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Multivariate analytic investigations for the identification of sub-populations within aphasia Clark, Campbell McGillivrary 1978

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MULTIVARIATE ANALYTIC INVESTIGATIONS FOR THE IDENTIFICATION OF SUB-POPULATIONS WITHIN APHASIA by Campbell M c G i l l l v r a r y C l a r k B . S c , M c G i l l U n i v e r s i t y , 1972 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF ARTS In THE FACULTY OF GRADUATE STUDIES Department o f Education We accept t h i s t h e s i s as conforming t o the r e q u i r e d standard THE UNIVERSITY OF BRITISH COLUMBIA August, 1978 © Campbell M c G i l l i v r a r y C l a r k , 1978 In p r e s e n t i n g t h i s t h e s i s in p a r t i a l f u l f i l m e n t o f the r e q u i r e m e n t s f o r an advanced degree at the U n i v e r s i t y o f B r i t i s h Co lumb ia , I ag ree that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s tudy . I f u r t h e r agree t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y purposes may be g r a n t e d by the Head o f my Department o r by h i s r e p r e s e n t a t i v e s . It i s u n d e r s t o o d that c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i thout my w r i t t e n p e r m i s s i o n . Department o f The U n i v e r s i t y o f B r i t i s h Co lumbia 2075 Wesbrook P l a c e V a n c o u v e r , Canada V6T 1W5 i i ABSTRACT Using m e d i c a l l y diagnosed a p h a s i c s , t h i s study attempted t o develop a c l a s s i f i c a t i o n system, based on s t a t i s t i c a l o r , more p r e c i s e l y , variance c r i t e r i a . Aphasia i s a language d i s o r d e r r e s u l t i n g from i n s u l t t o the b r a i n . Besides having d i r e c t r a m i f i c a t i o n s on aphasia theory and research s t r a t e g i e s , the techniques used.here may be a p p l i c a b l e t o other a t y p i c a l p o pulations. S p e c i f i c a l l y , the o u t l i n e d m u l t i v a r i a t e procedures can provide i n s i g h t i n t o i n t r a - p o p u l a t i o n d i s t r i b u t i o n s . The r e s u l t i n g d i s t r i b u t i o n can then be used as a b a s i s f o r f a c t o r i a l designs i n f u t u r e research. The sample c o n s i s t e d o f seventy-two m e d i c a l l y diagnosed aphasics who had r e c e i v e d speech therapy f o r v a r y i n g time p e r i o d s . P r i o r t o and at the t e r m i n a t i o n of treatment, subjects were assessed on a w e l l - s t a n d a r d -i z e d and r e l i a b l e aphasia b a t t e r y , the Porch Index o f Communication A b i l i t y . T his instrument c o n s i s t s o f eighteen subtests and purports t o measure three dimensions of communication a b i l i t y : one v e r b a l , one g e s t u r a l , and one graphic. Post-treatment subtest scores were f a c t o r analyzed t o determine the f a c t o r s t r u c t u r e of the P.I.C.A. and t h i s s t r u c t u r e was compared w i t h Porch's f o r m u l a t i o n s . Two subtests were d e l e t e d from t h i s a n a l y s i s due t o c e i l i n g e f f e c t s . Using the f a c t o r score c o e f f i c i e n t s from t h i s a n a l y s i s , f a c t o r scores f o r the pre-treatment subtests were generated. These f a c t o r scores were submitted t o a h i e r a r c h i c a l c l u s t e r a n a l y s i s i n order t o determine the optimal number o f groups w i t h i n t h i s sample. A s e r i e s of step-wise, d i s c r i m i n a n t analyses, u s i n g the f a c t o r scores as p r e d i c t o r s , confirmed t h a t a six-group s o l u t i o n was best. Group d i s t r i b u t i o n s were then examined w i t h respect t o current models o f aphasia. The f i n d i n g s . i i i support Porch's formulations with respect to the underlying demensions of the P.I.C.A. However, the results suggested that 1) two subtests were too easy for a l l subjects and therefore should be discarded, and 2) two other subtests may not, i n fact, reflect symbolic language function. In addition, evidence of a general language factor was also found. These findings were also compared to a factor analysis on "'. Porch's standardization sample. The five derived dimensions of commun-ication a b i l i t y were : 1) verbal fluency, 2) writing (agraphia),. 3) gestural demonstration with, varying input modalities, 4) pantomime, and 5) copying. These dimensions were discussed within the context of previous aphasia research. The grouping analysis indicated that the groups were distributed on a severity continuum not a salient features model of aphasia. Only one of the six groups was suggestive of differential impairment with respect to communication modalities, but this group was small (n = 4) and therefore must be considered judiciously, In addition, the applicability of these procedures was discussed within the context of multivariate research.. The power of multivariate designs rests on minimizing the number of groups and dependent variables and maximizing the number of subjects, and the present procedures should aid i n meeting these c r i t e r i a . Specifically, factor analysis reduces the number of dependent variables and yet allows for a representative sample of dependent variables. Cluster analysis groups Individuals Based on the similarities of their performance and thus relatively homogenous groups are formed. The distribution of these groups can form the basis for subsequent factorial designs. W.T. Rogers i v TABLE OF CONTENTS CHAPTER I - PROBLEM AREA Introduction 1 Etiology, Symptoms and Models of Aphasia 1 Aphasia as a Representative Atypical Population ft Methodological Problems i n Examining Aphasia 6 Multivariate S t a t i s t i c a l Concerns 10 Factor Analysis 11;. Grouping Procedures 12 Summary of Procedure 12 CHAPTER II - LITERATURE REVIEW Introduction 1ft. Models of Aphasia 1ft History of Research 2.0: The Porch Index of Communication Ability 23 CHAPTER III - METHODS Introduction 30 Experimental Paradigm and S t a t i s t i c a l Procedure 30 Sample 33 Instrumentation 3^ ANALYSES Factor Analysis 3^ Hierarchical Analysis 35 Discriminant Analysis and Analysis of Variance 36 CHAPTER IV - RESULTS Sample 38 Factor Analysis 40 Hierarchical Analysis 49 Univariate Analysis 53 Qualitative Statements Concerning Groupings 57 V CHAPTER V - CONCLUSIONS AND DISCUSSION I n t r o d u c t i o n 59 L i m i t a t i o n s of This Study 59 F a c t o r A n a l y s i s 60 H i e r a r c h i c a l A n a l y s i s 63 Grouping and Current Aphasia Theory 64 Conclusions Relevant t o the P.I.C.A. 64 Methodological Concerns I n t r o d u c t i o n 67 F a c t o r A n a l y s i s 68 H i e r a r c h i c a l A n a l y s i s 69 D i r e c t i o n s of Future Research 70 REFERENCES 7 5 - 7 7 v i LIST OP TABLES Table 1 D e s c r i p t i o n o f P.I.C.A. Subtests 24 Table 2 M u l t i d i m e n s i o n a l Scoring Categories o f the P.I.C.A. 25 Table 3 Measure of R e l i a b i l i t y f o r the P.I.C.A. 28 Table 4 Data A n a l y s i s Procedure 32 Table 5 Means and Standard D e v i a t i o n s : Porch's and Study Samples 39 Table 6 I n t e r - C o r r e l a t i o n M a t r i x o f Post Treatment P.I.C.A. Subtest Scores 41 Table 7 C r i t e r i a Data f o r E s t i m a t i n g No. of F a c t o r s 43 Table 8 R e s u l t s o f Oblique Transformations 44 Table 9 I n t e r F a c t o r C o r r e l a t i o n M a t r i x 47 Table 10 F a c t o r P a t t e r n M a t r i x 48 Table 11 R e s u l t s o f C l u s t e r A n a l y s i s 50 Table 12 Means and Standard D e v i a t i o n s f o r F i v e F a c t o r s on S i x Groups 52 Table 13 Analyses of Variance f o r the F i v e Factors 54 Table 14 Scheffe's M u l t i p l e Comparisons on Fa c t o r s by Group 56 Appendix A - F a c t o r A n a l y s i s o f Porch's S t a n d a r d i z a t i o n Sample 72 1 F a c t o r P a t t e r n M a t r i x Obtained on Porch's S t a n d a r d i z a t i o n Data 73 2 F a c t o r . C o r r e l a t i o n M a t r i x • • \ " 74 v i i • LIST OF FIGURES Figure 1 Porch's M u l t i d i m e n s i o n a l S c o r i n g System 26 Figure 2 Overview of Experimental Paradigm 31 F i g u r e 3 Scree Test 42 1 CHAPTER 1 I n t r o d u c t i o n With advancing d i a g n o s t i c t o o l s and s t a t i s t i c a l techniques, e m p i r i c a l study o f a t y p i c a l p opulations has become both more f e a s i b l e and meaningful. M e t h o d o l o g i c a l l y , these populations present p a r t i c u l a r problems i n terms of sampling. Instrumentation, experimental design and subsequent a n a l y s i s . I n the present study, I n d i v i d u a l s diagnosed as having aphasic or language d i s o r d e r s r e s u l t i n g from i n s u l t t o the b r a i n formed the a t y p i c a l p o p u l a t i o n o f i n t e r e s t . I m p l i c a t i o n s of s p e c i f i c s t a t i s t i c a l procedures on current aphasia t h e o r i e s and r e s e a r c h were I n v e s t i g a t e d . F i r s t , the language dimensions u n d e r l y i n g the d i s o r d e r were examined, u s i n g a standard, r e l i a b l e , and po p u l a t i o n - a p p r o p r i a t e instrument. Second, e m p i r i c a l d i f f e r e n t i a t i o n o f groups w i t h i n the p o p u l a t i o n was i n v e s t i g a t e d u s i n g dimensions o f language or communication a b i l i t i e s d e r i v e d I n the f i r s t phase. By u s i n g a standardized and accepted t e s t b a t t e r y , the Porch Index o f Communication A b i l i t y , the r e l a t i o n s h i p between t h i s b a t t e r y and current models o f aphasia was f u r t h e r e x p l i c a t e d . The c r i t e r i a f o r the development o f t h i s r e l a t i o n -s h i p was e m p i r i c a l l y d e r i v e d r a t h e r than being n o s o l o g i c a l l y o r c l i n i c a l l y based. E t i o l o g y , Symptoms and Models o f Aphasia By d e f i n i t i o n , aphasia i s a language d i s o r d e r r e s u l t i n g from i n s u l t t o the b r a i n (Walton, 1974). The i n s u l t may be e i t h e r i n t e r n a l (e.g. c e r e b r a l v a s c u l a r accident) or e x t e r n a l (e.g. head i n j u r y ) . Considerable r e s e a r c h has been done on the recovery r a t e s o f i n t e r n a l versus e x t e r n a l i n j u r e d i n d i v i d u a l s . I n g e n e r a l , the r e s u l t s suggest t h a t e x t e r n a l i n j u r i e s have a b e t t e r prognosis f o r improvement, but perhaps not f o r 2 recovery, than i n t e r n a l i n j u r i e s . The d i f f e r e n t i a t i o n between improvement and recovery, although r a r e l y made i n the l i t e r a t u r e , may be fundamental t o aphasia research. S p e c i f i c a l l y , the magnitude o f the i n s u l t has d i r e c t b e a r i n g on the s e v e r i t y of the d i s o r d e r . I n other words, two 'aphasic' i n d i v i d u a l s may not appear s i m i l a r i n t h e i r a b i l i t y t o commun-i c a t e or use language. For example, one may not be able t o comprehend or produce language i n any modality w h i l e the other may have minor word-finding d i f f i c u l t y when speaking. However, the more s e v e r e l y impaired i n d i v i d u a l has a b e t t e r prognosis f o r improvement of language s k i l l s immediately a f t e r I n s u l t , w h i l e the l e s s Impaired i n d i v i d u a l has a b e t t e r prognosis f o r recovery of language s k i l l s ( G e r s t e i n , 19750-This example, besides i l l u s t r a t i n g the d i f f e r e n c e between improvement and recovery, a l s o serves t o h i g h l i g h t the vast d i s c r e p a n c i e s found among 'aphasics'. These d i s c r e p a n c i e s i n language a b i l i t i e s have l e d researchers and c l i n i c i a n s t o develop q u a l i t a t i v e c a t e g o r i z a t i o n systems based on aphasic symptoms. F o r example, Howes' model (Howes, 1964) d i f f e r e n t i a t e s aphasics dichotomously, based on v e r b a l production from a f r e e speech sample. The two groups are : 1) fluent. - able t o produce speech; and 2) d y s f l u e n t - d i f f i c u l t i e s i n producing speech spontaneously. Using a psychometric b e t t e r y , Weisenburg and McBride developed a f o u r - f o l d c l a s s i f i c a t i o n system as f o l l o w s : 1) predominantly r e c e p t i v e , marked by d i f f i c u l t i e s i n comprehending language; 2) predominantly e x p r e s s i v e , marked by d i f f i c u l t i e s i n speech p r o d u c t i o n ; 3) anomic, marked by d i f f i c u l t i e s i n naming; and 4) both expressive and r e c e p t i v e , or mixed symptoms (Weisenburg and McBride, 1935). However, Weisenburg and McBride s t r e s s e d t h a t there was a general impairment o f language f u n c t i o n 3 and t h a t t h e i r model attempted d i s t i n c t i o n s based on the more predominant symptoms. The pressure of language d i s o r d e r s has been a s s o c i a t e d w i t h d y s f u n c t i o n I n , or damage t o , p a r t i c u l a r areas of the b r a i n , u s u a l l y In the l e f t hemisphere. For example, two. types of aphasia, Broca's and W ernicke ' s , are a s s o c i a t e d w i t h l e s i o n s i n p a r t i c u l a r areas of the b r a i n (Walton, 1 9 7 4 ) . . G e n e r a l l y , I t i s u s u a l l y accepted t h a t the l e f t temporal lobe i s a s s o c i a t e d w i t h the decoding of a u d i t o r y language u n i t s ; the l e f t o c c i p i t a l lobe w i t h decoding of v i s u a l language u n i t s and the l e f t p a r i e t a l w i t h the encoding and thus symbolic p r o d u c t i o n of language u n i t s i n the normal right-handed person. However, t h i s model cannot be adhered t o s t r i c t l y as the b r a i n i s not c l e a r l y d e l i n e a t e d i n geographical s t r u c t u r e and language processes are probably I n t e r a c t i v e and at times interdependent ( P e n f i e l d and Roberts, 1 9 6 6 ) . The mapping o f speech centres f o r the naming response by P e n f i e l d (.1966) and more r e c e n t l y by Whittaker (.1977), c l e a r l y i n d i c a t e d t h a t a p a r t i c u l a r f u n c t i o n may be l o c a l i z e d but t o a number of s i t e s w i t h i n the b r a i n . Moreover, these s i t e s may vary between and, i n t e r e s t -i n g l y , w i t h i n i n d i v i d u a l s (Whittaker, 1 9 7 7 ) . I t i s w i t h i n t h i s context of type of i n s u l t ( i n t e r n a l versus e x t e r n a l ) , predominant s i t e and most s a l i e n t p r e s e n t i n g symptoms of I n s u l t , t h a t aphasia r e s e a r c h has been concentrated when examining treatment or recovery e f f e c t s . For example, Weisenburg and McBride's f o u r - f o l d c l a s s i f i c a t i o n system i s o f t e n used t o b l o c k or s t r a t i f y s u b jects i n f a c t o r i a l r esearch design. 4 In a d d i t i o n , considerable e f f o r t has been d i r e c t e d t o the development of r e l i a b l e and t h e o r e t i c a l l y appealing measurement instruments. Instruments i n p s y c h o l i n g u i s t i c models of aphasia use r a t i n g schemes f o r f r e e v e r b a l production i n v o l v i n g such dimensions as semantic s t r u c t u r e , c o r r e c t word usage, neologism, c l a n g a s s o c i a t i o n s , r e p e t i t i o n s and amount of v e r b a l output (Howes and Geschwlnd, 1964). As suggested by the dimensions assessed, these models are p r i m a r i l y concerned w i t h v e r b a l output. I n c o n t r a s t , psychometric b a t t e r i e s have been developed which attempt t o evaluate an aphasic's a b i l i t y t o do s p e c i f i c t a s k s . These b a t t e r i e s may Involve such s k i l l s as naming an o b j e c t , demonstrating i t s use, v e r b a l i z i n g i t s use, w r i t i n g i t s name, w r i t i n g a sentence d e s c r i b i n g i t s use, w r i t i n g t o d i c t a t i o n or f o l l o w i n g v e r b a l commands (Eisenson, 1971). Two c r i t e r i a have been employed I n the development of these b a t t e r i e s : r e l i a b i l i t y and v a l i d i t y w i t h respect t o a p a r t i c u l a r model of aphasia. U n f o r t u n a t e l y , these c r i t e r i a are not u s u a l l y found c o n c u r r e n t l y . An o b v i o u s l y r e l a t e d q u e stion t o t e s t development per se i s "what are the rrunimum number of language dimensions or t e s t s r e q u i r e d t o d e s c r i b e adequately aphasic language d e f i c i t s ? " I n a broader context, the question becomes "what i s language?" Aphasia as a Representative A t y p i c a l P o p u l a t i o n Two f a c t o r s appear t o come Into, p l a y I n the d e l i n e a t i o n o f a t y p i c a l p o p u l a t i o n s from the normal p o p u l a t i o n : f i r s t , h i s t o r y o r e t i o l o g y and second, observable b e h a v i o u r a l d e f i c i t s o r anomalies. For a p h a s i c s , the e t i o l o g y may be l a b e l l e d as I n s u l t t o the b r a i n , r a t h e r than a p r e c i s e medical d i a g n o s i s . W i t h i n a medical context, the nature o f the I n s u l t o b v i o u s l y has d i r e c t r a m i f i c a t i o n s f o r t r e a t -ment i n terms.of chemotherapy or s u r g i c a l I n t e r v e n t i o n . However, the 5 more p r e c i s e medical diagnosis does not have d i r e c t r a m i f i c a t i o n s f o r b e h a v i o u r a l i n t e r v e n t i o n or therapy. Therefore, w i t h i n t h i s context, the e t i o l o g y or h i s t o r y l e a d i n g t o aphasia, namely an i n s u l t t o the b r a i n , may be considered equivalent or common t o a l l p a t i e n t s . The s i t e of t h i s i n s u l t has been a s s o c i a t e d w i t h s p e c i f i c b e h a v i o u r a l d e f i c i t s . However, the i n i t i a l c l a s s i f i c a t i o n r e s t s upon impairment of language f a c i l i t i e s . T his impairment i s the common be h a v i o u r a l d e f i c i t among aphaslcs. Once t h i s i n i t i a l c l a s s i f i c a t i