER LENGTH 6 B I G R A M POSITION
PH PI PK PL PO PP PR PS
PT PU PW PY
Qu RA RB RC
RD RE
RG
RH RI
1ST
2ND
3RD
4TH
5TH
SUM
108 2.033 313 2.496 0 0.000 688 2.838 1075 3.031 0 0.000 610 2.785
35 1.544 193 2.286 6 .778 3 .477 101 2.004 195 2.290 239 2.378
222 2.346 714 2.854 9 .954 2 267 3.355 1455 3.163 496 2.695 855 2.932
11 1.041 22 1.342 0 0.000 27 1.431 0 0.000 166 2.220
15 1.176 52 1.716 0 0.000 1564 3.194 46 1.663 3 .471 0 0.000 7 .845 0 0.000 75 1.875 0 0.000 0 0.000 64 1.806
55 1.740 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000
7 .845 0 0.000 727 2.862 0 0.000 0 0.000
9 .954 156 2.193 3 .477 12 1.079 233 2.367 298 2.474 6 .778 7 .845 19 1.279 17 1.230 0 0.000 0 0.000 91 1.959
211 2.324 298 2.474 0 0.000 0 0.000 25 1.398 0 0.000
269 2.430 132 2.121 404 2.606 360 2.556 1436 3.157 417 2.620 0 0.000 1756 3.245
41 1.613 44 1.643 528 2.723 118 2.072 909 2.959 381 2.581 0 0.000 268 2.428
40 1.602 40 1.602 0 0.000 875 2.942 2364 3.374 0 0.000 0 0.000 0 0.000
243 2.386 3 39 2.530 819 2.913 27 1.431 25 1.398 391 2.592 1841 3.265 225 2.352 953 2.979 1426 3.154 8061 3.906 889 2.949 30 1.477 3567 3.552
70 1.845 817 2.912 0 0.000 0 0.000 0 0.000 2643 3.422 47
0.000 30 1.477 312 2.494
674 2.829 9 .954 21 1.322 73 1.863 709 2.851 91 1.959 0 0.000 1231 3.090
218
CHAPTER 5
BIGRAM FREQUENCIES FOR WORDS OF LETTER LENGTH 6 B I G R A M POSITION
RK RL RM RN RO
RP RR
RS RT RU RV
RY SA SC SD SE SH SI SK
SL SM
1ST
2ND
3RD
4TH
5TH
SUM
0 0.000 0 0.000 0 0.000 0 0.000 254 2.405 0 0.000 0 0.000 0 0.000 0 0.000 220 2.342 0 0.000 0 0.000 530 2.724 722 2.859 0 0.000 1846 3.266 1464 3.166 836 2.922
0 0.000 0 0.000 15 1.176 30 1.477 1520 3.182 0 0.000 100 2.000 0 0.000 154 2.188 85 1.929 4 .602 207 2.316 11 1.041 74 1.869 0 0.000 58 1.763 6 .778 0 0.000 67 1.826 196 2.292 0 0.000
542 2.734 140 2.146 745 2.872 561 2.749 953 2.979 50 1.699 311 2.493 340 2.531 286 2.456 124 2.093 293 2.467 0 0.000 35 1.544 220 2.342 44 1.643 677 2.831 276 2.441 897 2.953
15 1.176 237 2.375 14 1.146 10 1.000 199 2.299 0 0.000 42 1.623 489 2.689 363 2.560 22 1.342 0 0.000 0 0.000 61 1.785 4 .602 0 0.000 1384 3.141 3 .477 228 2.358
44 1.643 0 0.000 49 1.690 399 2.601 32 1.505 0 0.000 0 0.000 1200 3.079 602 2.780 0 0.000 0 0.000 543 2.735 0 0.000 0 0.000 0 0.000 819 2.913 188 2.274 0 0.000
601 2.779 377 2.576 823 2.915 1000 3.000 2958 3.471 50 1.699 453 2.656 2029 3.307 1405 3.148 451 2.654 297 2.473 750 2.875 637 2.804 1020 3.009 44 1.643 4784 3.680 1937 3.287 1961 3.292
25 1.398 3 .477 34 1.531
45 1.653 0 0.000 13 1.114
0 0.000 0 0.000 13 1.114
210 2.322 490 2.690 206 2.314
73 1.863 291 2.464 146 2.164
219
APPENDIX 5.2 BIGRAM FREQUENCIES FOR WORDS OF LETTER LENGTH 6 BIGRAM POSITION 3RD 1ST 2ND
SN SO
SP SQ
SR
ss ST SU
sw SY
TA TC TE TF TH TI TL
TM
TO TP
TR
36 1.556 886 2.947 698 2.844 143 2.155 0 0.000 0 0.000 2484 3.395 704 2.848 83 1.919 481 2.682 519 2.715 0 0.000 203 2.307 0 0.000 1419 3.152 145 2.161 0 0.000 0 0.000 508 2.706 0 0.000 614 2.788
0 0.000 0 0.000 56 1.748 0 0.000 15 1.176 313 2.496 59 1.771 0 0.000 0 0.000 7 .845 1251 3.097 0 0.000 57 1.756 0 0.000 363 2.560 31 1.491 0 0.0011 7 .845 202 2.305 0 0.000 807 2.948
0 0.000 25 1.398 21 1.322 0 0.000 0 0.000 562 2.750 1132 3.054 607 2.783 152 2.182 0 0.000 416 2.619 0 0.000 505 2.703 16 1.204 1739 3.240 1352 3.131 50 1.699 0 0.000 74 1.869 35 1.544 63 1.799
4TH
5TH
SUM
0 0.000 817 2.912 0 0.000 0 0.000
0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 565 2.752 1104 3.043 0 0.000 0 0.000 28 1.447 38 1.580 0 0.000 380 2.580 0 0.000 637 2.804 0 0.000 0 0.000 0 0.000 54 1.732 0 0.000 0 0.000
36 1.556 1728 3.238 775 2.889 143 2.155 18 1.255 1440 3.158 4921 3.692 1395 3.145 235 2.371 516 2.713 2366 3.374 76 1.881 5502 3.741 16 1.204 4493 3.653 1725 3.237 1512 3.180 7 .a45 1523 3.183 35 1.544 1694 3.229
3
.477 0 0.000 142 2.152 84 1.924 0 0.000 0 0.000 142 2.152 76 1.881 4357 3.639 0 0.000 335 2.525 197 2.294 1462 3.165 0 B.000 685 2.836 0 0.000 130 2.114
220
CHAPTER 5
BIGRAM FREQUENCIES FOR WORDS OF LETTER LENGTH 6
BIGRAM POSITION 2ND 1ST 3RD
TS TT TU TW TY UA
UB
uc UD
UE UF UG
UI UL UM ON
uo UP UR
us UT
0 0.000 0 0.000 370 2.568 144 2.158 7 .845 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 874 2.942 0 0.000 74 1.869 31 1.491 69 1.839 31 1.491
304 2.483 199 2.299 183 2.013 0 0.000 23 1.362 44 1.643 577 2.761 52 1.716 203 2.307 96 1.982 59 1.771 134 2.127 133 2.124 209 2.320 7 59 2.880 333 2.522 31 1.491 188 2.274 1544 3.189 316 2.500 492 2.692
58 1.763 2414 3.383 809 2.908 0 0.000 0 0.000 175 2.243 82 1.914 29 1.462 73 1.863 5 .699 4 .602 316 2.500 44 1.643 47 1.672 40 1.602 352 2.547 0 0.000 150 2.176 1086 3.036 356 2.551 41 1.613
4TH
5TH
SUM
0 0.000 118 2.072 148 2.170 0 0.000 8 .903 374 2.573 7 .845 145 2.161
1618 3.209 2736 3.437 1430 3.155 144 2.158 817 2.912 597 2.776 666 2.823 226 2.354
54 1.732 394 2.595 4 .602 883 2.946
1256 3.099 5 .699 0 0.000 0 0.000 779 2.892 4 .602 0 0.000 0 0.000 4 .602 343 2.535 0 0.000 0 0.000
48 1.681 1145 3.059 311 2.493 934 2.970 43 1.633 162 2.210 1078 3.033 177 2.248 149 2.173
0 0.000 64 1.806 128 2.107 4 .602 0 0.000 14 1.146 62 1.792 338 2.529 62 1.792
334 2.524 838 2.923 67 1.826 1333 3.125 225 2.352 1465 3.166 1238 3.093 2497 3.397 74 1.869 588 2.769 3801 3.580 1256 3.099 775 2.889
APPENDIX 5 . 2
221
BI G R A M FREQUENCIES FOR WORDS OF LETTER LENGTH 6 B I G R A M POSITION
uu
ux UY
uz VA
VE VI VO
vu WA
WB WD
WE
WH WI WL WM WN
WO WR
ws
1ST
2ND
3RD
4TH
5TH
SUM
0 0.000 0 0.000 0 0.000 0 0.000
0 0.000 27 1.431 35 1.544 20 1.301 0 0.000 163 2.212 0 0.000 20 1.301 0 0.000 36 1.556 0 0.000 0 0.000 147 2.167 4 .602 79 1.898 0 0.000 0 0.000 38 1.580 4 .602 0 0.000 0 0.000
0 0.000 0 0.000 0 0.000 0 0.000 48 1.681 322 2.508 1185 3.074
20 1.301 0 0.000 0 0.000 0 0.000
0 0.000 4 .602 0 0.000 0 0.000 17 1.230 347 2.540 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 8 .903 0 0.000 0 0.000 0 0.000 3 .477 0 0.000
20 1.301 31 1.491 35 544 20 301 467 669 884 3.275 1507 3.178 345 2.538 7 ,845 2038 3.309 16 1.204 48 1.681
383 2.583 123 2.090 309 2.490 251 2.400 7 .845 898 2.953 0 0.000 0 0.000 226 2.354 90 1.954 910 2.959 0 0.000 0 0.000 0 0.000 341 2.533 180 2.255 0 0.000
51 1.708 0 0.000 1039 3.017 16 1.204 28 1.447 145 2.161 0 0.000 87 1.940 0 0.000 10 1.000 5 .699 0 0.000 0 0.000 3 .477
19 1.279 929 2.968 13 1.114 23 1.362 0 0.000
65 1.813 0 0.000 12 1.079 418 2.621 0 0.000 7 .845 115 2.061 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000
51 1.708 0 0.000 0 0.000 48 1.681
936 2.971 94 1.973 1083 3.035 118 2.072 10 1.000 94 1.973 345 2.538 180 2.255 51 1.708
222
CHAPTER 5
B I G R A M FREQUENCIES FOR WORDS OF LETTER LENGTH 6 B I G R A M POSITION
WT WY XA
xc XE
XF XI XL
xo XP XT
xu
1ST
2ND
3RD
4TH
5TH
SUM
0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000
0 0.000 0 0.000 0 0.000 276 2.441 5 .699 18 1.255 42 1.623
161 2.207 43 1.633 9 .954 276 2.441
0 0.000 11 1.041 169 2.228 146 2.164 0 0.000 43 1.633 0 0.000 7 .845 5 .699 4 .602 0 0.000 0 0.000 0 0.000 0 0.000
17 1.230 7 .845 6 -778 15 1.176 43 1.633 20 1.301 435 2.638 49 1.690
155 2.190 0 0.000 0 0.000 0 0.000 13 1.114 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 332 2.521 0 0.000 0 0.000 0 0.000 0 0.000
0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000
0 0.000 0 0.000 0 0.000 0 0.000 0 0.000
6 .778 43 1.633 9 .954 0 0.000 0 0.000 0 0.000 49 1.690 6 .778 0 0.000 0 0.000 10 1.000 80 1.903 0 0.000
XY
0 0.000
YA
26 1.415 0 0.000 0 a.OOO 89 1.949
YC YD YE
YG YH
YI YL
0 0.000 0 0.000 7 .845 0 0.000
0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 3 .477 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000
18 1.255 18 1.255 91 1.959 6 .778 11 1.041 169 2.228 156 2.193 80 1.903 46 1.663 43 1.633 14 1.146 11 1.041 440 2.643 43 1.633 20 1.301 442 2.645 49 1.690
APPENDIX 5 . 2
223
B I G R A M FREQUENCIES FOR WORDS OF LETTER LENGTH 6
B I G R A M POSITION 1ST 3RD 2N D ~~
YM YN
YO
YP YR
YS YT YW ZA
ZE ZI ZL
0 0.000 0 0.000 18 1.255 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000
20
6 .778
ZY
0 0.000 0 0.000
zz
54 1.732 12 1.079 0 0.000 10 1.000 22 1.342 551 2.741 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000
