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Sentence comprehension by children after closed head injury Noort, Marilyn 1989

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SENTENCE COMPREHENSION BY CHILDREN AFTER CLOSED HEAD INJURY by MARILYN NOORT B. A., University of British Columbia, 1986 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE Faculty of Graduate Studies The School of Audiology and Speech Sciences We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA September, 1989 © Marilyn Noort, 1989 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. 1 further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. The University of British Columbia Vancouver, Canada Department of DE-6 (2/88) A B S T R A C T T h i s study i s an invest igat ion o f c losed head-in jured ( C H I ) c h i l d r e n ' s ab i l i ty to assign thematic roles to nouns i n sentences o f v a r y i n g syntactic structure. S e v e n C H I c h i l d r e n , aged 9 to 15 years, part ic ipated as subjects. A l l subjects were at least t w o months post-onset and demonstrated s y m p t o m stabi l izat ion. T h e procedure repl icated a task des igned by C a p l a n , B a k e r and Dehaut (1985), w h i c h requires that subjects enact o r a l l y presented sentences by m a n i p u l a t i n g toy animals . F o u r questions were addressed: 1) Is the assignment o f thematic ro le more d i f f i c u l t i n some sentence structures than i n others for c l o s e d head- in jured and n o r m a l ch i ldren? 2) D o C H I c h i l d r e n have more d i f f i c u l t y ass igning thematic ro le than d o n o r m a l ch i ldren? 3) A r e any part icular sentence types re la t ive ly more susceptible to interpretation b r e a k d o w n than other sentence types? 4) Does the pattern o f sentence interpretation b r e a k d o w n i n C H I c h i l d r e n resemble that f o u n d i n C H I adults and aphasic adults? T h e c losed head in jured subjects as a group p r o d u c e d m o r e errors than the age- and sex-matched controls . Futhermore , some sentence structures were more d i f f i c u l t to interpret than were others for both head in jured and cont ro l subjects. T h e h ierarch ica l order o f d i f f i c u l t y f o r both groups was s i m i l a r to the order f o u n d for adult c losed head in jured patients and adult aphasics. Severa l syntactic structural features -- n o n c a n o n i c a l w o r d order, presence o f a th ird thematic ro le , and presence o f a second v e r b — were s h o w n to in f luence sentence c o m p l e x i t y . These features affect syntactic interpretation b y bra in in jured subjects regardless o f e t io logy. T h e results o f this study suggest that strategies used for sentence pars ing are s i m i l a r across bra in in jured populat ions , regardless o f age. i i T A B L E OF CONTENTS A B S T R A C T ii T A B L E OF CONTENTS iii LIST OF TABLES v A C K N O W L E D G E M E N T S vii CHAPTER 1: INTRODUCTION 1 Aphasia in Adults after Closed Head Injury 3 Aphasia in Children after Closed Head Injury 6 Disorders of Syntactic Comprehension 12 CHAPTER 2: M E T H O D 15 Procedure 15 Subjects 16 Individual subject descriptions 17 Subject 1 - KP 17 Subject 2 - K T 18 Subject 3 - K F 19 Subject 4 - K V 20 Subject 5 - D T 21 iii Subject 6 - RB 22 Subject 7 - WG 23 CHAPTER 3: RESULTS 25 CHAPTER 4: DISCUSSION 33 BIBLIOGRAPHY 40 APPENDIX 44 iv L I S T O F T A B L E S T a b l e 1. Sentence T y p e s Tested w i t h Themat i c R o l e Battery 16 T a b l e 2. Subject Descr ip t ions 17 T a b l e 3. M e a n s and standard deviat ions b y sentence type for c o m b i n e d C F f l and n o r m a l cont ro l groups 26 T a b l e 4 . A n a l y s i s o f V a r i a n c e S u m m a r y : c o m b i n e d c losed head in jured and n o r m a l contro l groups 26 T a b l e 5. Resul ts o f T u k e y ' s Procedure (experiment-wise error rate o f 0.05) a p p l i e d across sentence type for c o m b i n e d C H I and contro l groups 27 T a b l e 6. M e a n s and standard deviat ions by sentence type for C H I group 28 T a b l e 7. A n a l y s i s o f V a r i a n c e S u m m a r y : C l o s e d H e a d Injured Subjects 28 T a b l e 8. M e a n s and standard deviat ions b y sentence type for n o r m a l cont ro l group . . . . 29 T a b l e 9. A n a l y s i s o f V a r i a n c e S u m m a r y : N o r m a l C o n t r o l Subjects 29 T a b l e 10. A n a l y s i s o f V a r i a n c e S u m m a r y : T w o factor (group) repeated measures (sentence type) 30 T a b l e 11. Quest ions addressed i n the present invest igat ion 34 v L I S T O F F I G U R E S F i g u r e 1. M e a n percent o f sentences answered correct ly by C H I (open bars) and n o r m a l cont ro l (slashed bars) subjects 25 v i A C K N O W L E D G E M E N T S I w i s h to express m y thanks to D r . C a r o l y n Johnson and D r . John G i l b e r t w h o gave me guidance and support throughout this project , to L y n n e B r o w n w h o helped locate subjects, and to the c h i l d r e n and parents w h o part ic ipated i n this study. I w o u l d also l i k e to thank John N i c o l w h o was a l w a y s w i l l i n g to help w h e n computers ingested documents or printers went berserk. S p e c i a l thanks are due to m y classmates, w h o he lped i n numerous w a y s over the last f i v e years, and to m y f r iend , R i c h a r d Lechle i tner , w h o gave m e encouragement, m o t i v a t i o n , and endless hours o f t y p i n g w h e n he c o u l d have been i n the mounta ins . v i i C H A P T E R 1 I N T R O D U C T I O N T h e term c l o s e d head in jury ( C H I ) i s used to describe traumatic bra in in jury w i t h resul t ing cerebral d y s f u n c t i o n o c c u r r i n g as a consequence o f nonpenetrat ing head in jury ( A d a m o v i c h , H e n d e r s o n and A u r b a c h , 1985). It excludes cases o f penetrating traumatic head in jury f r o m m i s s i l e w o u n d s and cases o f nontraumatic head i n j u r y o c c u r r i n g f r o m such incidents as cardiovascular accidents, neoplasm o r abscess. T h e most c o m m o n causes o f C H I are m o t o r v e h i c l e accidents and fa l l s . In the U n i t e d States, the est imated inc idence o f traumatic head in jury is 200 per 100,000 p o p u l a t i o n per year (Annegers and K u r l a n d , 1979). F o r those under 35 years o f age i t is the most c o m m o n cause o f death (Annegers , G r a b o w , K u r l a n d and L a w s , 1980). A m o n g adults, males are m o r e l i k e l y than females to suffer head in jur ies . T h e male/ female in jury rat io i s approximate ly equal i n c h i l d r e n and adults over 7 0 years o f age ( F i e l d , 1976). E q u i v a l e n t C a n a d i a n inc idence i n f o r m a t i o n is unavai lab le but l i k e l y approximates rates i n the U n i t e d States. C l o s e d head in jury is associated w i t h d i f fuse brain in jury and concuss ion . Investigations o f the pa thophys io logy o f c losed head in jury have suggested that t w o types o f t rauma occur : p r i m a r y impact in jury and secondary bra in in jury . P r i m a r y impact injuries result from direct impact and acceleration forces w h i c h o c c u r at the m o m e n t o f in jury . A c c e l e r a t i o n o f the s k u l l produces shearing and tearing o f neural tissue cor t i ca l ly and subcor t i ca l ly . D i r e c t impact forces produce contusions o f the bra in surface w h i c h m a y appear at the points o f impact or i n areas remote f r o m this point as the bra in comes into 1 contact with the bony surface of the skull. Secondary brain injuries are not uncommon and include subdural or epidural haematomas, intracerebral haemorrhages, cerebral edema leading to occlusion of cerebral blood vessels and compression of brain stem structures, and infection. Head injury often produces immediate loss of consciousness. A period of confusion and anterograde amnesia usually follow emergence from coma. Recovery of language functions is determined in part by the location, nature and severity of brain injury. It is essential to obtain relevant neurophysiological data in the assessment and treatment of aphasia following closed head injury. Studies of recovery of speech and language abilities in children after closed head injury have yielded differing clinical pictures. One of these differences involves the impairment and recovery of auditory comprehension. The current head injury research literature on this subject is difficult to interpret due to differences in etiology of subjects' brain injuries and testing procedures across studies. Methods used to test comprehension have often yielded only gross measures of abilities. Few studies have reached conclusions about the nature of syntactic comprehension abilities among head injured children. Most investigations which do address comprehension have used tests which either allow interpretation of sentences based on pragmatic or semantic knowledge or which are confounded by demands of short-term memory. The purpose of this investigation was to examine comprehension of oral language by children who had suffered external head trauma, after spontaneous recovery had occurred. The study focused on the children's ability to assign thematic roles to noun phrases in sentences of varying complexity. The following questions were addressed: 1. Is the assignment of thematic role more difficult in some sentence structures than in others for closed head injured and normal children? 2. Do CHI children have more difficulty assigning thematic role than do normal children? 