o n i s done, then f u r t h e r d i f f e r e n t i a t i o n i s done based on the s a l i e n t f e a t u r e s of the d i s o r d e r . The two c r i t e r i a o f a t y p i c a l populations may become obscure due t o the approaches or concerns of d i f f e r e n t areas of e x p e r t i s e . For example, a deaf c h i l d may be deaf f o r a v a r i e t y o f reasons ( i n n e r ear damage, or temporal lobe damage, etc . ) Dependent upon the nature of t h i s h e a r i ng l o s s , medical i n t e r v e n t i o n may be of d i r e c t b e n e f i t . Therefore, f o r the medical c l i n i c i a n s i t i s of prime importance t o thoroughly examine the e t i o l o g y of the d i s o r d e r . For the t h e r a p i s t attempting t o r e t r a i n the c h i l d , i t i s of prime importance t o know the b e h a v i o u r a l nature of the l o s s (e.g. profound, h i g h frequency, e t c . ) . Therefore, two c l a s s i f i c a t i o n systems occur - one based on medical e t i o l o g y and one based on b e h a v i o u r a l d e f i c i t s . However, as w i t h aphasics, a general statement can be made, such as: "An i n s u l t t o hearing apparatus has occurred which r e s u l t s i n d e f i c i t s i n a u d i t o r y monitoring." The procedures t o be o u t l i n e d provide a means f o r determining i n t r a - p o p u l a t i o n s t r a t i f i c a t i o n . As a t y p i c a l p opulations may be comprised of r e l a t i v e l y s i m i l a r or d i s s i m i l a r i n d i v i d u a l s , i t would be of d i r e c t b e n e f i t t o d e r i v e e m p i r i c a l groupings which r e f l e c t the type of behaviour-a l d e f i c i t s . S p e c i f i c a l l y , the i n t r a - p o p u l a t i o n d i s t r i b u t i o n would 6 provide estimates of p o p u l a t i o n homogeneity. Aphasics, due t o t h e i r e t i o l o g y and b e h a v i o u r a l d e f i c i t s , are r e p r e s e n t a t i v e o f a t y p i c a l p o p ulations. I n a d d i t i o n , conceptual models of d e f i c i t are w e l l -e s t a b l i s h e d and thus provide a means of comparison once s t a t i s t i c a l l y d e r i v e d groupings are e s t a b l i s h e d . Methodological Problems i n Examining Aphasia Three methodological concerns a r i s e when examining a t y p i c a l p o p u l a t i o n s , namely: res e a r c h d e s i g n , measurement and s t a t i s t i c a l a n a l y s i s . One area of enquiry which has been overlooked i n aphasia r e s e a r c h i s how w e l l t h i s p o p u l a t i o n conforms t o the b a s i c t e n e t s u n d e r l y i n g e m p i r i c a l or experimental I n v e s t i g a t i o n . I t i s the i n t e n t o f t h i s study t o show t h a t , by i n v e s t i g a t i n g t h i s q u e s t i o n , f u r t h e r i n s i g h t may be gained i n t o the phenomena of aphasia, as w e l l as i n t o the development of b e t t e r r e s e a r c h methods f o r i t s study. I n order t o i n v e s t i g a t e t h i s q u e s t i o n , the c l a s s i c a l experimental model as espoused by F i s h e r (1935) w i l l f i r s t be reviewed b r i e f l y and then the phenomenon of aphasia w i l l be i n v e s t i g a t e d I n the context of t h i s experimental model. F i s h e r suggests t h a t the p o p u l a t i o n of i n t e r e s t be randomly sampled, s e l e c t e d members randomly assigned t o groups, treatment and non-treatment a p p l i e d , and then the groups compared on a p r e v i o u s l y d e f i n e d v a r i a b l e ( s ) , i n order t o determine i f d i f f e r e n c e s e x i s t on these v a r i a b l e s which can be a s c r i b e d t o d i f f e r e n t i a l treatment e f f e c t s . C e r t a i n assumptions are made w i t h respect t o the p o p u l a t i o n of i n t e r e s t , the treatment(s) and the dimensions a f f e c t e d by treatment, so t h a t s t a t i s t i c a l i n v e s t i g a t i o n s can be performed. S p e c i f i c a l l y , i t I s assumed tha t the p o p u l a t i o n o f i n t e r e s t i s the universe and t h a t the dimension(s) * 7 o f " i n t e r e s t i s (are) d i s t r i b u t e d normally and Independently w i t h i n the universe. Therefore, by randomly sampling the p o p u l a t i o n o f i n t e r e s t , a group or groups r e p r e s e n t a t i v e of the p o p u l a t i o n may be obtained such t h a t : 1) e r r o r can be assumed t o be randomly, normally and Independently d i s t r i b u t e d w i t h i n the group(s); and 2) the assumptions of homogeneity of vari a n c e i n the u n i v a r i a t e case and homogeneity o f variance and covariance i n the m u l t i v a r i a t e case are not v i o l a t e d . Treatment i s then a p p l i e d , i m p l y i n g i t I s s t r i c t l y d e f i n e d and c o n t r o l l e d . This process then allows f o r the t r e a t e d and untreated groups t o be compared w i t h the assumption t h a t v a r i a b i l i t y may be p a r t i t i o n e d i n t o t h a t which i s r e l a t e d t o treatment and t h a t which r e l a t e d t o I n d i v i d u a l d i f f e r e n c e s w i t h i n the p o p u l a t i o n ( i . e . e r r o r v a r i a n c e ) . Given the aforementioned assumption, t h i s e r r o r variance i s then d i s t r i b u t e d as x 2 w i t h the appropriate number of degrees o f freedom; s i m i l a r l y , under the n u l l h y pothesis, the treatment variance i s assumed t o be d i s t r i b u t e d as x 2 a l s o and thus g i v e s r i s e t o a c e n t r a l F-value. However, i f the treatment variance i s not d i s t r i b u t e d . I n accordance w i t h the e r r o r variance - i n other words, as a n o n - c e n t r a l F-value -then the researcher f a l l s t o accept the n u l l hypothesis (Morrison, 1975). When the phenomenon o f aphasia i s examined w i t h i n the context of t h i s experimental model,, c e r t a i n questions a r i s e based on e t i o l o g i c a l concerns and the d e f i n i t i o n o f language dimensions o r f u n c t i o n . F i r s t , can language dimensions be assumed t o be normally and Independently d i s t r i b u t e d w i t h i n the aphasic population? In other words, are language dimensions Independent or dependent and how are they d i s t r i b u t e d w i t h i n a p o p u l a t i o n which has a r i s e n due t o untoward and u n c o n t r o l l e d e n v i r o n -mental events which, r e s u l t i n i n s u l t t o the b r a i n ? In order t o examine these q u e s t i o n s , one must assume t h a t the I n i t i a l treatment i s the I n s u l t 8 t o the b r a i n . This treatment, by i t s n a t u r e , i s u n c o n t r o l l e d and u n c o n t r o l l a b l e . S p e c i f i c a l l y , the treatment i s u n c o n t r o l l e d f o r I n terms of s i t e , s e v e r i t y and type of I n s u l t . The assumption t h a t i n s u l t t o b r a i n causes marked and measurable changes I n an I n d i v i d u a l ' s a b i l i t y t o perform c e r t a i n or many t a s k s has been w e l l - e s t a b l i s h e d by case s t u d i e s , normal versus head-injured designs, and c l i n i c a l o bservation (Walker et a l , 1 9 6 9 ; K l o n o f f et a l , 1 9 7 8 ) . From these forms of r e s e a r c h a higher order question emerges: d i f f e r e n t i a l groups a r i s e from i n s u l t t o the b r a i n ? Given.the nature o f b r a i n i n s u l t , i t i s m o r a l l y and e t h i c a l l y i mpossible t o ' c o n t r o l ' treatment; r a t h e r , one must examine e x i s t i n g groups post trauma. This change i n the temporal o r d e r i n g of F i s h e r ' s experimental paradigm — from sampling, treatment, then assessment o f d i f f e r e n c e t o (uncontrolled) treatment d i c t a t i n g s e l e c t i o n — f o r c e s the researcher t o use a l t e r n a t e ' approaches f o r the e v a l u a t i o n of d i f f e r e n t i a l changes subsequent t o trauma. Unless the meaningful aphasic groupings can be d e l i n e a t e d subsequent t o trauma and before remedial treatment, the e v a l u a t i o n of post trauma treatment m o d a l i t i e s i s confounded at best. Therefore, post hoc attempts t o c l a s s i f y aphasic symptoms a f t e r trauma but before remedial treatment u s i n g s t a t i s t i c a l — o r , more s p e c i f i c a l l y , v a r i a n c e / v a r i a b i l i t y c o n s i d e r a t i o n s — would seem warranted. As mentioned p r e v i o u s l y , the phenomenon of d i f f e r e n t i a l e f f e c t s has long been recognized I n aphasiology. However, there i s evidence t o suggest t h a t the models suggesting d i f f e r e n t i a l c l a s s i f i c a t i o n system may be unduly Influenced by h i s t o r i c a l events a f f e c t e d by the type, s i t e and s e v e r i t y o f I n s u l t s (Golden, 1 9 7 7 ) . In a d d i t i o n , the development of these c l a s s i f i c a t i o n s systems was not r e l a t e d t o the systematic or 9 e m p i r i c a l p a r t i t i o n i n g o f v a r i a b i l i t y or variance based on measured t e s t performance. For example, Howes dichotomous c l a s s i f i c a t i o n system i s based on a d i f f e r e n t i a l e f f e c t model, and uses only v e r b a l production t o d i s c r i m i n a t e groups,•while Scheulle's (1969) model i s based on a s e v e r i t y continuum. N e i t h e r researcher has s y s t e m a t i c a l l y examined h i s data t o determine the optimal p a r t i t i o n i n g of v a r i a b i l i t y i n terms of group membership ( i . e . number and t y p e ) . I n a d d i t i o n , both researchers h i g h l i g h t j u s t one aspect of aphasia. However, recent developments i n computer technology now make p o s s i b l e the examination of performance i n terms of m u l t i v a r i a t e models. The importance of such procedures becomes apparent when the question of treatment e f f i c a c y i s considered. In p a r t i c u l a r , i f i n s u l t t o b r a i n causes d i f f e r e n t types of aphasic d i s o r d e r s , then i t i s reasonable t o hypothesize t h a t d i f f e r e n t treatment s t r a t e g i e s w i l l have d i f f e r e n t i a l e f f e c t s on s p e c i f i c groups. Even w i t h i n a s e v e r i t y model such a procedure, i s r e l e v a n t because the l e v e l o f s e v e r i t y d i c t a t e s the l e v e l o f a c c e s s i b i l i t y t o s p e c i f i c treatment m o d a l i t i e s . Therefore, I n order t o generate more powerful designs t o gauge the e f f i c a c y o f s p e c i f i c treatments on p a r t i c u l a r types of aphasics, an examination o f the c h a r a c t e r i s t i c s o f an aphasic p o p u l a t i o n , and how these c h a r a c t e r i s t i c s are d i s t r i b u t e d , would seem warranted. H i s t o r i c a l l y , such an approach has been used by Head (1926) and Weisenburg and McBride (1935) — w i t h o u t , however, the advantage of current m u l t i v a r i a t e s t a t i s t i c a l a n a l y s i s techniques. Given t h a t language d i s o r d e r s have many dimensions o r p o s s i b l e areas of d e f i c i t , a m u l t i d i m e n s i o n a l t e s t b a t t e r y must be used i n order t o assess f u l l y the s e v e r i t y and type, o f d i s o r d e r . The m u l t i d i m e n s i o n a l aphasia t e s t b a t t e r y must a l s o be r e l i a b l e and a v a l i d measure of 10 communication a b i l i t i e s . Most instruments p r e s e n t l y a v a i l a b l e are screening t e s t s u s i n g dichotomous s c o r i n g techniques, such as the Halstead Wepman Aphasia Screening Test ( 1959) and designed on the b a s i s o f an e x i s t i n g model o f aphasia such as Eisenson's Examining f o r Aphasia ( 1 9 5 4 ) . The s t a n d a r d i z a t i o n o f many aphasia t e s t s has been poor due t o the l i m i t e d number o f sub j e c t s a v a i l a b l e w i t h i n a g i v e n s e t t i n g . One t e s t b a t t e r y , c o n t a i n i n g 18 s u b t e s t s , which was designed and standardized t o remedy t h i s s i t u a t i o n i s the Porch Index o f Communication A b i l i t y (P.I.C.A.) (Porch, 1 9 6 8 ) . P a r t i c u l a r a t t e n t i o n was p a i d t o development o f a r e l i a b l e and thereby g e n e r a l i z a b l e Instrument I n terms of communication d e f i c i t s r e f l e c t e d by a p a r t i c u l a r set o f scores. I n a d d i t i o n , the task s s e l e c t e d were common and recognized t e s t s o f aphasia d e f i c i t s . Therefore, the instrument o f choice f o r t h i s study was the P.I.C.A. M u l t i v a r i a t e S t a t i s t i c a l Concerns and Procedures Relevant t o the P.vI.C.A.  Although aphasic d i s o r d e r s have not been viewed con c e p t u a l l y as a unldimensional problem, technology has l i m i t e d a n a l y s i s s t r a t e g i e s . Rather, i t has been suggested t h a t language d i s o r d e r s are m u l t i d i m e n s i o n a l , and t o assess f a i r l y a language d i s o r d e r m u l t i p l e t e s t s should be given I n order t o determine areas o f asset and d e f i c i t . Such a model c l e a r l y suggests t h a t m u l t i v a r i a t e s t a t i s t i c a l techniques are r e q u i r e d as w e l l as mult i d i m e n s i o n a l assessment instruments. However, as the power and s e n s i t i v i t y o f m u l t i v a r i a t e designs are determined by the number o f s u b j e c t s , groups and dependent v a r i a b l e s , i t i s e s s e n t i a l t o minimize the number o f dependent v a r i a b l e s and groups based on variance c o n s i d e r a t i o n s , 11 w h i l e maximizing the number of su b j e c t s (Morrison, 1 9 7 5 ) . The purpose o f t h i s study was f i r s t t o determine the optimum number o f language dimensions t o describe aphasic performance e l i c i t e d by the P.T.C.A. by f a c t o r a n a l y s i s and then t o determine what the optimum grouping o f su b j e c t s would be based on these dimensions by h i e r a r c h a l grouping a n a l y s i s . Such a procedure would then a l l o w f o r group p r o f i l e s based on a f i n i t e number o f language dimensions t o be produced. These p r o f i l e s would then a l l o w the s a l i e n t c h a r a c t e r i s t i c s o f group membership t o be determined. F a c t o r A n a l y s i s As suggested by Porch and confirmed by f a c t o r a n a l y s i s ( C l a r k et a l , I n p r e s s ) , there are three dimensions o f language a b i l i t i e s u n d e r l y i n g the ' P.I.C.A. Therefore, i t would be redundant t o i n c l u d e a l l eighteen sub-t e s t s i n a m u l t i v a r i a t e design. This redundancy makes the explanations cumbersome, p a r t i c u l a r l y i n view o f the l i m i t e d sample s i z e r e a d i l y a v a i l a b l e f o r research work. For example, i n a two group design, eighteen degrees o f freedom would be used by dependent v a r i a b l e s r a t h e r than perhaps three . The r e d u c t i o n i n degrees of freedom has two major advantages. F i r s t , degrees o f freedom which would have been a s c r i b e d t o the dependent v a r i a b l e s would now be a s s o c i a t e d w i t h the e r r o r - v a r i a n c e thus reducing the e r r o r variance estimate. Second, as the number of o v e r a l l t e s t s of s i g n i f i c a n c e i s reduced, the o v e r a l l experiment-wise e r r o r i s a l s o reduced. Therefore, a f a c t o r a n a l y s i s o f the data may s i g n i f i c a n t l y reduce the number o f dependent v a r i a b l e s as w e l l as p r o v i d i n g b e t t e r i n s i g h t i n t o the t r u e dimensions u n d e r l y i n g the v a r i a b l e s and thus i n the development o f a c l e a r e r conceptual model (Gorsuch, 1 9 7 4 ) . For t h i s study, the f i r s t a n a l y s i s was a f a c t o r a n a l y s i s o f data obtained 12 on the eighteen P.I.C.A. subtests. The language dimensions derived from this analysis were then compared to both Porch's formulation and other aphasia models of communication a b i l i t y . Grouping Procedures (Hierarchical Cluster Analysis) Pre treatment factor scores were then derived and submitted to a hierarchical cluster analysis i n order to determine the minimum number of groups required to adequately represent subsamples within the sample (Patterson and whittaker, 1973). The c r i t e r i a for this grouping decision was variability considerations i n terms of minimizing within group vari a b i l i t y , while maximizing between group va r i a b i l i t y . Although this solution w i l l optimize groupings, i t should provide insight Into possible factorial strategies i n future research. To investigate how well these groups were differentiated by this procedure, a step-wise discriminant analysis was done on possible solutions (Nie et a l , 1975). Although the prediction rates and F-values were a r t i f i c i a l l y inflated, a rough indication of group homogeneity was obtained. In addition, the group profiles were plotted, compared with each other and with existing models of aphasia. Summary of Procedures and Their Conceptual Ramifications In order to do this study, a group of aphasics (n = 72) were assessed on a multidimensional aphasia test battery, the P.I.C.A. The sampling of aphasics was not s t r a t i f i e d on an existing model of aphasia. Rather, the sample consisted of consecutive admissions to a rehabilitation hospital and to whom speech therapy for aphasia was given. These aphasics were given the P.I.C.A. both pre and post- treatment. The post-treatment subtest scores were then factor analyzed and factor scores for the pre-13 treatment scores were estimated. These factor scores were then submitted to a cluster analysis. The derived grouping were then examined with respect to t h e i r d i s t r i b u t i o n i n v u l t i v a r i a t e space. These procedures allowed f o r : 1) the language dimensions underlying aphasic disorders to be examined; and 2) the empirical d i f f e r e n t i a t i o n of groups within t h i s population. 