9 .954 0 0.000 326 2.513 0 0.000 0 0.000 0 0.000 26 1.415 46 1.663 22 1.342 11 1.041 11 1.041 0 0.000 0 0.000 6 .778 24 1.380
4TH
5TH
SUM
6 .778 0 0.000 12 1.079 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000
0 0.000 4 .602 0 0.000 0 0.000 8 .903 482 2.683 0 0.000 0 0.000 17 1.230 47 1.672 0 0.000 0 0.000 0 0.000 6 .778 0 0.000
69 1.839 16 1.204 3 56 2.551 10 1.000 30 1.477 1033 3.014 26 1.415 46 1.663
0 0.000 73 1.863 8 .903 24 1.380 0 0.000 0 0.000 17 1.230
39 1.591 131 2.117 19 1.279 24 1.380 6 .778 12 1.079 41 1.613
224
CHAPTER 5
B I G R A M FREQUENCIES FOR WORDS OF LETTER LENGTH 7 B I G R A M POSITION ~~~
AB
AC AD
AE
AF AG AH A1 AJ AK
AL AM AN
A0 AP AQ AR
AS AT AU
AV
1ST
2ND
3 RD
4TH
5TH
6TH
SUM
178 2.250 356 2.551 285 2.455 0 0.000 150 2.176 629 2.799 0 0.000 34 1.531 0 0.000
101 2.004 521 2.717 87 1.940 4 .602 5 .699 66 1.820 0 0.000 433 2.636
64 1.806 543 2.735 593 2.773 0 0.000 81 1.908 175 2.243 0 0.000 838 2.923
166 2.220 65 1.813 180 2.000 0 0.000 0 0.000 200 2.301 6 .778 270 2.431
5 .699 432 2.635 328 2.516 11 1.041 0 0.000 635 2.803 0 0.000 661 2.820
0 0.000 5 .699 180 2.255 0 0.000 0 0.000 3 .477 0 0.000 0 0.000
514 2.711 1922 3.284 1573 3.197 15 1.176 236 2.373 1708 3.232 6 .778 2236 3.349
0 0.000
0 0.000 40 1.602 185 2.267 40 1.602 1086 3.036 0 0.000 319 2.504 0 0.000 953 2.979 138 2.140
0 0.000 0 0.000 3015 3.479 561 2.749 352 2.547 0 0.000 4 .602 0 0.000 547 2.738 82 1.914
189 2.276 44 1.643 157 2.196
972 2.988 125 2.097 80 1.903
0 0.000 67 1.826 650 2.813 89 1.949 582 2.765 0 0.000 67 1.826 0 0.000 365 2.562 111 2.045 853 2.931 908 2.958 21 1.322
3 .477
1162 3.065 0 0.800 253 2.403 14 1.146 304 2.483 238 2.377
3 .477 4 .602 574 2.759 78 1.892 740 2.869 4 .602 465 2.667 0 0.000 1936 3.287 480 2.681
393 2.594 5 .699 4 .602
32 1.505 3 .477 0 0.000
0 0.000 439 2.642 315 2.498
40 1.602 652 2.814 4 59 2.662 894 2.951 5 .699 232 2.365 4 .602 1160 3.064 555 2.744 477 2.679 3 .477 2 58 2.412
151 2.179 5515 3.742 1542 3.188 4816 3.683 9 .954 1340 3.127 18 1.255 5265 3.721 1604 3.205 2916 3.465 1088 3.037 520 2.716
APPENDIX 5.2
225
BIGRAM F R E Q U E N C I E S F O R W O R D S OF L E T T E R L E N G T H 7 BIGRAM P O S I T I O N 1ST 2N D 3RD AW AX AY A2 BA BB BD BE BI BJ BL BO BR BS BT BU BV BY CA
cc CE
49 1.690 0 0.000 0 0.000 0 0.000 308 2.489 0 0.000 0 0.000 2413 3.383 150 2.176 0 0.000 182 2.260 195 2.290 702 2.846 0 0.000 0 0.000 197 2.294 0 0.000 0 0.000 813 2.910 0 0.000 782 2.893
26 1.415 101 2.004 154 2.188 20 1.301 17 1.230 0 0.000 6 .778 13 1.114 79 1.898 65 1.813 21 1.322 8 .903 11 1.041 95 1.978 0 0.000 0 0.000 92 1.964 0 0.000 45 1.653 157 2.196 26 1.415
85 1.929 0 0.000 202 2.305 33 1.519 50 1.699 63 1.799 8 .903 177 2.248 43 1.633 161 2.207 8 .903 14 1.146 127 2.104 8 .903 0 0.000 31 1.491 0 0.000 0 0 * 000 1059 3.025 108 2.033 153 2.185
4TH
5TH
6TH
SUM
10 1.000 17 1.230 35 1.544 0 0.000 175 2.243 23 1.362 0 0.000 502 2.701 73 1.863 0 0.000 397 2.599 98 1.991 4 .602 0 0.000 9 .954 76 1.881 0 0.000 0 0.000 119 2.076
0 0.000 0 0.000 18 1.255 0 0.000 3 .477 0 0.000 0 0.000 188 2.274 33 1.519 0 0.000 364 2.561 17 1.230
0 0.000 0 0.000 252 2.401 0 0.000 0 0.000 0 0.000 0 0.000 7 .845 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 18 1.255 0 0.000 0 0.000 0 0.000 60 1.778 194 2.288 0 0.000 1291 3.111
170 2.230 118 2.072 661 2.820 53 1.724 553 2.743 86 1.934 14 1.146 3300 3.519 378 2.577 226 2.354 972 2.988 332 2.521 844 2.926 121 2.083 9 .954 304 2.483 92 1.964 66 1.820 2746 3.439 289 2.461 3498 3.544
Q 0.000 711 2.852
0 0.000 0 0.000 0 0.000 0 0.000
Q 0.000 6 .778 516 2.713 24 1.380 535 2.728
226
CHAPTER 5
B I G R A M FREQUENCIES FOR WORDS OF LETTER LENGTH 7 B I G R A M POSITION 1ST 2N D 3RD CH
CI CK
CL CN CO
CQ CR
CS CT
cu CY DA DB DC DD DE
DF DG DH
DI
1075 3.031 94 1.973 0 0.000 748 2.874 0 0.000 2983 3.475 0 0.000 413 2.616 0 0.000 0 0.000 344 2.537 16 1.204 140 2.146 0 0.000 0 0.000 0 0.000 1546 3.189 0 0.000 0 0.000 0 0.000 517 2.713
267 2.427 131 2.117 0 0.000 0 0.000 0 0.000 101 2.004 27 1.431 56 1.748 6 .778 125 2.097 5 .699 0 0.000 18 1.255 0 0.000 0 0.000 81 1.908 10 1.000 0 0.000 0 0.000 5 .699 63 1.799
202 2.305 554 2.744 307 2.487 293 2.467 3 .477 372 2.571 8 .903 49 1.690 0 0.000 719 2.857 145 2.161
5 .699 3 .477 0 0.000 0 0.000 98 1.991 385 2.585 0 0.000 37 1.568 7 .845 285 2.455
4TH
5TH
6TH
SUM
718 2.856 513 2.710 304 2.483 72 1.857 0 0.800 156 2.193 0 0.000 0 0.000 0 0.000 2 34 2.369 94 1.973 0 0.000 40 1.602 9 .954 4 .602 13 1.114 502 2.701 18 1.255 41 1.613 0 0.000 1004 3.002
32 1.505 139 2.143 22 1.342 127 2.104
78 1.892 0 0.000 32 1.505 0 0.000 0 0.000 27 1.431
2372 3.375 1431 3.156 665 2.823 1240 3.093 3 .477 3639 3.561 35 1.544 518 2.714
0
0.000 0 0.000 0 0.000 0 0.000 0 0.000 340 2.531 0 0.000 0 0.000 96 1.982 3 .477 0 0.000 0 0.000 727 2.862 0 0.000 0 0.000 0 0.000 5 .699
(1
0.000 0 0.000 103 2.013 911 2.960 0 0.000 71 1.851 46 1.663 0 0.000 0 0.000 0 0.000 629 2.799 0 0.000 0 0.000 0 0.000 0 0.000
109 2.037 2329 3.367 588 2.769 92 1.964 343 2.535 12 1.079 4 .602 192 2.283 3799 3.580 18 1.255 78 1.892 12 1.079 1874 3.273
227
APPENDIX 5 . 2 B I G R A M FREQUENCIES FOR WORDS OF LETTER LENGTH 7 B I G R A M POSITION 2ND 1ST 3RD
DJ DL
DM DN
DO DR
DS DT
DU DV
DW DY
0 0.000 0 0.000 0 0.000 0 0.000 218 2.338 372 2.571 0 0.000 0 0.000 32 1.505 0 0.000 0 0.000 21 1.322
EA
231 2.364
EB
0 0.000 85 1.929 70 1.845 0 0.000 236 2.373 0 0.000 0 0.000 0 0.000
EC ED EE
EF EG EH EI
6 .778 0 0.000 20 1.301 0 0.000 45 1.653 0 0.000 0 0.000 0 0.000 7 .845 110 2.041 3 .477 4 .602 2239 3.350 28 1.447 1753 3.244 614 2.788 560 2.748 386 2.587 261 2.417 48 1.681 243 2.386
0 0.000 20 1.301 0 0.000 11 1.041 35 1.544 129 2.111 5 .699 4 .602 138 2.140 0 0.000 11 1.041 0 0.000 934 2.970 4 .602 4 54 2.657 6B 1.778 226 2.354 8 .903 18 1.255 0 0.000 28 1.447
4TH
5TH
6TH
SUM
0 0.000 78 1.892 0 0.000 4 .602 116 2.064 178 2.250 0 0.000 0 0.000 251 2.400 0 0.000 5 .699 0 0.000
0 0.000 136 2.134 13 1.114 0 0.000 199 2.299 5 .699 0 (jl. 0 0 0 7 .845
0 0.000 0 0.000 0 0.000 0 0.000 7 .845 0 0.000 8 67 2.938 0 0.000 0 0.000 0 0.000 0 0.000 510 2.708 0 0.000 0 0.000 0 0.000 7760 3.890 28 1.447 0 0.000 0 0.000 0 0.000 0 0.000
6 .778 234 2.369 33 1.519 15 1.176 620 2.792 684 2.835 872 2.941 11 1.041
683 2.834 0 0.000 336 2.526 159 2.201 105 2.821 203 2.307 32 1.505 72 1.857 251 2.400
11 1.041 0 0.000 0 0.000 0 0.000 364 2.561 52 1.716 6 40 2.806 210 2.322 919 2.963 23 1.362 267 2.427 0 0.000 35 1.544
439 2.642 110 2.041 19 1.279 535 2.728 4451 3.648 84 1.924 3268 3.514 8873 3.948 1838 3.264 8 56 2.932 578 2.762 120 2.079 5 57 2.746
228
CHAPTER 5
BIGRAM FREQUENCIES FOR WORDS OF LETTER LENGTH 7 BIGRAM POSITION 2N D 1ST 3 RD
EJ EK EL EM EN
EO
EP EQ ER ES ET EU EV EW EX
EY EZ
FA FE FF FI
0 0.000 0 0.000 139 2.143 168 2.225 747 2.873 0 0.000 12 1.079 70 1.845 37 1.568 45 1.653 . 58 1.763 0 0.000 205 2.312 0 0.000 954 2.980 11 1.041 0 0.000 674 2.829 554 2.744 0 0.000 707 2.849
4TH
5TH
6TH
SUM
11 1.041 74 1.869 2714 3.434 1760 3.246 6658 3.823 2 47 2.393 557 2.746 205 2.312 11577 4.064 5936 3.773 3027 3.481 96 1.982
0 0.000 0 0.000 1007 3.003 270 2.431 1505 3.178 27 1.431 85 1.929 0 0.000 2492 3.397 1100 3.041 693 2.841 36 1.556 264 2.422 9 .954 38 1.580 26 1.415 11 1.041 7 .845
0 0.000 0 0.000 127 2.104
111 2.045 32 1.505 0 0.000 3 .477 0 0.000 95 1.978
0 0.000 0 0.000 200 2.301 146 2.164 1159 3.064 123 2.090 20 1.301 0 0.000 2156 3.334 59 1.771 147 2.167 10 1.000 621 2.793 47 1.672 0 0.000 0 0.000 3 .477 3 18 2.502
403 2.605 59 1.771 231 2.364
94 1.973 101 2.004 98 1.991
17 1.230 0 0.000 166 2.220
0 0.000 20 1.301 0 0.000
11 1.041 0 0.000 869 2.939 696 2.843 1751 3.243 97 1.987 265 2.423 135 2.130 1985 3.298 1214 3.084 1557 3.192 50 1.699
0 0.000 74 1.869 372 2.571 167 2.223 291 2.464 0 0.000 175 2.243 0 0.000 761 2.881 574 2.759 476 2.678 0 0.000
766 2.884 48 1.681 57 1.826 12 1.079 0 0.000 0 0.000 0 0.000 595 2.775 0 0.000
313 2.496 1205 3.081 0 0.000 0 0.000 0 0.000 4146 3.618 2944 3.469 96 1.982 0 0.000 0 0.000 4 .602 91 1.959 121 2.083 0 0.000 0 0.000
1967 3.294 140 2.146 1150 3.061 173 2.238 14 1.146 1094 3.039 1068 3.029 775 2.889 1202 3.080