2 3. A r e any part icular sentence types re la t ive ly more susceptible to interpretation b r e a k d o w n than other sentence types i n the y o u n g C H I populat ion? 4. D o e s the pattern o f sentence interpretation b r e a k d o w n i n C H I c h i l d r e n resemble that f o u n d i n C H I adults and aphasic adults? A n s w e r s to the above questions m a y p r o v i d e i n f o r m a t i o n about strategies that head in jured c h i l d r e n use to make syntactic interpretations. A p h a s i a i n A d u l t s after C l o s e d H e a d Injury Investigations o f speech and language after c l o s e d head in jury i n adults have d i sc losed a broad range o f language defects, i n c l u d i n g reduced w o r d f l u e n c y , a n o m i a , v e r b a l paraphasias, and disorders o f reading and w r i t i n g . C o g n i t i v e , attentional , behaviour ia l and m e m o r y def ic i ts coexis t to produce a c o m p l e x c l i n i c a l picture that is not t y p i c a l o f the c lass ica l aphasia syndromes. T h o m s e n (1976) referred to the language disorder f o l l o w i n g c losed head in jury as " m u l t i s y m p t o m a t i c aphasia . " E a r l y studies o f the head- in jured p o p u l a t i o n ( A r s e n i , C o n s t a n t i n o v i c i , I l i escu , D o b r o t a , and G a g e a , 1970; R u s s e l l , 1932; L e w i n , 1966; H o o p e r , 1969) reported an i n i t i a l p e r i o d o f complete b r e a k d o w n o f language abi l i t ies . C o g n i t i v e impairments were often reported, w i t h decreased short-term m e m o r y and attention span cons idered the p r i m a r y areas o f def ic i t . H o w e v e r , these ear ly studies had the purpose o f e x a m i n i n g the course o f recovery i n general i n the c l o s e d head in jured popula t ion and d i d not focus o n language abi l i t ies i n part icular . W h i l e speech and language abi l i t ies were u s u a l l y cons idered , eva luat ion o f these funct ions was usua l ly cursory and general i n nature. H o w e v e r , several recent studies o f the head i n j u r e d p o p u l a t i o n have focused o n language and speech impairments . T h o m s e n (1975) conducted a l o n g term study o f twe lve c losed head in jured patients w i t h a m e a n age o f 25 1/2 years, w h o were unconsc ious at the t ime o f in jury and w h o had 3 s y m p t o m s o f aphasia four months post in jury. O n examinat ion twe lve to fifty months post in jury , f o u r o f the twe lve patients had no symptoms o f aphasia. H o w e v e r , l inguis t i c analysis o f spontaneous speech revealed aphasic traits i n one o f these patients and i m p a i r m e n t o f v e r b a l l earning i n the three others. A m o n g the aphasic patients, the most frequent symptoms were a n o m i a , verba l paraphasia, agraphia, and perseverat ion. T h o m s e n noted a res idua l dec l ine i n such c o m p l e x verba l s k i l l s as deta i led v e r b a l descr ipt ion and the use o f antonyms, s y n o n y m s , and metaphors. In a second invest igat ion i n w h i c h patients were tested at least one year after in jury , there was an o v e r a l l t rend o f i m p r o v e m e n t . N o n e h a d i m p a i r e d comprehens ion o f speech, as tested. H o w e v e r , T h o m s e n d i d not i d e n t i f y or describe the tests o f comprehens ion o f spoken language e m p l o y e d i n her study. G r o h e r (1977) documented the m e m o r y and language s k i l l s o f fourteen patients w i t h a m e a n age o f 31 years w h o h a d suffered c l o s e d head trauma. H e reported progressive i m p r o v e m e n t o v e r a f o u r m o n t h p e r i o d . A t four months post in jury , n a m i n g to confrontat ion h a d recovered to n o r m a l levels i n a l l patients. O f nine patients w h o i n i t i a l l y h a d exh ib i ted spastic dysarthria , s ix demonstrated n o r m a l art iculat ion. T h e language s k i l l s o f a l l patients were adequate for conversat ional purposes a l though G r o h e r noted that "nine o f the fourteen patients carr ied o n conversat ions w h i c h were inappropriate i n length , and their thought content was often confused and s e l d o m relevant to the d i s c u s s i o n " (p.218). N a m i n g to confrontat ion , w h i c h was i n i t i a l l y i m p a i r e d i n a l l subjects, recovered complete ly . Or thographic language s k i l l s were characterized b y errors i n s p e l l i n g , incomple te sentence construct ion and errors o f syntax. G r o h e r emphas ized that patients w h o d isp lay a seemingly " n o r m a l " ab i l i ty to communica te m a y have pers is t ing i n a b i l i t y to use auditory i n f o r m a t i o n i n p r o b l e m s o l v i n g tasks. Sarno (1980) e x a m i n e d the verba l behaviour o f f i f t y - s i x c l o s e d head in jured patients referred to a rehabi l i ta t ion m e d i c i n e centre. T h e f o l l o w i n g four subtests o f the 4 Neurosensory Center C o m p r e h e n s i v e E x a m i n a t i o n for A p h a s i a ( N C C E A ) were administered about seven months post in jury : V i s u a l N a m i n g , W o r d F l u e n c y , Sentence Repet i t ion , and the T o k e n Test . A f t e r testing, patients were c lass i f ied into three diagnost ic categories: a) aphasic , b) dysarthric w i t h s u b c l i n i c a l aphasic disorder and c) s u b c l i n i c a l a p h a s i a 1 A l l groups s h o w e d some degree o f aphasic impairment , w i t h c l i n i c a l l y aphasic patients representing the most severe, dysarthrics intermediate and the s u b c l i n i c a l group the mildest . Consis tent w i t h T h o m s e n ' s f i n d i n g , Sarno reported that a l l patients h a d either a language disorder or dysar thr ia , o r both. E v e n the mi ldes t group, the s u b c l i n i c a l category, emerged as s ign i f i cant ly i m p a i r e d o n a l l four subtests. S a m o c o n c l u d e d the "the use o f sophist icated, neurol inguis t i c measures w i t h [the head injured] p o p u l a t i o n is needed to detect subtle de f i c i t s " (p. 691). H e i l m a n , Sagran, and G e s c h w i n d (1971) studied the verba l abi l i t ies o f thirteen c losed head in jured patients w i t h a m e a n age o f 57 years w h o s h o w e d s y m p t o m s o f aphasia. Patients were tested w h e n alert and co-operat ive after rega in ing consciousness . N i n e patients were c lass i f i ed as h a v i n g anomic aphasia and four as h a v i n g W e r n i c k e ' s aphasia. S i x out o f the n ine patients w i t h anomic aphasia had some addi t ional defect o f h igher cor t i ca l f u n c t i o n , i n c l u d i n g r ight- lef t c o n f u s i o n , f inger agnosia , d y s c a l c u l i a , dysgraphia , and d y s l e x i a . Unfor tunate ly , the examiners were not able to investigate patients ' progress over the l o n g term. L e v i n , G r o s s m a n , Sarwar and M e y e r s (1981) studied the recovery o f language over several years i n twenty-one aphasic C H I patients d u r i n g i n i t i a l hospi ta l iza t ion . T h e age range o f patients w a s between 17 and 50 years, w i t h a m e d i a n age o f 22 years. T h e f o l l o w i n g subtests o f the M u l t i l i n g u a l A p h a s i a E x a m i n a t i o n ( M A E ) were adminis tered: 'The term "subclinical aphasia" refers to language which has recovered to normal levels in almost all areas, but which contains persisting specific defects such as anomia or word finding difficulties. 5 V i s u a l N a m i n g , Sentence Repet i t ion , C o n t r o l l e d W o r d A s s o c i a t i o n , T o k e n Test , A u d i t o r y C o m p r e h e n s i o n o f W o r d s and Phrases, and R e a d i n g C o m p r e h e n s i o n . Resul ts indicated that s ix patients h a d a spec i f i c l inguis t i c disturbance i n w h i c h o n l y a s ingle f u n c t i o n was i m p a i r e d , s ix patients h a d more general ized l inguis t i c d y s f u n c t i o n , and nine patients obta ined n o r m a l scores o n a l l tests. T h e most c o m m o n def ic i t a m o n g patients w i t h specif ic def ic i ts was a n o m i a . N o n e o f these patients s h o w e d i m p a i r e d comprehens ion . A m o n g those w i t h genera l ized l inguis t i c disturbance, a l l s h o w e d i m p a i r m e n t o f comprehens ion o f o r a l language. L e v i n and his coworkers also analyzed C T scan results i n re la t ion to the p r o f i l e o f language, and f o u n d that persistent a n o m i a w i t h n o r m a l comprehens ion after C H I was associated w i t h m i l d di f fuse bra in in jury , w h i l e general ized l i n g u i s t i c def ic i t i n v o l v i n g both p r o d u c t i o n and comprehens ion funct ions was related to severe d i f fuse bra in damage and g l o b a l cogni t ive def ic i t . B u t l e r - H i n z , C a p l a n , and Waters (unpubl ished manuscript) e x a m i n e d comprehens ion def ic i ts i n C H I adults and adult stroke patients. A toy a n i m a l m a n i p u l a t i o n task deve loped b y C a p l a n et a l . (1985) was administered to thirty E n g l i s h and thirty F r e n c h speaking i n d i v i d u a l s . T e n subjects i n each group had suffered c losed head injuries . A g e s ranged f r o m 16 to 57 years a n d a l l patients were tested at least t w o months post in jury. C o m p r e h e n s i o n def ic i ts were f o u n d i n a l l C H I subjects. Furthermore , patterns o f comprehens ion b r e a k d o w n were evident and were s i m i l a r to the patterns o f b r e a k d o w n seen a m o n g adult stroke patients. These patterns were based o n the presence o f several syntactic features ident i f i ed by the authors. A p h a s i a i n C h i l d r e n after C l o s e d H e a d Injury Studies that have e x a m i n e d l inguis t i c def ic i ts i n c h i l d r e n w i t h bra in in jury have usual ly i n c l u d e d subjects w i t h v a r y i n g e t io logy and severity o f in jury . G u t t m a n ' s (1942) r e v i e w 6 was the earliest comprehens ive examinat ion o f the symptomato logy and recovery o f c h i l d h o o d aphasia. In a group o f thirty c h i l d r e n aged 2 to 14 years that i n c l u d e d nine cases o f head in jury , G u t t m a n reported that s ixteen patients were aphasic . In a l l o f these cases, aphasia w a s character ized by a reduct ion o f v e r b a l p r o d u c t i o n and seemingly spared comprehens ion . R e c o v e r y o f language was r a p i d , but speech was m a r k e d b y hesitancy and dysarthr ia . Patients general ly d i d not exhib i t obv ious paraphasic errors. G u t t m a n (1942) observed that the pattern o f l inguis t i c def ic i t was at least par t ia l ly age dependent. In patients under age 10, les ions i n the cor t i ca l areas be l i eved to be responsible for language resulted i n a reduct ion o f spontaneous speech. In patients 10 years a n d older , speech was u s u a l l y f luent , and the pattern o f aphasia more c l o s e l y resembled that o f aphasic adults. A l a j o u a n i n e and L h e r m i t t e (1965) studied th i r ty - two aphasic c h i l d r e n between 6 and 15 years o l d w i t h left hemisphere les ions , i n c l u d i n g thirteen cases w i t h h e a d in jury . T h e c h i l d r e n were s tudied over several years, w i t h the f irst examinat ion tak ing p lace w i t h i n an average o f three months post in jury . Tests p e r f o r m e d i n c l u d e d the W e c h s l e r for c h i l d r e n ( W I S C ) or W e c h s l e r - B e l l e v u e , according to age, B e n d e r ' s and R e y ' s * T e r m a n - M e r r i l l , arrangement o f cubes ( K O H S ) and progressive matr ix ( P M 47). Consis tent w i t h G u t t m a n ' s f i n d i n g s , the authors reported a reduct ion o f express ion, i n c l u d i n g o r a l and wri t ten language, and gestures. Dysar thr ia occurred i n twenty- two patients, w i t h the features o f the dysarthr ia s i m i l a r to those f o u n d i n adults. P r o d u c t i v e language w a s m a r k e d b y reduced v o c a b u l a r y and s i m p l i f i e d syntax, but agrammat ism was not present. In contrast to aphasia i n adults, the authors f o u n d that logorrhea and perseveration d i d not occur and p h o n e m i c and semantic paraphasias were v e r y rare. T e n o f