Journal of Clinical and Experimental Neuropsychology 1991, Vol. 13, NO.5, pp. 703-710
0168-8634/91/1305-0703$3.00 Q Swets & Zeitlinger
Idiosyncratic Word Associations Following Right Hemisphere Damage* Guila Glosser and Harold Goodglass Aphasia Research Center, Department of Neurology, Boston University School of Medicine
ABSTRACT Single oral word associations produced by right-hemisphere-damaged(RHD) stroke patients and age-matched healthy controls were analyzed to assess the right-hemisphere contribution to lexical-semantic processes. RHD patients did not differ from normals in terms of response times, in syntactic class of the response word, or in numbers of errors in response to words drawn from different grammaticalcategories and words differing in imageabilityl concreteness. Groups also did not differ in the number of high frequency, popular, associations produced. Despite their apparently intact ability to access high-frequency lexical associates, RHD patients, particularly those with frontal-lobe lesions, also sporadically produced lexical responses that were idiosyncratically related or that were totally unrelated to the stimulus word. An attentional disorder is suggested to explain these pragmatically deviant lexical associations.
A number of recent studies have addressed the contribution of the right hemisphere to lexical processing through analyses of the performance deficits of patients with acquired lesions in the right hemisphere. The data generally indicate that the right hemisphere contributes minimally to phonological and syntactic processes (Joanette, Goulet, & Hannequin, 1990). Studies of right-hemispheredamaged (RHD) patients, however, have revealed deficits in certain semantic aspects of lexical comprehension and production. These deficits are typically seen in tasks that require higher level and “controlled” cognitive processing of lexical semantic information. For example, RHD patients show impaired appreci ation of connotative and metaphoric word meanings on semantic judgement tasks (Brownell, 1988). There have been suggestions that RHD patients are specifically impaired in their ability to manipulate concrete or imageable language.
* We thank Carole Palumbo who performed the CT scan analyses. We are grateful to the administration and staff of Northeast Rehabilitation Hospital for allowing us to examine their patients. This research was supported in part by NINCDS Grant NS-06209. Address Correspondence to: Guila Glosser. Ph.D, Department of Neurology, Graduate Hospital, 1 Graduate Plaza, Philadelphia, PA 19146, USA. Accepted for publication: November 15, 1990.
704
GUlLA GLOSSER AND HAROLD GOODGLASS
These patients evidence specifically impaired learning and memory for lists of concrete-imageable words, but not for abstract words (Jones-Gotman & Milner, 1978; Villardita, Grioli, & Quattropani, 1988). It has also been suggested that RHD patients may be impaired in their application of pragmatic social knowledge to lexical comprehension and production (Chiarello & Church, 1986). This suggestion is based on other demonstrations of deficits in processing pragmatic aspects of complex, contextualized linguistic material following RHD (Gardner, Brownell, Wapner, & Michelow, 1983). The word-association paradigm represents one method for examining the lexical abilities of RHD patients. Experimental analyses of word-association responses have been used to test hypotheses regarding the organization and accessibility of the semantic lexicon in normals (e.g., Cramer, 1968) as well as in brain-damaged patients (e.g.. Gewirth, Shindler, & Hier, 1984; Goldfarb & Halpern, 1981; Howes, 1967). In the word-association procedure, it is possible to assess the “correctness” of the linguistic response with reference to certain formal phonological, syntactic, or semantic criteria. Among normals, predictable variations occur in different word-associationresponse measures (Cramer, 1968). For example, normal subjects’ latency to produce a lexical associate varies reliably in relation to the grammatical class of the stimulus word, and the form class of the response word is also predictably related to the grammatical class of the stimulus word. Normal adherence to these recognized variations in word-association response measures may be taken to indicate the degree to which subjects retain preserved knowledge of and access to “correct” linguistic rules and forms. The word-association paradigm is also suited for examining qualitative aspects of semantic lexical relationships. In particular, the large corpus of data on the word-association responses of normal subjects makes it possible to assess the “appropriateness” of the semantic relationship between the stimulus word and the linguistic response with respect to normative social use. The word-association paradigm, therefore, also yields data about the integrity of subjects’ pragmatic lexical abilities. METHODS Subjects
The RHD group consisted of 16 right-handed patients who suffered a single right-hemisphere cerebrovascular accident (as verified by CT scan) at least two months prior to participation in the study (mean months post stroke = 37.7). The NC group included 31 healthy control subjects. There were no significant differences between these two groups in age (M= 59.49), years of formal education (M = 12.57), and scores (M = 53.26) on the Boston Naming Test (Kaplan, Goodglass, L Weintraub, 1983). Stimuli and Procedure Stimuli consisted of words from Palermo and Jenkins’ (1964) word-associationlist. Stimulus words were drawn from the categories of concrete nouns ( n =4), abstract nouns ( n =4), adjectives ( n = 8). verbs ( n = 8). and functors (n = 8). Mean word frequencies (Francis & Kucera, 1982) did not differ for the concrete nouns, abstract nouns, adjectives, and