229
APPENDIX 5 . 2 B I G R A M FREQUENCIES FOR WORDS OF LETTER LENGTH 7
B I G R A M POSITION 3RD 2ND 1ST
FL FO FR FS FT FU FW FY GA GD
GE GG
GR
GS GT
19 1.279 137 2.137 0 0.000 0 0.000 55 1.740
72 1.857 0 0.000 0 0.000 0 0.000 8 .903 188 2.274 0 0.000
0 0.000 0 0.000 0 0.000 23 1.362 0 0.000 0 0.000 0 0.000
326 2.513 966 2.985 459 2.662 23 1.362 139 2.143 623 2.794 18 1.255
89 1.949 21 1.322 0 0.000 927 2.967 0 0.000
89 1.949
974 2.989 0 0.000 0 0.000 0 0.000 158 2.199 106 2.025 0 0.000 102 2.009 0 0.000
2269 3.356 511 2.708 534 2.728 19 1.279 308 2.489 135 2.130 1218 3.086 106 2.025 34 1.531
0 0.000 0 0.000 318 2.502 0 0.000
0 0.000 0 0.000 0 0.000 0 0.000
0 0.000 76 1.881 98 1.991 0 0.000
0 0.000 157 2.196 0 0.000 910 2.959 0 0.000
0 0.000
0 0.000 107 2.029 0 0.000 89 1.949 144 2.158
0 0.000 47 1.672 26 1.415 429 2.632 1.633
0 0.000 18 1.255 0 0.000 7 68 2.885 0 0.000
221 2.344
161 2.207
9 07 2.958
120 2.079 361 2.558 19 1.279 71 1.851 0 0.000 94 1.973 0 0.000 0 0.000
327 2.515 56 1.748 0 0.000 0 0.000 4 .602 416 2.619 0 0.000 34 1.531
46 1.663 0 0.000 0 0.000 41 1.613 0 0.000 0 11.000 4 .602 0 0.000
15 1.176 117 2.068 0 0.000 4 .602 25 1.398 708 2.850 0 0.000 0 0.000
GO
SUM
2.207 10 1.000
GI
GN
6TH
0 0.000 0 0.000 28 1.447
6 .778
GM
5TH
206 2.314 668 2.825 421 2.624
GH
GL
4TH
626 2.797 0 0.000 0 0.000 0 0.000 0 0.000 3 .477 0 0.000 0 0.000 34 1.531 0 0.000 0 0.000 0 0.000 0 0.000
29 1.462
161
19 1.279 18 1.255
43
976 2.989 25 1.415 3123 3.495 187 2.272
CHAPTER 5
230
BIGRAM FREQUENCIES FOR WORDS OF LETTER LENGTH 7 BIGRAM POSITION 1ST 2ND 3RD GU
GY HA HE
HF HI HL
HM HN HO
HR HS HT
HU HW HY IA
IB IC
ID IE
4TH
5TH
6TH
SUM
267 2.421 0 0.000 67 1.826 19 1.279 0 0.000 148 2.170 9 .954 0 0.000 34 1.531 217 2.336 0 0.000 0 0.000
21 1.322 0 0.000 397 2.599 155 2.190 9 .954 731 2.864 0 0.000 0 0.000 0 0.000 794 2.900 0 0.000 0 0.000
19 1.279 0 0.000 32 1.505 2568 3.410 0 0.000 56 1.748 58 1.763 12 1.079
0 0.000 35 1.544 0 0.000 32 1.505 0 0.000 0 0.000 0 0.000 0 0.000
347 2.540 35 1.544 1807 3.257 4060 3.609 9 .954 2353 3.372 67 1.826 12 1.079
0 0.000 863 2.936 0 0.000 0 0.000
0 0.000 0 0.000 884 2.946 781 2.893 0 0.000 385 2.585 0 0.000 0 0.000 0 0.000 761 2.881 1053 3.022 0 0.000
0 0.000 85 1.929 0 0.000 0 0.000
0 0.000 0 0.000 0 0.000 26 1.415
34 1.531 2720 3.435 1053 3.022 26 1.415
0 0.000 401 2.603 0 0.000 3 .477 0 0.000 0 0.000 0 0.000 17 1.230 0 0.000
0 0.000 27 1.431 0 0.000 72 1.857 55 1.740 203 2.307 526 2.721 57 1.756 41 1.613
0 0.000 7 .845 0 0.000 0 0.000 0 0.000 40 1.602 288 2.459 108 2.033 446 2.649
117 2.068 0 0.000 40 1.602 0 0.000 79 1.898 85 1.929 888 2.948 432 2.635 853 2.931
60 1.778 3 .477 0 0.000 0 0.000 719 2.857 0 0.000 794 2.900 498 2.697 1323 3.122
907 2.958 0 0.000 0 0.000 70 1.845 76 1.881 0 0.000 350 2.544 49 1.690 69 1.839
1084 3.035
40 1.602 0 0.000 427 2.630 505 2.703 0 0.000 1033 3.014 0 0.000 0 0.000
4 38 2.641 40 1.602 145 2.161 929 2.968 328 2.516 2846 3.454 1161 3.065 2732 3.436
APPENDIX 5.2
231
B I G R A M FREQUENCIES FOR WORDS OF LETTER LENGTH 7 B I G R A M POSITION
IF IG IK IL
IM
IN I0
IP IQ IR
IS IT
IU IV
IX I2 JA JE JO
JU KA
1ST
2ND
3RD
4TH
5TH
6TH
SUM
0 0.000 34 1.531 0 0.000 32 1.505 249 2.396 825 2.916 0 0.000 0 0.000
90 1.954 489 2.689 3 .477 791 2.898 899 2.954 1068 3.029 67 1.826 16 1.204
126 2.100 98 1.991 0 0.000 429 2.632 280 2.447 538 2.731 24 1.380 100 2.000
38 1.580 195 2.290 20 1.301 201 2.303 252 2.401 941 2.974 933 2.970 10 1.000
0 0.000 0 0.000 7 .845 126 2.100 19 1.279 582 2.834 6 .778 39 1.591
347 2.540 977 2.990 49 1.690 1972 3.295 1751 3.243 11841 4.073 2381 3.377 169 2.228
0 0.000 18 1.255 42 1.623 51 1.708
6 .778 162 2.210 927 2.967 957 2.981 0 0.000 117 2.068 75 1.875 22 1.342 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000
0 0.000 80 1.903 192 2.283 976 2.989
12 1.079 166 2.220 220 2.342 419 2.622
93 1.968 161 2.207 19 1.279 393 2.594 52 1.716 7787 3.891 1351 3.131 4 .602 0 0.000 264 2.422 704 2.848 636 2.803
0 0.000 21 1.322 47 1.672 235 2.371
18 1.255 711 2.852 2132 3.329 3274 3.515
22 1.342 291 2.464 0 0.000 15 1.176 3 .477 76 1.881 62 1.792 26 1.415 4 .602
0 0.000 216 2.334 14 1.146 57 1.756 0 0.000 2 54 2.405 0 0.000
48 1.681 190 2.279 0 0.000 79 1.898 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000
0 0.000 0 0.000 9 .954 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000
70 1.845 8 14 2.911 98 1.991 173 2.238 114 2.057 349 2.543 192 2.283 237 2.375 45 1.653
0 0.000 0 0.000 0 0.000 0 0.000 111 2.045 19 1.279 130 2.114 211 2.324 21 1.322
0
0.000 20 1.301
CHAPTER 5
232
B I G R A M FREQUENCIES FOR WORDS OF LETTER LENGTH 7
BIGRAM POSITION 1ST 2ND 3RD
KE KI KL KM KN KO
KP KR
KS KU
KW KY
213 2.328 183 2.262 0 0.000 0 0.000 104 2.017 0 0.000 0 0.000 11 1.041 0 0.000 0 0.000 0 0.000 0 0.000
LA
312 2.494
LB
0 0.000 0 0.000 0 0.000 706 2.849
LC LD
LE LF LG
LH LI
0 0.000 0 0.000 0 0.000 497 2.696
4TH
5TH
6TH
SUM
3 94 2.595 0 0.000 127 2.104 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000
56 1.748 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000
94 2 2.974 1128 3.052 130 2.114 7 .845 151 2.179 15 1.176 16 1.204
0 0.000
11 1.041
81
120 2.079 3 .477 17 1.230 5 .699 2592 3.414
0 0.000 43 1.633 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000
3 .477 4 .602 0 0.000 0 0.000 47 1.672 0 0.000 0 0.000 0 0.000
276 2.441 898 2.953 3 .477 7 .a45 0 0.000 15 1.176 16 1.204 0 0.000
0 0.000 0 0.000 0 0.000 5 .699 890 2.949
0 0.000 0 0.000 11 1.041 0 0.000
39 1.591 0 0.000 6 .778 0 0.000
0 0.000 3 .477 0 0.000 0 0.000
341 2.533
525 2.720
465 2.667
1.908 0 0.000 0 0.000 0 0.000 59 1.771
0 0.000 13 1.114 13 1.114 429 2.632 0 0.000 0 0.000 0 0.000 219 2.340
3 .477 73 1.863 135 2.130 226 2.354 88 1.944 21 1.322 14 1.146 378 2.577
0 0.000 0 0.000 71 1.851 661 2.820 5 .699 0 0.000 0 0.000 2380 3.377
0 0.000 0 0.000 0 0.000 1478 3.170 0 0.000 9 .954 0 0.000 73 1.863
0.000 0 0.000 18 1.255 993 2.997 733 2.865 0 0.000 0 0.000 9 .954
0
3 .477 86 1.934 2 37 2.375 4493 3.653 826 2.917 30 1.477 14 1.146 3556 3.551
APPENDIX 5 . 2
233
B I G R A M FREQUENCIES FOR WORDS OF LETTER LENGTH 7 B I G R A M POSITION 1ST 2ND 3RD
LK LL LM LN LO
LP LR
LS LT LU LV LW
0 0.000 0 0.000 0 0.000 0 0.000 429 2.632 0 0.000 0 0.000 0 0.000 0 0.000 39 1.591 0 0.000 0 0.000
LY
7 .845
MA
901 2.955 0 0.000 1222 3.087 0 0.000
MB
ME
MF MI ML MM MN
833 2.921 0 0.000 0 0.000 0 0.000
0 0.000 133 2.124 0 0.000 0 0.000 425 2.628 0 0.000 273 2.436 0 0.000 22 1.342 87 1.940 4 .602 0 0.000 16 1.204 213 2.328 30 1.477 273 2.436 0 0.000 78 1.892 0 0.000 19 1.279 0 0.000
154 2.188 1528 3.184 4 -602 25 1.398 225 2.352 76 1.881 0 0.000 13 1.114 107 2.029 92 1.964 13 1.114 5 .699 5 .699 235 2.371 561 2.749 251 2.400 43 1.633 306 2.486 5 .699 177 2.248 0 0.000
4TH
5TH
6TH
SUM
7 .845 209 2.320
0 0.000 569 2.755 0 0.000 0 0.000 113 2.053 0 0.000 35 1.544 253 1.301
0 0.000 110 2.041 7 .845 47 1.672 16 1.204 0 0.000 0 0.000 484 2.685
161 2.207 2549 3.406
292 2.465 27 1.431 44 1.643 0 0.000 0 0.000 162 2.210 7 .845 442 2.645 0 0.000
33 1.519 0 0.000 0 0.000 0 0.000 1924 3.284 58 1.763 0 0.000 246 2.391 0 0.000
35 1.544 0 0.000 25 1.398 36 1.556
0 0.000 0 0.000 0 0.000 13 1.114
0 0.000 0 0.000 288 2.459 0 0.000 0 0.000 0 0.000 133 2.124 214 2.330 16 1.204 19 1.279 17 1.230 440 2.643 114 2.057 241 2.382 4 .602 297 2.473 11
1.041 38 1.580 7 .845
11 1.041 72 1.857 1496 3.175 76 1.881 308 2.489 517 2.713 587 2.769 4 59 2.662 77 1.886 24 1.380 1969 3.294 2009 3.303 712 2.852 2675 3.427 47 1.672 1549 3.190 16 1.204 2 59 2.413 56 1.748
234
CHAPTER 5
BIGRAM FREQUENCIES FOR WORDS OF LETTER LENGTH 7
B I G R A M POSITION
1ST
2ND
3RD
4TH
5TH
6TH
SUM
471 2,673 0 0.000 0 0.000 0 0.000 180 2.255 42 1.623 358 2.554 0 0.000 0 0.000 0 0.000 394 2.595 0 0.000
90 1.954 197 2.294 0 0.000 0 0.000 17 1.230 0 0.000 131 2.117 3 .477 195 2.290 127 2.104 38 1.580 36 1.556
136 2.134 602 2.780 4 .602 603 2.780 0 0.000 0 0.000 476 2.678 0 0.000 448 2.651 596 2.775 718 2.856 55 1.740
0 0.000 117 2.068 0 0.000 0 0.000 159 2.201 0 0.000 92 1.964 0 0.000
0 0.000 0 0.000 0 0.000 227 2.356 0 0.000 112 2.049 38 1.580 0 0.000