the th i r ty - two patients s h o w e d disorders o f o r a l comprehens ion . A m o n g those under 10 years o f age, understanding o f spoken language was almost a lways i m p a i r e d (eight out o f nine chi ldren) . R e c o v e r y o f auditory comprehens ion was r a p i d , h a v i n g reso lved to near n o r m a l levels b y s ix months after onset 7 o f aphasia. W h e n the c h i l d r e n were c o m p a r e d b y age l e v e l , i t was f o u n d that f o r those under 10 years o f age the reduct ion o f v e r b a l express ion w a s more severe and disorders o f ar t iculat ion were m o r e frequent than for older ch i ldren . F o l l o w - u p examinat ions at s ix months after onset o f aphasia revealed n o r m a l speech i n s ix out o f t w e n t y - t w o c h i l d r e n . A m o n g the r e m a i n i n g sixteen, w o r d - f i n d i n g , agrammat ism, and art iculat ion prob lems r emained . There were also d i f f i cu l t ies w i t h higher l e v e l language funct ions (descript ion, narrat ion, d e f i n i t i o n o f words) . Severe a lex ia remained i n h a l f o f the subjects. A f t e r one year post in jury , t w e n t y - t w o o f the th i r ty - two c h i l d r e n had regained n o r m a l or near ly n o r m a l language. Fourteen had subtle alterations o f language o n tests o f narrat ion, construct ion o f sentences and d e f i n i t i o n o f words . T h e authors c o n c l u d e d that the extent o f recovery f r o m aphasia a m o n g c h i l d r e n is greater than a m o n g adult aphasics. T h e y attributed this recovery to the neural p las t i c i ty o f the y o u n g c h i l d ' s bra in . H e c a e n (1976) studied the verba l abi l i t ies o f twenty- two c h i l d r e n , 3 1/2 to 15 years o f age, w i t h cor t i ca l les ions ; sixteen o f the c h i l d r e n were C H I patients. Test methodology was not d iscussed but l i k e l y i n c l u d e d standardized tests o f language funct ion . N i n e t e e n c h i l d r e n were f o u n d to be aphasic, i n c l u d i n g 8 8 % o f the cases w i t h left hemisphere les ion and 3 2 % o f the c h i l d r e n w i t h r ight hemisphere l e s ion . H e c a e n noted t w o characteristics w h i c h were consistent w i t h the f indings o f prev ious studies: frequent m u t i s m and rare, i f not absent, paraphasia . A r t i c u l a t o r y disorders were frequent. D i s o r d e r s o f auditory verba l comprehens ion appeared i n more than a th i rd o f the cases. These f i n d i n g s are i n agreement w i t h those o f A l a j o u a n i n e and Lhermi t te (1965) but i n contradic t ion to G u t t m a n (1942) or B r a n c o - L e f e v r e (1950), w h o stated that auditory comprehens ion prob lems were rare i n c h i l d h o o d aphasia. A l s o i n agreement w i t h A l a j o u a n i n e and L h e r m i t t e , H e c a e n noted that comprehens ion d i f f i cu l t ies occurred o n l y i n the acute p e r i o d , w i t h r a p i d and complete recovery o f this func t ion . H e also noted that this def ic i t o n l y occurred i n 8 children with temporal lobe lesions. Alexia2 resolved rapidly while disorders of writing were the most common symptom during the acute period and the least likely to resolve. Acalculia3 was very frequent. Hecaen noted that, "although recovery is certainly more striking than in the adult, it is important to stress the persistence, at times permanently, of mild verbal deficits" (p. 125). In a later investigation, Hecaen (1983) reexamined the twenty-six earlier cases along with thirty new cases. Etiology of subjects was mixed, and included twelve traumatically closed head injuries. Thirty-four children were right-handed and had left sided lesions. Of these, twenty-three showed symptoms of aphasia. The frequency of aphasia in children under 10 years was greater than for older children. As in his earlier study, Hecaen found that mutism was the predominant clinical symptom. Furthermore, he found that the incidence of mutism was far greater with acute head injury (85%), than with progressive lesions (20%). Dysarthria was found in 52% of cases, and was more common among younger children, head injured children, and those with anterior lesions. As in his earlier study, Hecaen found that disorders of auditory comprehension were quite frequent, occurring in more than one-third of the cases but resolved rapidly and completely. In agreement with Alajouanine and Lhermitte, Hecaen found that logorrhea was absent and verbal paraphasias were rare. Word rinding difficulties were frequent and tended to persist. Alexia was common in the early stages but usually disappeared quickly. Anteriorly located lesions were associated with more disturbance of all aspects of language, including ^The prefix "a-" denotes an absence. Hence, "alexia" means inability to read. The prefix "dys-" conveys the idea of a reduction. "Dyslexia" thus means a level of reading which is less ihan expected. In clinical and research literature, these prefixes are often used interchangeably. 3Inability to use mathematical symbols. 9 auditory a n d v i s u a l v e r b a l comprehens ion , than temporal located les ions. Persistence of aphasic s y m p t o m s appeared to be l i n k e d to the s ize o r bi lateral i ty o f the les ions . L e v i n and E i s e n b e r g (1979) administered the N C C E A to s ix ty - four c h i l d r e n a n d adolescents w h o sustained blunt trauma to the head. L i n g u i s t i c defects were f o u n d i n 3 1 % percent o f the cases. A n o m i a was the most prominent def ic i t . O r a l comprehens ion as tested w i t h the T o k e n Test was affected i n 1 1 % o f the cases. V e r b a l repet i t ion was least affected. N e a r l y h a l f o f the cases exhib i ted i m p a i r e d verba l l earn ing and m e m o r y . T h e authors c o n c l u d e d that " s u b c l i n i c a l language disorder occurs after C H I i n c h i l d r e n w i t h a f requency comparable to that f o u n d i n adults" ( L e v i n , 1981, p . 454) . Speech and language abi l i t ies o f eight C H I c h i l d r e n w h o h a d passed the spontaneous recovery p e r i o d were invest igated by M i t c h e l l (1985). A series o f standardized tests were administered. These i n c l u d e d : T h e Peabody Picture V o c a b u l a r y Test , the T o k e n Test, the A u d i t o r y C o m p r e h e n s i o n Test for Sentences, and the C l i n i c a l E v a l u a t i o n o f Language F u n c t i o n s - P r o d u c t i o n subtests. T h e language o f C H I c h i l d r e n was character ized b y reduced auditory comprehens ion , perseveration, w o r d - f i n d i n g d i f f i cu l t i es and sequencing problems . Measures o f auditory comprehens ion s h o w e d reduced retention o f l i n g u i s t i c deta i l , perhaps due to l imi ta t ions o f m e m o r y . P r o d u c t i v e syntax was intact for a l l subjects. M i t c h e l l c o n c l u d e d that def ic i t s observed i n comprehens ion and p r o d u c t i o n were l e x i c a l l y rather than syntact ica l ly based and suggested that syntax " is a robust p h e n o m e n o n w h i c h is h i g h l y resistant to d i s r u p t i o n " (p. 62). H v o z d a n s k i (1986) invest igated w o r d - f i n d i n g abi l i t ies o f f i v e o f the subjects studied by M i t c h e l l . She f o u n d that results were determined i n part b y test m e t h o d o l o g y . Subjects w h o rece ived scores w i t h i n the n o r m a l range o n standardized tests such as the B o s t o n N a m i n g Test c o u l d exhib i t a n a m i n g def ic i t i n conversat ional speech. C l o s e d head in jured subjects also p r o d u c e d s i m p l i f i e d language m a r k e d b y reduced m e a n length o f utterance ( ( 10 and s i m p l i f i e d syntax. T h e language o f head in jured c h i l d r e n i n c l u d e d m o r e hesitations and pauses, w h i c h H v o z d a n s k i interpreted as indica t ive o f w o r d - f i n d i n g d i f f i cu l t i es . M e t a l i n g u i s t i c s k i l l s (e.g. antonyms, h o m o n y m s , metaphors) were also reduced i n the head i n j u r e d p o p u l a t i o n . These studies y i e l d several features i n c o m m o n w i t h respect to the c l i n i c a l picture of c h i l d h o o d versus adult aphasia f o l l o w i n g c l o s e d head in jury . S o m e o f the proposed dif ferences are as f o l l o w s : 1) A c q u i r e d aphasia p r o d u c e d by C H I i n c h i l d r e n i s character ized b y a reduct ion i n output, hesi tancy, fa i lure to init iate speech, and p o s s i b l y m u t i s m , w h i l e nonf luent expressive aphasia i s rarely f o u n d i n adults w i t h C H I (Gut tman, 1942; H e c a e n , 1976; A l a j o u a n i n e and L h e r m i t t e , 1965). 2) C h i l d r e n rare ly exhib i t o b v i o u s paraphasic errors, j a r g o n , or perseveration (Gut tman, 1942; A l a j o u a n i n e and Lhermi t te , 1965). Despi te these s imi lar i t ies , differences i n the c l i n i c a l picture o f c h i l d h o o d aphasia s t i l l exist across studies. O n e prominent inconsis tency concerns auditory comprehens ion . W h i l e some studies have suggested that auditory comprehens ion def ic i ts are rare i n c h i l d h o o d aphasia (Gut tman, 1942; B r a n c o - L e f e v r e , 1950), others report frequent comprehens ion def ic i ts i n at least the acute p e r i o d (Hecaen, 1976; A l a j o u a n i n e and L h e r m i t t e , 1965; L e v i n and E i s e n b e r g , 1979). These studies suggest the presence o f auditory comprehens ion def ic i ts f o l l o w i n g C H I but are not indica t ive o f the ro le that syntactic structure p lays i n aural sentence comprehens ion f o l l o w i n g bra in trauma. 