14 CHAPTER II LITERATURE REVIEW Introduction Three main topics pertinent to aphasia are reviewed i n this chapter. F i r s t , historical and current models of aphasia are discussed. Second, methodological advances, are briefly described, with particular reference to multivariate approaches. Finally, the standardization and psycho-metric properties of the Porch Index of Communication Abil i t y (P.I.C.A.) are reviewed. Models of Aphasia The phenomenon of aphasia has been recognized since b i b l i c a l times and explanatory constructs have been based on grounds ranging from philosophical to medical. Interestingly, the loss of speech or language and the associated right-sided motor involvement was considered God's retribution for sin in earlier times. Although today's models of aphasia are somewhat more advanced i n terms of causation, they are not appreciably more advanced i n terms of f a c i l i t a t i n g recovery or prognosis. Within conceptual models of aphasia, three separate approaches to the problem may be differentiated as follows: 1) neurological - based on the site of the lesion; 2) behavioural - based on salient features of def i c i t s ; and 3) linguistic ' - •  based on deficits i n language usage, grammer and f a c i l i t y . Although i n practice these models are not independent, for the purpose of explication they are treated separately In this review. Within a s t r i c t model of neurology, the diagnosis of aphasia i s only made when the diagnostic data indicates a manifest disruption of l e f t hemisphere function and this disruption can be shown to affect language 15 f a c i l i t y adversely (Walton, 1 9 7 4 ) . With the advancing d i a g n o s t i c techniques (e.g. C.A.T. and B r a i n Scans, E.E.G.'s), the i d e n t i f i c a t i o n and l o c a l i z a t i o n o f these f o c a l o r d i f f u s e d i s r u p t i o n s have become more f e a s i b l e and accurate. For.example, Naeser and Hayward ( 1977) have shown, u s i n g computerized a x i a l tomography (C.A.T.), t h a t the s e v e r i t y o f the aphasia d i s o r d e r i s d i r e c t l y r e l a t e d t o the s i z e and d e n s i t y o f the blood mass or s w e l l i n g o f the blood v e s s e l s . For cases o f c e r e b r a l v a s c u l a r accidents r e s u l t i n g from embolis, aneurylsms or thrombosis, such a procedure provides i n s i g h t i n t o both the magnitude of the d i s o r d e r and by s e r i a l scans, the amount o f recovery o r degeneration of b r a i n t i s s u e s . I n t h i s model, the d i f f e r e n t i a t i o n o f d y s a r t h r i a , the i n a b i l i t y t o produce speech due t o involvement of neuromuscular mechanisms, from aphasia i s based on the s i t e o f the l e s i o n . S p e c i f i c a l l y , f o r the diagnosis o f d y s a r t h r i a t o be made, the l e s i o n must occur i n the b r a i n stem. Three o b j e c t i o n s t o t h i s model occur when other c r i t e r i a are considered. F i r s t , the p a t i e n t may not be able t o produce speech w i t h a l e s i o n i n the l e f t hemisphere, but t e s t s o f language u s i n g other m o d a l i t i e s (e.g. w r i t i n g ) suggest language f u n c t i o n i s preserved. Therefore, w i t h i n the confines o f the n e u r o l o g i c a l d i a g n o s t i c model, the p a t i e n t i s apha s i c , but w i t h i n a speech/language continuum, the p a t i e n t i s d y s a r t h r i c . Second, f o r . t h e d i a g n o s i s o f aphasia t o be made, the l e s i o n s i t e must be confirmed t o be i n the l e f t hemisphere and the p a t i e n t must e x h i b i t speech/language impairment. The question a r i s e s concerning what i s language impairment, I n t h a t p e r f e c t language or normal language f a c i l i t y has hot:;been c l e a r l y d e f i n e d (Lesak, 1 9 7 6 ) . For example, I n a m i l d 16 conduction-type aphasia, the p a t i e n t can understand commands and a c c u r a t e l y respond in;.a v e r b a l modality t o h i s t o r i c a l q u e s t i o n s , but has great d i f f -i c u l t y i n generating spontaneous speech. On s p e c i f i c language t e s t s , the degree o f d e f i c i t may be profound b u t , w i t h i n the normal s o c i a l c o n text, not n o t i c e a b l e . Rather, the p a t i e n t may be des c r i b e d as s o c i a l l y r e t i r i n g o r shy (Goodglass and Kaplan, 1972). The t h i r d o b j e c t i o n t o t h i s model i s t h a t i t assumes brain-behaviour r e l a t i o n s h i p s are i n v a r i a t e . Namely, language/speech mechanisms are l a t e r a l i z e d t o the l e f t hemisphere. Although a r e l a t i o n s h i p does e x i s t , the evidence f o r exceptions t o the model i s l a r g e . The major p o p u l a t i o n which c o n t r a d i c t s o r at l e a s t does not wholly support t h i s r e l a t i o n s h i p i s left-handed i n d i v i d u a l s , where i n language/speech f u n c t i o n s may be l a t e r a l i z e d t o e i t h e r hemisphere o r d i s t r i b u t e d between the hemispheres (Lezak, 1976). Behavioural models o f aphasia attempt t o c a t e g o r i z e aphasics based on the most s a l i e n t c l i n i c a l f e a t u r e s . Two h i s t o r i c a l types o f aphasia which are s t i l l recognized d i a g n o s t i c c a t e g o r i e s are Broca's (1861) and Wernicke's ( l88l) . Both these types o f aphasia were r e l a t e d t o s p e c i f i c l e s i o n s i t e s i n the l e f t hemisphere found on autopsy. I n a d d i t i o n , both have c h a r a c t e r i s t i c c l i n i c a l o r b e h a v i o u r a l f e a t u r e s . Broca's aphasia i s marked by the i n a b i l i t y t o produce meaningful speech w h i l e the p a t i e n t s t i l l comprehends v e r b a l Input. Wernicke's i s marked by the i n a b i l i t y t o comprehend speech or language w h i l e v e r b a l production i s r e l a t i v e l y i n t a c t . With these types o f aphasia, a s i t e - f u n c t i o n school o f b r a i n f u n c t i o n developed. I t was f e l t t h a t each b e h a v i o u r a l a c t i o n o r , i n these cases, d e f i c i t was r e l a t e d t o a s p e c i f i c and l o c a l d y s f u n c t i o n i n the b r a i n . This premise l e d t o the development o f b e h a v i o u r a l c l a s s i -f i c a t i o n systems based on the most s a l i e n t c l i n i c a l f e a t u r e s . 17 I t should be noted, however, I n c o n t r a s t t o the s i t e - b e h a v i o u r schools o f b r a i n damage, Hughllng Jackson and h i s f o l l o w e r s espoused t h a t i n s u l t t o the b r a i n caused general d y s f u n c t i o n of c o g n i t i v e process and although some d e f i c i t s were more severe, c o g n i t i o n per se was decreased. Jackson f u r t h e r suggested t h a t t h i s general d y s f u n c t i o n was of more Importance than s p e c i f i c d e f i c i t s w i t h respect t o a p a t i e n t ' s day-to-day f u n c t i o n . However, t h i s view was considered the m i n o r i t y (Head, 1 9 2 6 ) . Modern b e h a v i o u r a l t h e o r i e s o f aphasia s t i l l r e f l e c t t h i s controversy of general versus s p e c i f i c d e f i c i t s r e l a t e d t o b r a i n damage. Two recent proponents of the g e n e r a l i s t p o s i t i o n are L u r i a and M i l n e r ( L u r l a , 1 9 6 6 ; M i l n e r , 1 9 7 2 ) . Both based t h e i r p o s i t i o n s on a language or communication model and argued t h a t i n s u l t t o any p a r t o f the c o r t e x adversely a f f e c t s one's a b i l i t y t o communicate. For example, i f a p a t i e n t has a d e f i c i t i n s p a t i a l p l a n n i n g (hypothesized t o be r i g h t hemisphere f u n c t i o n ) then the p a t i e n t ' s a b i l i t y t o d e s c r i b e or o r a l l y i n t e r p r e t t h i s type o f problem w i l l be a l s o reduced. I n t e r e s t i n g l y , besides t h e i r own r e s e a r c h , current research a l s o support t h i s p o s i t i o n . Winner and Gardner ( 1 9 7 8 ) found t h a t r i g h t hemisphere damaged p a t i e n t s had more d i f f i c u l t y I n I n t e r p r e t i n g metaphora and tended t o choose l i t e r a l I n t e r p r e t a t i o n s o f metaphors, w h i l e p a t i e n t s w i t h l e f t hemisphere a n t e r i o r l e s i o n s (aphasics) approximated normals I n t h e i r performance and seemingly s t i l l understood metaphorical language. Both L u r i a ' s and M i n e r ' s p o s i t i o n s argue f o r an i n t e r a c t i v e and interdependent model o f b r a i n damage. Both suggest t h a t u s i n g a d e f i c i t or s i t e o f l e s i o n w i t h a s s o c i a t e d s p e c i f i c c o g n i t i v e l o s s e s model i s too s i m p l i s t i c . However, the m a j o r i t y of current c a t e g o r i z a t i o n systems assume th a t aphasia i s s o l e l y a language problem. More i m p o r t a n t l y , these systems 18 m a i n t a i n t h a t observable or measurable d e f i c i t s i n other forms o f c o g n i t i o n are p u r e l y a f u n c t i o n of a p a t i e n t ' s d e f i c i t s i n language f a c i l i t y . S c h uelle's (1969) approach probably represents the bridge p o i n t i n t h a t i t supports the f i r s t a s s e r t i o n , but disputes the second. S c h e u l l e contended t h a t the major d i f f e r e n c e among aphasics i s the s e v e r i t y of the impairment, not s p e c i f i c l o s s of f u n c t i o n (e.g. a u d i t o r y comprehension). Thus, aphasia i s a .unitary concept r e p r e s e n t i n g language impairment. However, she a l s o contended t h a t aphasics may have other l e s i o n s a f f e c t i n g v i s u a l p e r c e p t u a l s k i l l s ( I . e . r i g h t hemisphere f u n c t i o n ) o r motor f u n c t i o n ( I . e . b r a i n stem). A c c o r d i n g l y , she generated the f o l l o w i n g f i v e - f o l d c l a s s i f i c a t i o n system: 1) simple aphasia; 2) aphasia w i t h v i s u a l p e r c e p t u a l d e f i c i t s ; 3) aphasia w i t h motor involvement; 4) aphasia w i t h v i s u a l p e r c e p t u a l and motor d e f i c i t s ; and 5) i n a c c e s s i b l e t o examination. Weisenberg and McBride's (1935) model o f c l a s s i f i c a t i o n i s based s o l e l y on a language model and does not i n v o l v e other c o g n i t i o n systems. T h e i r r e s e a r c h a l s o supported a general language impairment model, but a l s o suggested t h a t p a t i e n t s could be d i f f e r e n t i a t e d f u r t h e r on a s a l i e n t f e a t u r e model. T h e i r groupings were as f o l l o w s : 1) predominantly expressive (Broca's); 2) predominantly r e c e p t i v e (Wernicke-'s); 3) both r e c e p t i v e and expressive d e f i c i t s ; and 4) anemic, marked by word f i n d i n g d i f f i c u l t i e s , but w i t h f l u e n c y and comprehension r e l a t i v e l y i n t a c t . Although Weisenberg and McBride d i d s t r e s s t h a t there was general language impairment, current c l i n i c a l and research p r a c t i c e s tend t o ignore the general aspect of impairment i n favour of h i g h l i g h t i n g the s a l i e n t f e a t u r e s . Rarely does one encounter research where su b j e c t s are f i r s t d i f f e r e n t i a t e d on s e v e r i t y continuum, then on a s a l i e n t f e a t u r e 19 c l a s s i f i c a t i o n . Rather, the f a c t o r i n g o r b l o c k i n g o f sub j e c t s i s based on an e x p r e s s i v e / r e c e p t i v e dichotomy. I n a c l i n i c a l s e t t i n g , the dia g n o s i s o f , f o r example, expressive aphasia i s m i s l e a d i n g o r at l e a s t incomplete because a u d i t o r y comprehension may a l s o be reduced. Probably, the most comprehensive b e h a v i o u r a l model o f aphasia has been suggested by Wepman and Jones ( 1 9 6 l ) . Using the e x p r e s s i v e / r e c e p t i v e dichotomy, Wepman and Jones f u r t h e r expanded i t through a l l input/output m o d a l i t i e s . T h e i r c l a s s i f i c a t i o n system i s too extensive t o review here, but i t w i l l s u f f i c e t o say t h a t a l l input m o d a l i t i e s — e.g. read i n g o f l e t t e r s , words, sentences, a u r a l r e c o g n i t i o n and comprehension o f l e t t e r s , words and sentences and t a c t i l e r e c o g n i t i o n — and a l l output m o d a l i t i e s — e.g. w r i t i n g , speech and g e s t u r a l — are evaluated. They argued t h a t b e h a v i o u r a l d e s c r i p t i o n o f s p e c i f i c d e f i c i t s i s the best means o f c l a s s i f y i n g aphasics. One major departure from t r a d i t i o n a l psychometric e v a l u a t i o n o f aphasics was done by Howes ( 1 9 6 4 ) . Howes viewed aphasia as p r i m a r i l y a speech/language problem and f e l t t r a d i t i o n a l psychometric assessment i n v o l v e d many hi g h e r l e v e l c o n s t r u c t s (e.g. i n t e l l i g e n c e ) not n e c e s s a r i l y r e l a t e d t o aphasia per se.. He t h e r e f o r e designed a s t r u c t u r e d method f o r . gat h e r i n g speech sample. A n a l y s i s o f t h i s sample u s i n g p r o d u c t i o n v a r i a b l e s — such as the number o f words, pauses, and meaningless u t t e r -ances — suggested a dichotomous model o f aphasia. Howes l a b e l l e d h i s two groups f l u e n t o r d y s f l u e n t . I t has been suggested t h a t these groupings are c o n s i s t e n t w i t h Weisenburg and McBride's e x p r e s s i v e / r e c e p t i v e c l a s s -i f i c a t i o n system (Howes, 1 9 6 4 ) . Therefore, by u s i n g a standardized but d i f f e r e n t assessment technique, a type o f c r o s s - v a l i d a t i o n has occurred i f one examines the d i f f e r e n c e s i n l a b e l l i n g i n the r e s p e c t i v e systems. 20 More i m p o r t a n t l y , however, Howes' method I n t e r e s t e d p s y c h o l i n g u i s t s and has l e d t o p s y c h o l i n g u i s t i c models o f aphasia based on language development or s p e c i f i c l i n g u i s t i c d e f i c i t s . These models are beyond the scope of the measurement procedure adopted i n the present study and t h e r e f o r e w i l l not be reviewed here. However, i t should be noted t h a t p s y c h o l i n g u i s t i c models o f aphasia have grown i n p o p u l a r i t y and represent a measurable p r o p o r t i o n of current research s t u d i e s ( W i l l i a m s , 1 9 7 6 ; Z u r i f et a l , 1 9 7 2 ; Z u r i f et a l , 1 9 7 4 ; Goodglass, 1 9 7 5 ) . A l l these c l a s s i f i c a t i o n systems were developed u s i n g standard and s p e c i a l l y designed psychometric t e s t i n g techniques. The problems encoun-t e r e d i n t e s t i n g a p h a s i c s , s c o r i n g responses and i n t e g r a t i n g r e s u l t s have been well-reviewed (Osgood and Mlron, 1963) and represent a volume i n themselves. However, bi a s e s and assumptions w i t h i n the t e s t s themselves o b v i o u s l y i n f l u e n c e I n t e r p r e t a t i o n s and subsequent t h e o r i z i n g . F a c t o r -a n a l y t i c s t u d i e s on these t e s t b a t t e r i e s u s u a l l y r e p o r t a l a r g e f i r s t e igen-yalue, thus suggesting a general language component. However, s p e c i f i c dimensions a l s o keep o c c u r r i n g across d i f f e r e n t t e s t b a t t e r i e s ( C a r r o l l , 1 9 4 l ; S c h e u l l e et a l , 1 9 6 2 ; C l a r k et a l , i n p r e s s ) . Moreover, modern a n a l y s i s techniques and computer f a c i l i t i e s are only now a l l o w i n g researchers t o gauge the r e l a t i v e weights o f these dimensions w i t h respect t o a s e v e r i t y model. I n t e r e s t i n g l y , the recent a r t i c l e s support these h i s t o r i c a l models, as w e l l as r e f l e c t i n g the complexity and s u b t l e t i e s o f the problem. H i s t o r y o f Research Methods The h i s t o r y o f methods employed I n aphasia r e s e a r c h I s c o n s i s t e n t w i t h the development o f methodological standards, only delayed i n terms 2 1 o f time. The phenomenon was w e l l e s t a b l i s h e d and recognized by the t u r n of the century. I n a d d i t i o n , c ausation paradigms based on concrete .•' : evidence were being espoused, e.g. those o f Broca and Wernicke. I n 1 9 2 1 , Head recognized the need f o r an aphasia t e s t b a t t e r y and developed one based on the assessment o f s i x t y - s e v e n aphasics. Using a case study methodology, Head developed probably the f i r s t comprehensive b a t t e r y f o r the assessment o f aphasia. I n 1 9 3 2 , Weisenburg and McBride r e a l i z e d the importance o f a c o n t r o l group i n d i f f e r e n t i a t i n g r e a l aphasic d e f i c i t s from i n d i v i d u a l d i f f e r e n c e s i n normal language a b i l i t i e s . I n t h e i r work, they used Head's o r i g i n a l t e s t s as w e l l as other standardized psycho-m e t r i c b a t t e r i e s i n an attempt t o develop a t e s t b a t t e r y f o r d i s t i n g u i s h -i n g aphasics from the general p o p u l a t i o n . I n 1 9 ^ 1 , C a r r o l l r e a l i z e d the power of f a c t o r a n a l y s i s I n d e l i n e a t i n g the u n d e r l y i n g dimensions o f aphasia. Although l i m i t e d by the a v a i l a b l e technology, C a r r o l l ' s work represents the f i r s t m u l t i v a r i a t e a n a l y s i s attempt on aphasic p o p u l a t i o n s . U n t i l t h i s time, research analyses were confined at best t o recognized u n i v a r i a t e procedures. During the 1 9 5 0's, aphasia research centred p r i m a r i l y on t e s t development and c l a s s i f i c a t i o n procedures. F a c t o r a n a l y s i s played a • major r o l e i n d e l i n e a t i n g language dimenisions. However, groupings . systems were then based on d e r i v e d f a c t o r dimensions, not upon the d i s c r i m i n a t i o n f u n c t i o n amount groups u s i n g these dimensions (Schuelle et a l , 1 9 6 2 ) . The t e s t s developed were designed p r i m a r i l y t o r e f l e c t e x i s t i n g c l a s s i f i c a t i o n systems. For example, Eisenson's Examining f o r Aphasia, r e f l e c t e d Weisenburg and McBride's c l a s s i f i c a t i o n system (Eisenson, 1 9 7 2 ) . However, dimensions u n d e r l y i n g items were assumed t o 22 be r e c e p t i v e o r expressive s k i l l s , but these assumptions were not i m p i r i c a l l y t e s t e d . I n c o n t r a s t t o t h e s e . ' s t a t i s t i c a l l y ' based models o r examinations of aphasia, the Boston School r e v e r t e d to a case study approach very s i m i l a r t o t h a t o f Head's. At present, they recognize nineteen d i s c r e t e types o f aphasia. Again, t h i s model i s based on s a l i e n t c h a r a c t e r i s t i c s r a t h e r than s e v e r i t y . Moreover, t h e i r model has s i x t e e n dimensions o f aphasic language (Goodglass and Geschwind, 1975). Obviously, some o f these dimensions must be h i g h l y I n t e r - r e l a t e d (e.g. a r t i c u l a t i o n and speech fluency) o r t h e i r c a t e g o r i z a t i o n system would be even more 16 extensive than I t I s now ( i . e . 