842 2.925 1264 3.102 4 .602 838 2.923 433 2.636 154 2.188 1176 3.070 16 1.204
509 2.707 450 2.653 638 2.805 0 0.000
NG
0 0.000
NH
0 0.000 3 .477 0 0.000 0 0.000 0 0.000
498 2.697 50 1.699 220 2.342 77 1.886 47 1.672 7 .845 9 .954 15 1.176 782 2.893
3 29 2.517 6 .778 193 2.286 0 0.000 115 2.061 3 .477
145 2.161 348 2.542 0 0.000 8 .903 77 1.886 0 0.000 81 1.908 13 1.114 228 2.358 244 2.387 4 24 2.627 25 1.398 309 2.490 0 0.000 1231 3.090 0 0.000 73 1.863 35 1.544
230 2.362 0 0.000 87 1.940 0 0.000 0 0.000 21 1.322
0 0.000 530 2.724 502 2.701 0 0.000 7212 3.858 0 0.000 9 .954 0 0.000 0 0.000 0 0.000
1380 3.140 1947 3.289 2714 3.434 116 2.064 8578 3.933 56 1.748 1743 3.241 77 1.886 235 2.371 66 1.820
4 .602 373 2.572 150 2.176
0 0.000 149 2.173 142 2.152
0 0.000 32 1.505 10 1.000
0 0.000 0 0.000 10 1.000
13 1.114 559 2.755 1679 3.225
MO
MP MR MS MU
MY NA NB NC ND NE
NF
NI
NJ NK
NL
NM NN
NO
0 0.000 0 0.000 585 2.767
235
APPENDIX 5 . 2 B I G R A M FREQUENCIES FOR WORDS OF LETTER LENGTH 7 B I G R A M POSITION 3 RD 1ST 2ND
NQ NR
NS NT NU NV
NX
NY NZ OA
OB
oc OD
OE
OF OG OH 01
OJ OK
OL
0 0.000 0 0.000 0 0.000 0 0.000 288 2.459 0 0.000 0 0.000 0 0.000
28 1.447 3 .477 3 57 2.553 242 2.384 69 1.839 88 1.944 71 1.851 46 1.663
0 0.000 0 0.000 229 2.360 51 1.708 0 0.000 0 0.000 237 2.375 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 7 .845
11 1.041 130 2.114 87 1.940 460 2.663 43 1.633 0 0.000 0 0.000 39 1.591 34 1.531 115 2.061 5 .699 0 0.000 888 2.948
10 1.000 10 1.000 2 38 2.377 1110 3.045 293 2.467 29 1.462 0 0.000 10 1.000 0 0.000 47 1.672 318 2.502 295 2.470 185 2.267 22 1.342 48 1.681 399 2.601 0 0.000 37 1.568 93 1.968 230 2.362 162 2.210
4TH
5TH
6T9
SUM
0 0.000 0 0.000 89 1.949 732 2.865 10 1.000 0 0.000 0 0.000 0 0.000 0 0.000 12 1.079 51 1.708 5 .699 14 1.146 0 0.000 7 .845
0 0.000 6 .778 946 2.976 332 2.521 42 1.623 0 0.000 0 0.000 3 .477 3 .477 0 0.000 0 0.000 8 .903 249 2.396 58 1.763 0 0.00a 29 1.462 0 0.000 80 1.903 0 0.000 3 .477 329 2.517
0 0.000 0 0.000 1197 3.078 1653 3.218 0 0.000 0 0.000 5 .699 467 2.669 0 0.000 0 0.000 0 0.000 0 0.000 25 1.398 0 0.000 16 1.204 0 0.000 0 0.000 0 0.000 0 0.000 36 1.556 264 2.422
38 1.580 19 1.279 2827 3.451 4069 3.609 702 2.846 117 2.068 76 1.881 526 2.721 14 1.146 189 2.276 685 2.836 819 2.913 516 2.713 80 1.903 308 2.489 476 2.678 47 1.672 2 59 2.413 98 1 991 293 2 467 720 3 236
9 .954 13 1.114 27 1.431 0 0.000 24 1.380 70 1.845
2 36
CHAPTER 5
BIGRAM FREQUENCIES FOR WORDS OF LETTER LENGTH 7 BIGRAM POSITION 1ST 2ND 3RD OM
ON
00
OP
OQ OR 0s
OT
ou
ov
ow
ox OY PA PD PE PF PG PH PI PK
25 1.398 5 .699 0 0.000 331 2.520 0 0.000 200 2.301 0 0.000 0 0.000
942 2.974 1044 3.019 356 2.551 140 2.146 0 0.000 1337 3.126 99 1.996 704 2.848
343 2.535 24 1.380
1348 3.130 164 2.215 681 2.833 0 0.000 51 1.708 59 1.771 3 .477 508 2.706 0 0.000 3 .477 4 .602 160 2.204 0 0.000
0 0.000 0 0.000 8 .903 949 2.977 0 0.000 810 2.908 0 0.000 0 0.000 57 1.756 317 2.501 0 0.000
133 2.124 143 2.155 55 1.740 379 2.579 0 0.000 274 2.438 187 2,272 1023 3.010 1108 3.045 238 2.377 413 2.616 0 0.000 3 .477 79 1.898 0 0.000 3 79 2.579 0 0.000 0 0.000 3 .477 265 2.423 7 .845
4TH
5TH
6TH
SUM
125 2.097 150 2.176 208 2.318 21 1.322 11 1.041 526 2.721 115 2.061 82 1.914
194 2.288 92 5 2.966 153 2.185 6 .778 0 0.000 1105 3.043 278 2.444 57 1.756
229 2.360 1664 3.221 0 0.000 89 1.949 0 0.000 195 2.290 0 0.000 13 1.114
1648 3.217 3931 3.595 772 2.888 966 2.985 11 1.041 3637 3.561 679 2.832 1879 3.274
1101 3.042 2 29 2.360 98 1.991 0 0.000 64 1.806 4 03 2.605 0 0.000 263 2.420 29 1.462 0 0.000 40 1.602 382 2.582 0 0.000
1261 3.101 53 1.724 245 2.389 0 0.000 13 1.114 0 0.000 0 0.000 571 2.757 0 0.000 0 0.000 0 0.000 23 1.362 0 0.000
0 0.000 0 0.000 112 2.049 9 .954 48 1.681 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 22 1.342 0 0.000
5161 3.713 708 2.850 1549 3.190
0 0.000
9 .954 187 2.272 1490 3.173 3 .477 2531 3.403 29 1.462 3 .477 126 2.100 1147 3.060 7 .845
237
APPENDIX 5 . 2 BIGRAM FREQUENCIES FOR WORDS OF LETTER LENGTH 7 B I G R A M POSITION 1ST 3RD 2N D
PL PM PO PP PR PS PT PU PW PY QU
RA RB
RC
RD RE
RF RG
RH RI
RK
468 2.670 0 0.000 412 2.615 0 0.000 2730 3.436 3 .477 0 0.000 321 2.507 0 0.000 0 0.000 358 2.554 311 2.493 0 0.000 0 0.000 0 0.000 2781 3.444 0 0.000 0 0.000 12 1.079 118 2.072 0 0.000
0 0.000 0 0.000 51 1.708 294 2.468 51 1.708 3 .477 G3 1.799 6 .778 6 .778 0 0.000 113 2.053 774 2.889 5 .699 8 .903 93 1.968 1463 3.165 0 0.000 63 1.799 0 0.000 1457 3.163 0 0.000
361 2.558 0 0.000 223 2.348 397 2.599 166 2.220 5 .699 141 2.149 128 2.107 0 0.000 0 0.000 199 2.299 280 2.447 50 1.699 173 2.238 102 2.009 870 2.940 340 2.531 212 2.326 307 2.487 858 2.933 350 2.544
4TH
5TH
6TH
SUM
289 2.461 6 .77 8 585 2.767 437 2.640 0 0.000 15 1.176 160 2.204 46 1.663 0 0.000 0 0.000 26 1.415 456 2.659 8 .903 99 1.996 37 1.568 661 2.820 13 1.114 183 2.262 0 0.000 12c15 3.081 7 .845
3 49 2.543 0 0.000 0 0.000 26 1.415 0 0.000 19 1.279 6 .778 0 0.000 0 0.000 0 0.000 23 1.362 2059 3.314 18 1.255 41 1.613 190 2.279 1219 3.086 0 0.000 18 1.255 0 0.000 74 1.869 53 1.724
0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 313 2.496 203 2.307 0 0.000 0 0.000 38 1.580 0 0.000 32 1.505 15 1.176 0 0.000 317 2.501 1087 3.036 0 0.000 0 0.000 0 0.000 0 0.000 39 1.591
1467 3.166 6 .778 1271 3.104 1154 3.062 2947 3.469 358 2.554 573 2.758 501 2.700 6 .778 38 1.580 719 2.857 3912 3.592 96 1.982 321 2.507 739 2.869 8081 3.907 353 2.548 476 2.678 319 2.504 3712 3.570 449 2.652
238
CHAPTER 5
BIGRAM FREQUENCIES FOR WORDS OF LETTER LENGTH 7 B I G R A M POSITION
1ST RL RM RN RO
RP RQ RR
RS RT RU
RV RW RY SA
SB
sc SD
0 0.000 0 0.000 0 0.000 247 2.393 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 257 2.410 0 0.000 0 0.000 0 0.000 163 2.212 0 0.000 454 2.657 0 0.000
SE
1655 3.219
SF
0 0.000 554 2.744 569 2.755
SH
SI
2ND 40 1.602 3 .477 0 0.000 2640 3.422 0 0.000 0 0.000 111 2.045 3 .477 123 2.090 182 2.260 0 0.000 0 0.000 26 1.415 0 0.000 0 0.000 22 1.342 0 0.000 17 1.230 0 0.000 23 1.362 0 0.000
3RD
4TH
5TH
6TH
SUM
199 2.299 372 2.571 494 2.694 1047 3.020 207 2.316 4 .602 630 2.799 4 59 2.662 842 2.925 5 .699 502 2.701 142 2.152
183 2.262 90 1.954 222 2.345 289 2.461 41 1.513 0 0.000 52 1.716 86 1.934 373 2.572 23 1.362 3 .477 15 1.176
219 2.340 20 1.301 45 1.653 302 2.480 6 .778 0 0.000 7 .845 53 1.724 388 2.589 5 .699 74 1.869 0 0.000
0 0.000 109 2.037 4 50 2.653 4 .602 0 0.000 0 0.000 0 0.000 2299 3.362
641 2.807 594 2.774 1211 3.083 4529 3.656 254 2.405 4 .602 800 2.903 2900 3.462 2082 3.318 472 2.674 579 2.763 157 2.196
42 1.623
0 0.000 128 2.107 0 0.000 0 0.000 59 1.771 1283 3.108 0 0.000 189 2.276 1154 3.062
0 0.000
1485 3.172 5 .699 0 0.000 0 0.000 0 0.000 1832 3.263 0 0.000 455 2.658 0 0.000
15 1.176 131 2.117 104 2.017 3 .477 241 2.382 0 0.000 204 2.310 416 2.619
18 1.255 0 0.000 0 0.000 0 0.000 777 2.890 16 1.204 0 0.000 58 1.833
3 56 2.551 0 0.000 0 0.000 0 0.000
1553 3.191 329 2.517 131 2.117 580 2.763 62 1.792 5805 3.764 16 1.204 1425 3.154 2207 3.344
APPENDIX 5.2
239
B I G R A M FREQUENCIES F O R WORDS OF LETTER LENGTH 7 B I G R A M POSITION
1ST
2ND
3RD
4TH
5TH
6TH
SUM
48 1.681 186 2.270 160 2.204 56 1.748 665 2.823 586 2.768 29 1.462
0 0.000 30 1.477 0 0.000 0 0.000 8 .903 70 1.845 3 .477
3 .477 14 1.146 5 .699 0 0.000 29 1.462 415 2.618 0 0.000
79 1.898 234 2.369 199 2.299 56 1.748 1179 3.072 1100 3.041 32 1.505
0 0.000 168 2.225 8 .903 206 2.314 0 0.000
5 .699
0 0.000 4 .602 0 0.000 0 0.000 170 2.230 0 0.000 0 0.000 0 0.000
6 .778 0 0.000 30 1.477 0 0.000 17 1.230 0 0.000 0 0.000
0 0.000 0 0.000 1586 3.200 1124 3.051 84 1.924
22 1.342 0 0.000 4 .602 0 0.000 290 2.462 2Y 1.462 0 0.000 0 0.000
0 0.000
.699
6 66 2.823 1550 3.190 317 2.501 44 1.643
326 2.513 338 2.529 2 33 2.367 0 0.000
31 1.491 140 2.146 0 0.000 0 0.000
644 2.809 1204 3.081 0 0.000 0 0.000
1835 3.264 4826 3.684 1880 3.274 128 2.107
SY
173 2.238
3 .477
203 2.307 0 0.000 0 0.000 0 0.000 374 2.573 0 0.000 0 0.000 1813 3.258
584 2.766 0 0.000 4 .602 0 0.000 161 2.207 0 0.000 0 0.000 38 1.580
0 0.000 826 2.917 0 0.000 0 0.000 0 0.000
