Syntactic comprehension deficits in agrammatism

Eleven agrammatic and 16 fluent aphasic patients were given a comprehension task consisting of simple, active and passive reversible sentences. The purpose of the study is to reconsider the comprehension disorders in agrammatism, and particularly of passive reversible sentences, to test to what extent Grodzinsky's trace deletion hypothesis (TDH) is generalizable to other types of NP-movement, and finally to ascertain whether the pattern of impairment observed in agrammatism differs from that of fluent aphasic patients. The study confirms that trace analysis may be selectively impaired in agrammatism. However, this deficit is not the only mechanism underlying comprehension disorders and cannot be said to occur in all agrammatic patients. Comprehension disorders also involve the processing of clitic object pronouns which also underly NP-movement. Finally, the impairment found in fluent aphasic patients differs, both in type and severity, from that of agrammatic patients, thus confirming the peculiar aspects of the agrammatic comprehension deficit suggested by Grodzinsky's TDH.     

Syntactic and semantic contributions to sentence comprehension in agrammatism

Five aphasic subjects, who demonstrated agrammatic speech, and eight control subjects were presented with a sentence-picture matching task in which the factors of syntactic complexity, semantic reversibility, and sentence plausibility were independently varied. A subset of the sentences was patterned after that presented by A. Caramazza and E. Zurif (1976, Brain and Language, 5, 572-583) who concluded that Broca's aphasics rely on semantic constraints instead of syntactic information for sentence comprehension. Our aphasic subjects showed the same pattern of performance on this subset of sentences. However, the results from the full set of sentence materials we tested show that the aphasic subjects could perform some sentence level syntactic analyses, even when syntactic information conflicted with semantic constraints. The aphasic subjects correctly interpreted most active and passive sentences. They failed, however, to assign thematic roles and adjectives in center-embedded relative sentences, and instead relied on nonsyntactic information. These results show that both semantic and syntactic information contributed to sentence comprehension in the aphasic subjects we tested, in contrast to previous claims that syntactic and semantic processes are completely dissociated in this population.     

Effects of clausal structure and word frequency in sentence processing

A phoneme-monitoring task was employed to test the effects of clausal structure and lexical ambiguity on sentence processing. Results supported the hypothesis that the clause serves as a psychologically real unit of sentence processing, with the semantic interpretation of each clause being assigned at the clause boundary. The frequency of the ambiguous or control word preceding the critical item in the phoneme-monitoring task was also found to affect the results obtained, with higher frequency words leading to longer mean reaction times.This research is based on a thesis submitted by the first author as partial fulfillment of the M.A. degree at The University of Iowa. Portions of this paper were presented at the meeting of the Psychonomic Society, San Antonio, Texas, 1978.     

Effects of clausal structure on subject-verb agreement errors

This paper explores the effect of manipulating the internal structure of a complex subject on the incidence of subject-verb agreement errors. Using the sentence completion task (Bock & Miller, 1991), this study followed up on Vigliocco and Nicol's (1995) finding that the syntactic distance between a head noun and a number-mismatching noun contained within a modifier has an impact on error incidence: the greater the distance, the lower the error rate. The study presented in this paper investigated whether this distance effect is purely syntactic; if so, then it would be expected that there would be fewer errors followingThe owner of the house which charmed the realtor... than followingThe owner of the house who charmed the realtors..., since in the latter, the mismatch is syntactically nearer the head noun. Results show no hint of a difference between the two, suggesting that the distance effect is more likely due totemporal distance rather than syntactic distance per se.This research was supported by grant 5 P60 DC 01409-05, a Research and Training Grant funded by the National Institute on Deafness and Other Communicative Disorders, National Institutes of Health, to the National Center for Neurogenic Communication Disorders, University of Arizona. I am grateful to Danielle Cvitanovic, Nicole Diamond and Brad Greenwell for their assistance in testing subjects and scoring responses. I wish to thank Merrill Garrett for reviewing an earlier draft of this paper.     