2 — i f the dimensions were t r u l y dlchotomous and Independent). M u l t i v a r i a t e s t a t i s t i c a l r e s e a r c h on the r e l a t i o n s h i p between language dimension and subsequent grouping procedures I s extremely sparse. For example, o n l y one study -. c o u l d be found which used both f a c t o r and c l u s t e r a n a l y s i s . Crockett (1976) both f a c t o r analyzed data obtained on the Neurosensory Centre Comprehensive Examination o f Aphasia (NCCEA) and d e r i v e d groupings based on c l u s t e r a n a l y s i s . However, these procedures were a p p l i e d Independently on the eighteen v a r i a b l e s o f the NCCEA. These procedures were a l s o a p p l i e d t o a f r e e speech sample measured over s i x t e e n v a r i a b l e s . As the purpose o f the study was t o show p o i n t s o f i n t e r f a c e and d i f f e r e n c e between these i n s t r u m e n t a t i o n procedures, the analyses were ap p r o p r i a t e . S i m i l a r l y , the study examined c o n t i n u i t y o f f i t between s t a t i s t i c a l l y d e r i v e d groupings and the two aphasia models represented by the instruments (Weisenberg and McBride; Howes and Geschwind). I n t h i s sense, the study d i d not examine n a t u r a l l y o c c u r r i n g 23 groups based on d e r i v e d f a c t o r dimensions; r a t h e r i t examined the . r e l a t i o n s h i p between performance and two e x i s t i n g models o f aphasia. The P.I.C.A. as an Assessment Instrument o f Aphasic Disorders When Porch developed the P.I.C.A., i t was w i t h the expressed purpose o f producing a mu l t i d i m e n s i o n a l b a t t e r y o f language f u n c t i o n . The b a t t e r y c o n s i s t s o f eighteen subtests w i t h t e n items per subtest. The tasks demands w i t h i n each subtest are the same (e.g. naming t e n d i f f e r e n t o b j e c t s ) . The t a s k demands f o r each o f the eighteen subtests are summarized i n Table 1 . Porch suggested t h a t these eighteen subtests measured three major language/communication dimensions: v e r b a l , g e s t u r a l and graphic. The presence o f these three language/communication dimensions was r e c e n t l y found I n a f a c t o r a n a l y s i s o f Porch's r e p o r t e d subtest I n t e r c o r r e l a t i o n m a t r i x ( C l a r k et a l , i n p r e s s ) . For a s c o r i n g system, Porch developed a m u l t i d i m e n s i o n a l model i n which the q u a l i t y o f the e l i c i t e d response t o each t a s k I s q u a n t i f i e d . F i v e dimensions o f response q u a l i t y were subsumed i n the s c o r i n g system: 1) accuracy — the degree o f c o r r e c t n e s s ; 2) responsiveness — the ease w i t h which the response i s e l i c i t e d ; 3) completeness — the degree t o which the t a s k i s c a r r i e d out i n i t s e n t i r e t y ; 4) promptness — response l a t e n c y ; and 5) e f f i c i e n c y — the degree o f f a c i l i t y demonstrated I n performing the motoric aspects o f the task. The s c o r i n g range i s from 1 (no response) t o 16 (a complete, prompt, and accurate response). A schematic overview o f t h i s s c o r i n g system I s presented i n Table 2 and Figure 1 . During s t a n d a r d i z a t i o n , twelve c l i n i c a l judges were asked t o rank these d e s c r i p t i o n s o f response q u a l i t y i n terms o f s e v e r i t y . The c o e f f i c i e n t o f concordance f o r these judgements was 0 . 9 3 -2ft TABLE 1 D e s c r i p t i o n of P.I.C.A. Subtests Subtest Response M o d a l i t y Task f o r Subject I V e r b a l d e s c r i b e purpose or f u n c t i o n of ob j e c t I I G e s t u r a l demonstrate f u n c t i o n o f object (ordered) I I I G e s t u r a l demonstrate f u n c t i o n o f objec t (unordered) IV V e r b a l name objec t V G e s t u r a l read card and c a r r i e s out I n s t r u c t i o n s ( f u n c t i o n a l d e s c r i p t i o n ) VI G e s t u r a l i d e n t i f y o b j e c t based on f u n c t i o n a l d e s c r i p t i o n V I I G e s t u r a l read card and c a r r i e s out i n s t r u c t i o n s (naming d e s c r i p t i o n s ) V I I I G e s t u r a l match p i c t u r e card w i t h o b j e c t IX V e r b a l complete sentence by naming o b j e c t d e s c r i b e d X G e s t u r a l p o i n t t o objec t named XI G e s t u r a l match s i m i l a r o b j e c t s X I I V e r b a l repeat name of objec t a f t e r examiner A • Graphic w r i t e sentence d e s c r i b i n g use of objec t B Graphic w r i t e names of obj e c t s c . Graphic w r i t e name of object t o a u d i t o r y d i c t a t i o n D Graphic w r i t e name a f t e r having i t s p e l l e d E Graphic copy name F . Graphic copy geometric shapes 25 TABLE 2 Mu l t i d i m e n s i o n a l S c o r i n g Categories o f the P.I.C.A. Score L e v e l D e s c r i p t i o n 16 COMPLEX Accurate j responsive, complex, immediate, e l a b o r a -t i v e response t o t e s t item. 15 COMPLETE Accurate, responsive, complete, immediate response t o t e s t item. 14 DISTORTED Accurate, responsive, complete response t o t e s t i t em, but w i t h reduced f a c i l i t y o f pro d u c t i o n . 13 COMPLETE-DELAYED Accurate, responsive, complete response t o the t e s t item, which i s s i g n i f i c a n t l y slow o r delayed 12 INCOMPLETE Accurate, responsive, response t o t e s t i t e m which i s l a c k i n g i n completeness. 11 INCOMPLETE-DELAYED Accurate, responsive,, incomplete response t o t e s t Item which i s s i g n i f i c a n t l y slowed o r delayed. 10 CORRECTED Accurate response t o t e s t i tem s e l f - c o r r e c t i n g a previous e r r o r without i n t e r v e n i n g v a r i a b l e s . 9 REPETITION Accurate response t o t e s t i t e m a f t e r a r e p e t i t i o n of the i n s t r u c t i o n s by request or a f t e r a p r o -longed delay. 8 CUED ' Accurate response t o t e s t i t e m s t i m u l a t e d by a cue, a d d i t i o n a l i n f o r m a t i o n , or another t e s t item. 7 RELATED Inaccurate response t o t e s t i t e m which i s c l e a r l y r e l a t e d t o or suggestive of an accurate response. 6 ERROR Inaccurate response t o the t e s t item. 5 INTELLIGIBLE I n t e l l i g i b l e response which i s not a s s o c i a t e d w i t h the t e s t i tem, e.g., p e r s e r v e r a t i v e o r automatic responses or an expressed I n d i c a t i o n o f i n a b i l i t y t o respond. 4 UNINTELLIGIBLE U n i n t e l l i g i b l e or incomprehensible responses which can be d i f f e r e n t i a t e d from other responses. 3 MINIMAL U n i n t e l l i g i b l e response which cannot be d i f f e r e n -t i a t e d from other responses. 2 ATTENTION P a t i e n t attends t o t e s t i t e m but gives no responses. 1 NO RESPONSE P a t i e n t e x h i b i t s no awareness o f t e s t item. 2 6 FIGURE 1 ACCURACY Porch's Multidimensional Scoring System Dimensions RESPONSIVENESS COMPLETENESS PROMPTNESS EF^CTENCY RESPONSE ACCURATE RELATED 6 ERROR NOT RELATED RESPONSIVE 10 CORRECTED REPEATED 8 CUED INTELLIGIBLE UNINTELLIGIBLE MINIMAL ATTENTION NO RESPONSE COMPLEX COMPLETE INCOMPLETE IMMEDIATE 1 3 SLOWED IMMEDIATE 12 IMMEDIATE 11 SLOWED " 16 EFFICIENT DISTORTED 15 EFFICIENT BINARY CHOICE SCORING SYSTEM BASED ON FIVE DJJYENSIONS 27 The b a t t e r y was standardized on 150 m e d i c a l l y diagnosed aphasic p a t i e n t s . No attempt was made t o apply a s t r a t i f i e d sampling technique based on e x i s t i n g conceptual models o f aphasia. However, i n comparison t o other t e s t s o f aphasia, t h i s b a t t e r y has a l a r g e s t a n d a r d i z a t i o n sample. F u r t h e r , i t represents a departure from other t e s t s which . c o n s i s t o f tas k s which d i f f e r e n t i a t e normals from aphasics. Due t o the nature o f the tasks on the P.I.C.A., any. normal speaking person should o b t a i n a p e r f e c t score. With respect t o psychometric r e l i a b i l i t y c r i t e r i a , t h i s t e s t i s extremely impressive. I n t e r n a l consistency estimates f o r the eighteen subtests range between 0.88 and 0.99. These r e s u l t s would suggest t h a t the multidimensional, s o c r i n g system I s c o n s i s t e n t across items f o r each sub t e s t . Moreover, i t supports the conceptual model t h a t the t a s k demands o f s p e c i f i c s u b t e s t s are s i m i l a r across items. R e l i a b i l i t y c o e f f i c i e n t s across r a t e r s are of the same magnitude across the eighteen subtests — 0.93 t o 0.99- These f i n d i n g s would suggest t h a t i f r a t e r s are t r a i n e d i n the admission o f the P.I.C.A., score assigned by d i f f e r e n t r a t e r s would be extremely s i m i l a r . S t a b i l i t y c o e f f i c i e n t s on a t e s t -r e t e s t model w i t h a two week i n t e r v a l range from 0.70 t o .9.8 f o r the eighteen s u b t e s t s . However, only one subtest's c o e f f i c i e n t was below 0 .81. These r e s u l t s would I n d i c a t e t h a t the dimensions o f language a b i l i t y the subtests purport t o measure are s t a b l e over time. I n a d d i t i o n , the eighteen subtests appear t o comprise a d i f f i c u l t y g r a d i e n t , as mean scores range from 6.01 t o 14.22. These r e l i a b i l i t y e s t i m a t e s , as w e l l as the mean f o r each s u b t e s t , are presented I n Table 3-28 TABLE 3 Measures o f R e l i a b i l i t y f o r the P.I.C.A. Tests: I n Order o f D i f f i -c u l t y Meanst I n t e r - R a t e r . R e l i a b i l i t y I n t e r n a l Consis-tency Hoyt's Anova S t a b i l i t y Test-Retest(<2 weeks) A 6 . 0 1 0.93 0.97 0.95 B 6.62 0.97 0.97+ 0.92 C 6.94 0.97* 0.96+ 0.96 D 7.39 0.97 O.96+ 0.92 I 8.40 0.99 0.98 0.97 E 8 .56 0.94* 0.95+ 0 . 8 5 V 8 .87 0.99 0.99 0190 I I 9-3.7 0.95 0.93+ 0 . 8 7 IV 9..45 0.99 0.98 0.97 IX 9.48 0.98 0.98 0.96 VI I 9-94 0.99 0.99 0 . 9 1 I I I 1 0 . 3 6 0.93* 0.95+ 0.88 F 10.49 0.95 0.96+ 0.98 XII 1 1 . 1 7 0.99 0.99 0.95 VI 12.00 0.99 0.96 0.94 X 1 2 . 6 7 0.99 0.96+ 0 . 8 1 V I I I 13-44 0.98 0.96 0.95 . ^ 14.22 0.95 0.88+ 0 . 7 0 n 150 30 150 40 * s i g n i f i c a n t d i f f e r e n c e (p <.05) found between mean scores of r a t e r s . + s i g n i f i c a n t d i f f e r e n c e found between c e r t a i n scores of subtest items. + standard d e v i a t i o n s not given i n manual. 29 As mentioned e a r l i e r , a f a c t o r a n a l y s i s o f Porch's report e d subtest i n t e r o c r r e l a t l o n m a t r i x supported the presence o f the three language dimensions p o s i t e d by Porch ( C l a r k , et a l , 1978). As the s p e c i f i c subtests loaded, i n the main, on f a c t o r s c o n s i s t e n t w i t h Porch's f o r m u l a t i o n s , t h i s f a c t o r a n a l y s i s provides evidence t o support the construct v a l i d i t y u n d e r l y i n g the P.I.C.A. Due t o the magnitude o f the f i r s t eigenvalue obtained from a p r i n c i p a l component a n a l y s i s on the re p o r t e d i n t e r - c o r r e l a t i o n m a t r i x and the h i g h and reasonably equivalent i n t e r - c o r r e l a t i o n s among f a c t o r s suggested by the optimal oblique t r a n s f o r m a t i o n , a second order f a c t o r a n a l y s i s was a l s o p e r -formed. The r e s u l t s o f t h i s a n a l y s i s suggested t h a t a higher order f a c t o r o f general communication a b i l i t i e s was a l s o present. I n t e r e s t -i n g l y subtest l o a d i n g on t h i s f a c t o r was p o s i t i v e l y c o r r e l a t e d w i t h the d i f f i c u l t y o f each subtest (Spearman's r = 0.68). S p e c i f i c a l l y , the e a s i e r t e s t s were more h i g h l y c o r r e l a t e d w i t h the gene r a l language f a c t o r . Therefore, t h i s a n a l y s i s gave support t o both s e v e r i t y and s p e c i f i c d e f i c i t t h e o r i e s o f aphasia. The f a c t o r p a t t e r n and s t r u c t u r e matrices are gi v e n I n Appendix A, Tables 1 and 2. The r e p o r t e d f i n d i n g s on the P.I.C.A. as a psychometric Instrument, as w e l l as the s t a n d a r d i z a t i o n procedure employed, I n d i c a t e t h a t i t I s an appropriate t e s t b a t t e r y t o evaluate aphasics and t o explore the dimensions u n d e r l y i n g t h i s d i s o r d e r . 30 CHAPTER I I I METHODS I n t r o d u c t i o n I n the f i r s t s e c t i o n o f t h i s chapter i s presented an overview o f the experimental paradigm and an o u t l i n e o f the s t a t i s t i c a l procedures employed. I n a d d i t i o n , t h i s s e c t i o n a l s o i d e n t i f i e s the areas o f conceptual i n t e r e s t t o be examined, l a t e r f o r s p e c i f i c stages o f the a n a l y s i s . The second s e c t i o n o f t h i s chapter presents the c r i t e r i a f o r the s p e c i f i c types o f a n a l y s i s employed. As many o f these analyses e i t h e r v i o l a t e t r a d i t i o n a l assumptions o r c a p i t a l i z e on c e r t a i n aspects of the data, the r a t i o n a l e f o r t h e i r use i s a l s o provided. Experimental Paradigm and S t a t i s t i c a l Procedures The temporal o r d e r i n g o f treatments and e v a l u a t i o n o f aphasic symptoms are presented i n F i g u r e 2. As mentioned e a r l i e r , i t has been shown th a t aphasics are d i f f e r e n t from the normal p o p u l a t i o n . However, the d i s t r i b u t i o n o f s k i l l s or d e f i c i t s at time 0 has never been examined u s i n g m u l t i v a r i a t e s t a t i s t i c a l techniques. Previous attempts to c l a s s i f y o r group s u b j e c t s used u n i v a r i a t e techniques (Howes, 1964), n e u r o l o g i c a l models o f d e f i c i t o r e x p r e s s i v e / r e c e p t i o n dimensions (Weisenburg and McBride, 1935). As s t a t i s t i c a l a n a l y s i s represents the main form o f argument i n terms o f treatment e f f i c a c y f o r groups, t h i s study attempted t o explore p o t e n t i a l groupings u s i n g s t a t i s t i c a l c r i t e r i a . The examination o f p o s s i b l e groups post-trauma but p r e -treatment ( i . e . 0 ) would then provide a f a c t o r i a l framework f o r subsequent research t o examine d i f f e r e n t i a l treatment e f f e c t s . 31 FIGURE 2 Overview o f Experimental Paradigm: Aphasic Research Time: X X 'treatment' r e s u l t i n g i n aphasia u n c o n t r o l l e d , environmental event assessment of changes subsequent t o trauma treatment l e a d i n g t o re c o v e r y / improvement e.g. time, r e l e a r n l n g o f s k i l l s , develop-ment of coping s t r a t e g i e s assessment o f r e s i d u a l or pure aphasic symptoms 32 TABLE 4 Data A n a l y s i s Procedure STEP 1. C a l c u l a t i o n o f mean and standard d e v i a t i o n f o r eighteen subtests at 0^ and Ov,. 2. Examination o f mean and standard d e v i a t i o n t o determine s u i t a b i l i t y f o r F a c t o r A n a l y s i s . 3. F a c t o r A n a l y s i s of subtests r e t a i n e d at 0^. 4. The generation of f a c t o r scores f o r subtests scores at 0^ u s i n g the d e r i v e d c o e f f i c i e n t s computed a t C^. 5. H i e r a r c h i c a l grouping a n a l y s i s o f f a c t o r scores at 0^. 6. D i s c r i m i n a n t a n a l y s i s o f p o s s i b l e s o l u t i o n s t o gauge the e f f i c a c y of s p e c i f i c grouping procedures. 7. C a l c u l a t i o n of means and standard d e v i a t i o n s f o r o p t i m a l s o l u t i o n . 8. One way analyses o f v a r i a n c e by group on d e r i v e d f a c t o r , dimensions. 9. Comparison of group means u s i n g Scheffe's m u l t i p l e comparison techniques. 10. Q u a l i t a t i v e statements concerning s p e c i f i c ' f a c t o r dimensions and d i s t r i b u t i o n o f groups. 11. Q u a l i t a t i v e statements concerning group p r o f i l e s . \ 33 With respect t o s t a t i s t i c a l methodology and techniques, the proposed procedures are presented i n Table 4. Steps 1 and 2 represent the examination of raw data t o a s c e r t a i n i t s s u i t a b i l i t y f o r f a c t o r a n a l y s i s and allowed f o r comparisons between t h i s sample and Porch's s t a n d a r d i z a t i o n sample. The f a c t o r a n a l y s i s (Step 3) o f the subtest scores at 0 2 reduced the number o f dependent v a r i a b l e s . I n a d d i t i o n , the d e r i v e d f a c t o r p a t t e r n was compared t o Porch's i n i t i a l f ormulations and the f a c t o r a n a l y s i s o f the s t a n d a r d i z a t i o n sample ( C l a r k et a l , i n p r e s s ) . I n Step 4, f a c t o r scores were generated f o r the pre-treatment assessment u s i n g the c o e f f i c i e n t s d e r i v e d from the f a c t o r a n a l y s i s at 0 2. Steps. 