0 0.000 167 2.223 0 0.000 35 1.544 0 0.000 2777 3.444 0 0.000 0 0.000 96 1.982
40 1.602
TA
0 0.000 214 2.330 3 .477 312 2.494 27 1.431 426 2.629 3 .477 4 .602 1242 3.094
216 2.334 2029 3.307 3 .477 351 2.545 27 1.431 5745 3.759 6 .I78 12 1.079 4979 3.697
SK
SL SM
SN SO
SP
SQ SR SS
ST SU
sw
TB TC TD TE TF TG TH
1412 3.150 3 .477 8 .903 1675 3.224
35 1.544 0 0.000 0 0.000 0 0.000 595 2.775 0 0.000 0 0.000 115 2.061
5
CHAPTER 5
240
BIGRAM FREQUENCIES FOR WORDS OF LETTER LENGTH 7
B I G R A M POSITION
6TH
SUM
2558 3.408 108 2.033 46 1.663 633 2.801 0 0.000 484 2.685 0 0.000 244 2.387 747 2.873 11 1.041 0 0.000 57 1.756
97 1.987 378 2.577 0 0.000 246 2.391 0 0.000 390 2.591 0 0.000 19 1.279 10 1.000 0 0.000 0 0.000 102 2.009
0 0.000 0 0.000 0 0.000 17 1.230 0 0.000 0 0.000 1678 3.225 16 1.204 0 0.000 0 0.000 1010 3.004 0 0.000
3558 3.551 578 2.762 82 1.914 1540 3.188 8 .903 2021 3.306 1895 3.278 1463 3.165 1483 3.171 812 2.910 1089 3.037 6 57 2.818
29 1.462 112 2.049 3 37 2.528 42 1.623 8 .903 127 2.104
142 2.152 105 2.021 15 1.176 71 1.851 0 0.000 783 2.894
0 0.000 224 2.350 134 2.127 107 2.029 0 0.000 974 2.989
4 .602 0 0.000 5 .699 -77 1.886 0 0.000 0 0.000
408 2.611 710 2.851 535 2.728 380 2.580 48 1.681 1955 3.291
19 1.279 0 0.000 28 1.447
214 2.330 0 0.000 490 2.690
57 1.756 0 0.000 95 1.978
0 0.000 0 0.000 188 2.274
507 2.705 4 .602 939 2.973
2N D
3RD
62 1.792 0 0.000 0 0.000 283 2.452 0 0.000 693 2.841 7 .845 0 0.000 192 2.283 28 1.447 76 1.881 0 0.000
68 1.833 35 1.544 0 0.000 297 2.473 0 0.000 278 2.444 0 0.000 177 2.248
773 2.888 57 1.756 36 1.556 64 1.806 8 .903 176 2.246 210 2.322 1007 3.003 203 2.307 773 2.888 0 0.000 294 2.468
UB
0 0.000
'JC
0 0.000 0 0.000 0 0.000 0 0.000 0 0.000
233 2.367 269 2.430 44 1.643 83 1.919 40 1.602 71 1.851 217 2.336 4 .602 138 2.140
TI TL TN TO TP TR TS TT TU TW TY UA
OD UE UF UG
UI UK
UL
0 0.000 0 0.000 0 0.000
331 2.520 0 0.000 3 .477 204 2.310
4TH
5TH
1ST
241
APPENDIX 5 . 2 B I G R A M FREQUENCIES FOR WORDS OF LETTER LENGTH 7 B I G R A M POSITION 1ST 2ND 3 RD UM UN
uo UP UR
US UT
0 0.000 247 2.393 0 0.000 29 1.462 12 1.079 223 2.348 92 1.964
UZ
0 0.000
VA
374 2.573 196 2.292 409 2.612
VE VI
vo
vu WA
WB WD WE
WF WH WI WK
60 1.778 4 .602 498 2.697 0 0.000 0 0.000 559 2.747 0 0.000 446 2.649 1018 3.008 0 0.000
216 2.334 481 2.682 3 .477 337 2.528 1185 3.074 631 2.800 508 2.706 29 1.462 5 .699 298 2.474 56 1.748 27 1.431 0 0.000 44 1.643 0 0.000 0 0.000 32 1.505 10 1.000 0 0.000 43 1.633 11 1.041
29 1.462 812 2.910 0 0.000 34 1.531 313 2.496 291 2.464 98 1.991 0 0.000 130 2.114 790 2.898 358 2.554 143 2.155 0 0.000 77 1.886 10 1.000 11 1.041 576 2.760 0 0.000 29 1.462 0 0.000 0 0.000
4TH
5TH
6TH
SUM
212 2.326 120 2.079 10 1.000 5 .699 444 2.647 156 2.193 258 2.412 0 0.000 278 2.444 245 2.389 892 2.950 27 1.431 0 0.000 169 2.228 0 0.000 32 1.505 867 2.938 0 0.000 0 0.000 377 2.576 0 0.000
30 1.477 162 2.210 0 0.000 13 1.114 936 2.971 933 2.970 95 1.978
207 2.316 23 1.362 0 0.000 6 .778 39 1.591 664 2.822 627 2.797 0 0.000 0 0.000 629 2.799 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000
694 2.841 1845 3.266 13 1.114 4 24 2.627 2929 3.467 2898 3.462 1678 3.225 29 1.462 867 2.938 3184 3.503 1715 3.234 257 2.410 4 .602 924 2.966 10 1.000 43 1.633 2163 3.335 10 1.000 475 2.677 1438 3.158 11 1.041
0 0.000 80 1.903 1026 3.011 0 0.000 0 0.000 0 0.000 136 2.134 0 0.000 0 0.000 129 2.111 0 0.000 0 0.000 0 0.000 0 0.000
242
CHAPTER 5
BIGRAM FREQUENCIES FOR WORDS OF LETTER LENGTH 7 B I G R A M POSITION 2ND 1ST 3RD
WL WM
0 0.000 0 0.000
WN
0 0.000
WO
389 2.590 0 0.000 370 2.568 0 0.000 9 .954 0 0.000
WP WR
ws WY XA
xc XE XH XI
XP XT
xw YA YB YC
YE YF
0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 28 1.447 0 0.000 0 0.000 9 .954 0 0.000
4TH
5TH
6TH
SUM
0 0.000 0 0.000 0 0.000 21 1.322 0 0.000 0 0.000 0 0.000 0 0.000
3 .477 0 0.000 0 0.000 0 0.000 27 1.431 4 .602 4 .602 23 1.362
31 1.491 3 .477 21 1.322 44 1.643 0 0.000 0 0.000 0 0.000 0 0.000
0 0.000 0 0.000 4 .602 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000
0 0.000 0 0.000 56 1.748 0 0.000 0 0.000 0 0.000 198 2.297 0 0.000
34 1.531 3 .477 81 1.908 4 54 2.657 27 1.431 374 2.573 202 2.305 32 1.505
435 2.638 49 1.690 20 1.301 32 1.505 40 1.602 298 2.474 80 1.903 0 0.000 0 0.000 0 0.000 0 0.000 11 1.041 0 0.000
8 .903 0 0.000 0 0.00(1 0 0.000 177 2.248 0 0.000 118 2.072 11 1.041 32 1.505 81 1.908 11 1.041 4 .602 0 0.000
0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000
0 0.000 0 0.000 31 1.491 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000
0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 38 1.580 0 0.000 0 0.000 0 0.000
5 .699 64 1.806 3 .477
0 0.000 99 1.996 0 0.000
0 0.000 6 .778 0 0.000
443 2.646 49 1.690 51 1.708 32 1.505 217 2.336 298 2.474 2 36 2.373 11 1.041 60 1.778 81 1.908 16 1.204 193 2.286 3 .477
243
APPENDIX 5 . 2 BIGRAM FREQUENCIES FOR WORDS OF LETTER LENGTH 7
YG YH YI
YL YM YN YO
YP YR
YS YT YW YZ
ZA
ZE Z I
ZL
zo
zu ZY
zz
B I G R A M POSITION 3RD 2ND 1ST
4TH
5TH
6TH
SUM
0 0.000 8 .903 0 0.000 12 1.079 81 1.908 13 1.114 0 0.000 3 .477 54 1.732 45 1.653 31 1.491 17 1.230 0 0.000 32 1.505 10 1.000 0 0.000 0 0.000 0 0.000 0 0.000 11 1.041 29 1.462
0 0.000 0 0.000 194 2.288 0 0.000 11 1.041 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 27 1.431 0 0.000 0 0.000 0 0.000 0 0.000 39 1.591 23 1.362 9 -954 6 .I78 0 0.000 0 0.000
0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 7 .845 0 0.000 0 0.000 10 1.000 0 0.000 33 1.519 0 0.000 0 0.000 27 1.431 0 0.000 0 0.000 0 0.000
0 0.000 0 0.000 0 0.000 0 0.000 3 .477 0 0.000 0 0.000 0 0.000 0 0.000 57 1.756 0 0.000 0 0.000 0 0.000 3 .477 100 2.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000
3 .477 8 .903 206 2.314 12 1.079 136 2.134 46 1.663 53 1.724 75 1.875 72 1.857 288 2.459 58 1.763 17 1.230 10 1.000 35 1.544 150 2.176 39 1.591 23 1.362 36 1.556 6 .I18 11 1.041 29 1.462
0 0.000 0 0.000 12 1.079 0 0.000 0 0.000 0 0.000 44 1.643 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 7 .84 5 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000
3 .417 0 0.000 0 0.000 0 0.000 41 1.613 33 1.519 9 .954 72 1.857 18 1.255 179 2.253 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.000 0 0.Q00 0 0.000
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6
Summary and Conclusion
T h e g o a l o f t h i s r e s e a r c h p r o j e c t was t o e v a l u a t e how t h e reader's higher-order knowledge a b o u t o r t h o g r a p h i c s t r u c t u r e i n t e r a c t s with f e a t u r a l information during t h e processing of l e t t e r s a n d w o r d s . The r e s e a r c h was c a r r i e d o u t u t i l i z i n g a g e n e r a l i n f o r m a t i o n p r o c e s s i n g model , which provided a formal framework from which hypotheses could be d e r i v e d and tested. The model a l o n g w i t h s u p p o r t i n g e v i d e n c e was d e s c r i b e d i n C h a p t e r 1. S i n c e t h e s t u d y o f v i s u a l p r o c e s s i n g i n r e a d i n g requires a n examination of t h e v i s u a l f e a t u r e s t h a t a r e functional during reading, t h e discussion i n Chapter 2 described those features u t i l i z e d i n t h e r e c o g n i t i o n of lowercase l e t t e r s . Understanding f e a t u r e d e t e c t i o n proved u s e f u l i n a c c o u n t i n g f o r some o f t h e f i n d i n g s i n t h e p e r c e p t u a l The s i g n i f i c a n t recognition tasks described i n Chapter 4. f i n d i n g w a s t h a t t h e s e a r c h f o r a t a r g e t l e t t e r was c r i t i c a l l y dependent o n t h e f e a t u r a l s i m i l a r i t y between t h e t a r g e t l e t t e r and t h e l e t t e r s i n t h e t e s t s t r i n g . The f u n d a m e n t a l p r o p e r t i e s o f t h e o r t h o g r a p h i c s t r u c t u r e of E n g l i s h w e r e d e s c r i b e d i n C h a p t e r 3. We d i s t i n g u i s h e d two b r o a d c a t e g o r i e s o f d e s c r i p t i o n s . T h e f i r s t was d e r i v e d f r o m s t a t i s t i c a l - r e d u n d a n c y measures based on t h e frequency with l e t t e r s e q u e n c e s , and words o c c u r i n natural which l e t t e r s , texts. The s e c o n d c a t e g o r y , r u l e - g o v e r n e d r e g u l a r i t y , was based on p h o n o l o g i c a l c o n s t r a i n t s o f E n g l i s h and s c r i b a l conventions governing t h e s p e l l i n g of English. Also included i n Chapter 3 was a b r i e f r e v i e w o f p r e v i o u s s t u d i e s o f orthography I n Chapter 4 , w e examined t h e p s y c h o l o g i c a l r e a l i t y o f various descriptions of orthographic s t r u c t u r e in perceptual r e c o g n i t i o n t a s k s and o v e r t judgment t a s k s . The r e c o g n i t i o n