11 D i s o r d e r s o f Syntact ic C o m p r e h e n s i o n In order to m a k e a quantitative assessment o f aphasia i n C F f l patients, researchers and c l in i c ians have frequently used the M u l t i l i n g u a l A p h a s i a E x a m i n a t i o n ( M A E ) (Benton, 1967) and the Neurosensory Center C o m p r e h e n s i v e E x a m i n a t i o n o f A p h a s i a ( N C C E A ) (Spreen and B e n t o n , 1969). B o t h o f these test batteries i n c l u d e the T o k e n Test ( D e R e n z i and V i g n o l o , 1962) to evaluate comprehens ion o f o r a l sentences. T h e T o k e n Test consists o f o r a l c o m m a n d s o r g a n i z e d i n sections ordered by increas ing length and syntactic c o m p l e x i t y . Test subjects are required to manipulate c o l o u r e d geometr ic f o r m s i n response to the c o m m a n d s . T h e abi l i ty to attribute m o d i f i c a t i o n , assign thematic roles and tempora l ly order actions i s assessed through the presentation o f var ious syntactic structures o f increas ing length and c o m p l e x i t y . W h i l e the T o k e n Test has p r o v e d to be use fu l i n d i s t i n g u i s h i n g patients cons idered aphasic f r o m n o r m a l subjects, its usefulness as a test o f the syntactic interpretation o f sentences has been quest ioned. C a p l a n (1987) out l ined several l imi ta t ions o f the test. F irs t , the T o k e n Test makes increas ing demands o n m e m o r y as syntactic demands increase (Lesser, 1976). S ince short-term m e m o r y i m p a i r m e n t is c o m m o n a m o n g C H I patients, errors cannot be re l i ab ly attributed to def ic i ts o f syntactic comprehens ion . S e c o n d , T o k e n Test scores are not arranged by syntactic structure. Therefore results are not revea l ing w i t h respect to speci f ic structures w h i c h are d i f f i c u l t for patients to interpret. T h i r d , the T o k e n Test inc ludes sentences c o n t a i n i n g subordinate temporal conjunct ions (before, after, unt i l ) . Patients m a y respond incorrec t ly to these sentences, not because o f an impairment o f syntactic c o m p r e h e n s i o n , but because they lack k n o w l e d g e o f a w o r d ' s m e a n i n g or because the act ion required is opposi te to the spoken order o f c lauses i n the test i t e m . C a p l a n states "the experience w i t h the T T , though v a l u a b l e i n the ident i f i ca t ion o f aphasic patients, does not c lear ly l ead to hypotheses 12 regarding the syntactic structures w h i c h are assigned and interpreted i n aphasia" (Caplan et a l . , 1975). C a p l a n a n d his c o w o r k e r s (1985) developed a test battery to investigate the syntactic determinates o f sentence comprehens ion . T h e battery consists o f f o r t y - f i v e sentences presented o r a l l y . In this task, subjects are required to demonstrate their understanding o f the thematic roles o f the nouns i n the sentences by m a n i p u l a t i n g toy animals p l a c e d i n front o f them. T h e roles o f short-term m e m o r y and motor-perceptual factors are r m n i m i z e d . In their study o f three groups o f adult stroke patients, the authors f o u n d that syntactic structure had a s ignif icant effect u p o n correct interpretation o f sentences. Furthermore , s i m i l a r patterns o f comprehens ion b r e a k d o w n across sentence types occurred across patient populat ions . C a p l a n a n d his col leagues ident i f i ed three "elementary structural features" w h i c h par t ia l ly determined the c o m p l e x i t y o f sentences f o r the aphasic p o p u l a t i o n : the presence o f a n o n c a n o n i c a l thematic ro le order, a th i rd thematic ro le , or a second verb. T h e c o m p l e x i t y o f the sentence interpretation task c o u l d be predic ted i n part by the number o f structural features a sentence contained. In a case study invest igat ing sentence comprehens ion by an agrammatic adult patient, C a p l a n a n d Futter (1986) suggested that a s i m p l e l inear order strategy was used by then-subject to assign thematic roles . T h i s strategy violates the set o f rules o f E n g l i s h sentence structure, w h i c h are based o n a h ierarchica l structure o f syntactic categories. T h e strategy used b y C a p l a n and Fut ter ' s subject therefore l e d to misinterpretat ion o f several sentence types. B u t l e r - H i n z , C a p l a n , and Waters (unpubl ished manuscript) adminis tered the t o y - a n i m a l m a n i p u l a t i o n procedure descr ibed above to examine the characteristics o f syntactic comprehens ion def ic i ts i n adults f o l l o w i n g c losed head injuries and strokes. T h e pattern o f 13 comprehens ion b r e a k d o w n i n these populat ions was s i m i l a r to that f o u n d a m o n g aphasic adults ( C a p l a n et a l . , 1985). E x p e r i m e n t a l Hypotheses T h e research questions that emerge f r o m the studies r e v i e w e d (see p . 3), stated as n u l l hypotheses, are: 1. T h e degree o f thematic role assignment d i f f i c u l t y is not dependent o n sentence structure f o r either c losed head in jured or n o r m a l ch i ldren . 2. There i s n o di f ference i n c losed head in jured and n o r m a l c h i l d r e n ' s ab i l i ty to assign thematic roles i n sentences. 3. There is no di f ference i n susceptibi l i ty o f var ious sentence types to interpretation b r e a k d o w n i n the y o u n g c losed head in jured popula t ion . 14 C H A P T E R 2 M E T H O D Procedure T h e present invest igat ion focused o n the ab i l i ty o f c losed-head in jured ( C H I ) ch i ldren to c o m p r e h e n d the assignment o f thematic roles to nouns. T h e procedure i n v o l v e d the use o f an object m a n i p u l a t i o n p r o t o c o l o r i g i n a l l y adopted f r o m language deve lopment research and used b y C a p l a n , B a k e r and Dehaut (1985). T h i s technique requires that subjects first attend to a sentence presented audi tor ia l ly , and then demonstrate their understanding o f the sentence b y m a n i p u l a t i n g toy animals . T h i s technique has been s h o w n to a l l o w patients ' patterns o f syntactic comprehens ion to be studied independent o f extraneous variables such as spatial preference strategies, manipula t ion preference strategies, and l e x i c a l pragmat ic effects ( C a p l a n et a l . , 1985). S t i m u l i consisted of: (i) act ive and passive sentences, (ii) cleft sentences o n the subjects and objects, ( i i i ) act ive and passive dat ive construct ions , ( iv) c o m p l e x sentences w i t h relat ive and con jo ined clauses. A n e x a m p l e o f each sentence type is g i v e n i n T a b l e 1. F i v e instances o f each type o f sentence were presented. T e s t i n g sessions were s i m i l a r to those out l ined by C a p l a n et a l . (1985). T h e y began w i t h br ie f conversat ions w i t h each subject and an explanat ion o f the testing procedure. E x p l a n a t i o n s were not standardized. Rather , they were m o d i f i e d as needed to m a k e the task c lear to each part ic ipant , as comprehens ion abil i t ies o f the subjects were var iable . A m e m o r y pretest h a d determined that each subject c o u l d ident i fy the animals i n the 15 T a b l e 1. Sentence T y p e s Tested w i t h T h e m a t i c R o l e Battery T y p e E x a m p l e 1. A c t i v e ( A ) T h e m o n k e y patted the rabbit . 2. Pass ive (P) T h e m o n k e y was touched b y the rabbit . 3. Clef t -subject ( C S ) It w a s the m o n k e y that hugged the goat. 4. Cle f t -ob jec t ( C O ) It was the rabbit that the m o n k e y k issed . 5. D a t i v e (D) T h e m o n k e y sent the rabbit to the turtle. 6. D a t i v e pass ive ( D P ) T h e m o n k e y was brought to the turtle b y the elephant. 7. C o n j o i n e d (C) T h e goat bit the m o n k e y and caught the elephant. 8. Subject-object re lat ive (SO) T h e elephant that the goat h u g g e d hi t the turtle. 9. Object-subject relat ive ( O S ) T h e elephant scratched the rabbit that caught the turtle. f o l l o w i n g arrays: 1 i t e m i n a 5 - i t em array; 2 i tems i n a 2 - i t e m array; 3 i tems i n a 3 - i tem array; 2 i tems i n a 6 - i tem array; and 3 i tems i n a 6- i tem array. T h e actual 45-sentence battery was then administered. In each sentence, o n l y the animals ment ioned i n the sentence were p l a c e d o n the table i n r a n d o m array. T h e experimenter then read the sentence and recorded the subject 's response. I n d i v i d u a l testing was carr ied out at the homes o f the subjects under r o u g h l y equivalent condi t ions . Seven t raumat ica l ly c losed-head in jured c h i l d r e n were selected and referred by speech-language pathologists f r o m three rehabi l i ta t ion centres i n the V a n c o u v e r area. A g e s ranged f r o m 9 to 15 years. There were four males and three females . N o n e o f the subjects had a Subjects 16 his tory o f hear ing i m p a i r m e n t or learning d isab i l i ty . A l l patients were tested at least two months post-onset and demonstrated s y m p t o m stabi l izat ion. H e a d - i n j u r e d c h i l d r e n were matched i n d i v i d u a l l y to contro l c h i l d r e n by age and sex. T a b l e 2 summarizes in format ion about each patient 's age at testing, age at in jury , sex, e t io logy , and l e s i o n loca t ion . I n d i v i d u a l subject descript ions Subject 1 - K P : K P sustained a severe head in jury i n a h i g h speed m o t o r v e h i c l e accident w h e n he was 11 years 11 months o f age (11;11). H e lost consciousness i m m e d i a t e l y and, o n admiss ion to hospi ta l , w a s f o u n d to have a fracture o f the r ight f ronta l and parieta l s k u l l extending to the base o f the s k u l l at the l e v e l o f the orbi ta l roof . A C T scan revea led brain shift from T a b l e 2. Subject Descr ip t ions A g e at A g e at C o m a L e s i o n Subject Sex Injury Tes t ing D u r a t i o n L o c a l i z a t i o n K P M 11 yrs . 15 yrs . 10 days bi lateral K T F 2 yrs . 12 yrs . 4 days left K F F 12 yrs . 13 yrs . 6 weeks bi lateral K V F 8 yrs . 9 yrs . 4 days r ight D T M 12 yrs . 13 yrs . < 7 days left W G M 9 yrs . 11 yrs . 4.5 months bi lateral R B M 12 yrs . 14 yrs . 3.5 months bi lateral 17 m i d l i n e to the left i n v o l v i n g the right lateral ventr ic les . A m i l d d i l a t i o n o f the left lateral ventr ic les and a haematoma i n the r ight f rontal parietal area were also evident. K P r e m a i n e d comatose for ten days . O n the tenth day post in jury he w a s able to obey s imple c o m m a n d s . H e attempted to mouthe w o r d s but was unable to achieve phonat ion . H e was able to wr i te his name. Ref lexes were intact but an o v e r a l l l e f t - s ided weakness was evident . A t t w o weeks post in jury , K P was able to n o d his head f o r "yes" and point to objects he wanted . B y the th i rd week post in jury, he responded to s i m p l e questions w i t h o n e - w o r d spoken answers, but his v o i c e was o f l o w intensity. A t one m o n t h post in jury , K P ' s speech consis ted o f one- and t w o - w o r d utterances. Speech was i m p r o v i n g r a p i d l y but most utterances were incomple te o r perseverative. W r i t t e n language consisted o f s ingle w o r d s and short sentences. A t t e n t i o n span and perceptual abil i t ies were l i m i t e d . Short - term m e m o r y was par t i cu lar ly weak . A t t w o months post in jury, language testing revealed abi l i t ies close to p r e m o r b i d levels . W o r d f i n d i n g d i f f i cu l t ies were s t i l l evident. C o g n i t i v e testing indicated cogni t ive abi l i t ies were at age l e v e l but h igher l e v e l funct ions r e m a i n e d problemat ic . A t three months post in jury , K P ' s language comprehens ion s k i l l s as tested were w i t h i n n o r m a l l imi t s . L a n g u a g e p r o d u c t i o n was b e l o w age l e v e l . W o r d r i n d i n g d i f f i c u l t i e s were evident i n conversat ional situations. Spontaneous speech was c i r