5 through 7 i n v o l v e d e v a l u a t i o n o f the grouping procedure. Steps 8:. and 9, although a l l o w i n g spurious r e s u l t s I n terms of c l a s s i c a l s t a t i s t i c a l t h e o r y , produced an estimate o f group d i f f e r e n c e s . Moreover, by u s i n g the most conservative m u l t i p l e comparison technique a v a i l a b l e , S c h e f f e ' s , the number of r e p o r t e d d i f f e r e n c e s were rninlmlzed, not maximized. By examining each f a c t o r s e p a r a t e l y , the d i s t r i b u t i o n o f groups r e l a t i v e - t o current aphasia theory was a l s o reviewed. F i n a l l y , the group p r o f i l e s were examined. Sample The sample•consisted o f seventy-two m e d i c a l l y diagnosed aphasics who had been admitted t o the G.F. Strong R e h a b i l i t a t i o n Centre f o r speech therapy. The c r i t e r i a f o r i n c l u s i o n i n the sample were: 2) therapy must have l a s t e d at l e a s t three months, unless the p a t i e n t was discharged because speech therapy was no longer deemed necessary; b) P.I.C.A. examinations p r i o r and subsequent t o treatment must have been done on a l l s u b j e c t s ; and c) a l l p r o t o c o l s must have been complete 34 (eighteen s u b t e s t s ) . Demographic data were c o l l e c t e d i n terms o f age, sex, education and d i a g n o s i s . Instrumentation The psychometric p r o p e r t i e s o f the P.I.C.A. have been reporte d I n Chapter 2. Subtests on which a c e l l i n g e f f e c t was observed .(X > 1 4 . 0 ) were discarded. I n c l u s i o n o f such subtests would a f f e c t the f a c t o r a n a l y s i s adversely. S p e c i f i c a l l y , f a c t o r dimensions could a r i s e which r e f l e c t v a r i a b l e s w i t h no var i a n c e . I n a d d i t i o n , the mean scores a t t a i n e d by t h i s sample were compared t o those r e p o r t e d by Porch. As Porch re p o r t e d no standard d e v i a t i o n s , a H o t e l l n g T 2 one sample procedure was used w i t h Porch's means considered as parameter estimates. ANALYSES Fac t o r A n a l y s i s A l l subtests which met the c r i t e r i o n f o r i n c l u s i o n were then f a c t o r analyzed. The post-treatment subtest scores ( i . e . 0 2 ) were used f o r t h i s a n a l y s i s as these scores best r e f l e c t r e s i d u a l aphasic d i s o r d e r s a f t e r treatment and thus more a c c u r a t e l y r e f l e c t t r u e aphasic d i s o r d e r s . The f a c t o r a n a l y s i s was completed i n two st e p s . F i r s t , p o s s i b l e s o l u t i o n s were determined based on the c o n f i g u r a t i o n o f the eigenvalues d e r i v e d from a p r i n c i p a l component a n a l y s i s at 0 2.. An I n i t i a l p r i n c i p a l components e x t r a c t i o n was obtained u s i n g the A l b e r t a General F a c t o r A n a l y s i s Programme (Hakstian and Bay, 1 9 7 2 ) . The r e s u l t i n g eigenvalues were examined t o determine the p o s s i b l e number o f f a c t o r s t o r e t a i n . Three c r i t e r i a were considered: 1) the number of eigenvalues g r e a t e r than one (Kaiser-Guttman Rule) (Guttman, 1 9 5 4 ) ; 2) the determination o f 35 i n f l e c t i o n p o i n t s from the graph o f eigenvalues versus o r d i n a l number of f a c t o r s (Scree Test) ( C a t t e l , 1 9 6 6 ) ; and 3) the percentage o f accounted v a r i a n c e . Por the second stage o f the a n a l y s i s , f a c t o r s o l u t i o n s were then obtained f o r each o f the number f a c t o r s suggested by the aforementioned c r i t e r i a u s i n g unweighted l e a s t squares analyses (Hakstian and Bay, 1 9 7 2 ) . The r e s i d u a l c o r r e l a t i o n matrices o f each s o l u t i o n were examined and the number o f c o r r e l a t i o n s l e s s than 0 . 1 5 counted. As the major purpose o f t h i s study was e x p l o r a t o r y , an o v e r f a c t o r e d s o l u t i o n was considered b e t t e r than an underfactored s o l u t i o n . The p r e f e r r e d s o l u t i o n was then transformed u s i n g a s e r i e s o f the H a r r i s - K a i s e r Method o f Oblique/Orthogonal Transformations. The best s o l u t i o n was determined by conforming t o simple s t r u c t u r e : the f a c t o r p a t t e r n w i t h the highest number of loadings <0.15 (hyperplane count) and w i t h the fewest number o f v a r i a b l e s l o a d i n g > 0 . 3 0 on more than one f a c t o r ( f a c t o r i a l c o m p l e x i t y ) . I n the case where s o l u t i o n s were equivalent i n terms o f these c r i t e r i a , the l e s s o b l i q u e s o l u t i o n was s e l e c t e d . I n order t o generate f a c t o r s c o r e s , the f a c t o r score c o e f f i c i e n t m a t r i x was then standardized by p r e - m u l t i p l y i n g i t by the i n v e r s e diagonal o v e r a l l standard d e v i a t i o n m a t r i x . The r e s u l t i n g m a t r i x was used t o estimate p r e - f a c t o r scores by the r e g r e s s i o n method (Hakstian and Bay, 1 9 7 2 ) . H i e r a r c h i c a l A n a l y s i s The p r e - f a c t o r scores were then submitted t o a h i e r a r c h i c a l grouping a n a l y s i s I n order t o determine the ' c o r r e c t ' o r o p t i m a l number o f groups. This procedure i n v o l v e s both irnnimizing wlthin-group v a r i a b i l i t y and 36 maximizing between-group v a r i a b i l i t y ( P a t t e r s o n and Whittaker, 1973). I n i t i a l l y , the a n a l y s i s began w i t h the number o f groups equal t o the number o f subjects ( i . e . , no within-group v a r i a b i l i t y , maximal between-group v a r i a b i l i t y ) . S i m i l a r s u b j e c t s were then c o l l a p s e d i n t o a group at each step u n t i l there was j u s t one group s o l u t i o n ( i . e . maximal wlthin-group v a r i a b i l i t y , no between-group v a r i a b i l i t y ) . At each Intermediate s t e p , the cumulative wlthln-group v a r i a b i l i t y term, the change i n t h i s term from the preceding s t e p , and a s t a b i l i t y Index (which r e l a t e s the change i n the e r r o r term t o o v e r a l l v a r i a b i l i t y and c o r r e c t s t h i s r a t i o by the number o f groups). were c a l c u l a t e d . I n a d d i t i o n , the percentage o f withln-group t o the o v e r a l l - v a r i a b i l i t y , and the change i n t h i s percentage, were c a l c u l a t e d . To determine the i d e a l number of groups f o r maximizing between-group v a r i a b i l i t y and thus minimize within-group v a r i a b i l i t y , the f o l l o w i n g c r i t e r i a were considered: 1) percentage o f o v e r a l l variance accounted f o r between groups; 2) the r e l a t i v e change i n t h i s percentage as the number o f groups decreased; and 3) the s t a b i l i t y index (values around one were considered a c c e p t a b l e ) . D i s c r i m i n a n t A n a l y s i s and A n a l y s i s o f Variance When a s e r i e s o f p o s s i b l e c l u s t e r s o l u t i o n s (e.g. 8. ,'7 or 6 groups) was i d e n t i f i e d , each o f the s o l u t i o n s was then examined u s i n g step-wise d i s c r i m i n a n t a n a l y s i s employing Wilk's Method (Nie et a l , 1975). The p r e d i c t o r v a r i a b l e s were i n i t i a l f a c t o r scores and the dependent v a r i a b l e s group membership. The o v e r a l l p r e d i c t i o n r a t e s o f each 37 s o l u t i o n were compared t o determine the best o r optimal s o l u t i o n . F i n a l l y , f o r the i d e a l s o l u t i o n , group means and standard d e v i a t i o n s were compared i n order t o determine the p a t t e r n i n g o r p r o f i l e s among groups. I n a d d i t i o n , a one-way a n a l y s i s o f vari a n c e was done on each de r i v e d f a c t o r by group. Scheffe's m u l t i p l e comparison technique (<* = 0 . 0 5 ) was used t o estimate r e a l d i f f e r e n c e s between groups on s p e c i f i c f a c t o r s . Due t o the methodology employed, any re p o r t e d d i f f e r e n c e s cannot be considered s i g n i f i c a n t i n the t r a d i t i o n a l sense. However, these t e s t s provided estimates o f the r e a l d i s t a n c e s between groups and provide i n s i g h t i n t o the d i s t r i b u t i o n ,6f these groups on s p e c i f i c f a c t o r s on language a b i l i t y . Although c l u s t e r a n a l y s i s c a p i t a l i z e s on e r r o r v a r i a b i l i t y , by a s c r i b i n g i t t o group membership when i t i s random, the o v e r a l l e f f i c i e n c y o f t h i s s o l u t i o n may be judged by the p r e d i c t i o n r a t e s f o r group membership and the percentage o f between-group • v a r i a b i l i t y . However, i t should be stressed, t h a t these s o l u t i o n s are optimal I n terms o f v a r i a b i l i t y and over-estimate between-group d i f f e r e n c e s . 38 CHAPTER IV RESULTS Sample Of the 72 m e d i c a l l y diagnosed a p h a s i c s , f o r t y were male. The mean age was 52.7 years w i t h a standard d e v i a t i o n o f 18.4 years and a range o f 20 t o 68. The average l e v e l o f education was 10.2 years w i t h a standard d e v i a t i o n o f 3-6. Medical d i a g n o s i s was d i s t r i b u t e d as f o l l o w s : 51 had c e r e b r a l v a s c u l a r a c c i d e n t s ; 19 had traumatic head-i n j u r i e s , a a n d 2 had b r a i n damage r e l a t e d t o anoxia. Time s i n c e onset ( i . e . time from X t o Ox) ranged from one t o fourteen months w i t h the mean bein g 4.67 months. The mean treatment time was 5.1 months w i t h a standard d e v i a t i o n o f 2.4 months. The obtained subtest means, and standard d e v i a t i o n s are re p o r t e d i n Table 5 f o r both pre and post-treatment. The means re p o r t e d by Porch (1969) are a l s o i n c l u d e d i n Table 5. Comparison o f the pre-treatment means w i t h Porch's standardized means r e v e a l e d t h a t the present sample d i f f e r e d s i g n i f i c a n t l y across the eighteen subtests ( H o t e l i n g T 2 = 147.5; p < .001). However, 95% simultaneous confidence I n t e r v a l s f o r each'subtest spanned the corresponding mean i n Porch's sample. Using a Spearman rank-order c o e f f i c i e n t t o assess the s t a b i l i t y o f the d i f f i c u l t y g radient across samples, a value o f 0.94 was obtained. , This r e s u l t i n d i c a t e s t h a t both samples encountered s i m i l a r r e l a t i v e d i f f i c u l t y w i t h the s p e c i f i c s u b t e s t s . For both subtests V I I I and XI the sample means at 0 2 (see F i g . 2) exceeded 14.0; the variances were 1.45 and 0.31 r e s p e c t i v e l y . Therefore, 39 TABLE 5 Means and Standard D e v i a t i o n s Porch's Sample and Study Sample 3, Subtests Porch Xs Pre-Treatment XPre S.D. Post-Treatment XPost S.D. D i f f e r e n c e Xs-XPre I 8.40 7 . 9 1 3.42 9 . 8 8 3 - 8 9 + 0 . 4 9 I I 9 - 3 7 1 0 . 8 6 3 . 0 3 11 .79 3 . 1 8 - 1 . 4 9 I I I 1 0 . 3 6 1 1 . 8 9 2 . 8 9 1 2 . 6 7 2 . 9 2 - 1 . 5 3 IV 9 - 4 5 9 . 2 0 4 . 1 1 1 0 . 6 5 ' 4 . 0 8 + . 2 5 V 8 . 8 7 1 0 . 9 0 3 - 3 7 1 2 . 0 3 2 . 9 3 - 1 . 0 3 V I . 1 2 . 0 0 1 2 . 6 0 2 . 8 9 1 3 . 5 8 2 . 4 3 - . 6 6 V I I 9 . 9 4 . 1 1 . 7 2 3 . 0 9 1 2 . 8 5 2.42 - 1 . 7 8 V I I I ' 1 3 - 4 4 14 .45 I . 6 7 14.64 • 1 . 4 5 - 1 . 0 1 IX 9-48 • 9.42 4.04 1 0 . 9 7 4 . 0 3 . 0 6 X 1 2 . 6 7 1 3 . 2 7 2 . 5 6 1 3 . 8 1 2 . 0 1 - . 6 0 XI 14 .22 14 .38 2 . 1 1 14 .93 0 . 3 1 - . 16 X I I 1 1 . 1 7 1 1 . 8 3 3 . 9 7 1 2 . 9 0 3 . 2 6 - . 6 3 A 6 . 0 1 6.64 2 . 7 5 7 - 9 5 3 . 0 2 - . 6 3 B 6 . 6 2 7-99 3 . 6 0 9 . 8 8 3 . 5 4 - 1 . 3 7 C 6 . 9 4 8 . 3 0 3 . 8 0 9 . 8 2 3 - 7 6 - I . 3 6 D 7-39 8 . 9 1 3 . 9 3 1 0 . 1 8 3 . 8 3 - 1 . 5 2 E 8 . 5 6 1 0 . 9 3 3 . 7 1 1 2 . 6 5 3 . 2 0 - 1 . 3 7 P • 1 0 . 4 9 1 1 . 9 9 3 - 3 1 1 3 . 3 6 2.46 - 1 . 5 0 n 150 72 72 t o r c h ' s standard subtest l a b e l l i n g ; d e s c r i p t i o n s provided i n Chapter I I , page 2 1 . 40 these two subtests were exluded from subsequent analyses. For the remaining s u b t e s t s , the means were w e l l d i s t r i b u t e d over the s c a l e ; the variances were reasonably comparable among subtests and c o n s i s t e n t over treatment ( i . e . a t 0^ and 0 2 ) . Therefore, s i x t e e n subtests were r e t a i n e d f o r f u r t h e r a n a l y s i s . F a c t o r A n a l y s i s The i n t e r c o r r e l a t i o n m a t r i x o f these subtests i s presented i n Table 6 . The f i r s t s i x eigenvalues obtained from the p r i n c i p a l component a n a l y s i s on post-treatment subtest scores were 1 0 . 5 0 , 1.42, 1 . 2 6 , 0 . 6 9 , 0 . 6 3 and 0 . 3 0 . The Kaiser-Guttman Rule suggested a minimum o f three f a c t o r s be r e t a i n e d w h i l e the Scree- Test suggested a maximum o f f i v e f a c t o r s be r e t a i n e d ( F i g . 3 ) . Therefore, unweighted l e a s t squares analyses were done-on t h r e e , f o u r and f i v e f a c t o r s o l u t i o n s . The r e s u l t s o f the p r i n c i p a l component a n a l y s i s and the three unweighted l e a s t squares analyses are presented i n Table 7- The t o t a l percentage o f accounted f o r variance i m p l i e d by the p r i n c i p a l component a n a l y s i s ( 9 0 . 6 $ ) and the dramatic Increase i n the number o f r e s i d u a l c o r r e l a t i o n s l e s s than 0 . 1 5 i n the f i v e f a c t o r unweighted l e a s t squares a n a l y s i s l e d t o the choice o f t h i s s o l u t i o n f o r a l l subsequent analyses'. S i m i l a r l y , as t h i s study was e x p l o r a t o r y i n nature, an o v e r f a c t o r e d s o l u t i o n was considered b e t t e r than an underfactored s o l u t i o n . Therefore, the f i v e f a c t o r s o l u t i o n was submitted t o a s e r i e s o f H a r r i s - K a i s e r o b l i q u e / orthogonal transformations (Hakstian and Bay, 1 9 7 2 ) . The i n i t i a l s e r i e s o f transformations ( v a r y i n g the degree o f obliqueness;(c) from 1 . 0 t o 0 . 0 by 0 . 1 at each step) suggested t h a t an 41 Table 6 In ter -Corre lat ion Matrix of Post Treatment P.I.C.A. Subtest Scores Used for Factor Analysis Test I I I I I I TV V VI VII IX X XII A B C I 1.00 I I 0.72 1.00 I I I 0.69 0.89 1.00 IV 0.92 0.68 0.64 1.00 V 0.70 0.76 0.75 0.69 1.00 VI 0.59 O.69 0.64 0.63 0.80 1.00 VII 0.72 0.72 0.66 0.73 0.84 0.85 1.00 IX 0.89 0.73 0.68 0.91 O.76 0.66 0.75 1.00 X 0.56 0.66 0.60 0.63 0.68 0.83 0.85 0.66 1.00 XII 0.66 0.55 0.54 0.72 0.43 0.47 0.52 0.73 0.53 1.00 A 0.78 0.61 0.55 0.68 0.62 0.47 O.63 0.61 0.45 0.47 1.00 B 0.75 0.60 0.53 0.74 0.66 0.57 0.71 0.64 0.53 0.49 0.83 1.00 C 0.76 O.58 0.50 0.75 0.62 0.55 O.67 0.65 .0.53 0.56 0.80 0.93 1.00 D 0.77 0.67 0.59 0.76 0.73 O.63 0.73 0.70 0.59 0.62 0.80 0.88 0.91 E 0.42 0.51 0.50 0.40 0.54 0.60 0.55 0.39 0.56 0.33 0.49 O.63 0.63 F 0.29 0.43 0.44 0.24 0.46 0.44 0.40 0.26 0.41 0.28 0.44 0.46 0.46 D E 1.00 0.65 1.00 0.52 0.77 1.00 42 F I G U R E 3 Scree Test ( P r i n c i p a l Component S o l u t i o n ) Eigenvalue 12 -11 -10 -9 -8 -7 -6 -5 -/ = i n f l e c t i o n p o i n t 4 -3 -• • - - • _ _ . _ _ » _ » • I I I I I I I I I ~ I - — I . ' / — : / / _ . 0 1 2 3 4 5 6 7 8 9 10 11 12 13 16 O r d i n a l F a c t o r Number 1 -43 TABLE 7 C r i t e r i a f o r E s t i m a t i n g Number o f Factors t o be Retained No. of Factors Fac t o r Method P r i n c i p a l Component Unweighted Least Squares Eigenvalues T o t a l Percentage of Accounted Variance Percentage o f R e s i d u a l C o r r e l a t i o n s <0.15 1 10.50 65.6 a 2 •1.42 74.5 a 3 1.26 82.4 52.3 4 0.69 86.7 54.7 *5 0.63 90.6 74.2* 6 0.30 92.5 a * S o l u t i o n of Choice Footnote - - not done 44 TABLE 8 Results of Oblique Transformations c . Hyp erp lane Count Factorial Complexity 1.00 5 12 0.90 15 7 0.80 25 6 0.70 28 5 0.60 36 4 0.50 38 3 0.40 43 3 0.30 44 3 0.20. 44 3 0.15 44 2 0.10 41 2 0.00 40 . 3 45 optimal s o l u t i o n f e l l between c = 0 . 1 0 and c = 0 . 2 0 . Therefore, f u r t h e r transformations were done s y s t e m a t i c a l l y v a r y i n g c between 0 . 1 0 and 0" .20. The optimal s o l u t i o n was found at c = 0 . 1 5 . The hyperplane count and the number o f f a c t o r i a l l y complex v a r i a b l e s f o r each o f the i n i t i a l t r a n s f o r m a t i o n s and f o r c = 0 . 1 5 are presented i n Table 8 . At c = 0 . 1 5 , the hyperplane count was at the maximum observed, 4 4 , w h i l e the f a c t o r i a l complexity was l i m i t e d t o two. The i n t e r f a c t o r c o r r e l a t i o n and f a c t o r p a t t e r n matrices f o r t h i s t r a n s f o r m a t i o n are presented I n Tables 9 and 10 r e s p e c t i v e l y . The i n t e r f a c t o r c o r r e l a t i o n m a t r i x i n d i c a t e d t h a t F a c t o r s 1 , 2 , 3 , 4 are h i g h l y r e l a t e d and t h e r e f o r e were measuring i n p a r t a common dimension. S p e c i f i c a l l y , c o r r e l a t i o n s among these f o u r f a c t o r s ranged from . 6 0 t o . 7 0 . However, F a c t o r 5 appeared t o be more independent i n t h a t the range o f I n t e r f a c t o r c o r r e l a t i o n s between F a c t o r 5 and each o f the f i r s t f o u r was 0 . 2 6 t o 0 . 5 0 . I t appeared t h a t F a c t o r 5 was e i t h e r a measure o f a d i f f e r e n t dimension o r language s k i l l than 'the other f o u r f a c t o r s , or a measure o f a non-language s k i l l . To c l a r i f y t h i s , the f a c t o r p a t t e r n m a t r i x was i n s p e c t e d w i t h s p e c i a l reference t o both subtest t a s k demands and Porch's hypothesized f a c t o r s t r u c t u r e . F a c t o r 1 had h i g h loadings on three of the. f o u r v e r b a l subtests (IV, IX, X I I ) ; each of these v a r i a b l e s had complexity one. The f o u r t h v e r b a l s u b t e s t , I , loaded on both F a c t o r 1 and F a c t o r 2 . Therefore, the f i r s t f a c t o r was assumed t o represent a measure o f v e r b a l f l u e n c y i n t h a t these f o u r subtests r e q u i r e the subject t o make a v e r b a l response. Subtest I , w i t h complexity 2 , was the most d i f f i c u l t o f the f o u r v e r b a l s u b t e s t s . 