.
246
CHAPTER 6
t a s k s a s s e s s e d t h e d e g r e e t o w h i c h k n o w l ed g e o f o r t h o g r a p h i c i n word p e r c e p t i o n , and t h e o v e r t s t r u c t u r e is u t i l i z e d j u d g m e n t t a s k s a s s e s s e d t h e d e g r e e - t o w h i c h t h i s k n o w l e d g e is consciously available. G i v e n o u r p r e v i o u s r e s u l t s ( M a s s a r o e t a l . , 1 9 7 9 ) , we had r e a s o n t o s u s p e c t d i f f e r e n c e s b e t w e e n r e a c t i o n time t a s k s an d of their sensitivities to the a c c u r a c y t a s k s i n terms u t i l i z a t i o n o f o r t h o g r a p h i c s t r u c t u r e . We b e g a n w i t h a d i r e c t c o m p a r i s o n b e t w e e n t h e s e two tasks, while simultaneously c o n t r a s t i n g a ru le-g o v ern ed meas u re and a s t a t i s t i c a l - r e d u n d a n cy measure o f o r t h o g r a p h i c s t r u c t u r e . Rep1 i c a t i n g o u r p r e v i o u s wo r k , w e f o u n d h i g h l y s i g n i f i c a n t e f f e c t s o f o r t h o g r a p h i c s t r u c t u r e i n t h e a c c u r a c y t a s k and r e l a t i v e l y s m a l l , and sometimes n o n s i g n i f i c a n t , effects in the r e a c t i o n time task. The n e x t s i x e x p e r i m e n t s a s s e s s e d w h a t a s p e c t s o f t h e two t a s k s a c c o u n t e d f o r t h e d i f f e r e n c e s t h a t were o b s e r v e d . We evaluated t h e influences of presenting t h e t a r g e t letter before o r a f t e r t h e test d i s p l a y , t h e c o n t r i b u t i o n of a f e a t u r e d e t e c t i o n s t r a t e g y , t h e r o l e of limited stimulus information, and t h e s e n s i t i v i t y o f s p e e d e d r e a c t i o n - t i m e e x p e r i m e n t s . The reason t h a t t h e magnitude of t h e e f f e c t a p p e a r s s m a l l e r f o r a h i g h a c c u r a c y r e a c t i o n - t i m e m e a s u r e is t h a t t h e d i f f e r e n c e s i n v i s u a l p r o c e s s i n g time a r e s m a l l r e l a t i v e t o t h e o v e r a l l In contrast, the stimulus r e a c t i o n time t o c o m p l e t e t h e t a s k . parameters a r e modified i n t h e accuracy t a s k t o keep average performance a t 75% c o r r e c t ; any d i f f e r e n c e s i n accuracy a r e then i n f l u e n c e d a l m o s t c o m p l e t e l y by v i s u a l processing. Supporting this interpretation, t h e p o s t hoc e v a l u a t i o n structure revealed of various measures of orthographic reasonably g o o d c o r r e l a t i o n s w i t h r e a c t i o n t i m e b u t much higher c o r r e l a t i o n s with accuracy. To p r o v i d e a q u a n t i t a t i v e d e s c r i p t i o n o f t a s k a c c u r a c y , we formalized t h e information processing model d e v e l o p e d i n C h a p t e r 1. T h i s model a l l o w s a f o r m a l d e s c r i p t i o n o f t h e f a c i l i t a t i v e e f f e c t of orthographic s t r u c t u r e on both r e a c t i o n time and t a s k a c c u r a c y . The b a s i c a s s u m p t i o n o f t h e model is t h a t k n o wl ed g e o f orthographic structure contributes an independent source of information about the letter string. Consequently, fewer v i s u a l f e a t u r e s a r e n e c e s s a r y t o resolve well-structured s t r i n g s than to resolve poorlystructured strings. The model was a p p l i e d t o t h e t a r g e t s e a r c h t a s k b y f o r m a l i z i n g a d e c i s i o n a l g o r i t h m assu m ed t o b e us ed by t h e s u b j e c t when f a c e d w i t h p a r t i a l information. The model p r o v i d e d a good q u a n t i t a t i v e d e s c r i p t i o n o f t h e r e s u l t s from t h e a c c u r a c y t a s k . The p a r a m e t e r s o f t h e m o d el were
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psychologically meaningful and the parameter values c o r r e s p o n d i n g t o t h e number o f l e t t e r s s e e n i n t h e t e s t s t r i n g s of t h e c o n t r i b u t i o n of p r o v i d e d a q u a n t i t a t i v e measure orthographic s t r u c t u r e . According t o t h e model, our r e a d e r s were able to recognize two additional letters in we 11-st r u c t u r e d s t r i n g s c o m p a r e d t o poo r l y - s t r uc t u r e d s t r i n g s T h i s i s a s u b s t a n t i a l e f f e c t c o n s i d e r i n g t h a t two l e t t e r s represent one-third of t h e s i x - l e t t e r test s t r i n g . We a l s o c a r r i e d o u t a s e r i e s o f o v e r t j u d g m e n t e x p e r i m e n t s t o assess which d e s c r i p t i o n s o f o r t h o g r a p h i c s t r u c t u r e a r e c o n s c i o u s l y a v a i l a b l e . We asked whether subjects could r e l i a b l y a s s i g n r a t i n g s o f how much a l e t t e r s t r i n g r e s e m b l e s written English on t h e b a s i s of t h e t y p i c a l i t y of t h e l e t t e r sequencing i n t h e test s t r i n g s . In addition, other subjects items on t h e b a s i s of were asked t o d i s c r i m i n a t e t h e rule-governed r e g u l a r i t y o r on t h e b a s i s of s t a t i s t i c a l redundancy. S u b j e c t s ' j u d g m e n t s were more a c c u r a t e l y d e s c r i b e d by rule-governed regularity than by s t a t i s t i c a l redundancy. F i n a l l y , t h e r a t i n g s o f t h e i n d i v i d u a l items c o r r e l a t e d q u i t e s t r o n g l y w i t h t h e i r a c c u r a c i e s and r e a c t i o n times i n t h e target search task. The f a c t o r i a l d e s i g n o f our e x p e r i m e n t s c o n t r a s t e d j u s t one measure of rule-governed r e g u l a r i t y with one measure of s t a t i s t i c a l r e d u n d a n c y . T h e r e f o r e , w e c o n d u c t e d a l a r g e number of post hoc c o r r e l a t i o n a l a n a l y s e s t o e v a l u a t e a wide range of m e a s u r e s o f o r t h o g r a p h i c s t r u c t u r e . The d e p e n d e n t m e a s u r e s were t h e r e a c t i o n t i m e s , a c c u r a c y , a n d r a t i n g r e s p o n s e s t o e a c h of 200 t e s t i t e m s . p o s i t i o n - s e n s i t i v e l o g bigram f r e q u e n c y p r o v i d e d t h e b e s t d e s c r i p t i o n o f p e r f o r m a n c e on t h e i n d i v i d u a l test items. However, o u r r u l e - b a s e d r e g u l a r i t y m e a s u r e a l s o p r o v i d e d a v e r y good d e s c r i p t i o n . In f a c t , our regularity measure c o r r e l a t e d v e r y h i g h l y with t h e b e s t frequency-based measure. T h e r e f o r e , we w e r e n o t s u c c e s s f u l i n c h o o s i n g b e t w e e n rule-governed r e g u l a r i t y and s t a t i s t i c a l redundancy i n t h e s e experiments. We were a l s o a b l e t o e v a l u a t e t h e m o s t a p p r o p r i a t e m e a s u r e s f o r a s t a t i s t i c a l - r e d u n d a n c y d e s c r i p t i o n . We o b t a i n e d information about the u t i l i t y of type versus token counts, t h e appropriate s c a l e f o r describing frequency of occurrence, position-sensitive versus position-insensitive counts of l e t t e r o c c u r r e n c e s , t h e r o l e o f word f r e q u e n c y , a n d t h e r e l a t i v e contributions of various serial positions i n determining t h e o r t h o g r a p h i c s t r u c t u r e o f a n item. What c o n c l u s i o n s c a n b e reached and what a r e t h e implications for future research and classroom
.
