Edgar Zurif

The acquisition of a new phonological contrast: The case of stop consonants in French-English bilinguals

Cross‐language studies have shown that Voice Onset Time (VOT) is a sufficient cue to separate initial stop consonants into phonemic categories. The present study used VOT as a linguistic cue in examining the perception and production of stop consonants in three groups of subjects: unilingual Canadian French, unilingual Canadian English, and bilingual French‐English speakers. Perception was studied by having subjects label synthetically produced stop‐vowel syllables while production was assessed through spectrographic measurements of VOT in word‐initial stops. Six stop consonants, common to both languages, were used for these tasks. On the perception task, the two groups of unilingual subjects showed different perceptual crossovers with those of the bilinguals occupying an intermediate position. The production data indicate that VOT measures can separate voicing contrasts for speakers of Canadian English, but not for speakers of Canadian French. The data also show that language switching in bilinguals is w...

An On-Line Analysis of Syntactic Processing in Broca′s and Wernicke′s Aphasia

This paper is about syntactic processing in aphasia. Specifically, we present data concerning the ability of Brocas and Wernickes aphasic patients to link moved constituents and empty elements in real time. We show that Wernickes aphasic patients carry out this syntactic analysis in a normal fashion, but that Brocas aphasic patients do not. We discuss these data in the context of some current grammar-based theories of comprehension limitations in aphasia and in terms of the different functional commitments of the brain regions implicated in Brocas and Wernickes aphasia, respectively.

Grammatical judgments of agrammatic aphasics

Abstract Effortful, agrammatic speech and relatively intact comprehension often appear to coexist in Brocas aphasia. The present study focusses on this discrepancy, and tests the claim that the agrammatic patient has more information about syntactic structure than is indicated in his speech. Agrammatic aphasics and non-neurological patients sorted words from a variety of sentences on the basis of how closely related they felt the words to be in each of those sentences. These word groupings served as input matrices for a hierarchical clustering analysis. The resultant subjective phrase structure trees show that while normal subjects are often constrained by surface syntactic properties, agrammatic patients operate on a hierarchical scheme that excludes anything nonessential to the intrinsic meaning of a sentence. These findings suggest that expressive agrammatism is only one aspect of an impairment involving all language modalities.

Neural basis for sentence comprehension: Grammatical and short-term memory components

We monitored regional cerebral activity with BOLD fMRI while subjects were presented written sentences differing in their grammatical structure (subject‐relative or object‐relative center‐embedded clauses) and their short‐term memory demands (short or long antecedent‐gap linkages). A core region of left posterior superior temporal cortex was recruited during all sentence conditions in comparison to a pseudofont baseline, suggesting that this area plays a central role in sustaining comprehension that is common to all sentences. Right posterior superior temporal cortex was recruited during sentences with long compared to short antecedent‐gap linkages regardless of grammatical structure, suggesting that this brain region supports passive short‐term memory during sentence comprehension. Recruitment of left inferior frontal cortex was most clearly associated with sentences that featured both an object‐relative clause and a long antecedent‐gap linkage, suggesting that this region supports the cognitive resources required to maintain long‐distance syntactic dependencies during the comprehension of grammatically complex sentences. Hum. Brain Mapping 15:80–94, 2001.

The effects of focal brain damage on sentence processing: An examination of the neurological organization of a mental module

The effects of prior semantic context upon lexical access during sentence processing were examined for three groups of subjects; nonfluent agrammatic (Brocas) aphasic patients; fluent (Wernickes) aphasic patients; and neurologically intact control patients. Subjects were asked to comprehend auditorily presented, structurally simple sentences containing lexical ambiguities, which were in a context strongly biased toward just one interpretation of that ambiguity. While listening to each sentence, subjects also had to perform a lexical decision task upon a visually presented letter string. For the fluent Wernickes patients, as for the controls, lexical decisions for visual words related to each of the meanings of the ambiguity were facilitated. By contrast, agrammatic Brocas patients showed significant facilitation only for visual words related to the a priori most frequent interpretation of the ambiguity. On the basis of these data, we suggest that normal form-based word retrieval processes are crucially reliant upon the cortical tissue implicated in agrammatism, but that even the focal brain damage yielding agrammatism does not destroy the normally encapsulated form of word access. That is, we propose that in agrammatism, the modularity of word access during sentence comprehension is rendered less efficient but not lost. Additionally, we consider a number of broader issues involved in the use of pathological material to infer characteristics of the neurological organization of cognitive architecture.