c u m l o c u t o r y and often soc ia l ly inappropriate . A t seven months post in jury, K P was attending regular classes at school fu l l t ime but required tutor ing i n a l l subjects, and m e m o r y lapses and w o r d - f i n d i n g d i f f i cu l t i e s were s t i l l apparent. A t the t ime o f this study, K P was attending regular h i g h s c h o o l classes fu l l t ime and no longer rece ived tutoring. K P is act ive i n compet i t ive f igure skat ing w i t h his sister. Subject 2 - K T : K T w a s struck b y a car w h i l e c ross ing the street w h e n she was 2; 3. She was struck on the left side o f the head and rendered i m m e d i a t e l y unconsc ious . She was admit ted to hospital 18 twenty minutes after the accident and was g i v e n medica t ion to decrease s w e l l i n g o f the brain . She was transferred to another hospi ta l f o r t y - f i v e minutes later. A C T scan revea led subdural haematoma and a basal s k u l l fracture. K T was comatose for f o u r days . O n the four th day she began to m a k e seizure type movements . H e r f irst v o c a l i z a t i o n post in jury occurred three months later, w h e n she g i g g l e d i n response to a j o k e . In the next f e w months , she began m a k i n g guttural sounds, then babb l ing sounds. B y e leven months post in jury , she had an inventory o f four o r f i v e w o r d s . A t t w e l v e months post in jury , she began r e c e i v i n g speech therapy i n a p r e s c h o o l environment . A t t w o years post in jury , K T ' s language was s t i l l a ma jor concern . H e r mother reported that K T had d i f f i c u l t y express ing her ideas but that language understanding was adequate for s i m p l e mater ia l . M e m o r y was a major p r o b l e m . A t the time o f testing f o r the present study, ten and a h a l f years post in jury , K T was independent ly m o b i l e and attended a class f o r educable menta l ly handicapped c h i l d r e n at a l o c a l s chool . She cont inued to have major m e m o r y p r o b l e m s and a n o m i a . Language comprehens ion w a s reportedly adequate f o r s imple mater ia l , but syntax was disordered i n sentence p r o d u c t i o n . Subject 3 - K F : K F was 12 years o f age w h e n the car she was r i d i n g i n was i n v o l v e d i n a head-on c o l l i s i o n . K F was severely in jured. T h e dr iver o f the car was k i l l e d . U p o n arr iva l o f the ambulance , she was i n respiratory arrest. O n a d m i s s i o n to hospi ta l , she h a d m u l t i p l e injuries i n c l u d i n g a severe c l o s e d head in jury . A C T scan one m o n t h post in jury s h o w e d a temporal haematoma a n d cerebral edema. In the intensive care unit , she required tracheostomy for p u l m o n a r y toilette and h a d an internal pseudomembraneous co l i t i s . She deve loped m a r k e d spastici ty i n her upper and l o w e r l i m b s . A t s ix weeks post in jury , she c o u l d f o l l o w s imple 19 one-step c o m m a n d s . B y four months post in jury , head cont ro l h a d i m p r o v e d and she c o u l d say "yes" and " n o , " n o d and shake her head appropriate ly , and apparently understand s imple questions. H e r speech w a s nasal and d y s a r t h r i a A t the t ime o f testing for the present study, one year post in jury , K F was independently m o b i l e i n a w h e e l c h a i r and had begun to w a l k short distances. M u s c l e tone remained elevated i n her upper and l o w e r l i m b s . She had a palatal l i f t to reduce nasal i ty but her speech r e m a i n e d d y s a r t h r i a She was sel f -conscious about the qual i ty o f her speech and, d u r i n g testing, was reluctant to be recorded o n audiotape. K F l i v e s at home w i t h her father and o lder sister. She n o w attends regular grade nine classes. A personal aide takes her to school and assists her w i t h w r i t i n g and personal care. She receives speech, p h y s i o - and occupat ional therapy once a w e e k as an outpatient i n a nearby hospi ta l . Subject 4 - K V : K V was 8 years o l d w h e n she suffered a moderately severe c l o s e d head in jury w h e n she was struck b y a car w h i l e c ross ing the street w i t h her mother. She was rendered immedia te ly unconsc ious . W h e n she ar r ived at hospi ta l her eyes opened to p a i n and she made incomprehens ib le voca l iza t ions . She had increased tone i n the upper extremities and her head was rotated to the left , apparently due to spasmodic tor t icol l i s related to her p r i m a r y brain in jury . A C T scan indica ted a s m a l l haemorrhage adjacent to the r ight lateral ventr ic le . K V r e m a i n e d comatose for four days . T h e tort icol l is reso lved i n the f o l l o w i n g weeks . She began t a l k i n g three weeks post in jury . K V l ives at h o m e w i t h her mother, father and younger brother. H e r f a m i l y came to C a n a d a i n M a r c h , 1986. K V ' s first language is Spanish and she h a d been speaking E n g l i s h f o r eighteen months at the t ime o f the accident. 20 A n educat ion report at one year and one month post in jury shows that K T at that t ime was exper ienc ing average academic achievement w i t h some m i l d auditory retention di f f icul t ies . She rece ived a moderately l o w score o n a test o f o n e - w o r d v o c a b u l a r y comprehens ion . Scores o n the W I S C - R were w e l l w i t h i n n o r m a l l i m i t s , w i t h the except ion o f the D i g i t Span subtest, w h i c h indica ted a m i l d auditory short-term m e m o r y def ic i t . K V is current ly enrol led i n a regular grade class at a p u b l i c s c h o o l i n her c o m m u n i t y where she is m a k i n g average academic progress. Subject 5 - D T : D T was 12 years o f age w h e n the m o t o r c y c l e he was r i d i n g was hit broadside by a car. H e w a s rendered i m m e d i a t e l y unconsc ious . O n a r r i v a l at a nearby hospi ta l , he was m o v i n g his l i m b s a b n o r m a l l y . H i s left p u p i l became di la ted and he had a general ized seizure. H e was transferred i m m e d i a t e l y to a larger f a c i l i t y and , en route, had another general ized seizure. A C T scan, made i m m e d i a t e l y o n a r r i v a l , revealed s w e l l i n g o f the left cerebral hemisphere and contus ion o f the left f rontal lobe . There was a deep haemorrhage i n the r e g i o n o f the left internal capsule . H e had no eye-opening response to p a i n and a G l a s g o w c o m a score o f 6/15. H e h a d r ight hemipares is w i t h almost no m o v e m e n t i n the r ight l o w e r l i m b s . A s c h o o l report wri t ten at nine months post in jury describes D T as a happy c h i l d w i t h average mathemat ica l and reading abi l i t ies , but w h o exhib i ted def ic i ts i n several areas o f l earn ing . D T had d i f f i c u l t y f o l l o w i n g ora l direct ions , had severe short-term m e m o r y defic i ts , was eas i ly distracted, and had a short attention span. H e c o u l d express h i m s e l f w e l l verba l ly , but h a d d i f f i c u l t y c o m p o s i n g wri t ten mater ia l . 21 Subject 6 - RB: RB was struck by a motor vehicle as he was crossing the road when he was 12 years of age. On arrival at hospital, he was comatose and had spastic posturing of all four limbs. An X-ray of the skull showed a fracture of the right side. A CT scan revealed a mild depression of the fracture and scattered bilateral contusions of the parietal lobes. At ten days postinjury, RB opened his eyes spontaneously, but did not respond to commands. At three weeks postinjury, he occasionally responded to instructions and could move all four limbs. At four weeks postinjury, RB was transferred to a rehabilitation hospital. A physical examination revealed normal cranial nerves, increased extensor tone on lower extremities and flexor tone on upper extremities. RB smiled at his mother but would not maintain eye contact. RB's condition continued to improve over the next few months, but changes in his personality were noted. RB had displayed social and behaviour problems prior to his accident. These problems were accentuated postinjury. RB frequently used abusive language. His behaviour was often erratic, threatening, and lacking in inhibition. An assessment at five months postinjury indicated that RB's language skills were near or above age expectancies. However, exceptions were noted in some language areas. For instance, RB had a poor memory for recent events and a decreased ability to recall known information on request. He had difficulty understanding idioms, metaphors, meaning carried by intonation, and extracting information from longer paragraph length spoken utterances. His spontaneous language output was excessive and disorganized, with rambling, repetitive themes of conversation. A language assessment at two and a half years postinjury indicated no obvious language deficits in conversation and a normal ability to follow oral commands of increasing length and complexity. Word retrieval was mildly impaired. RB was still using coarse, inappropriate language in conversation. 22 Subject 7 - WG: WG was struck by a car while crossing the street and sustained a severe closed head injury five days before he turned 9 years of age. He was rendered immediately unconscious and was taken to a nearby hospital where he suffered a right focal seizure which lasted three minutes. His breathing pattern was noted to be abnormal. There was increased muscle tone on both his right and left side and unusually dense left hemiparesis. He was transferred immediately by helicopter to a larger facility. A CT scan taken on arrival revealed multiple haemorrhagic contusions throughout the brain, small subdural bleeds bilaterally, compressed ventricles, deformation of the peduncles, and multiple skull fractures. A later CT scan, made eight days postinjury showed that haemorrhagic areas had resolved and that there were lower tenuation areas throughout the brain in the frontal lobes, temporal lobes and particularly in the right parietal lobes. An EEG made fifteen days postinjury was highly abnormal. His mother described WG as being a sociable, outgoing and happy child before the accident. He was reportedly a good student, although no academic records are available. WG began receiving speech and language therapy one and a half months postinjury at a rehabilitation centre and continued treatments there for six months. At the initiation of therapy, WG demonstrated generalized responses to sensory stimuli. By four months postinjury localized responses were observed. At five months, WG was able to respond to simple commands and consistent yes/no responses were established. He could spontaneously use several gestures, sometimes in sequence, to communicate his needs (e.g. "you-me-go-kitchen-drink"). Severe attentional deficits were evident. He had very limited control of his oral musculature and could vocalize only /a/ and /vol. At six months postinjury, WG continued to have severe difficulties in speech production, producing only two vowels (/a/ and /if) consistently. He was oriented to himself and his surroundings, but demonstrated only 23 "concrete processing." He was able to point to one inch by one inch pictures to communicate in structured situation but refused to use this means of communication in naturally occurring situations. During the seventh and eighth month of recovery, when W G received therapy as an outpatient, formal testing was not completed because of WG's limited attention span. He continued to demonstrate difficulty with orientation to time. He was able to learn new activities and remember component steps over time. Processing of language was significantly slowed and his attention span for activities was limited to five to ten minutes. At the time of testing for the present investigation, two years and two months postinjury, W G was receiving speech and language therapy as an outpatient from a rehabilitation centre near his home. His speech was fluent but marked by hesitations and an uncoordinated breathing pattern. Limited attention span continued to be a problem. 