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p r a c t i c e ? A l t h o u g h we were n o t s u c c e s s f u l i n c h o o s i n g b e t w e e n rule-governed r e g u l a r i t y and s t a t i s t i c a l redundancy i n t h e s e experiments, a d d i t i o n a l experiments might b e s u c c e s s f u l . Given the b e s t statistical-redundancy measure, i t should be possible t o d e v e l o p a new s e t o f t e s t items t o c o n t r a s t t h i s m e a s u r e w i t h a r u l e - g o v e r n e d r e g u l a r i t y m e a s u r e . We p l a n t o f o l l o w t h e by c o n t r a s t i n g l o g bigram l o g i c of t h e p r e s e n t s t u d i e s f r e q u e n c y an d r e g u l a r i t y m e a s u r e s i n t a r g e t s e a r c h and o v e r t judgment t a s k s . Although t h e s e two measures a r e highly correlated, i t s h o u l d b e p o s s i b l e t o d i s t i n g u i s h b e t w e e n t h em . Given t h e r e s u l t s , i t w i l l still be n e c e s s a r y t o c a r r y o u t p o s t h o c c o r r e l a t i o n s t o d e t e r m i n e i f some o t h e r m e a s u r e m i g h t provide even a b e t t e r d e s c r i p t i o n . This research has the promise of l e a d i n g t o t h e d e s c r i p t i o n t h a t b e s t r e f l e c t s t h e kn o wl ed g e o f o r t h o g r a p h i c s t r u c t u r e u s e d i n t h e c o u r s e o f normal r e a d i n g . A r r i v i n g a t a good d e s c r i p t i o n o f o r t h o g r a p h i c s t r u c t u r e should b e b e n e f i c i a l i n t h e development of reading i n s t r u c t i o n . Given t h a t t h e u t i l i z a t i o n of o r t h o g r a p h i c s t r u c t u r e is a n important co m p o n e n t in letter and word recognition, i n s t r u c t i o n a l m a t e r i a l s should be designed t o f a c i l i t a t e c h i l d r e n ' s understanding of t h i s s t r u c t u r e . Current phonics p r o g r a m s a d d r e s s o n l y t h e c o r r e s p o n d e n c e s b e t w e e n s p e l l i n g and sound, n o t t h e c o n s t r a i n t s i n English orthography. Y a s s a r o and T a y l o r ( 1 9 7 9 ) s k e t c h a s e r i e s o f c l a s s r o o m g am es t h a t m i g h t b e employed t o t e a c h c h i l d r e n common l e t t e r p a t t e r n s a n d t h e l o c a t i o n s i n words t h e s e l e t t e r p a t t e r n s a r e most l i k e l y t o b e found. D e l i n e a t i n g t h e b e s t description of orthographic s t r u c t u r e m i g h t f a c i l i t a t e t h e t e a c h i n g an d l e a r n i n g o f t h i s structure
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Holt,
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Glossary a c c u r a c y t a s k : a t a s k i n which accuracy is t h e primary dependent measure; i n the target search task, average p e r f o r m a n c e i s m a i n t a i n e d a t 7 5 % c o r r e c t by a d j u s t i n g t h e d u r a t i o n of t h e t e s t s t r i n g and/or t h e p r o c e s s i n g time available. a n ag r am : a p e r m u t a t i o n o f t h e l e t t e r s c o m p r i s i n g a word. bigram: a t w o - l e t t e r
cluster.
catch t r i a l : --
a t r i a l d u r i n g which t h e t a r g e t l e t t e r d o e s appear in t h e test s t r i n g .
not
feature detection: a p r o c e s s which answers t h e q u e s t i o n of w h e t h e r o r n o t a p a r t i c u l a r f e a t u r e is p r e s e n t a n d / o r p r o v i d e s i n f o r m a t i o n a b o u t t h e d e g r e e t o which t h e f e a t u r e is present. fourier analysis: t h e d e s c r i p t i o n of a v i s u a l d i s p l a y i n terms o f i n t e n s i t y a n d f r e q u e n c y o f c o m po n en t s i n e w av es. f u l l report: g i v e n a d i s p l a y o f items, s u b j e c t s a r e asked r e p o r t a l l o f t h e items i n t h e d i s p l a y . g e n e r a t e d a b s t r a c t memory: modality-free a n a l o g o u s t o s h o r t - t e r m memory.
(abstract)
graphemic c o n s t r a i n t s : see s c r i b a l c o n s t r a i n t s .
263
to
storage,
264
GLOSSARY
high s p a t i a l f r e q u e n c i e s : t h e h i g h f r e q u e n c i e s o f analyses of a visual display. homophones: d i f f e r e n t w o r d s such as right/write.
t h a t a r e pronounced
a
fourier
identically,
i n f o r m a t i o n : s o u r c e o f knowledge a v a i l a b l e t o t h e r e a d e r ; for example, t h e f e a t u r a l information i n p r e p e r c e p t u a l s t o r a g e o r t h e r e a d e r ' s memory o f l e t t e r p a t t e r n s i n t h e l a n g u a g e . l e x i c o n : s t o r a g e o f p e r c e p t u a l and c o n c e p t u a l c o d e s o f w o r d s i n l o n g - t e r m memory; e a c h word h a s p e r c e p t u a l c o d e s s u c h a s t h e s o u n d and v i s u a l p a t t e r n o f t h e word and c o n c e p t u a l codes such a s its meaning. l o n g - t e r m memory: r e l a t i v e l y permanent s t o r e of knowledge t e r m o f c o d e s , r u l e s , and p r o c e d u r e s ( s c h e m a t a ) .
low s p a t i a l
f r e q u e n c i e s : t h e low f r e q u e n c i e s a n a l y s i s of a v i s u a l display.
of
a
in
fourier
morpheme i d e n t i t y : r e t e n t i o n of spelling similarity s e m a n t i c a l l y - r e l a t e d words, such a s cone/conic.
of
nonword: a l e t t e r s t r i n g t h a t d o e s n o t s p e l l a word; s o m e t i m e s u s e d t o mean t h a t t h e l e t t e r s t r i n g a l s o d o e s not c o n f o r m t o s t a n d a r d English s p e l l i n g , i.e., i t v i o l a t e s English orthography. orthographic regularity: d e s c r i p t i o n of orthographic s t r u c t u r e b a s e d upon r u l e s and g e n e r a l i z a t i o n s a b o u t t h e o b s e r v e d p a t t e r n s of English orthography; a l s o referred t o a s rule-based description. orthographic structure: the spelling constraints i n a written language; i n E n g l i s h , f o r example, g i v e n i n an i n i t i a l p o s i t i o n , r i s more l i k e l y t o f o l l o w t h a n 2. o v e r t judgments: judgments about the s p e l l i n g of l e t t e r s t r i n g s ; s t u d i e d t o a s s e s s what knowledge of o r t h o g r a p h y is c o n s c i o u s l y a v a i l a b l e a n d c a p a b l e o f r e p o r t . p a r a l l e l processing: when i n f o r m a t i o n a b o u t two o r m o r e is processed simultaneously.
items
GLOSSARY
265
perceptual recognition: see primary recognition. phonological constraints: the constraints on English orthography that derive from the allowable sequences of sounds in English words. positional frequency: see position-sensitive measure. position-dependent measure: see position-sensitive measure. position-independent measure: see position-insensitive measure. position-insensitive measure: a statistical-redundancy description of orthographic structure which counts letter sequences on the bases of occurrence in words of specific lengths without regard to position of occurrence; also referred to a s position-independent measure. position-sensitive measure: a statistical-redundancy description of orthographic structure which counts letter sequences on the basis of occurrence in specific positions in words of specific lengths; also referred to as position-dependent measure or positional-frequency. postcue: when a target letter follows a test string. precue: when a target letter precedes a test string. preperceptual visual storage: holds features passed on feature detection for roughly one quarter of a second.
by
primary recognition: joint evaluation and integration of the features in preperceptual storage and knowledge of orthographic structure in long-term memory; the outcome is a synthesized percept; also referred to as perceptual recog n i t ion. probabilistic description: see statistical redundancy. pseudoword: a nonword that conforms to English spelling. reaction time (RT) task: task in which reaction time is the primary dependent measure; in the high-accuracy target search task, for example, accuracy is kept near perfect by
266
GLOSSARY
keeping t h e interval.
test
string
present
r e g u l a r it y : see o rthog r a p h i c r e g u l a r i t y
during
the
response
.
r u l e-based d e s c r i p t ion: see o r thog r a p h ic r e g u l a r it y
.
scribal constraints: the constraints in the selection of letters for either representing sounds o r marking graphemic, graphotactic , o r morphological functions; a l s o referred t o a s graphemic c o n s t r a i n t s . secondary recognition: transforms v i s u a l percept held in s y n t h e s i z e d memory i n t o meaning h e l d i n g e n e r a t e d a b s t r a c t memory. single-letter positional frequency: t h e frequency w i t h which a l e t t e r o c c u r s i n a s p e c i f i c p o s i t i o n i n words o f a s p e c i f i c l e n g t h i n a sample of t e x t . s p e e d e d fl task: s u b j e c t s a r e i n s t r u c t e d t o r e s p o n d m o r e in the q u i c k l y t h a n t h e time n e e d e d f o r h i g h a c c u r a c y ; t a r g e t s e a r c h t a s k , s u b j e c t s l e a r n t o respond i n synchrony w i t h a n e x t e r n a l s i g n a l whose r e l a t i v e o n s e t i s a d j u s t e d t o k e e p p e r f o r m a n c e a t 7 5 % c o r r e c t ; b o t h a c c u r a c y an d RT a r e evaluated a s dependent measures. of s t a t i s t i c a l redundancy: category of descriptions o r t h o g r a p h i c s t r u c t u r e d e r i v e d from c o u n t s o f l e t t e r s o r l e t t e r sequences occurring in t h e w r i t t e n language; a l s o called probabilistic description. ~ summed_c o u n_ t s : t h_ e sum o f i n d i v i d u a l f r e q u e n c i e s o f t h e l e t t e r s o r letter clusters i n a l e t t e r string.
s y n t h e s i z e d v i s u a l memory: h o l d s p e r c e p t u a l o u t c o m e s o f p r i m a r y recognition process. target letter: i n t h e t a r g e t s e a r c h t a s k , t h e l e t t e r whose presence o r absence i n t h e t e s t s t r i n g of l e t t e r s must b e reported
.
target -
s e a r c h~ task: t h e s u bj e c t i s g i v e n a t a r g e t l e t t e r and t h e t a s k is t o i n d i c a t e whether o r n o t t h e t a r g e t l e t t e r is contained i n a t e s t s t r i n g of l e t t e r s .
GLOSSARY
267
test string: i n the t a r g e t search task, the l e t t e r s t h a t m u s t be e v a l u a t e d i n t e r m s o f p r e s e n c e o r a b s e n c e o f t h e t a r g e t letter. t o k e n c o u n t : a c o u n t b a s e d on t h e number of t o t a l o c c u r r e n c e s -o f an i t e m ; f o r e x a m p l e , t h e t o t a l number o f o c c u r r e n c e s o f a l l words c o n t a i n i n g a p a r t i c u l a r l e t t e r . trigram: *e
a three-letter
cluster.
count: a c o u n t b a s e d on t h e number o f u n i q u e o c c u r r e n c e s o f an item; f o r e x a m p l e , t h e number o f u n i q u e words containing a particular l e t t e r .