Sentence processing and the mental representation of verbs

Abstract This study examines verb processing during sentence comprehension. We describe two experiments that assess whether or not a verbs representational complexity affects real-time sentence processing in normal listeners. Complexity is defined in terms of the kinds of structural information arrayed against verbs in their lexical entries—syntactic subcategorization and argument structure. Subjects had to perform a complex secondary task presented in the immediate vicinity of the verb while listening to a sentence for meaning. Reaction times to this secondary task show that the relevant verb complexity metric for sentence processing involves the argument structure of verbs and not syntactic subcategorization, and that it is the number of different argument structure possibilities for a verb that counts in this respect. These data reflect the operation of a processing device that momentarily activates all argument structures for a verb in the verbs immediate temporal vincinity during sentence comprehension.

Semantic feature representations for normal and aphasic language

Abstract Aphasic and non-neurological patients grouped nouns on the basis of similarity of meaning. These word groupings served as input matrices for hierarchical clustering and multidimensional scaling analyses. The emergent structures suggest that, while the normal adult has a number of levels upon which to organize his lexicon, the adult aphasics lexicon can be characterized as a set of partial entries that are tied to affective and situational data. The results also suggest that semantic feature representations derived from similarity-of-meaning judgments are of relevance in the study of factors which influence actual language performance.

Right-Hemispheric Damage and Verbal Problem Solving Behavior'

Abstract Patients with right-hemisphere damage, who ostensibly have no linguistic impairment, are relatively incapable of solving two-term series problems in which comparative adjectives in the premise and question are antonymic. This finding suggests that such verbal reasoning depends, in part, upon nonlinguistic imaginal processes subserved by the right hemisphere. In this manner, the right hemisphere is often required for the full elaboration of linguistic input.

The Critical Role of Group Studies in Neuropsychology: Comprehension Regularities in Broca's Aphasia

We reexamine the empirical record of the comprehension abilities of Brocas aphasic patients. We establish clear, commonly accepted, selection criteria and obtain a pool of results. We then subject these results to a detailed statistical analysis and show that these patients comprehend certain canonical sentences (actives, subject relatives, and clefts with agentive predicates) at above-chance levels, whereas comprehension of sentences that contain deviations from canonicity (passives, object-gap relatives, and clefts) is distinct and is at chance. That the latter is the case, and patients indeed guess at such structures, we show by comparing the distribution of individual results in passive comprehension to that of a model for such guessing-an analogous series of tosses of an unbiased coin. The two distributions are virtually identical. We conclude that the groups performance is stable, and well-delineated, despite intersubject variation whose source is now identified. This means that certain comprehension tests may not always be used for the diagnosis of individual patients, but they do characterize the group. It also means that group studies are not just a valid option in neuropsychology; they are a must, since demonstrations like ours indiciate very clearly that single-case studies may be misleading. As we show, the findings from any one patient, without the context of a group, may give a distorted picture of the pathological reality. Our conclusions thus promote studies of groups of brain-damaged patients as a central tool for the investigation of brain/behavior relations.

The relation between gesture and language in aphasic communication

Abstract Effective communication in aphasia depends not only on use of preserved linguistic capacities but also (and perhaps primarily) on the capacity to exploit alternative modalities of communication, such as gesture. To ascertain the capacity of aphasic patients to use gesture in their spontaneous communication, informally structured interviews were conducted with two Wernickes aphasics and two Brocas aphasics, as well as with four normal controls. The performances of the patient groups were compared on the physical parameters of gesture, the points in the communication where gestures occurred, and several facets of the semantics and pragmatics of gesture. Generally speaking, the gestures of the aphasics closely paralleled their speech output: on most indices, the performance of the Wernickes aphasics more closely resembled that of the normal controls. Wernickes aphasics differed from normals in the clarity of their language and gestures: While individual linguistic units were often clear, the relation among units was not. In contrast, the Brocas aphasics equaled or surpassed the normal controls in the clarity of their communications. The results offer little support for the view that aphasic patients spontaneously enhance their communicative efficacy through the use of gesture; these findings can, however, be interpreted as evidence in favor of a “central organizer” which controls critical features of communication, irrespective of the modality of expression.