46 F a c t o r 2 had high loadings on f o u r o f the s i x subtests Porch l a b e l l e d as g r a p h i c . Each o f these subtests had complexity o f one. These fo u r subtests (A, B, C, D) a l l r e q u i r e the subject t o w r i t e h i s responses. Therefore, t h i s f a c t o r was assumed t o r e f l e c t the p a t i e n t s ' competency i n expressing h i m s e l f I n w r i t t e n language. F a c t o r 3 had h i g h loadings on three (VT, VTI, X) o f Porch's s i x g e s t u r a l s u b t e s t s . Each o f these subtests had complexity of one. I n a d d i t i o n , g e s t u r a l subtest V loaded complexly on t h i s f a c t o r and F a c t o r 4. These subtests r e q u i r e a g e s t u r a l demonstration of compre-hension f o r e i t h e r a u d i t o r y o r v i s u a l l y (reading) presented commands. Fac t o r 4 had h i g h loadings on the remaining two g e s t u r a l subtests ( I I and I I I ) . Each of these subtests had complexity o f one. Both r e q u i r e the subject t o demonstrate the f u n c t i o n of presented s t i m u l i and r e l y on the g e s t u r a l modality o f communicate the i n s t r u c t i o n s . Although Factors 3 and 4 appeared t o r e f l e c t somewhat d i f f e r e n t dimensions o f communication s k i l l , they had the highest i n t e r - f a c t o r c o r r e l a t i o n ( r = 0.70) and, i n p a r t , r e f l e c t e d Porch's g e s t u r a l dimension may be f u r t h e r d i f f e r n t i a t e d , dependent upon mode o f i n s t r u c t i o n ( i . e . v e r b a l , reading or pantomime). F a c t o r 5 had h i g h loadings on two remaining graphic subtests (E, F ) . Each o f these subtests had complexity o f one. U n l i k e the other f o u r graphic subtests which r e q u i r e the p a t i e n t t o w r i t e , these two subtests r e q u i r e the p a t i e n t only t o copy l e t t e r s t o geometric shapes. Given the content of these two subtests and the r e l a t i v e l y lower i n t e r -f a c t o r c o r r e l a t i o n s , i t was hypothesized t h a t these two subtests do not t r u l y r e f l e c t language/communication a b i l i t i e s , but r a t h e r a v i s u a l / 47 TABLE 9 Inter-Factor Correlation Matrix Factor 1 2 3 4 5 1 1.00 2 0.69 1.00 3 0.65 0.61 1.00 4 0.67 0.60 0.70 1.00 5 0.26 0.50 0.48 0.43 1.00 48 TABLE 10 F a c t o r P a t t e r n M a t r i x Subtest M o d a l i t y F - l F-2 F-3 F-4 F-5 X I I V e r b a l 0.99 -0.16 -0.14 -0.08 0.25 IX V e r b a l 0.70 0.05 0.19 0.15 -0.11 TV V e r b a l 0.68 0.29 -0.13 0.02 -0.14 I V e r b a l 0.48 0.45 -0.02 0.22 -0.17 A Graphic 0.02 0.84 -0.09 0.02 -0.05 B Graphic 0.05 0.95 0.08 -0.03 0.02 C Graphic 0.17 0.86 0.02 0.16 0.12 D ;? Graphic 0.18 0.68 0.06 -0.00 0.16 VI G e s t u r a l 0.04 -0.08 0.87 0.05 0.10 V I I G e s t u r a l -0.01 0.22 0.82 0.04 0.10 X G e s t u r a l 0.26 -0.20 0.82 0.08 0.15 V G e s t u r a l -0.14 0.26 0.52 0.42 0.09 I I I G e s t u r a l 0.12 -0.11 0.06 0.93 0.10 I I G e s t u r a l 0.12 0.03 • 0.08 0.75 0.04 F Graphic • -0.11 0.11 -0.05 0.15 0.75 E . Graphic 0.07 0.21 0.18 -0.02 0.72 j 49 p e r c e p t u a l process. S p e c i f i c a l l y , t h i s f a c t o r c o r r e l a t e d h ighest w i t h f a c t o r s r e q u i r i n g motor responses (rP2 = 0.50, rP3 = 0.48, rP4 = 0.43) and lowest w i t h F a c t o r 1 ( v e r b a l f l u e n c y , r = 0.26). H i e r a r c h i c a l A n a l y s i s F a c t o r scores were d e r i v e d on. the pre-treatment scores u s i n g the procedure p r e v i o u s l y o u t l i n e d and expressed I n terms o f T-score u n i t s (X = 50, S.D. = 10). These scores were then submitted t o a h i e r a r c h i c a l grouping a n a l y s i s . For b r e v i t y , the l a s t nine steps of t h i s a n a l y s i s are summarized I n Table 11. The reason f o r only examining these l a s t steps o f the a n a l y s i s becomes obvious when the s p e c i f i c aspects of v a r i a b i l i t y are considered. F i r s t , at the n i n t h step only 14.5% o f the t o t a l v a r i a b i l i t y was p a r t i t i o n e d i n t o wlthin-group v a r i a b i l i t y . Second, the amount o f v a r i a b i l i t y added t o w i t h i n group v a r i a b i l i t y from the t e n t h step t o the n i n t h was only 1.2% o f the t o t a l v a r i a b i l i t y . These f i g u r e s suggested t h a t at t h i s stage o f the a n a l y s i s , the e x i s t i n g groups were i n t e r n a l l y r e l a t i v e l y homogeneous and t h a t s i m i l a r groups were s t i l l b e i n g combined. As the a n a l y s i s proceeded from nine groups t o one, the i n c r e a s e of a d d i t i o n a l w i t h i n group v a r i a b i l i t y was marked, thus suggesting d i s s i m i l a r groups were being combined. The percentage Increase i n wlthin-group v a r i a b i l i t y between steps I s presented I n the l a s t column of Table 11. These f i g u r e s suggested t h a t u n t i l the six-group s o l u t i o n , r e l a t i v e l y s m a l l p o r t i o n s o f the t o t a l v a r i a b i l i t y ( i . e . 1.2 t o 2.4%) were being p a r t i t i o n e d I n t o w i t h i n group o r e r r o r v a r i a b i l i t y . A f t e r the six-group s o l u t i o n , t h i s percentage rose more r a p i d l y . Therefore, 50 TABLE 11 Results o f C l u s t e r A n a l y s i s No. of Groups (Step No.) Cumulative E r r o r A E r r o r Index % of T o t a l V a r i -ance % o f Change 9 5371.9 453.4 1-39 14 .5 1.2 8 6095.2 723.3 5.36 16.5 2.0 7 6878.4 783.2 0.66 18.6 2.1 6 7769.2 890.8 0.96 21.0 2.4 5 9055-5 1286.3 ' 2.66 24.5 3.5 4 11003.1 1947.7 2.57 29.8 5-3 3 14011.9 3008.8 2.18 37.9 8.1 2 20986.5 6974.6 3-95 56.8 18.9 1 36945.6 15959.1 2.57 . 100 43.2 51 the six-group s o l u t i o n was deemed b e s t , I n t h a t a f t e r t h i s step there was evidence t h a t r e l a t i v e l y homogeneous groups were not being combined. At t h i s step only 21.0% o f the t o t a l v a r i a b i l i t y was w i t h i n group v a r i a b i l i t y ; the remaining 79.0% was accounted f o r by between-group v a r i a b i l i t y . I n order t o gauge the o v e r a l l group homogeneity f o r t h i s s o l u t i o n and t o compare i t s e f f i c a c y w i t h s o l u t i o n s u s i n g fewer groups, a s e r i e s o f step-wise d i s c r i m i n a n t a n a l y s i s u s i n g Wilk's Method was done on the 6, 5, and 4 group s o l u t i o n s u s i n g the d e r i v e d f a c t o r s scores as p r e d i c t o r s . The r e s p e c t i v e p r e d i c t i o n r a t e s were 97-2%, 93.1% and 91.6%. T h i s decrease i n accuracy o f p r e d i c t i o n f u r t h e r suggested t h a t the six-group s o l u t i o n s t i l l represented r e l a t i v e l y homogeneous groups and t h a t s o l u t i o n s u s i n g a s m a l l e r number o f groups combined d i s s i m i l a r groups. Therefore, the six-group s o l u t i o n was r e t a i n e d f o r f u r t h e r examination. The r e s p e c t i v e means, standard d e v i a t i o n s of the f a c t o r scores and group s i z e s are presented i n Table 12. (High scores i n d i c a t e d less.impairment). Except f o r Group VI (n = 4) , the f i v e remaining groups were o f reasonable s i z e (range 9 t o 20) and t h e r e f o r e were assumed t o be r e p r e s e n t a t i v e o f r e a l aphasic symptoms. Group VI was e i t h e r a d i s c r e t e and reasonably r a r e type o f aphasic d i s o r d e r o r i d i o s y n c r a t i c t o t h i s sample. Therefore, w i t h respect t o the d i s c u s s i o n o f the P.I.C.A. and aphasic groupings, Group VI was considered s e p a r a t e l y . The most s t r i k i n g f e a t u r e of the f i v e d e r i v e d groups was t h a t f o r each f a c t o r they appear t o be d i s t r i b u t e d on a s e v e r i t y continuum and not a s a l i e n t f e a t u r e model. S p e c i f i c a l l y , f o r F a c t o r s 1, 3 and 4, the group sc o r e s , when rank-ordered according t o group membership, were 52 TABLE 12 Means and Standard Deviations f o r F i v e F a c t o r s on S i x Groups Group F a c t 0 r n 1 2 3 4 5 1 20 X 59.1 59.5 57-1 56.8 55.0 S.D. 3.18 4.13 2.02 3.35 3.30 11 9 X 56.5 46.5 54.3 55.0 49.5 S.D. 2.31 3.38 3.44 5.17 4.70 I I I 15 X 45.0 46 .9. 52.8 48.3 56.5 S.D. 4.92 7.03 3-75 4.66 3.90 IV 13 X 39.4 39.8 41.5 43.7 46.9 S.D. 3-32 4.10 8.48 8.03 5-97 V 11 X 35.8 38,-5 31.9 31.1 31.8 S.D. 4.80 - 5.36 8.93 4.08 6.43 VI 4 1 53-2 39.0 40.3 46.3 23.9 S.D. 3.54 3.72 9-97 6.47 4.13 53 c o n s i s t e n t across these f a c t o r s f o r the r e s p e c t i v e groups. F a c t o r 2 has only one 'cross-over; where Group I l l ' s score was s l i g h t l y h i g h e r (+0.4) than Group I I . I n a l l p r o b a b i l i t y , t h i s was a f u n c t i o n o f sampling v a r i a b i l i t y . F a c t o r 5 a l s o had one 'cross-over' but here Group I l l ' s score was the b e s t o f the f i v e groups. The r e s u l t s , t h e r e f o r e , suggest t h a t these groups represent an o v e r a l l s e v e r i t y dimension o f aphasic d i s o r d e r s and i n i t i a l l a b e l s f o r the groups would be m i l d ( i . e . Group 1) t o severe Impairment ( i . e . Group V ) . U n i v a r i a t e A n a l y s i s In order t o gauge the e f f i c a c y o f the c l u s t e r i n g s o l u t i o n on the s p e c i f i c f a c t o r dimensions, a one-way a n a l y s i s o f variance was done on each f a c t o r . The r e s u l t s o f these analyses are sumarlzed I n Table 13. As would be expected, h i g h l y s i g n i f i c a n t between-group F-values " were obtained. S i m i l a r l y , the grouping procedure accounted f o r 86.0% of the t o t a l v a r i a b i l i t y on F a c t o r 1, 7^.7% on F a c t o r 2, 71.9% on Factor. 3, 7^.9% on F a c t o r 4, and 83.1% on F a c t o r 5. These f i g u r e s , although i n f l a t e d , h i g h l i g h t how much s t a t i s t i c a l power might be obtained by f a c t o r i n g s u bjects on impairment l e v e l s p r i o r t o experimental manipulation. As aphasia theory has h i s t o r i c a l l y been based on u n i v a r i a t e a n a l y s i s procedures, the examination o f groupings on s p e c i f i c f a c t o r s was warranted. Using Scheffe's m u l t i p l e comparison technique, the degree o f d i f f e r e n c e between p a r t i c u l a r groups on s p e c i f i c f a c t o r s was estimated. These comparisons are summarized I n Table 14. On F a c t o r 1, three d i s t i n c t groups emerged. Groups I , I I , and VI were s i m i l a r and e x h i b i t the l e a s t amount of Impairment I n v e r b a l f l u e n c y . Groups IV and V were 54 TABLE 13 Analyses o f Variance f o r the F i v e Factors FACTOR 1 Source Between Groups W i t h i n Groups T o t a l D.F. 5 66 71 Sum of Squares 5953.7 973.1 6926.7 Percent 86.0 F-value 80.8 F-prob. 0.000 FACTOR 11 Source Between Groups W i t h i n Groups: T o t a l D.F. 5 66 71 Sum of Squares 4844.6 1637.2 6481.7 Percent 74.7 F-value 39.1 F-prob. 0.000 FACTOR 111 Source Between Groups W i t h i n Groups T o t a l D.F. 5 66 71 Sum o f Squares 5967.9 . 2327.9 8295.8 Percent 71.9 F-value 33.8 : F-prob. 0.000 FACTOR I V Source Between Groups W i t h i n Groups T o t a l D.F. ,5 66 71 Sum of Squares 5368.7 1796.9 7165.6 Percent: 74.9 : F-value 39-44 F-prob. 0.000 FACTOR V Source Between Groups W i t h i n Groups T o t a l D.F. 5 66 71 Sum o f Squares 7310.9 1488.2 8799.1 Percent: 83.1 F-value 64.85 F-prob. 0.000 55 a l s o s i m i l a r and had the severest amount o f impairment i n v e r b a l f l u e n c y . Group I I I f e l l between these two c l u s t e r s , being s i g n i f i c a n t l y more impaired than Groups I , I I or V I , but s i g n i f i c a n t l y l e s s impaired than Groups TV o r V. Por F a c t o r 2, the w r i t i n g dimension, Group I e x h i b i t e d the least, impairment and was s i g n i f i c a n t l y b e t t e r than the f i v e remaining groups. Groups I I and I I I appeared s i m i l a r and were s i g n i f i c a n t l y l e s s impaired than Group V. Groups IV and VI's performance was s i m i l a r and f e l l between Groups I I and I I I and Group V. For F a c t o r 3, the v a r i a b l e input modality g e s t u r a l f a c t o r , the performance o f Groups I , I I , and I I I was s i m i l a r and s i g n i f i c a n t l y l e s s impaired than the other groups. Groups TV and VI's performance was s i m i l a r , but Group IV performed s i g n i f i c a n t l y b e t t e r than Group V. For F a c t o r 4, the. pantomime - g e s t u r a l dimension, the performance o f Groups I and I I was s i m i l a r w i t h Group I being s i g n i f i c a n t l y b e t t e r than the other f o u r groups. Group V was the most impaired group being s i g n i f i c a n t l y lower than a l l other groups. Groups VI and IV were s i m i l a r and s i g n i f i c a n t l y more impaired than Group I I . Group I I I f e l l between Group I I and Group V I . For F a c t o r 5 , the v i s u a l - p e r c e p t u a l f a c t o r s , Groups I and I I I were l e a s t impaired and s i m i l a r . I n a d d i t i o n , these groups were s i g n i f i c a n t l y l e s s impaired than Groups IV, V or V I . Groups V and V I were most impaired and s i g n i f i c a n t l y more impaired than a l l other groups. Group TV f e l l between these two extremes, being s i g n i f i c a n t l y l e s s impaired than Groups V and V I , but s i g n i f i c a n t l y more impaired than Groups 56 TABLE 14 Scheffe M u l t i p l e Conparisons on Factors by Group (Homogenous Groups are Underlined) Group3" F a c t o r High Low I I I I VI I I I rv V 2 I I I I I I IV VI V 3 I I I I I I IV . VI V 4 I I I I I I IV VI V 5 I I I I I I IV V VI 57 I and I I I . Group I I was s i m i l a r t o Groups I and IV, but s i g n i f i c a n t l y more impaired than Group I I I . Q u a l i t a t i v e Statements Concerning Groupings Group 1: This group was the l e a s t Impaired group on f o u r o f the f i v e f a c t o r s . On F a c t o r 5, Group I I performed b e t t e r , but not s i g n i f i c a n t l y b e t t e r . Therefore, Group I may be termed as showing m i l d impairment on a l l f i v e dimensions of language a b i l i t y . Group I I : Group I I e x h i b i t e d s i g n i f i c a n t l y more impairment than Group I on only the second f a c t o r . On a l l other f a c t o r s the mean scores were lower, but not s i g n i f i c a n t l y . These f i n d i n g s would suggest t h a t t h i s group may be described as e x h i b i t i n g m i l d t o moderate impairment of language a b i l i t i e s . Group I I I : This group e x h i b i t e d s i g n i f i c a n t l y more impairment than Group I on three o f the f i v e f a c t o r s , F a c t o r s 1, 2 and 4. On three o f the f i v e f a c t o r s , Groups I I and I I I were s i m i l a r . On F a c t o r 1, Group I I I showed s i g n i f i c a n t l y more impairment but on F a c t o r 5, t h i s t r e n d was reversed. However, as the r e l a t i o n s h i p between F a c t o r 5 and language a b i l i t i e s per se was tenuous, t h i s group may be l a b e l l e d as e x h i b i t i n g moderate impairment. Group IV: This group e x h i b i t e d s i g n i f i c a n t l y more impairment on a l l f i v e f a c t o r s than Group I . More i m p o r t a n t l y i t performed at a s i g n i f i -c a n t l y lower l e v e l than Group I I I on three o f the f i v e f a c t o r s . These f i n d i n g s would I n d i c a t e t h a t t h i s group e x h i b i t e d moderate t o severe impairment. 58 Group V: On a l l f i v e factors., t h i s group e x h i b i t e d s i g n i f i c a n t l y more Impairment than Groups I , I I or I I I . On Fact o r s 3, 4 and 5, t h i s group's performance was s i g n i f i c a n t l y more Impaired than Group IV. E x c l u d i n g Group V I , t h i s group had the lowest mean score on a l l f i v e f a c t o r s . Therefore, t h i s group may be de s c r i b e d as e x h i b i t i n g severe impairment of language a b i l i t i e s . Group VI: Given the s m a l l s i z e of t h i s group (n = 4), the r e s u l t s on t h i s group must be viewed c a u t i o u s l y as they may be i d o s y n c r a t i c t o t h i s p a r t i c u l a r sample. However, t h i s group had the only p r o f i l e which was c o n s i s t e n t w i t h a s a l i e n t f e a t u r e o r d e f i c i t model o f aphasia. S p e c i f i c a l l y , t h i s group was s i m i l a r t o Groups I and I I on the v e r b a l f l u e n c y f a c t o r , thus suggesting m i l d t o moderate d e f i c i t s i n t h i s area. However, on F a c t o r 5, the mean score o f 23.9 was suggestive o f gross impairment and was s i m i l a r t o the mean obtained by Group V, only lower. On F a c t o r s 2 , 3 and 4, t h i s group's mean score f e l l between Groups IV and V and thereby a l s o performed a t s i g n i f i c a n t l y lower l e v e l than Group I . Therefore, t h i s group may be described as e x h i b i t i n g m i l d impairment i n v e r b a l f l u e n c y , moderate t o severe d e f i c i t s I n w r i t i n g and g e s t u r a l s k i l l s and gross Impairment I n copying t a s k s . 