Syntactic loss versus processing deficit: an assessment of two theories of agrammatism and syntactic comprehension deficits

This research evaluated Grodzinsky's (1984, 1986a) syntactic loss and Kolk and van Grunsven's (1985) working memory impairment explanations of syntactic comprehension deficits in agrammatic aphasics. Four aphasic patients were evaluated who showed different patterns of impairment on morphological and structural aspects of production. The comprehension tasks compared performance on full and truncated passive sentences. The syntactic loss hypothesis predicted worse performance on truncated than full passives, while the working memory deficit hypothesis predicted the reverse. Neither hypothesis was supported, as the patients performed at a similar level on both types of passives. In addition, there was little relation between the patients' production indices and their comprehension level. The results argue against any global theory of agrammatism that attempts to attribute all agrammatic speech and co-occurring syntactic comprehension deficits to the same source.     

Syntactic structure and the garden path

The experiment investigated locally ambiguous English sentences containing “complement” verbs such as believe, which can be followed either by a direct object or by a complement clause. These two sentence types were compared with unambiguous sentences in which the complement clause was introduced by the word that. Subjects processed numerous examples of these sentences in a word-by-word self-paced reading task. At the disambiguation point after the ambiguous noun phrase, longer reading times were obtained for reduced complement constructions compared with direct object sentences. Such an effect has been attributed to the operation of the parsing principle Minimal Attachment (Frazier and Rayner, 1982). This principle predicts that subjects assume falsely that the noun phrase after the complement verb in the reduced complement constructions is the direct object, resulting in the need for subsequent structural reanalysis. However, longer times in the disambiguating zone were also found for the unambiguous that complements. Thus, the complexity difference seems not to represent “garden-pathing” as a result of the operation of Minimal Attachment, but may instead reflect the extra complexity caused by having to handle two sets of clausal relations instead of just one.     

Finiteness and verb-second in German agrammatism

This study presents results from sentence-completion and grammaticality-judgement tasks with seven German-speaking agrammatic aphasics and seven age-matched control subjects examining verb finiteness marking and verb-second (V2) placement. The patients were found to be selectively impaired in tense marking in the face of preserved mood and agreement marking. Moreover, our results revealed that V2 scores varied across our patients, with some showing impaired and others preserved V2 performance. These findings will be discussed in the light of different syntactic accounts of agrammatism.     

Syntactic structure and acoustic pattern in speech perception Arthur Wingfield

The interaction of syntactic structure and acoustic pattern in perceptual segmentation of heard speech was investigated using sentences recorded with intonation patterns appropriate to their underlying structure and sentences where intonation was placed in direct conflict with the underlying structure. Speech samples were monitored through dichotic earphones with messages switched from one ear to the other either between or within major linguistic constituents. Analysis of errors in source localization and in sentence reproduction suggested a primary role of acoustic pattern in segmentation is to cue underlying syntactic structure. Two subsidiary experiments provided evidence that observed effects were related to active perceptual processing of the speech signal.     

Tense and agreement in German agrammatism

This study presents results from sentence-completion and grammaticality-judgment tasks with 7 German-speaking agrammatic aphasics and 7 age-matched control subjects examining tense and subject-verb agreement marking. For both experimental tasks, we found that the aphasics achieved high correctness scores for agreement, while tense marking was severely impaired. To account for the observed tense-agreement dissociation, we suggest that the functional category T(ense)/INFL(ection) is tense-defective in agrammatic aphasia, i.e., it is specified for [+/-Realis], but not for [+/-Past]. It will also be argued that other accounts, specifically the tree-pruning model, do not explain our findings.     

Comprehension of nonlexical categories in agrammatism

The focus of the paper is a proposal advanced by Grodzinsky (1984, 1986, 1990) concerning a possible syntactic deficit in agrammatism with respect to nonlexical categories. Eight native speakers of Serbo-Croatian, who presented a clinical picture of Broca's aphasia with agrammatism, were tested. Subject's sensitivity to traces and their knowledge of the inflectional and determiner system was investigated using a grammaticality judgment paradigm. The processing load was further minimized by use of short sentences that unequivocally exemplified different syntactic violations. These steps led to significant improvement in the performance of agrammatic aphasics, a result that is incompatible with the claim that the content of nonlexical elements is lost in agrammatism.A partial account of the findings was presented at the 31 st Meeting of the Academy of Aphasia, October 24–26, 1993. Tucson, Arizona. The authors gratefully acknowledge help in data collection from Mile Vukovi, Faculty of Defectology, University of Belgrade, and from Jovanka Jezdimirovi and Veronika Ispanovi-Radojkovi, the Institute for Mental Health in Belgrade. This research was supported in part by a grant (HD-01994) to Haskins Laboratories from the National Institute of Child Health and Human Development.     