RIGHT-HEMISPHERE WORD-ASSOCIATIONS
705
verbs, but the mean word frequency for the functors was significantly higher than that for each of the other four word categories. Because of the particular functors (conjunctions, propositions, and pronouns) sampled in the Palermo and Jenkins list, it was not possible to completely match word frequencies across all word classes. Subjects were individually administered the word-association test. The 32 stimulus words were presented orally and in a fixed random order to all subjects. Subjects were instructed to say the first word-association to the stimulus word quickly. Responses were tape recorded, and response latency was measured with a stopwatch. Measures
For each of the stimulus word categories the following response measures were computed: (1) Reaction time was computed as the mean latency, in seconds, to utter the first wordassociation. (2) Errors consisted of perseverations (either of a subject’s prior response or a prior stimulus item), multiword responses, repetitions of the stimulus word (or production of a variant that maintained the base morpheme of the stimulus word), and null responses. (3) Grammatical class was coded for those response words that could be assigned unambiguously to a single grammatical category of either noun, verb, adjective, or functor. No distinction was made between concrete and abstract nouns in coding the grammatical class of the response words. The proportions of all grammatically coded words that were not congruent with the grammatical category of the stimulus word were then computed. (4) Popular responses were high-frequency word-associates that matched one of the three most commonly occurring responses to the stimulus word in Palermo and Jenkins’ (1964) normative sample. (5) Idiosyncratic associations were low-frequency wordassociates that occurred less than 3 times in lo00 responses to the stimulus word in Palermo and Jenkins’ (1964) normative sample.
RESULTS Response measures were each submitted to two-way analyses of variance (ANOVAs) with groups as the between-subjects factor and stimulus category (concrete nouns, abstract nouns, adjectives, verbs, and functors) as the withinsubjects factor. There were significant main effects of stimulus category in all of the analyses, but there were no significant Group x Stimulus Category interactions for any of the response measures. The absence of Group x Stimulus Category interaction effects on all of the dependent measures indicates that RHD patients behaved in a manner comparable to normals in response to variations in the grammatical category and in the concreteness of stimulus words. Specifically, RHD patients did not show any greater or lesser sensitivity to differences between abstract and concrete nouns than did normals. Mean values for each of the response measures collapsed over the five stimulus word categories are presented in Table 1. There were n o significant main effects of subject group for reaction time, for total errors, for proportions of response words that were grammatically noncongruent with the stimulus word, or for the number of popular associations. RHD patients produced significantly more idiosyncratic word-associations than did normals ( F (1,45) = 5.35; p
0168-8634/91/1305-0703$3.00 Q Swets & Zeitlinger
Idiosyncratic Word Associations Following Right Hemisphere Damage* Guila Glosser and Harold Goodglass Aphasia Research Center, Department of Neurology, Boston University School of Medicine
ABSTRACT Single oral word associations produced by right-hemisphere-damaged(RHD) stroke patients and age-matched healthy controls were analyzed to assess the right-hemisphere contribution to lexical-semantic processes. RHD patients did not differ from normals in terms of response times, in syntactic class of the response word, or in numbers of errors in response to words drawn from different grammaticalcategories and words differing in imageabilityl concreteness. Groups also did not differ in the number of high frequency, popular, associations produced. Despite their apparently intact ability to access high-frequency lexical associates, RHD patients, particularly those with frontal-lobe lesions, also sporadically produced lexical responses that were idiosyncratically related or that were totally unrelated to the stimulus word. An attentional disorder is suggested to explain these pragmatically deviant lexical associations.
A number of recent studies have addressed the contribution of the right hemisphere to lexical processing through analyses of the performance deficits of patients with acquired lesions in the right hemisphere. The data generally indicate that the right hemisphere contributes minimally to phonological and syntactic processes (Joanette, Goulet, & Hannequin, 1990). Studies of right-hemispheredamaged (RHD) patients, however, have revealed deficits in certain semantic aspects of lexical comprehension and production. These deficits are typically seen in tasks that require higher level and “controlled” cognitive processing of lexical semantic information. For example, RHD patients show impaired appreci ation of connotative and metaphoric word meanings on semantic judgement tasks (Brownell, 1988). There have been suggestions that RHD patients are specifically impaired in their ability to manipulate concrete or imageable language.
* We thank Carole Palumbo who performed the CT scan analyses. We are grateful to the administration and staff of Northeast Rehabilitation Hospital for allowing us to examine their patients. This research was supported in part by NINCDS Grant NS-06209. Address Correspondence to: Guila Glosser. Ph.D, Department of Neurology, Graduate Hospital, 1 Graduate Plaza, Philadelphia, PA 19146, USA. Accepted for publication: November 15, 1990.