59 CHAPTER V DISCUSSION AND CONCLUSION I n t r o d u c t i o n The purpose of t h i s study was t o explore a methodological procedure f o r the examination and I d e n t i f i c a t i o n of sub-populations w i t h an a t y p i c a l p o p u l a t i o n . Therefore, t h i s d i s c u s s i o n i s d i v i d e d Into two p a r t s . The f i r s t considers the f i n d i n g s o f t h i s study w i t h i n the context o f current aphasia theory and, i n p a r t i c u l a r , i nstrumentation. The second attempts t o i l l u s t r a t e the p l a c e and p o t e n t i a l of t h i s type of a n a l y s i s procedure I n the I n i t i a l assessment o f other a t y p i c a l p o p u l a t i o n s . The r e s u l t s of t h i s study are used as concrete examples of the research p o t e n t i a l of t h i s type o f a n a l y s i s . L i m i t a t i o n s of t h i s Study Before examining the a c t u a l f i n d i n g s and i m p l i c a t i o n s o f t h i s study t o aphasia theory and r e s e a r c h , c e r t a i n l i m i t a t i o n s w i t h i n t h i s study should be reviewed. F i r s t , the l i m i t e d sample s i z e suggests t h a t the findings- should be viewed c a u t i o u s l y I n terms o f g e n e r a l i z a t i o n . A c c o r d i n g l y , experimental r e p l i c a t i o n across d i f f e r e n t samples i s advised before u s i n g the o u t l i n e d c a t e g o r i z a t i o n system and d e r i v e d f a c t o r domains i n a treatment-oriented research design. Second, the c a t e g o r i z a t i o n system only p e r t a i n s t o the P.I.C.A. and t h e r e f o r e may be Inappropriate f o r other aphasia assessment Instruments. T h i r d , the s t a t i s t i c a l procedures used are designed t o g i v e optimal o r maximal s o l u t i o n s w i t h i n the c o n s t r a i n t s o f the data. Therefore, the reporte d r e s u l t s a r e , I n a l l p r o b a b i l i t y , estimates o f upper, not lower, bounds. 60 With respect t o t h i s sample r e p r e s e n t i n g an aphasic group, the subtest means suggest language Impairment c o n s i s t e n t w i t h the dia g n o s i s of aphasia. I n a d d i t i o n , when compared t o Porch's s t a n d a r d i z a t i o n sample, t h i s group d i d not score s i g n i f i c a n t l y d i f f e r e n t l y on any s p e c i f i c subtest although over a l l comparisons a s i g n i f i c a n t H o t e l l l n g ' s T 2 was obtained. However, two subtests ( V I I I and XI) were discarded because o f observed c e l l i n g e f f e c t s . Therefore, only s i x t e e n o f Porch's eighteen subtests were Included f o r f u r t h e r a n a l y s i s . F a c t o r A n a l y s i s The f a c t o r a n a l y s i s procedure employed suggested t h a t a f i v e - f a c t o r s o l u t i o n would be best f o r the data c o l l e c t e d i n t h i s study. T h i s s o l u t i o n accounted f o r 90.6% of the t o t a l variance among the s i x t e e n post-treatment s u b t e s t s , thus I n d i c a t i n g t h a t the s k i l l s assessed by t h i s b a t t e r y may be described by s u b s t a n t i a l l y fewer than s i x t e e n dimensions or t e s t s . The e x c l u s i o n o f subtests V I I I and XI s p l i t Porch's g e s t u r a l dimension i n t o two h i g h l y c o r r e l a t e d f a c t o r s . I n the f a c t o r a n a l y s i s of Porch's o r i g i n a l data, ( C l e r k et a l , i n p r e s s ) , these two subtests ( V I I I and XI) anchored Porch's g e s t u r a l dimension ( t h e i r r e s p e c t i v e loadings being O.96 and O.89). This 'anchoring' i s s t a t i s t i c a l l y r e l a t e d t o the o r i g i n a l l a c k o f v a r i a n c e i n these two subtests. I n the present study, the e x c l u s i o n o f these two subtests y i e l d e d two g e s t u r a l f a c t o r s , which i n t u r n l e d t o a r e d u c t i o n o f f a c t o r i a l complexity among the g e s t u r a l v a r i a b l e s . S p e c i f i c a l l y , I n the present a n a l y s i s only one of the s i x g e s t u r a l subtests was complex; w h i l e the f a c t o r a n a l y s i s of Porch's s t a n d a r d i z a t i o n sample y i e l d e d f o u r f a c t o r i a l l y complex g e s t u r a l v a r i a b l e s . 61 This f i v e f a c t o r s o l u t i o n a l s o separated Porch's graphic dimension i n t o two f a c t o r s . The f o u r graphic subtests which r e q u i r e d a w r i t t e n response (A, B, C, D) defined one dimension, w h i l e the two graphic subtests (E, P) r e q u i r i n g a copying response, i d e n t i f i e d the second. Other than the d i f f e r e n t i a t i o n of the two hypothesized f a c t o r s Into f o u r s u b - f a c t o r s , the r e s u l t s o f t h i s f a c t o r a n a l y s i s were remarkably c o n s i s t e n t w i t h both Porch's f o r m u l a t i o n and the f a c t o r a n a l y s i s performed on Porch's i n i t i a l data f o r h i s t e s t b a t t e r y . S p e c i f i c a l l y , w i t h respect t o Porch's f o r m u l a t i o n s , a v e r b a l , two g e s t u r a l and two graphic dimensions could be i d e n t i f i e d . More i m p o r t a n t l y , only one subtest (I) loaded across m o d a l i t i e s ( i . e . having r e l a t i v e l y h i g h loadings on both v e r b a l and g e s t u r a l dimensions). Although i t was f a c t o r i a l l y complex, subtest V loaded on the two g e s t u r a l dimensions. The f i v e d e r i v e d f a c t o r s are c o n s i s t e n t w i t h p r e v i o u s l y suggested dimensions of aphasic d i s o r d e r s . F a c t o r 1 , the v e r b a l f l u e n c y dimension, i s c l e a r l y r e l a t e d t o Howes f l u e n t / d y s f l u e n t continuum or dichotomy (Howes, 1 9 6 4 ) . F a c t o r 2 , the w r i t i n g dimension,has been c l i n i c a l l y l a b e l l e d agraphia, the I n a b i l i t y t o w r i t e words (Walton, 1 9 7 4 ) . More Importantly, d i s r u p t i o n I n t h i s s k i l l has been, a s s o c i a t e d w i t h three d i s c r e t e types o f aphasia, namely, t r a n s c o r t i c a l sensory aphasia, t r a n s c o r t i c a l motor aphasia and a l e x i a w i t h agraphia (Goodglass and Geschwind, 1 9 7 5 ) . F a c t o r 3 , a g e s t u r a l output modality u s i n g a v a r i e t y of input m o d a l i t i e s , supports the m u l t i - m o d a l i t y model of Wepman and Jones ( 1 9 6 l ) . F a c t o r 4 , the pure g e s t u r a l dimension, i s i n accord w i t h the assessment of pantomime I n aphasia (Goodglass, 1 9 6 3 ) . F a c t o r 62 5, the copying dimension, may not represent a t r u e dimension of aphasia. S p e c i f i c a l l y , the i n a b i l i t y t o copy designs or l e t t e r s does not r e q u i r e comprehension or expression w i t h a symbolic language model. However, the dimension may represent a general a p r a x i a , the I n a b i l i t y t o c a r r y out a ' w i l l e d ' motor response even though motor and sensory pathways are I n t a c t (Walton, 1974). The f i n d i n g s t h a t (1) the d e r i v e d f a c t o r s can be r e l a t e d t o b e h a v i o u r a l d e f i c i t s a s s o c i a t e d w i t h aphasia; (2) t h i s and the previous f a c t o r a n a l y s i s done on t h i s b a t t e r y are r e l a t i v e l y c o n s i s t e n t ; and (31 the support f o r Porch's hypothesized dimension support the construct v a l i d i t y o f the P.I.C.A. However, what i s of f u r t h e r I n t e r e s t I n regard t o t h i s b a t t e r y i s the magnitude, o f the I n t e r f a c t o r c o r r e l a t i o n s , both I n t h i s and the previous study. For t h i s sample, the f a c t o r s were more h i g h l y c o r r e l a t e d than f o r the previous one. S t a t i s t i c a l l y , these h i g h e r I n t e r f a c t o r c o r r e l a t i o n s are i n p a r t accounted f o r by the Increase I n factors. (5 versus 3) which reduced the f a c t o r i a l complexity and allowed s p e c i f i c dimensions t o be b e t t e r d e f i n e d . For example, the highest i n t e r - f a c t o r c o r r e l a t i o n was between the two g e s t u r a l f a c t o r s ( r = Q.70). Therefore, although, a higher order f a c t o r a n a l y s i s was not done, the h i g h i n t e r c o r r e l a t i o n s between F a c t o r s 1 t o 4 again suggested a. h i g h e r order f a c t o r o f general language a b i l i t i e s . F a c t o r 5 appeared t o be somewhat o f an o u t r i d e r t o t h i s model. This f a c t o r has a r e l a t i v e l y low c o r r e l a t i o n w i t h F a c t o r 1 ( r = 0.26) and, although the magnitude o f the remaining i n t e r - f a c t o r c o r r e l a t i o n s w i t h F a c t o r 5 were higher (0.50, 0.48, Q.43), they were s t i l l lower than a l l other i n t e r - f a c t o r c o r r e l a t i o n s (range 0.60 t o 0.70). Perhaps Facto r 5 r e q u i r e s a non-language s k i l l (e.g. v i s u a l a c u i t y ) together 63 w i t h a motor response congruent w i t h F a c t o r s 2, 3, and 4. Such a hypothesis would c a l l i n t o q u e stion the v a l i d i t y o f subtests E and F as measures o f language a b i l i t i e s . H i e r a r c h i c a l A n a l y s i s The h i e r a r c h i c a l grouping a n a l y s i s added f u r t h e r support f o r a general s e v e r i t y model of aphasia. A l t o g e t h e r s i x groups were i d e n t i -f i e d . F i v e o f these were ordered upon a s e v e r i t y continuum, not a s a l i e n t f eatures model. For these f i v e groups s i g n i f i c a n t changes i n o r d i n a l r a n k i n g o f means only occurred once on the f i v e f a c t o r s . I n a d d i t i o n , t h i s ' s i g n i f i c a n t ' crossover occurred on F a c t o r 5-The s i x t h I d e n t i f i e d group was i n c o n s i s t e n t w i t h t h i s s e v e r i t y model. However, t h i s group was s m a l l (n = 4) and i t s lowest mean was on F a c t o r 5. I n a d d i t i o n , t h i s group was equivalent t o the l e a s t impaired groups on the v e r b a l f l u e n c y f a c t o r and e x h i b i t e d moderate impairment on the remaining f a c t o r s . Therefore, the question a r i s e s whether t h i s group's most s a l i e n t d e f i c i t was 'aphasia'. I n other words, i n d i v i d u a l s i n t h i s group may have e x h i b i t e d m i l d aphasic symptoms, but i n a d d i t i o n they may have had more extensive damage t o other b r a i n mechanisms. Given the low r e p r e s e n t a t i o n w i t h i n t h i s group, any statements concerning I t must be viewed j u d i c i o u s l y . Besides the q u a l i t a t i v e aspects o f t h i s grouping procedure, o v e r a l l e f f i c a c y I n terms of v a r i a b i l i t y c o n s i d e r a t i o n s and p r e d i c t i o n r a t e s were extremely impressive. I n terms o f o v e r a l l v a r i a b i l i t y , the six-group s o l u t i o n suggested t h a t the groups were r e l a t i v e l y homo-genous, w i t h 79 .0% of the t o t a l v a r i a b i l i t y between groups. The m u l t i p l e d l s c r i i n i n a n t a n a l y s i s p r e d i c t i o n r a t e o f 91.2% provided f u r t h e r c o n f i r m a t i o n , 64 suggesting there was v i r t u a l l y no overlap between groups i n m u l t i -v a r i a t e space. Grouping and Current Aphasia Theory When s p e c i f i c f a c t o r dimensions r e l a t i v e t o d e r i v e d groups are examined, the r e l a t i o n s h i p between these dimensions and current aphasia models becomes apparent. As mentioned e a r l i e r , F a c t o r 1 c l e a r l y represents Howe's v e r b a l f l u e n c y dimension. More i m p o r t a n t l y , I f one examines the r e l a t i v e group s i z e s and t h e i r d i s t r i b u t i o n along the f a c t o r , i t I s c l e a r how a dichotomous model of v e r b a l f l u e n c y / d y s f l u e r i c y can be evolved. I n a d d i t i o n , g iven the r e p o r t e d F-value and the number of s i g n i f i c a n t d i f f e r e n c e s found, a two^group a n a l y s i s Cue, f l u e n t / d y s f l u e n t ) , would i n a l l p r o b a b i l i t y produce, a s i g n i f i c a n t d i f f e r e n c e . S p e c i f i c a l l y , Groups I , I I and V I (n = 331 would be Howes ' f l u e n t ' aphasics w h i l e Groups IV and V (n = 24} would be termed 'dysfluent'. Group II I : (n = 15). does, f a l l between these two c a t e g o r i e s , but I n Howes' model the h i g h scores would be f l u e n t , the low scores d y s f l u e n t . However, by u s i n g the grouping procedure employed here, i t i s apparent t h a t f l u e n c y s k i l l s I n f a c t are d i s t r i b u t e d along a continuum and are not p u r e l y dichotomous. S i m i l a r arguments can be made f o r the w r i t i n g and the two g e s t u r a l dimensions I n terms of t h e i r r e p r e s e n t a t i o n I n aphasia models". A c c o r d i n g l y , the f i n d i n g s i n d i c a t e d the l i m i t a t i o n s o f examining aphasia on a u n i - v a r i a t e model with, respect t o developing a theory of aphasia. Conclusions Relevant t o the"P.I.C.A. Although, the P.I.C.A. i s a w e l l - s t a n d a r d i z e d and recognized aphasia 65 b a t t e r y , the r e s u l t s obtained i n t h i s study suggested t h a t a t most I t measured f i v e , dimensions o f language/communication a b i l i t y and th a t these dimensions were h i g h l y i n t e r - r e l a t e d . Such f i n d i n g s may i n d i c a t e t h a t the P.I.C.A. I s a more elaborate t e s t than necessary, i n t h a t many of the subtests may be redundant or provide minimal unique i n f o r m a t i o n w i t h respect t o communication a b i l i t i e s per se. S p e c i f i c a l l y , subtests V I I I and XI appeared t o be too easy f o r both the subjects I n t h i s sample and i n Porch's sample. Subtests E and F d i d not appear t o be d i r e c t l y r e l a t e d t o symbolic language f o r m u l a t i o n . With the e x c l u s i o n of these f o u r t e s t s , the b a t t e r y s t i l l uses fou r t e e n subtests t o assess a suggested continuum of impairment. For the c l i n i c i a n these r e s u l t s suggest t h a t p a r t i c u l a r a t t e n t i o n be p a i d t o the l e v e l o f d i f f i c u l t y when monitoring treatment gains. S p e c i f i c a l l y , the noted c e l l i n g e f f e c t on subtests V I I I and XI may 'wash out' Improvement I n g e s t u r a l s k i l l s . I n e f f e c t , u s i n g these two subtests i s s i m i l a r t o adding a constant, and thus they may I n f l a t e I n i t i a l mean scores. For example, I f an i n d i v i d u a l scores p e r f e c t l y on a l l e i g h t g e s t u r a l t a s k s , the o v e r a l l g e s t u r a l mean I s 15-0. I n comparison, another i n d i v i d u a l may score t e n on the s i x other g e s t u r a l t a s k s and f i f t e e n on subtests V I I I and XI (not an u n l i k e l y set of scores) and thus o b t a i n an o v e r a l l mean o f 11.25. Because o f the c e l l i n g on t e s t s V I I I and X I , the. r e a l d i f f e r e n c e between these two i n d i v i d u a l s I s lessened (3-75 u n i t s not 5-0). More i m p o r t a n t l y , i f the second I n d i v i d u a l Improves on each o f the s i x subtests by 2.0 u n i t s , the o v e r a l l mean can only r i s e by 1.5 u n i t s , thus under-e s t i m a t i n g the r e a l improvement. As the subtests appear t o be h i g h l y 66 r e l i a b l e , i t may be worthwhile t o consider them independently i n terms of r e t e s t . Or, a f t e r the I n i t i a l assessment the c l i n i c i a n c ould s e l e c t a group of subtests which would be repeated on r e t e s t based on a subject's performance. Although t h i s procedure would v i o l a t e standard-i z a t i o n procedures, i t would provide a more accurate estimate of t r u e gains and be more economical i n terms of time. Two concerns of t h i s procedure are s t a t i s t i c a l r e g r e s s i o n and maturation o r , s p e c i f i c a l l y , spontaneous recovery. However, changes measured by the Instrument which are a r e s u l t o f spontaneous recovery, do not i n d i c a t e t h a t the Instrument i s not measuring r e a l changes r a t h e r c a u s a t i o n I s undermined. However, t h i s procedure I s s u s c e p t i b l e t o s t a t i s t i c a l r e g r e s s i o n towards the mean and the c l i n i c i a n t h e r e f o r e should s e l e c t both above and below the s t a n d a r d i z a t i o n mean whenever p o s s i b l e . To the r e s e a r c h e r , these r e s u l t s suggest t h a t i n i t i a l grouping of an aphasic sample should be done on s e v e r i t y continuum i f the P.I.C.A. i s the dependent measure. I n a d d i t i o n , the f a c t o r a n a l y s i s suggested at a maximum the P.I.C.A. measures f i v e dimensions of communication a b i l i t i e s not eighteen. This r e d u c t i o n i n dependent v a r i a b l e s gains considerable s t a t i s t i c a l power and reduces the p o t e n t i a l o v e r a l l experiment-wise e r r o r r a t e . I n a d d i t i o n , model or conceptual development Is l e s s cumbersome. I n i t i a l subests means and standard d e v i a t i o n should be reviewed w i t h respect t o c e i l i n g e f f e c t s as s p e c i f i c subtests appear too easy f o r a l l s u b j e c t s . 67 METHODOLOGICAL CONCERNS I n t r o d u c t i o n With respect t o . a t y p i c a l p opulations i n g e n e r a l , the o u t l i n e d procedures may provide i n s i g h t I n to b e t t e r d e l i n e a t i o n o f these populations. The aphasic sample used here f o r explanatory purposes has much i n common w i t h other a t y p i c a l p o pulations. S p e c i f i c a l l y , aphasics can be d i f f e r e n t i a t e d from the general p o p u l a t i o n due t o d e f i c i t s I n language a b i l i t i e s . Although, these d e f i c i t s . a r e r e l a t e d t o brain-behaviour r e l a t i o n s h i p s , many other p o p u l a t i o n s e x i s t which can be d i f f e r e n t i a t e d from the g e n e r a l p o p u l a t i o n based on s p e c i f i c areas o f d e f i c i t s . Examples o f these populations" are the deaf, r e a d i n g d i s a b l e d , l e a r n i n g d i s a b l e d , m i n i m a l l y b r a i n damaged, e p i l e p t i c s or p s y c h i a t r i c p o p u l a t i o n s . F o r each, of these p o p u l a t i o n s , i t i s p o s s i b l e t o d i f f e r e n t i a t e the p o p u l a t i o n from normals and u s u a l l y there i s one main dimension f o r t h i s d i s c r i m i n a t i o n . Once the p o p u l a t i o n i s I d e n t i f i e d , however, I t v i o l a t e s the 'true' experimental paradigm I n the same manner as the aphasic p o p u l a t i o n . Therefore, the question of i n t r a - p o p u l a t i o n distribution,becomes important with, respect t o research i n t o remediation. Dependent upon the h i s t o r i c a l l e v e l o f enquiry i n t o such p o p u l a t i o n s , the researcher must chose the a p p r o p r i a t e l e v e l f o r I n i t i a l i n v e s t i g a t i o n . For example, a p h a s i o l o g l s t s have developed s e v e r a l conceptual models of c l a s s i f i c a t i o n as w e l l as some ps y c h o m e t r i c a l l y appealing t e s t b a t t e r i e s . By u s i n g m u l t i v a r i a t e techniques i t was p o s s i b l e i n t h i s study t o examine these conceptual c l a s s i f i c a t i o n models and an e m p i r i c a l l y d e r i v e d c l a s s i f i c a t i o n model t o be explored and f u r t h e r developed. 