24 C H A P T E R 3 R E S U L T S The mean percent of correct sentences by sentence type for C H I subjects and normal control subjects is shown in Figure 1. Individual subjects scores are summarized by sentence type in the Appendix. The means and standard deviations of subjects' scores for each sentence type for the control and C H I groups as a whole are presented in Table 3. A n analysis of variance summary is presented in Table 4 . Figure 1. Mean percent of sentences answered correcdy by C H I (open bars) and normal control (slashed bars) subjects. (n=7) MEAN PERCENT CORRECT 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% _ ! ? ! l I ! I I • \ I i A P C S C O DA DP C S O O S SENTENCE TYPE 25 T a b l e 3 . M e a n s and standard deviat ions by sentence type for c o m b i n e d C H I and n o r m a l c o n t r o l groups (n=14). Sentence T y p e M e a n s .d. A c t i v e 5.0 0.0 C l e f t subject 4.9 0.3 D a t i v e act ive 4.7 0.5 C o n j o i n e d 4.7 0.5 Pass ive 4.6 1.1 C l e f t object 4.6 0.8 D a t i v e passive 4.1 1.7 Object-subject re lat ive 4.0 1.2 Subject-object relat ive 3.5 1.6 T a b l e 4 . A n a l y s i s o f V a r i a n c e S u m m a r y : c o m b i n e d c losed head in jured and n o r m a l control groups. Source o f V a r i a t i o n d f S S M S between treatments 8 36.52 4.57 F = 9.52 w i t h i n treatments 104 112.86 1.09 T o t a l 112 149.37 * A n analysis o f var iance w i t h repeated measures o n the sentence type factor revealed a s igni f icant effect o f this factor o n the number o f correct responses (F(8,104)=9.52, p <.01). T u k e y ' s honest ly s igni f icant dif ference ( H S D ) procedure was a p p l i e d at an exper imentwise error rate o f .05 to determine w h i c h means d i f f e r f r o m others. Resul ts are s h o w n i n Table 5 . F o r C H I and n o r m a l contro l scores considered as a w h o l e , sentence type S O was 26 s igni f i cant ly m o r e d i f f i c u l t than a l l other sentence types except D P and O S . Sentence type A w a s s ign i f i cant ly easier than D P , S O and O S , and sentence type C S r e c e i v e d s igni f icant ly higher scores than d i d S O and O S . N o n e o f the m e a n scores o f other sentence types di f fered s ign i f i cant ly from each other. N u l l hypothesis 1 (p. 15) is rejected. A n a l y s e s o f var iance w i t h repeated measures o n the sentence type factor were also conducted for each group separately. M e a n scores and standard deviat ions for the C H I group are s h o w n o n T a b l e 6. A n analysis o f var iance s u m m a r y i s p r o v i d e d i n T a b l e 7. T u k e y ' s honest ly s igni f icant di f ference procedure was a p p l i e d and revea led o n l y t w o signif icant di f ferences : sentence type S O was more d i f f i c u l t than types A and C S for C H I subjects. T a b l e 5 . Resul ts o f T u k e y ' s Procedure (experiment-wise error rate o f 0.05) a p p l i e d across sentence type for c o m b i n e d C H I and contro l groups (n=14). A C S D A C P C O D P O S S O Note: Sentence types under l ined b y a c o m m o n l i n e are not s igni f i cant ly different from each other; sentence types not under l ined by a c o m m o n l ine are s igni f i cant ly different . 27 T a b l e 6. M e a n s and standard deviat ions b y sentence type for C H I group (n=7). Sentence T y p e M e a n s.d. A c t i v e 5.0 0.0 C l e f t subject 4.9 0.4 C o n j o i n e d 4.6 0.5 D a t i v e act ive 4.4 0.5 C l e f t object 4.4 1.1 Pass ive 4.3 1.5 D a t i v e pass ive 3.7 2.2 Object-subject re lat ive 3.7 1.4 Subject-object relat ive 3.1 2.0 T a b l e 7. A n a l y s i s o f V a r i a n c e S u m m a r y : C l o s e d H e a d Injured Subjects Source o f V a r i a t i o n d f S S M S between treatments 8 20.29 2.54 F = 3.1 w i t h i n treatments 48 89.14 1.86 T o t a l 109.43 T h e same procedures were a p p l i e d to the scores o f the n o r m a l c o n t r o l group. Resul ts are s h o w n o n T a b l e 8. A n analysis o f variance s u m m a r y i s presented i n T a b l e 9. F o r this group, the m e a n scores associated w i t h S O are s igni f i cant ly more e levated than those o f A , P , and C S . P a i r e d compar isons o f a l l other sentence types s h o w e d no s igni f icant differences. 28 T a b l e 8. M e a n s and standard deviat ions by sentence type for n o r m a l c o n t r o l group (n=7). Sentence T y p e M e a n s.d. A c t i v e 5.0 0.0 C l e f t subject 5.0 0.0 D a t i v e act ive 5.0 0.0 Pass ive 5.0 0.0 C o n j o i n e d 4.9 0.4 C l e f t object 4.9 0.4 D a t i v e passive 4.4 1.1 Object-subject relat ive 4.3 1.3 Subject-object relat ive 3.9 1.1 T a b l e 9. A n a l y s i s o f V a r i a n c e S u m m a r y : N o r m a l C o n t r o l Subjects Source o f V a r i a t i o n d f S S M S between treatments 8 9.56 1.20 F = 3.2 w i t h i n treatments 48 23 .72 .49 T o t a l 56 33.28 Subjects ' scores were a n a l y z e d i n a two-factor analysis o f var iance w i t h repeated measures o n one factor. T h e between-subjects factor was G r o u p : C H I and n o r m a l controls . T h e repeated measure was sentence type. A n analysis o f var iance s u m m a r y is presented i n T a b l e 10. A s igni f icant m a i n effect was f o u n d for the G r o u p factor (F( l ,108)=6 .38 , p <.05). C l o s e d head in jured subjects rece ived s igni f i cant ly l o w e r o v e r a l l scores than d i d n o r m a l controls . N u l l hypothesis 2 (p. 15) is rejected. 29 T a b l e 10. A n a l y s i s o f V a r i a n c e S u m m a r y : T w o factor (group) repeated measures (sentence type) Source o f V a r i a t i o n d f S S M S between treatments 17 36.52 between subjects (group) 1 6.67 6.670 F = 6.38 repeated measure (sentence type) 8 27.87 3.484 F = 3.33 interact ion 8 1.98 .248 F = .24 w i t h i n treatments 108 112.86 1.045 T o t a l 125 149.37 T h e group b y sentence type interact ion was not f o u n d to be s igni f icant (F(8,108)=0.24, p > 0.1), i n d i c a t i n g that the C H I group d i d not s igni f i cant ly d i f fer f r o m the n o r m a l control group for any sentence type. A s ignif icant m a i n effect was f o u n d f o r the Sentence T y p e factor (F(8,108)=3.33, p <.01). N u l l hypothesis 3 (p. 15) is rejected. Post hoc compar isons were not carr ied out as the effect o f sentence type was cons idered i n the analysis o f var iance conducted o n the t w o groups as a w h o l e and o n each group separately. A c o m p a r i s o n o f tables 5 and 6 shows that the r a n k i n g o f sentence types b y d i f f i c u l t y is s i m i l a r for the C H I and n o r m a l contro l groups. H o w e v e r , whereas sentence type P was m o r e d i f f i c u l t than C and C O f o r the C H I group the reverse was true for the n o r m a l contro l group. A l s o , i n contrast to results f r o m the n o r m a l contro l group, the mean score for sentence type C was higher than for D A i n the C H I group. Otherwise , rank scores are s i m i l a r for the t w o groups and resembles the order f o u n d b y C a p l a n et a l . (1985). 30 Sentence-parsing Strategies Subject responses were analyzed for patterns w h i c h c o u l d revea l strategies for sentence pars ing . Because subjects K T and W G gave a m u c h larger number o f erroneous responses than other subjects, their responses were ana lyzed separately. O n s ingle v e r b sentences ( A , P , C S , C O ) , K T s h o w e d a strong tendency to interpret the f irst n o u n as agent and the second as theme. S ixteen out o f the twenty (16/20) two-place verb sentences were interpreted this w a y . K T s h o w e d a s i m i l a r tendency w i t h three-place v e r b sentences ( D , D P ; 5/10), a l though responses to D P sentences were quite var ied . O n c o m p l e x sentences ( C , S O , O S ) , K T almost a lways chose the th i rd n o u n as theme o f the second verb (14/15). T h e first n o u n was usua l ly assigned the ro le o f the agent o f the first v e r b (10/15). H e r choice as agent o f the second verb was d i v i d e d between the first noun (8/15), the second n o u n (6/15) and the t h i r d n o u n (1/15). W G ' s responses to var ious sentence-type were h i g h l y var iable . O n one-place s ingle v e r b sentences, his o n l y error i n v o l v e d ass igning the ro le o f agent to the f irst noun . W G had a h i g h error rate o n three-place verb and c o m p l e x sentences. O n three-place verb sentences, he interpreted 5 0 % o f the presentations incorrec t ly (5/10). M o s t errors occurred w i t h D P sentence construct ions. There d i d not appear to be any pattern i n the assignment o f thematic r o l e o n these sentences. W G misinterpreted about 4 7 % (7/15) o f the c o m p l e x sentences. F o r these sentences, he usua l ly assigned the ro le o f agent o f the first verb to the first n o u n (11/15). T h e third n o u n was usua l ly assigned the ro le o f theme o f the second verb (10/15). A s s i g n m e n t o f theme o f the first v e r b and agent o f the second verb was var iab le . It m a y be important to note that W G was reported to have a reduced attention span. S ince c o m p l e x and three-place verb sentence are longer than s imple sentences, he m a y have experienced d i f f i c u l t y attending to a l l o f the i n f o r m a t i o n presented i n the longer sentences and u s i n g i n f o r m a t i o n to assign thematic roles . 