704
GUlLA GLOSSER AND HAROLD GOODGLASS
These patients evidence specifically impaired learning and memory for lists of concrete-imageable words, but not for abstract words (Jones-Gotman & Milner, 1978; Villardita, Grioli, & Quattropani, 1988). It has also been suggested that RHD patients may be impaired in their application of pragmatic social knowledge to lexical comprehension and production (Chiarello & Church, 1986). This suggestion is based on other demonstrations of deficits in processing pragmatic aspects of complex, contextualized linguistic material following RHD (Gardner, Brownell, Wapner, & Michelow, 1983). The word-association paradigm represents one method for examining the lexical abilities of RHD patients. Experimental analyses of word-association responses have been used to test hypotheses regarding the organization and accessibility of the semantic lexicon in normals (e.g., Cramer, 1968) as well as in brain-damaged patients (e.g.. Gewirth, Shindler, & Hier, 1984; Goldfarb & Halpern, 1981; Howes, 1967). In the word-association procedure, it is possible to assess the “correctness” of the linguistic response with reference to certain formal phonological, syntactic, or semantic criteria. Among normals, predictable variations occur in different word-associationresponse measures (Cramer, 1968). For example, normal subjects’ latency to produce a lexical associate varies reliably in relation to the grammatical class of the stimulus word, and the form class of the response word is also predictably related to the grammatical class of the stimulus word. Normal adherence to these recognized variations in word-association response measures may be taken to indicate the degree to which subjects retain preserved knowledge of and access to “correct” linguistic rules and forms. The word-association paradigm is also suited for examining qualitative aspects of semantic lexical relationships. In particular, the large corpus of data on the word-association responses of normal subjects makes it possible to assess the “appropriateness” of the semantic relationship between the stimulus word and the linguistic response with respect to normative social use. The word-association paradigm, therefore, also yields data about the integrity of subjects’ pragmatic lexical abilities. METHODS Subjects
The RHD group consisted of 16 right-handed patients who suffered a single right-hemisphere cerebrovascular accident (as verified by CT scan) at least two months prior to participation in the study (mean months post stroke = 37.7). The NC group included 31 healthy control subjects. There were no significant differences between these two groups in age (M= 59.49), years of formal education (M = 12.57), and scores (M = 53.26) on the Boston Naming Test (Kaplan, Goodglass, L Weintraub, 1983). Stimuli and Procedure Stimuli consisted of words from Palermo and Jenkins’ (1964) word-associationlist. Stimulus words were drawn from the categories of concrete nouns ( n =4), abstract nouns ( n =4), adjectives ( n = 8). verbs ( n = 8). and functors (n = 8). Mean word frequencies (Francis & Kucera, 1982) did not differ for the concrete nouns, abstract nouns, adjectives, and
RIGHT-HEMISPHERE WORD-ASSOCIATIONS
705
verbs, but the mean word frequency for the functors was significantly higher than that for each of the other four word categories. Because of the particular functors (conjunctions, propositions, and pronouns) sampled in the Palermo and Jenkins list, it was not possible to completely match word frequencies across all word classes. Subjects were individually administered the word-association test. The 32 stimulus words were presented orally and in a fixed random order to all subjects. Subjects were instructed to say the first word-association to the stimulus word quickly. Responses were tape recorded, and response latency was measured with a stopwatch. Measures
For each of the stimulus word categories the following response measures were computed: (1) Reaction time was computed as the mean latency, in seconds, to utter the first wordassociation. (2) Errors consisted of perseverations (either of a subject’s prior response or a prior stimulus item), multiword responses, repetitions of the stimulus word (or production of a variant that maintained the base morpheme of the stimulus word), and null responses. (3) Grammatical class was coded for those response words that could be assigned unambiguously to a single grammatical category of either noun, verb, adjective, or functor. No distinction was made between concrete and abstract nouns in coding the grammatical class of the response words. The proportions of all grammatically coded words that were not congruent with the grammatical category of the stimulus word were then computed. (4) Popular responses were high-frequency word-associates that matched one of the three most commonly occurring responses to the stimulus word in Palermo and Jenkins’ (1964) normative sample. (5) Idiosyncratic associations were low-frequency wordassociates that occurred less than 3 times in lo00 responses to the stimulus word in Palermo and Jenkins’ (1964) normative sample.
RESULTS Response measures were each submitted to two-way analyses of variance (ANOVAs) with groups as the between-subjects factor and stimulus category (concrete nouns, abstract nouns, adjectives, verbs, and functors) as the withinsubjects factor. There were significant main effects of stimulus category in all of the analyses, but there were no significant Group x Stimulus Category interactions for any of the response measures. The absence of Group x Stimulus Category interaction effects on all of the dependent measures indicates that RHD patients behaved in a manner comparable to normals in response to variations in the grammatical category and in the concreteness of stimulus words. Specifically, RHD patients did not show any greater or lesser sensitivity to differences between abstract and concrete nouns than did normals. Mean values for each of the response measures collapsed over the five stimulus word categories are presented in Table 1. There were n o significant main effects of subject group for reaction time, for total errors, for proportions of response words that were grammatically noncongruent with the stimulus word, or for the number of popular associations. RHD patients produced significantly more idiosyncratic word-associations than did normals ( F (1,45) = 5.35; p