68 F a c t o r A n a l y s i s The power o f m u l t i v a r i a t e designs i s r e l a t e d t o the number of dependent v a r i a b l e s , groups and s u b j e c t s . I d e a l l y , the number of dependent v a r i a b l e s should be minimized and yet r e p r e s e n t a t i v e of the domain of s k i l l s b e i n g sampled (e.g.. language/communication a b i l i t i e s ) . F a c t o r a n a l y s i s a l l o w s the researcher t o f u l l f i l these r e s t r a i n t s , given t h a t the I n i t i a l t e s t b a t t e r y I s r e l i a b l e and at some p o i n t v a l i d . I d e a l l y , a set of Independent f a c t o r score c o e f f -i c i e n t s enhances the a c c e p t a b i l i t y of such a procedure. I n the case re p o r t e d here, the f a c t o r score c o e f f i c i e n t s are not independent but o u t s i d e v a l i d i t y measures i n d i c a t e t h a t the f a c t o r s t r u c t u r e o f the P.I.C.A. i s reasonably s t a b l e and c o n s i s t e n t w i t h hypothesized dimensions. One Issue which has long plagued f a c t o r a n a l y s t s i s how t o determine the number of f a c t o r s t o be r e t a i n e d . This study e s t a b l i s h e d a minimum by u s i n g the K a i s e r Guttman Rule and maximum by u s i n g a Scree Test from the r i g h t s i d e of the eigenvalue p l o t . P o s s i b l e s o l u t i o n s were then submitted t o an unweighted l e a s t squares a n a l y s i s and the r e s i d u a l c o r r e l a t i o n matrices examined. This procedure suggested t h a t f i v e f a c t o r s , two more than suggested by the K a i s e r -Guttman Rule, best represented the dimensions w i t h i n the P.I.C.A. This study should emphasize the n e c e s s i t y of u s i n g m u l t i p l e c r i t e r i a when determining the number o f f a c t o r s t o be r e t a i n e d . I n a d d i t i o n , a f u r t h e r c r i t e r i a of i n t e r p r e t a b i l l t y should be a p p l i e d t o the f i n a l f a c t o r p a t t e r n matrix. O v e r a l l , the d e r i v e d f a c t o r s and the v a r i a b l e loadings were co n c e p t u a l l y c o n s i s t e n t i n t h i s study. 69 H i e r a r c h i c a l A n a l y s i s Once the minimum number o f r e p r e s e n t a t i v e dependent v a r i a b l e s has been d e l i n e a t e d , the second means of g a i n i n g s t a t i s t i c a l power i n a m u l t i v a r i a t e design i s by m i n i m i z i n g the number o f groups. However, because of variance and covariance c o n s i d e r a t i o n s , these groups should be as i n t e r n a l l y homogeneous as p o s s i b l e . In t h i s p a r t i c u l a r case, the c l u s t e r a n a l y s i s suggested t h a t a six-group s o l u t i o n best f i t these c r i t e r i a . S p e c i f i c a l l y , the number of p o t e n t i a l groups was reduced from 72 t o 6, w i t h only 21% o f the t o t a l m u l t i v a r i a t e v a r i a b i l i t y w i t h i n the groups. More i m p o r t a n t l y , t h i s s o l u t i o n i n d i c a t e d t h a t subjects should be grouped on a s e v e r i t y continuum r a t h e r than I n terms of a s a l i e n t f e a t u r e s model. This f i n d i n g i n i t s e l f i s o f b e n e f i t i n t h a t the s a l i e n t f e a t u r e s model i s the accepted grouping procedure, both f o r r e s e a r c h and c l i n i c a l p r a c t i c e . Therefore, i n a d d i t i o n t o p r o v i d i n g an 'optimal' grouping procedure, t h i s a n a l y s i s a l s o r a i s e d questions concerning the o v e r a l l conceptual v a l i d i t y o f many aphasia models. Although c l u s t e r a n a l y s i s does c a p i t a l i z e upon e r r o r , thus I n f l a t i n g the between-group v a r i a b i l i t y estimates, t h i s aspect of the a n a l y s i s does not a f f e c t c onclusions drawn from the group p r o f i l e s . In t h i s p a r t i c u l a r study, the step-wise d i s c r i m i n a n t a n a l y s i s suggested the amount o f overlap i n m u l t i v a r i a t e space between these s i x groups was minimal. Again, however, experimental r e p l i c a t i o n should be s t r e s s e d as the means f o r e s t a b l i s h i n g both the s t a b i l i t y and g e n e r a l -I z a b l l i t y o f these r e s u l t s . 70 D i r e c t i o n s f o r Future Research As w i t h a l l experimental s t u d i e s , the f i r s t recommendation f o r f u t u r e research i s r e p l i c a t i o n o f t h i s study. As the f i n d i n g s i n t h i s study are strong i n terms o f aphasia, r e p l i c a t i o n would provide estimates o f t h e i r s t a b i l i t y and g e n e r a l i z a b i l i t y . I f the f i n d i n g s were found to.be both s t a b l e and appropriate f o r other aphasic samples, then a model of grouping f o r treatment could be evolved t o evaluate d i f f e r e n t i a l treatment e f f i c a c i e s . The second l i m i t a t i o n o f these f i n d i n g s i s g e n e r a l i z i n g from these r e s u l t s t o other aphasia Instruments. Although the P.I.C.A. i s p s y c h o m e t r l c a l l y the best instrument t o evaluate aphasia, I t may be co n c e p t u a l l y b i a s e d towards a s e v e r i t y model of aphasia. Therefore, t o develop a s t a t i s t i c a l or e m p i r i c a l model of aphasia, other aphasia instruments should be analyzed u s i n g these procedures. I f the groupings or group p r o f i l e s appear t o be a f u n c t i o n of i n s t r u m e n t a t i o n , then one must conclude t h a t the instruments are c o n c e p t u a l l y biased. I f , however, the 'groupings' appear t o be a f u n c t i o n o f s e v e r i t y or impairment, then one must conclude t h a t aphasia i s a general d e f i c i t a f f e c t i n g language a b i l i t i e s . I f the l a t t e r c o n c l u s i o n I s found, then there are d e f i n i t e i m p l i c a t i o n s f o r the d i f f e r e n t i a t i o n o f c l i n i c a l / t r e a t m e n t and brain/behaviour s t u d i e s or research. I n a d d i t i o n , the p a t i e n t s used i n t h i s study had traumatic i n s u l t t o the b r a i n . The nature of the I n s u l t suggests t h a t l a r g e areas o f the cortex were probably Involved and t h e r e f o r e one may assume th a t the b e h a v i o u r a l l o s s e s were a c c o r d i n g l y more general than I n the case 71 o f a d i s c r e t e s m a l l l e s i o n (e.g. e p i l e p s y ) . However, traumatic h i s t o r i e s now account f o r the vast m a j o r i t y o f aphasics. F i n a l l y , t h i s study r a i s e s some question concerning the number o f u s e f u l subtests on the P.I.C.A. and the number o f f a c t o r s o r dimensions o f language dimensions• being measured by t h i s instrument. By excluding two ' c e l l i n g ' g e s t u r a l s u b t e s t s , the i n i t i a l p o s t u l a t e d g e s t u r a l dimension subdivided i n t o two f a c t o r domains. With t h i s r e d u c t i o n I n subtests the graphic dimension was a l s o subdivided as subtests E and F had more weight I n the a n a l y s i s (12.5% r a t h e r than 11.1% of the t o t a l v a r i a n c e ) . This brealcing o f the graphic dimension i n t o two makes more inherent conceptual sense as subtests E and F do not t r u l y r e q u i r e language a b i l i t i e s . Moreover, these r e s u l t s suggest t h a t subtests VTII and XI add minimal Information t o c l i n i c a l i n t e r p r e t a t i o n o f the P.I.C.A. and may i n f a c t d i s t o r t r e a l d i f f e r e n c e s among subjects and hide improvement f o r a s p e c i f i c s u b j e c t . Therefore, these r e s u l t s suggested t h a t a r e v i s i o n of the P.I.C.A. co u l d provide a more economical instrument i n terms o f time., and a more accurate instrument i n terms o f assess i n g the degree o f language impairment and the degree o f improvement f o l l o w i n g treatment. 72 APPENDIX A F a c t o r A n a l y s i s o f Porch's S t a n d a r d i z a t i o n Sample 73 APPENDIX A TABLE 1 Factor Pattern Matrix Harris Kaiser Oblique Transformation c = 0.3 Group Test Factor 1 . Factor 2 Factor 3 1 0.78 0.21 0.05 IV 0.88 0.13 0.06 Verbal IX 0.87 0.13 0.06 XII 0.76 0.04 ,. . 0.18 A 0.13 0.83 0.00 B 0.09 0.92 0.00 C 0.00 0.95 0.04 Graphic D 0.12 0.86 0.06 E 0.01. 0.68 0.28 F 0.07 0.37 0.59 I I 0.15 0.25 0.62 I I I 0.17 0.24 0.60 V 0.12 0.44 0.40 Gestural VI 0.36 0.02. 0.65 VII 0.11 0.39 0.49 VIII 0.13 0.05 0.96 X 0.37 0.08 0.67 XI. . . . 0.09, 0.16. 0.89 74 APPENDIX A TABLE 2 Factor Correlation Matrix Factor 1 2 3 1 1.00 2 0.51 1.00 3 0.52 0.50 1.00 75 REFERENCES C a r r o l l , J.A. A f a c t o r a n a l y s i s o f v e r b a l a b i l i t i e s . Psychometrika, 1 9 4 1 , 6 , 2 7 9 - 3 0 7 . C a t t e l , R.B. The scree t e s t f o r the number o f f a c t o r s . M u l t i v a r i a t e  B e h a v i o u r a l Research, 1 9 6 6 , 1 , 245-257. C l a r k , C , Cr o c k e t t , D., & K l o n o f f , H. F a c t o r a n a l y s i s o'f the Porch Index o f Communication A b i l i t y . B r a i n and Language ( i n p r e s s ) . C r o c k e t t , D. M u l t i v a r i a t e comparison o f Howes' and Weisenburg and McBride's models o f aphasia on the Neurosensory Center Comprehensive Examination. P e r c e p t u a l and Motor S k i l l s , 1 9 7 6 , 4 3 , 7 9 5 - 8 0 6 . Eisenson, J . Examining f o r aphasia. New York: P s y c h o l o g i c a l Corporation, 1 9 5 4 . Eisenson, J . Aphasia I n a d u l t s : b a s i c c o n s i d e r a t i o n s . I n T r a v i s (Ed), the Handbook o f Speech Pathology and Audiology, New- York, Appleton-Century-Crofts, 1971-F i s h e r , R.A. The design of experiments. London: O l i v e r and Boyd, 1935-G e r s t e i n , J.S. R e h a b i l i t a t i o n p o t e n t i a l . I n J . L i c h t (Ed), Stroke and I t s R e h a b i l i t a t i o n , Baltimore,: Waverly Press I n c . , 1 9 7 5 . Golden, J . Dynamics of head i n j u r y . J o u r n a l of P h y s i c a l R e h a b i l i t a t i o n , 1 9 7 7 , 1 5 , 5 9 - 7 4 . Goodglass, H., & Geschwind, N. Language d i s o r d e r . I n Jones (Ed) the Handbook o f P e r c e p t i o n , Speech and Language, New York: Academic P r e s s , 1975-Goodglass, H., Hyde, M., & Blumstein, S. Frequency p i c t u r a b l l i t y and the a v a i l a b i l i t y o f nouns i n aphasia. Cortex, 1 9 6 9 , 3 , 104-112. Goodglass, H., & Kaplan, E. The assessment o f aphasia and r e l a t e d d i s o r d e r s . P h i l a d e l p h i a : Lea and Febiger, 1 9 7 2 . Gorsuch, R. F a c t o r a n a l y s i s . P h i l a d e l p h i a : Saunders, 1 9 7 4 . Guttman, L. Some necessary c o n d i t i o n s f o r common f a c t o r a n a l y s i s . Psychometrika, 1 9 5 4 , 1 9 , 149-1.84. Hakstian, A.R. A computer program f o r oblique f a c t o r t r a n s f o r m a t i o n u s i n g the g e n e r a l i s e d H a r r i s - K a i s e r procedure. E d u c a t i o n a l and P s y c h o l o g i c a l  Measurement, 1 9 7 0 , 3 0 , 7 0 3 - 7 3 6 . H a k s t i a n , A.R., & Bay, K.S. A l b e r t a g e n e r a l f a c t o r a n a l y s i s programme (AGFAP), U n i v e r s i t y o f A l b e r t a : D i v i s i o n o f E d u c a t i o n a l Research S e r v i c e s , 1 9 7 2 . 76 Halstead, W.C., & Wepman,- J.M. The Halstead-Wepman aphasic screening t e s t . J o u r n a l o f Speech arid Hearing D i s o r d e r s , 1 9 5 9 , 14, 9 - 1 5 . Head, J . Aphasia and k i n d r e d d i s o r d e r s of speech, V o l . 1 & 1 1 , London: Hafner, 1926^ Howes, D. A p p l i c a t i o n of the word-frequency concept t o aphasia. I n (A.V.S. de Reuch and M O'Connor (Eds), LBA Foundation Symposium on Disorders o f Language, Boston: L i t t l e Brown and Company, 1 9 6 4 . Howes, D., & Geschwind, M. Q u a n t i t a t i v e s t u d i e s of aphasic language. I n D. Rioch and E. Welnstein (Eds), Disorders of Communication, Balt i m o r e : W i l l i a m s and W l l k l n s , 196T~. K l o n o f f , H., Low, M., & C l a r k , C. Head i n j u r i e s I n c h i l d r e n : a p r o s p e c t i v e f i v e year study. J o u r n a l of Neurology, Neurosurgery and  P s y c h i a t r y , 1 9 7 7 , 4 b , 1 2 1 1 - 1 2 1 9 . Lezak, M. Neuropsychological assessment. New York: Oxford U n i v e r s i t y P r e s s , 1976^ L u r i a , A. Higher c o r t i c a l f u n c t i o n s i n man. New York: B a s i c Books, 1 9 6 6 . M i l n e r , B. Interhemlspherlc d i f f e r e n c e s i n the l o c a l i z a t i o n of p s y c h o l o g i c a l proccesses i n man. B r i t i s h M edical B u l l e t i n , 1 9 7 2 . 1 7 , 2 7 2 - 7 7 . Morrison, D. M u l t i v a r i a t e s t a t i s t i c a l . m e t h o d s . New York: McGraw H i l l , 1 9 7 5 . Naeser, M.A., & Hayward, R.W. C o r r e l a t i o n s beteen s i z e and d e n s i t y of CT scan l e s i o n s i t e s and s e v e r i t y o f aphasia I n s t r o k e p a t i e n t s . I n A b s t r a c t s : Academy o f Aphasia 1 5 t h Annual Meeting, Montreal, 1 9 7 7 . N l e , N., H u l l , C , J e n k i n s , J . , Stelnbrenner, K., & B e r t , D. S t a t i s t i c a l package f o r s o c i a l sciences ( 2 n d Ed). New York: McGraw H i l l , 1975-Osgood, C.E., & Miron, M. (Eds). Approaches t o the study of aphasia. Urbana:•University of I l l i n o i s P r e s s , 1 9 6 3 . P a t t e r s o n , J . , & Whittaker, J . H i e r a r c h i c a l grouping a n a l y s i s w i t h o p t i o n a l contingency c o n s t r a i n . (U.B.C: GROUP), Vancouver: U.B.C. Computer Centre, 1973-P e n f i e l d , . W., & Roberts, L. Speech and b r a i n mechanisms. P r i n c e t o n : P r i n c e t o n U n i v e r s i t y P r e s s , 1 9 6 6 . 77 Porch, B. Porch Index o f conmurrlcation a b i l i t y : Theory and development ( V o l . 1 ) , A d m i n i s t r a t i o n s c o r i n g and I n t e r p r e t a t i o n ( V o l . 11). Los Angeles: C o n s u l t i n g P s y c h o l o g i s t s P r e s s , 1968. S c h u e l l , H., J e n k i n s , J . , & C a r r o l l , J . A f a c t o r a n a l y s i s o f the Minnesota t e s t f o r d i f f e r e n t i a l d i a g n osis o f aphasia. J o u r n a l o f  Speech and Hearing-Research, 1962, 5> 349-69-S c h e u l l , H., J e n k i n s , S., & Jlminez Pabon, E. Aphasia I n a d u l t s . New York: Harper & Row, 1969. Walker, A.E., Caveness, W.F., & C r l t c h l e y , J.D. The l a t e e f f e c t s o f head  i n j u r y . S p r i n g f i e l d : C C . Thomas, 1969• Walton, J.N. E s s e n t i a l s o f neurology. Toronto: J.B. Leppincott Co., 1974. Weisenburg, T., & McBrlde, K.E. Aphasia. New York: The Commonwealth Fund, 1935. Wepman, J . , & Jones, J . Studies i n aphasia: an approach t o t e s t i n g . Chicago: Education I n d u s t r y S e r v i c e , 1961. Whittaker, H. E l e c t r i c a l s t i m u l a t i o n mapping o f language i n the c e r e b r a l - c o r t e x . I n A b s t r a c t s : Academy of. Aphasia 15th Annual Meeting, Montreal, 1977-W i l l i a m s , J.M. Sy n e s t h e t i c a d j e c t i v e s : a p o s s i b l e law of semantic change. Language, 1976, 52, 461-478. Winner, E., & Gardner, H. The comprehension, o f metaphor I n b r a i n damaged p a t i e n t s . B r a i n , 1977, 10, 717-729. Z u r i f , E., Caramazzo, A., & G a l v i n , G. Semantic f e a t u r e r e p r e s e n t a -t i o n s f o r normal and aphasic language. B r a i n and Language, 1974, 7, 167-187. Z u r i f , E., Caramazza, A., & Myerson, R. Grammatical judgments o f agrammatlc aphasics. Neuropsychologia, 1972, 10, 403-417. KLONOFF, H., CLARK,:-;C. "Measurement o f S t a f f A t t i t u d e s Towards Computerization", H o s p i t a l and Community P s y c h i a t r y , 2 6 : 8 2 3 - 8 2 5 ( 1 9 7 5 ) . KLONOFF, H., CLARK, C. "Drug Patt e r n s I n the Chronic Marijuana User". The I n t e r n a t i o n a l J o u r n a l o f the A d d i c t i o n s , 1 1 : 7 1 - 8 0 ( 1 9 7 6 ) . KLONOFF, H., CLARK, C , HORGAN, J . , KRAMER, P. and McDOUGALL, G. "The MMPI P r o f i l e of P r i s o n e r s of War", J o u r n a l o f C l i n i c a l Psychology, 3 2 : 6 2 3 - 6 2 7 ( 1 9 7 6 ) . CROCKETT, D.J., KLONOFF, H., CLARK, C. "The E f f e c t s o f Marijuana on V e r b a l i z a t i o n and Thought Processes", J o u r n a l o f P e r s o n a l i t y Assessment, 40: 5 8 2 - 5 8 7 ( 1 9 7 6 ) . ' KLONOFF, H., McDOUGALL, G., CLARK, C , HORGAN, J . and KRAMER, P. "The Neuropsychological, P s y c h i a t r i c and P h y s i c a l E f f e c t s of Prolonged and Severe S t r e s s T h i r t y Years L a t e r " , J o u r n a l of Nervous and Mental Disease, 163: 246-252 ( 1 9 7 6 ) . KLONOFF, H., LOW, M.D. and CLARK, C. "Head I n j u r i e s i n C h i l d r e n : A Pr o s p e c t i v e , F i v e Year Follow-up", J o u r n a l of Neurology, Neurosurgery and P s y c h i a t r y , 40: 1211-1219 ( 1 9 7 7 ) . CLARK, C , CROCKETT, D.J. and KLONOFF, H. "Factor A n a l y s i s o f the Porch Index o f Communication A b i l i t y " , J o u r n a l o f B r a i n and Language. A p r i l 1 9 7 7 . CLARK, C , CROCKETT, D.J. and KLONOFF, H. "A M u l t i v a r i a t e Model f o r Anal y z i n g the E f f e c t s of Treatment i n Aphasic P a t i e n t s " . (Submitted f o r p u b l i c a t i o n ) . KLONOFF, H., CLARK, C. and TAGGART, M. "A H o s p i t a l Computer System". (Submitted f o r p u b l i c a t i o n ) 

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