31 T h e responses o f the f i v e other subjects were considered as a w h o l e . O n s ingle verb sentences, errors a lmost never occurred (1/100) and i n v o l v e d assignment o f the agent role to the f irst n o u n ( K P - p a s s i v e ) . O n the three-place v e r b sentences, errors were almost never occurred (2/50). O n e error occurred w h e n the th i rd n o u n was assigned the role o f theme and the second n o u n assigned the role o f goa l ( K F - d a t i v e ) . A n o t h e r error i n v o l v e d misinterpretat ion o f the prepos i t ion " to" ( R B - d a t i v e ) . T h e f i v e subjects misinterpreted the c o m p l e x sentences i n 9 % o f the presentations (8/75). Responses to c o m p l e x sentences were var iab le and not revea l ing o f strategies used to assign thematic ro le . 32 C H A P T E R 4 D I S C U S S I O N T h e purpose o f this invest igat ion was to examine comprehens ion o f o r a l language by c h i l d r e n w h o have suffered c l o s e d head in juries . T h i s w a s e luc idated i n four questions presented i n the in t roduct ion . These questions are presented again i n T a b l e 11 f o r ease of reference. Resul t s o f the present study p r o v i d e i n f o r m a t i o n w h i c h m a y be used to address these f o u r questions: 1. A s s i g n m e n t o f thematic ro le f o l l o w s a h ierarchica l order o f d i f f i c u l t y based o n sentence type. T h i s order o f d i f f i c u l t y is s i m i l a r for the n o r m a l and C H I c h i l d populat ions . 2. C H I c h i l d r e n have more d i f f i c u l t y ass igning thematic roles to nouns i n o r a l l y presented sentences than d o n o r m a l ch i ldren . 3. N o part icular sentence type was re la t ive ly m o r e susceptible to interpretation b r e a k d o w n than was any other sentence type after c l o s e d head in jury . T h e di f ference between per formance o f C H I c h i l d r e n and n o r m a l c h i l d r e n o n sentence interpretation tasks was o f about the same magnitude across sentence types. 4. T h e h ierarchica l order o f d i f f i c u l t y b y sentence type i n the y o u n g C H I p o p u l a t i o n resembles the order f o u n d a m o n g C H I adults (But ler et a l . , u n p u b l i s h e d manuscript) and aphasic adults ( C a p l a n et a l . , 1985). 33 T a b l e 11. Quest ions addressed i n the present invest igat ion 1. Is the assignment o f thematic ro le more d i f f i c u l t i n some sentence structures than i n others f o r c l o s e d head in jured and n o r m a l ch i ldren? 2. D o C H I c h i l d r e n have more d i f f i c u l t y ass igning thematic ro le than d o n o r m a l chi ldren? 3. A r e any part icular sentence types re la t ive ly more susceptible to interpretation b r e a k d o w n than other sentence types i n the y o u n g C H I populat ion? 4. D o e s the partem o f sentence interpretation b r e a k d o w n i n C H I c h i l d r e n resemble that f o u n d i n C H I adults and aphasic adults? T h e results o f this study suggest that syntactic structure is a factor af fect ing the accuracy o f thematic ro le assignment b y the y o u n g C H I p o p u l a t i o n . T h e s imi lar i ty between rank order o f sentence types for n o r m a l and C H I c h i l d r e n suggests that the syntactic features w h i c h affect interpretation o f thematic ro le are the same for both populat ions . C a p l a n , B u t l e r and Dehaut (1985) ident i f ied three "elementary structural features" w h i c h contr ibuted to the relat ive d i f f i c u l t y o f thematic ro le assignment b y adult aphasic s: n o n c a n o n i c a l w o r d order, presence o f a th ird thematic ro le , and presence o f a second verb . Resul ts o f the present study indicate that these structural features are par t ia l determinants o f sentence interpretation d i f f i c u l t y i n the y o u n g C H I p o p u l a t i o n . Because o f the s m a l l n u m b e r o f subjects, some o f these effects appear as tendencies. T h e ro le o f the f irst feature, w o r d order, can be seen i n A , P , D A , and D P sentence-types. T h e active f o r m o f a sentence tended to be easier than the passive f o r m w h e n there was an equivalent number o f arguments around a verb ( A versus P ; D A versus D P ) . S i m i l a r l y , sentences w i t h equivalent argument structures around verbs were more d i f f i c u l t w h e n they contained two preverba l n o u n phrases than w h e n they were i n c a n o n i c a l f o r m ( C O versus C S ; S O versus C and O S ) . 34 T h e second feature ident i f i ed b y C a p l a n et a l . was the presence o f a th i rd thematic ro le . T h e effect o f this feature was not d i rec t ly assessed independent o f sentence length. S ing le -verb test sentences possessing a th i rd thematic role ( D , D P ) contained more w o r d s than s ingle-verb t w o thematic ro le sentences ( A , P ) . T h e sentence length factor w o u l d have been c o n t r o l l e d w i t h the i n c l u s i o n o f act ive and passive con jo ined theme sentences as demonstrated i n the f o l l o w i n g : 1) T h e m o n k e y hit the elephant and the rabbit (active con jo ined theme) 2) T h e turtle was hit b y the goat and the elephant (passive con jo ined theme). H o w e v e r , e v e n w h e n sentences w i t h a th ird thematic role were c o m p a r e d w i t h embedded sentences o f equal length w h i c h conta ined o n l y t w o thematic roles ( D versus C S ) , they were f o u n d to be more d i f f i c u l t to interpret. T h e th i rd structural feature ident i f ied b y C a p l a n et a l . (1985) was presence o f a second verb . T h i s feature was f o u n d to affect sentence interpretation i n the y o u n g C H I popula t ion . Sentences w i t h t w o verbs tended to be more d i f f i c u l t than one verb sentences w h e n c a n o n i c a l w o r d order was contro l l ed ( C and O S versus A and CS', S O versus C O ) . T h u s i t seems that the three structural features ident i f i ed b y C a p l a n as par t ia l ly de termining accuracy o f thematic ro le assignment i n an aphasic adult also affect thematic role assignment i n C H I c h i l d r e n . It i s important to remember that structural features are not the o n l y factors determining task per formance . W h i l e the toy a n i m a l manipula t ion task was des igned to m i n i m i z e effects o f m e m o r y , the roles o f attention and m e m o r y m a y not be comple te ly r u l e d out as factors contr ibut ing to performance. T w o C H I subjects i n part icular demonstrated attention 35 p r o b l e m s d u r i n g the test session and, according to independent c l i n i c a l reports, suffered a degree o f short- term m e m o r y def ic i t . It s h o u l d be noted that subject age was l i k e l y a part ia l determinant o f per formance o n this task. N o r m a l subjects, w h o ranged i n age f r o m 9 to 15 years, demonstrated a poorer performance o n the toy a n i m a l m a n i p u l a t i o n task than d i d n o r m a l adults i n other studies ( C a p l a n , et a l . , 1985; B u t l e r , et a l . , unpubl i shed manuscr ipt) . Invest igat ion o f i n d i v i d u a l responses indicate that the y o u n g C H I p o p u l a t i o n uses a strategy based o n l inear order o f n o u n presentation to assign thematic roles i n at least some o f the sentences presented. K T had a strong tendency to assign roles according to the c a n o n i c a l order o f thematic roles i n E n g l i s h s imple one-verb sentences. She assigned the roles o f agent, theme and goa l to the f irst , second, and th i rd nouns respect ively , thus r e l y i n g o n l inear order o f o ra l presentation f o r thematic ro le assignment. T h i s tendency is seen to a lesser degree a m o n g other C H I subjects. H o w e v e r , the l inear order ing strategy is not a p p l i e d to a l l sentence types, but appears o n l y i n responses o f C H I subjects to s imple sentences w i t h one- and two-place verbs . It does not appear i n the same subjects ' responses to c o m p l e x sentences. Strategies used to assign thematic roles i n c o m p l e x sentences are not o b v i o u s i n results from the present study. T h e use o f a strategy based o n l inear order o f presentation m a y not be r u l e d out. Further invest igat ion w i t h a greater var ie ty and more presentations o f c o m p l e x sentence types m a y reveal more about assignment strategies not obv ious from the present results. L o w scores obtained by W G o n longer sentences ( D P , C , S O , O S ) suggest that def ic i ts o f attention affect comprehens ion o f o r a l sentences. W h e n the amount o f in format ion d i d not exceed attention l imi ta t ions , assignment o f thematic ro le , i n W G ' s case, appeared to be r a n d o m . Research invest igat ing n o r m a l c h i l d language development has indicated that, w h i l e k n o w l e d g e o f basic syntax, that i s , constructions w i t h c a n o n i c a l w o r d order , i s acquired by 36 age 5 , s p e c i a l i z e d syntactic rules for c o m p l e x constructions are gradual ly mastered from age 5 to 10 ( K a r m i l o f f - S m i t h , 1986). U n t i l c h i l d r e n have acquired these spec ia l ized rules, i t has been proposed that they apply interpretive strategies w h i c h h o l d f o r s imple construct ions to m o r e c o m p l e x sentence constructions w h i c h they cannot yet process f u l l y . O n e o f these strategies, the M i n i m a l Dis tance P r i n c i p l e ( M D P ) ( C h o m s k y , 1969, p . 11), states that "the i m p l i c i t subject o f a complement verb is the n o u n phrase most c l o s e l y preced ing i t . " T h e M D P holds for almost a l l verbs i n E n g l i s h . H o w e v e r , sentences w i t h verbs such as promise and tell d o not h o l d to the M D P . C a r o l C h o m s k y (1969) f o u n d that c h i l d r e n start out a p p l y i n g the M D P to a l l sentence types. A n o t h e r p r o p o s e d strategy , or " p r i m i t i v e r u l e " ( C r o m e r , 1970, p . 405) used by y o u n g n o r m a l c h i l d r e n equates surface subject w i t h deep o r l o g i c a l subject. U s e o f this rule leads to an erroneous interpretation i n w h i c h John is the l o g i c a l subject o f the in f in i te i n sentences l i k e John is easy to see. Investigations o f c h i l d r e n ' s interpretation o f sentences conta in ing re lat ive clauses have l e d to several hypotheses. T h e "para l le l funct ion hypothes is" (She ldon , 1974), proposes that sentences i n w h i c h the head N P o f the relat ive clause p lays the same grammat ica l role i n both the matr ix and the relat ive clause are easier for c h i l d r e n to interpret than sentences i n w h i c h the N P shifts f u n c t i o n . T h i s hypothesis accounts f o r the earl ier comprehens ion o f sentences l i k e e x a m p l e 1 than sentences l i k e e x a m p l e 2 : 1) T h e goat that k i c k s the rabbit k i s s e d the m o n k e y . 