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Author Index A
Adams, N., 5 8 , 67 A l l p o r t , A., viii A n d e r s o n , I . H., 1 1 - 1 2 A n i s f e l d , M. A . , 25 A t k i n s o n , R. C . , 56 B
B a d d e l e y , A . D . , 7 , 64 B a r b u t o , P . F . , 27 B a r o n , J , , viii, 6 2 B e a l , A. L . , 2 4 B j o r k , E. L . , 62 Bouma, H., 1 2 , 1 5 - 1 6 , 43-45, B o u w h u i s , D . , G . 26 B r e i t m e y e r , B . G., 1 9 B r o a d b e n t , D. E . , 1 9 , 1 4 1 , B r o w n e l l , H . , 58, 67 B r u n e r , J. S., 6 , 2 4 Byrnes, J., 24
52-53
C
C a r r , T. H . , i x C a t t e l l , J . M., 1 1 - 1 2 C h a n d l e r , J . P . , 59 Chomsky, N . , 35 C l a r k , H . H . , 51 269
270
AUTHOR I N D E X
C o n g e r , B. , 1 3 2 Creelman, C. D.,
93
D D e a r b o r n , W.
F.,
11-12
E
E g e t h , H. E s t e s , W.
25 v i i i , 5, 62
E., R.,
F F a n t , C. G . M . , F r a n c i s , W. N.,
14 26-27,
126-127,
149
G
Ganz, L., 1 9 G e o f f r i o n , L. D . , 5 G i b s o n , E . J . , v i i i , 1, 1 5 , 2 5 , 29-38, G i l m o r e , G. C., 25 Green, D. M . , 1 7
H Halle, M., 14 Hammond, M., 2 5 , 29-30 H a v i l a n d , S . E . , 58, 67 Henderson, L., v i i i Huey, E . B . , 1, 1 3 Hung, D. L . , 2 9 J
,
J a k o b s o n , ' R. 14 J o h n s o n , N. F., v i i i J o h n s t o n , J. C . , 2 6 , 1 0 1 , 1 3 2 J o n e s , R. D . , 7 4 , 77-18 J u e l , C. L.r 27 J u o l a , J. F., 56, 68
32
AUTHOR INDEX
K
Kallrnan, H. J . , 5 8 K a u s l e r , D. H., 3 3 K i n g , J. F . , 2 7 Klitzke, D., 105 Kleiman, G. M . , 2 9 K o l e r s , P . A., 1 0 8 K r u e g e r , L. E . , v i i i , 7, 4 7 K u c e r a , H., 2 6 - 2 7 , 1 2 6 - 1 2 7 , 1 4 9 K u r a t h , H., 3 5 L
L a n d a u e r , T. K . , 2 7 - 2 8 L e f t o n , L. A., 2 4 L e v i n , H., viii, 1 Levy, B. A . , 2 9 L e w i s , S. S., 2 9 - 3 0 Lipscomb, c . , 7 4 , 7 7 - 7 8 Lorge, I . , 2 5 M
Macey, W. H., 2 7 Mason, M . , 2 6 , 3 7 - 3 8 , M a s s a r o , D. W.,ix, 2,
132 5-8, 56-58, 62,
1 7 , 19, 2 1 , 2 6 , 2 9 , 38-47, 43, 74, 77-78, 96, 105, 246, 248 Mayzner, M . S . , 26, 4 8 , 9 1 McClelland, J . L . , 26, 1 0 1 , 1 3 2 Newhort, D, J . , 2 4 Meyer, D. E . , 7 4 , M i l l e r , G. A., 6 , 2 4 M i l l e r , T. J . , 6 8
N Neisser, U.,
14,
43
0
Oden, G . C . , 2 1 , O l i v i e r , D. G . , 1 2 7 - 1 2 8 , O l s e n , G. A . , 3 3
131
271
AUTHOR INDEX
272
Osser, H . ,
1 5 , 2 5 , 29-30
P P i c k , A . , 2 5 , 29-30 P o d g o r n y , P., 1 3 1 P o l l a t s e k , A . , ix P o s t m a n , L . , 6 , 2 4 , 27-28, P y l e s , T., 32
131-132
R
R e d e r , L. M . , 5 8 , 6 7 R e e d , A. V., 7 5 , 1 0 5 R e i c h e r , G. M., 6 , 6 2 R u b e n s t e i n , H . , 29-30 R u b e n s t e i n , M . A . , 29-30 Ruddy, M. G., 74 S
S a v i n , H. B . , 27-28 S c h i f f , W., 15 S c h m u l l e r , J., 7 , 1 7 , 1 9 , 4 3 S c h o l z , R. , 7 4 , 77-78 S c h u l z , R. W., 25-26 S c h v a n d e v e l d t , R. W., 7 4 S e l f r i d g e , 0. G., 1 4 S h a n n o n , C. E., 6 , 24 S h a p i r o , R . G., 7, 47 S h e b i l s k e , W. , 3 S h e p a r d , R. N., 1 3 1 S h u r c l i f f , A . , 25-26, 29-30, 1 3 2 S i d m a n , M., 47 S k a a r , E., 6 2 S m i t h , E. E., 4 , 29-30, 5 8 , 6 7 , 1 3 2 S m i t h , J., 15 S o l o m o n , R. L . , 27-28, 1 3 1 S o l s o , R. L., 27 S p e n c e r , H . , 11-13 S p o e h r , R. T., 1 3 2 S p r a g i n s , A. B., 2 4 S p r e e n , O., 26 S t r e e t e r , L. A . , 27-28 S w e t s , J. A . , 1 7
AUTHOR I N D E X
27 3
T T a y l o r , G . A . , 26, 3 8 - 4 7 , 5 7 - 5 8 , 1 3 1 , 248 T h o m p s o n , M. C . , 6, 5 7 - 5 8 , 6 2 T h o r n d i k e , L. L . , 2 5 T h u r s t o n , I . , 62 T i n k e r , M. A . , 11 T o w n s e n d , J . T . , 15 T o p p e r , G. E . , 27 T r a v e r s , J. R . , 127-128, 1 3 1 T r e s s e l t , M. E . , 2 6 , 48, 9 1 T u l v i n g , E., 6 T u r v e y , M. T . , 56 T z e n g , 0. J . L . , 2 9
68,
93,
105,
U
U n d e r w o o d , 8. J . ,
25-26
V
Vachek, J., V e n e z k y , R.
33 L.,
26,
29,
31,
W
W a l l a c h , M. A . , 24 Wang, W. S-Y., 29 W h e e l e r , D. D . , 6, 6 2 W h o r f , B. L . , 35 W o l i n , B. R . , 2 6 W o o d w o r t h , R. S., 3
Y
Y onas, A . ,
25-26,
29-30,
132
33,
35,
38-47,
57-58,
96
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Subject Index A
a c c u r a c y t a s k , 40,47-48, anagram, 38 a w a r e n e s s , 81
56-61,
246-247
B b i g r a m , 25-29 bigram c o u n t s ,
60-244
c c a t c h t r i a l , 39 c l a s s r o o m p r a c t c e , 779 c o n f u s i o n m a t r i c e s , 14-15 c o n s o n a n t s p e l l i n g , 31-32
D d e c i s i o n , 1 7 - 1 8 , 5 6 , 57 d ' m e a s u r e , 17-18
E E n g l i s h n e s s , 127-128 e n v e l o p e , 15-16, 1 9
275
276
SUBJECT INDEX
F f e a t u r e a n a l y s i s , 2 , 13-14 f e a t u r e d e t e c t i o n , 3-4, 19-21 f e a t u r e d e t e c t i o n s t r a t e g y , 43-46, f e a t u r e s , 3 , 5 , 1 4 , 14-21 fourier analysis, 19 f r e q u e n c y s c a l e , 130-132 f u l l r e p o r t , 6 , 24-25
6 8 , 71-73
G
g e n e r a t e d a b s t r a c t memory, 8
H high s p a t i a l f r e q u e n c i e s , 19 homophones, 33
i n f o r m a t i o n , 2 , 73-74 i n f o r m a t i o n p r o c e s s i n g m o d e l , 1-8, 55-62,
K k n o w l e d g e , 2 , 74
L l e g i b i l i t y of t e x t , 11-13 l e t t e r - s o u n d c o r r e s p o n d e n c e s , 29-30 lexicon, 8 l i n g i u s t , 34 l o n g - t e r m memory, 3 , 8 low s p a t i a l f r e q u e n c i e s , 1 9
M m a s k i n g s t i m u l u s , 6 , 1 5 , 1 7 , 40 memory, 2-3 morpheme i d e n t i t y , 32 m o r p h e m i c f e a t u r e s , 32-33
66-67
S U B J E C T INDEX N n o n w o r d , 25
o r d e r e d a p p r o x i m a t i o n s t o E n g l i s h , 24-25 o r t h o g r a p h i c r e g u l a r i t y , 38 o r t h o g r a p h i c s t r u c t u r e , 2 , 4-9, 2 3 - 3 6 , 245 o v e r t j u d g m e n t s , 8 1 - 9 0 , 247
P p a r a l l e l p r o c e s s i n g , 5 , 56 p a i r e d j u d g m e n t s , 81, 87-89, 120-123 perceptual recognition, 8 perceptual unit, 5 p e r i p h e r a l v i s i o n , 13, 15, 19 p h o n o l o g i c a l c o n s t r a i n t s , 30-31 p h o n o l o g i c a l l y - b a s e d d e s c r i p t i o n s , 29-30 p o s i t i o n - i n s e n s i t i v e measure, 132 p o s i t i o n - s e n s i t i v e measure, 132 p o s t c u e , 47-48, 62-66 p r e c u e , 4 7 - 4 8 , 62-66 p r e p e r c e p t u a l v i s u a l s t o r a g e , 3-4, 56 p r i m a r y r e c o g n i t i o n , 4-5, 7 - 8 , 5 6 p r i m i n g , 74 p r o c e s s , 2-3 p r o c e s s i n g time, 1 4 p s e u d o w o r d s , 2 4 , 8 2 - 8 5 , 115 p s y c h o l o g i s t s , 34
R r a t i n g s , 8 1 , 8 1 - 8 7 , 113-119 r e a c t i o n - t i m e t a s k , 3 7 - 3 8 , 4 7 - 4 8 , 6 8 - 6 1 , 246-247 r e a d i n g , 1-2 r e a d i n g i n s t r u c t i o n , 1 - 2 , 247-248 recoding, 8 redundancy, 6 rehearsal, 8 R e i c h e r - W h e e l e r p a r a d i g m , 6 - 7 , 40 r u l e - b a s e d d e s c r i p t i o n , 2 3 - 2 4 , 30-36, 3 8 , 9 6 , 1 2 9 , 247 r u l e - g o v e r n e d r e g u l a r i t y , 23-24, 30-36, 3 8 , 9 6 , 1 2 9 , 247
277
SUBJECT INDEX
278
S saccades, 3 s c r i b a l c o n s t r a i n t s , 31-32 secondary recognition, 4 , 8 s h o r t- t e rm memo r y , 7-8 s i m i l a r i t y , 4 3 - 4 6 , 5 1 - 5 4 , 64-65, 72-73 s i n g l e - l e t t e r p o s i t i o n a l f r e q u e n c y , 3 7 , 48 s i n g l e - l e t t e r p o s i t i o n a l f r e q u e n c y c o u n t s , 149-159 speed-accuracy paradigm, 75 s p e e d e d RT t a s k , 75-82 s t a g e o f p r o c e s s i n g , 2-3 s t a t i s t i c a l r e d u n d a n c y , 23-29, 247 s t i m u l u s items, 97-98, 143-148 summed c o u n t s , 37 s y n t h e s i z e d v i s u a l memory, 8 , 56
T t a r g e t l e t t e r , 37-39 t a r g e t s e a r c h t a s k , 3 7 , 37-81 t a r g e t t r i a l , 39 template, 14 t e s t s t r i n g , 37-39 t o k e n c o u n t , 27-28, 128-130 t r i g ram , 2 7 t y p e c o u n t , 27-28, 128-130
V v o w e l s p e l l i n g s , 31-32
w word f r e q u e n c y , 1 4 1 word r e c o g n i t i o n , 1 - 2 ,
4