Syntactic structure modifies attention during speech perception and recognition

The present paper demonstrates the interaction of syntactic structure and speech perception with a response task which minimizes the effects of memory: reaction time (RT) to clicks during sentences. (1) In 12-word unfamiliar sentences each with two clauses, RT is relatively slow overall to clicks located at the end of the first clause but decreases as a function of clause length. Clicks at the beginning of the second clause are not affected by length of the preceding clause. (2) In familiar sentences, RT is relatively fast to clicks located at the end of a clause while RT to clicks at the beginning of clauses is relatively unaffected by familiarity. (3) RT is not fastest overall to clicks located between clauses either in novel or familiar sentences. (4) As in previous studies, the subject's subsequent judegment of the location of the click tone are towards the clause break. (5) We could find no systematic interaction between RT and subjective click location. Findings (1) to (3) are consistent with the view that perceptual processing alternates between attending to all external stimuli and developing an internal representation of the stimuli. Finding (3) is in conflict with an “information channel” view of immediate attention to speech, which would predict high sensory attention to non-speech stimuli between clauses. However, findings (4) and (5) indicate that the channel view of perception may be correct for that perceptual processing which occurs after the immediate organization of the speech stimulus into major segments.     

Syntactic component in language responsible cognitive structure: Neurological evidence

From the results of a broad ranging comprehension test, a hierarchy of difficulty emerged that is shared by the two groups of aphasics (Broca's and Wernicke's aphasics) and by the control group of normal subjects. The parallelism has been interpreted as a confirmation of the hypothesis that syntactic competence is not inaccessible either in Wernicke's or in Broca's aphasia. The Minimal Distance Principle, as a relevant recognition principle, has been studied, and although not confirmed by the scores has been brought to the fore both by the correlations between the variables under study and by the correlations with the concomitant variables of age and level of education.     

Impaired artificial grammar learning in agrammatism

It is often assumed that language is supported by domain-specific neural mechanisms, in part based on neuropsychological data from aphasia. If, however, language relies on domain-general mechanisms, it would be expected that deficits in non-linguistic cognitive processing should co-occur with aphasia. In this paper, we report a study of sequential learning by agrammatic aphasic patients and control participants matched for age, socio-economic status and non-verbal intelligence. Participants were first exposed to strings derived from an artificial grammar after which they were asked to classify a set of new strings, some of which were generated by the same grammar whereas others were not. Although both groups of participants performed well in the training phase of the experiment, only the control participants were able to classify novel test items better than chance. The results show that breakdown of language in agrammatic aphasia is associated with an impairment in artificial grammar learning, indicating damage to domain-general neural mechanisms subserving both language and sequential learning.     

Dissociations among functional categories in Korean agrammatism

This study investigated the hypothesis that the syntactic trees formed by individuals with agrammatic aphasia cannot be constructed any higher than an impaired node as suggested by the tree-pruning hypothesis (Friedman, 1994; Friedmann & Grodzinsky, 1997) and hypothesis. It also examined their following implication that the members of a certain functional category are subject to the same degree of impairment. Two experiments were conducted to investigate a Korean agrammatic patient's use and understanding of three functional categories--Mood, Tense, and Complementizer. The results showed a dissociation among functional categories that preserves the higher node while leaving the lower node impaired both in production and comprehension. Another dissociation was found among members of the same category depending on their linear position in the clause. These results contrast with the predictions of the tree-pruning hypothesis, suggesting that the nearer to the end of the clause a functional element is located, the better it is preserved in Korean agrammatism.