2) T h e m o n k e y kisses the goat that k i c k s the rabbit . H o w e v e r , T a v a k o l i a n (1977) c o n c l u d e d that a "con jo ined clause analys is " better accounted f o r the pattern o f interpretation that c h i l d r e n make o f sentences c o n t a i n i n g relat ive clauses. T h i s hypothesis states that c h i l d r e n interpret these sentences as i f they conta ined t w o 37 con jo ined clauses. A th i rd hypothesis , termed a "process ing heuris t ic" by its originators (de V i l l i e r s , T a g e r F l u s b e r g , H a k u t a and C o h e n , 1976) states that c h i l d r e n use a l inear order strategy that interprets N - V - N strings as agent-action-object. Resul ts o f the present and previous invest igations ( C a p l a n et a l . , 1985, B u t l e r et al) have suggested that C H I c h i l d r e n and adults and aphasics use a strategy to assign thematic ro le based o n l inear order o f n o u n and verb presentation for at least some sentence structures. T h i s strategy appears s i m i l a r to the process ing heurist ic proposed b y de V i l l i e r s et a l . (1976). T h e strategies that developmenta l l iterature suggest are used b y n o r m a l d e v e l o p i n g c h i l d r e n to interpret sentences m a y be s i m i l a r to those used by C H I c h i l d r e n and adults , and by adult aphasics. M o r e research is needed i n this area before conclus ions can be made. W h i l e n o r m a l adults rarely make errors o f sentence interpretation o n the task adminis tered i n this study ( C a p l a n et a l . , 1985, B u t l e r et a l , u n p u b l i s h e d manuscr ipt) inaccurate responses o f n o r m a l contro l subjects i n this invest igat ion were f a i r l y frequent. Fur thermore , as w i t h the head in jured subjects, accuracy o f interpretation a m o n g the n o r m a l c h i l d r e n v a r i e d w i t h sentence type. Responses o f n o r m a l c h i l d r e n f o r m e d a hierarchy o f sentence types based o n d i f f i c u l t y o f interpretation w h i c h was s i m i l a r to that f o u n d o n examinat ion o f C H I and aphasic subject responses. T h e f i n d i n g s o f the present study are i n apparent contradic t ion to those studies w h i c h have s h o w n either no comprehens ion defic i ts (Gut tman, 1942; B r a n c o - L e f e v r e , 1950), or r a p i d and complete recovery o f comprehens ion ( A l a j o u n i n e and L h e r m i t t e , 1965; H e c a e n , 1976; 1983) i n C H I c h i l d r e n ; the f i n d i n g s are, however , i n agreement w i t h those studies f i n d i n g res idua l defects o f comprehens ion ( L e v i n and E i s e n b e r g , 1979; M i t c h e l l , 1985). H o w e v e r , w h i l e M i t c h e l l c o u l d not demonstrate that comprehens ion def ic i ts were syntact ica l ly based, the present f indings suggest that syntactic structure at least par t ia l ly 38 determines ab i l i ty to c o m p r e h e n d sentences. T h e dif ference between f i n d i n g s m a y be due to test m e t h o d o l o g y . F e w studies have e x a m i n e d comprehens ion us ing methods that c o n t r o l l e d m e m o r y , behavioura l , semantic or pragmatic factors. L o n g te rm recovery o f language and cogni t ive funct ions by c h i l d r e n w i t h head injuries have been s h o w n to be substantial but incomplete . M i l d l inguis t i c and cogni t ive impai rments m a y not be evident f r o m results o f assessment w i t h convent iona l test batteries. Sarno ' s c o n c l u s i o n that "the use o f sophisticated, neurol inguis t ic measures w i t h this p o p u l a t i o n is needed to detect subtle def ic i t w h i c h can permit enl ightened c l i n i c a l judgement" (Sarno, 1980, p . 691) seem par t i cular ly v a l i d i n l ight o f the present f indings . 39 B I B L I O G R A P H Y A l a j o u a n i n e , T . H . & L h e r m i t t e , F . 1965. A c q u i r e d A p h a s i a i n c h i l d r e n . B r a i n , 88, 653-662. A n n e g e r s , J . F . , & K u r l a n d , L . T . 1979. 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Changing patterns of childhood aphasia. Annals of  Neurology, 3, 273-280. 43 APPENDIX Individual Subject Responses Table A- l . Responses and scores for KP by sentence type. 1 2 Active (The monkey patted the rabbit) *1,2: 5/5 1 2 Passive (The monkey was touched by the rabbit) 1,2: 1/5 *2,1: 4/5 1 2 Cleft subject (It was the elephant that kissed the turtle) *1,2: 5/5 1 2 Cleft object (It was the elephant that the turtle touched) *2,1: 5/5 1 2 3 Dative (The elephant took the turtle to the rabbit) *1,2,3: 5/5 1 2 3 Dative passive (The monkey was brought to the turtle by the elephant) *3,1,2: 5/5 1 2 3 Conjoined (The monkey patted the rabbit and pushed the turtle) * 1,2; 1,3: 5/5 1 2 3 Subject-object relative (The elephant that the goat hugged hit the turtle) *2,1;1,3: 5/5 1 2 3 Object-subject relative (The elephant scratched the rabbit that caught the turtle) 2,1;2,3: 1/5 *1,2;2,3: 4/5 Note: The numerals above sentences denote the nouns as they occur from left to right within each sentence. The numerals below sentences represent subjects' responses. The first numeral of a series represents an agent role, the second numeral a theme role, and the third numeral a goal, when this role exists, as in sentence types D and DP. Where two verbs occur in a sentence, thematic roles around each verb are separated by a semi-colon. Numeral before the semi-colon describe thematic roles for the first noun as it occurs in a sentence. Numerals after the colon represent the ratio of subject responses of the type described. For example, KP interpreted one of five object-subject relative clause sentences as having the second noun theme of the first verb, the first noun agent of the first verb, the second noun agent of the second verb and the third noun theme of the second verb. The correct interpretation of each sentence type is denoted by *. This notation system is borrowed from Caplan and Futter (1986). 44 Table A-2. Responses and scores for KF by sentence type. 1 2 Active (The monkey patted the rabbit) *1,2: 5/5 1 2 Passive (The monkey was touched by the rabbit) *2,1: 5/5 1 2 Cleft subject (It was the elephant that kissed the turtle) *1,2: 5/5 1 2 Cleft object (It was the elephant that the turtle touched) *2,1: 5/5 1 2 3 Dative (The elephant took the turtle to the rabbit) 1,3,2: 1/5 *1,2,3: 4/5 1 2 3 Dative passive (The monkey was brought to the turtle by the elephant) *3,1,2: 5/5 1 2 3 Conjoined (The monkey patted the rabbit and pushed the turtle) *1,2;1,3: 5/5 1 2 3 Subject-object relative (The elephant that the goat hugged hit the turtle) 2,1;2,3: 1/5 1,2;1,3: 1/5 *2,1;1,3: 3/5 1 2 3 Object-subject relative (The elephant scratched the rabbit that caught the turtle) l,2;(l+2),3: 1/5 * 1,2;2,3: 4/5 45 Table A-3. Responses and scores for KV by sentence type. 1 2 Active (The monkey patted the rabbit) *1,2: 5/5 1 2 Passive (The monkey was touched by the rabbit) *2,1: 5/5 1 2 Cleft subject (It was the elephant that kissed the turtle) *1,2: 5/5 1 2 Cleft object (It was the elephant that the turtle touched) *2,1: 5/5 1 2 3 Dative (The elephant took the turtle to the rabbit) * 1,2,3: 5/5 1 2 3 Dative passive (The monkey was brought to the turtle by the elephant) •3,1,2: 5/5 1 2 3 Conjoined (The monkey patted the rabbit and pushed the turtle) * 1,2;1,3: 5/5 1 2 3 Subject-object relative (The elephant that the goat hugged hit the turtle) *2,1;1,3: 5/5 1 2 3 Object-subject relative (The elephant scratched the rabbit that caught the turtle) * 1,2:2.3: 5/5 46 Table A-4. Responses and scores for RB by sentence type. 1 2 Active (The monkey patted the rabbit) *1,2: 5/5 1 2 Passive (The monkey was touched by the rabbit) *2,1: 5/5 1 2 Cleft subject (It was the elephant that kissed the turtle) *1,2: 5/5 1 2 Cleft object (It was the elephant that the turtle touched) *2,1: 5/5 1 2 3 Dative (The elephant took the turtle to the rabbit) *U,3: 4/5 other: 1/5 (interpreted "to" as "from") 1 2 3 Dative passive (The monkey was brought to the turtle by the elephant) *3,1,2: 5/5 1 2 3 Conjoined (The monkey patted the rabbit and pushed the turtle) 3,2;3,1: 1/5 * 1,2; 1,3: 4/5 1 2 3 Subject-object relative (The elephant that the goat hugged hit the turtle) 3,1;1,2: 1/5 *2,1;1,3: 4/5 1 2 3 Object-subject (The elephant scratched the rabbit that caught the turtle) *1,2;2,3: 5/5 47 Table A-5. Responses and scores for DT by sentence type. 1 2 Active (The monkey patted the rabbit) *1,2: 5/5 1 2 Passive (The monkey was touched by the rabbit) *2,1: 5/5 1 2 Cleft subject (It was the elephant that kissed the turtle) *1,2: 5/5 1 2 Cleft object (It was the elephant that the turtle touched) *2,1: 5/5 1 2 3 Dative (The elephant took the turtle to the rabbit) * 1,2,3: 5/5 1 2 3 Dative passive (The monkey was brought to the turtle by the elephant) *3,1,2: 5/5 1 2 3 Conjoined (The monkey patted the rabbit and pushed the turtle) *1,2;1,3: 5/5 1 2 3 Subject-object relative (The elephant that the goat hugged hit the turtle) *2,1;1,3: 5/5 1 2 3 Object-subject relative (The elephant scratched the rabbit that caught the turtle) 1,2;3,2: 1/5 *1,2;2,3: 4/5 48 Table A-6. Responses and scores for KT by sentence type. 1 2 Active (The monkey patted the rabbit) *1,2: 5/5 1 2 Passive (The monkey was touched by the rabbit) 1,2: 4/5 *2,1: 1/5 1 2 Cleft subject (It was the elephant that kissed the turtle) 2,1: 1/5 *1,2: 4/5 1 2 Cleft object (It was the elephant that the turtle touched) 1,2: 3/5 •2,1: 2/5 1 2 3 Dative (The elephant took the turtle to the rabbit) 2,1,3: 1/5 *1,2,3: 4/5 1 2 3 Dative passive (The monkey was brought to the turtle by the elephant) 1,2,3: 1/5 2,1,3: 2/5 2,3,1: 1/5 other: 1/5 (picked up 1 and put 2 behind 3) *3,1,2: 0/5 1 2 3 Conjoined (The monkey patted the rabbit and pushed the turtle) 1,2;2,3: 1/5 *1,2;1,3: 4/5 1 2 3 Subject-object relative (The elephant that the goat hugged hit the turtle) 1,3;2,3: 1/5 2,1;2,3: 2/5 1,2;1,3: 1/5 other: 1/5 (arranged 1, 2 and 3 together) *2,1;1,3: 0/5 1 2 3 Object-subject relative (The elephant scratched the rabbit that caught the turtle) 2,1;3,1: 1/5 1,2;1,3: 3/5 *1,2;2,3: 1/5 49 Table A-7. Responses and scores for WG by sentence type. 1 2 Active (The monkey patted the rabbit) *1,2: 5/5 1 2 Passive (The monkey was touched by the rabbit) *2,1: 5/5 1 2 Cleft subject (It was the elephant that kissed the turtle) * U : 5/5 1 2 Cleft object (It was the elephant that the turtle touched) 1,2: 1/5 *2,1: 4/5 1 2 3 Dative (The elephant took the turtle to the rabbit) 1,3,2: 1/5 * 1,2,3: 4/5 1 2 3 Dative passive (The monkey was brought to the turtle by the elephant) 1,2,3: 1/5 2,1,3: 1/5 2,3,1: 1/5 other: 1/5 (picked up 1 and put 2 behind 3) *3,1,2: 1/5 1 2 3 Conjoined (The monkey patted the rabbit and pushed the turtle) 3,2;1,3: 1/5 *1,2;1,3: 4/5 1 2 3 Subject-object relative (The elephant that the goat hugged hit the turtle) 1,3; 1,2: 1/5 2,1;0,0: 1/5 1,2;1,3: 1/5 1,2;2,1: 1/5 *2,1;1,3: 1/5 1 2 3 Object-subject relative (The elephant scratched the rabbit that caught the turtle) 2,1;3,1: 1/5 0,0;2,3: 1/5 *1,2;2,3: 3/5 50 

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