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Biomedical subjects

L P Shapiro

Publications and source records attributed to L P Shapiro.

25 records · Page 2Linked to original sources
PubMed1990

Verb processing during sentence comprehension in aphasia.

This study examines verb processing during on-line sentence comprehension in aphasia. We describe two experiments that explore whether a group of Broca's aphasics, who were agrammatic in comprehension as well as speech, a group of fluent aphasics, and a group of normal controls are sensitive to the argument structure arrangements of verbs. Subjects had to perform a complex secondary task both in the immediate vicinity of the verb and also at a point well past the verb while listening to sentences for meaning. Reaction times to this secondary task show that both normal controls and agrammatic Broca's aphasic subjects activate multiple argument structure possibilities for a verb in the vicinity of the verb, yet at a point downstream from the verb such effects disappear. These data suggest that the problems agrammatic subjects show with verbs in sentence comprehension, and the general lexical access deficit also recently claimed to be part of the agrammatics' problem, may not extend to the real-time processing of verbs and their arguments. Fluent aphasic subjects, on the other hand, do not show sensitivity to the argument structure properties of verbs, suggesting that these patients may have a semantic-like sentence processing deficit.

Aged↗
PubMed1990

Predicate-argument structure as a link between linguistic and nonlinguistic representations.

We present a study wherein a severe Broca's aphasic patient was trained to learn symbols representing both pure transitive and dative predicates--predicates differing in argument structure--in a visually based artificial language (c-ViC). We found a decrease in performance when two symbols, rather than one, were used to depict these "verbs." However, this decrease in performance was more pronounced for symbols representing pure transitive verbs--those that allow only one argument structure--than for symbols representing dative verbs--those that allow two different argument structures. Also, dative "verbs" yielded better performance when they were inserted in more complex, three-argument "sentences" than when they were inserted in two-argument "sentences." The opposite pattern was found for pure transitives. These results are discussed in terms of our claim that argument structure serves as a point of connection between linguistic information and non-linguistic visual information and in terms of the possibility that argument structure entries are shaped by the form in which visual information is parsed.

Aged↗
PubMed1989

Verb processing during sentence comprehension: contextual impenetrability.

This paper examines verb processing during sentence comprehension. We describe two experiments that assess the interaction between verb complexity and the structural information contained in a sentence. Verb complexity is defined in terms of a verb's possible argument structure arrangements--linguistic information arrayed against a verb's entry in the mental lexicon. Normal subjects had to perform a 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 all of a verb's possible argument structures are momentarily and exhaustively activated in the vicinity of the verb, even in sentences that are structurally biased toward one particular argument structure. We thus argue that verb processing in sentences involves a contextually impenetrable subcomponent of the language comprehension system.

Adult↗
PubMed1989

Comprehension of lexical subcategory distinctions by aphasic patients: proper/common and mass/count nouns.

Previous research has found that agrammatic Broca aphasic patients have particular difficulty using determiners like "a" and "the" for the purposes of sentence comprehension. In this study, we test whether or not such difficulty extends to the level where lexical subcategories are distinguished by these articles. The absence or presence of a determiner distinguishes proper from common nouns (e.g., "ROSE" vs. "A ROSE"), and mass from count nouns (e.g., "GLASS" vs. "A GLASS"). Groups of agrammatic Broca and fluent aphasic subjects were required to point to one of two pictures in response to a sentence such as "Point to the picture of rose" or "Point to the picture of a rose". Sentences were presented in either printed or spoken form. Results indicated that for the agrammatic Broca patients, printed presentation yielded significant improvement over spoken presentation only for the proper noun/common noun distinction. Performance was significantly poorer for the mass noun/count noun distinction as compared to the proper/common distinction for these patients, and mass nouns proved particularly difficult. Interpretable patterns were not observed on either subcategory distinction for the fluent aphasic subjects. Current theories of agrammatism cannot fully explain these data. An independent explanation is offered that suggests proper noun/common noun is a universal semantic distinction. On the other hand, the mass noun/count noun distinction is more purely syntactic, and thus is particularly difficult for agrammatic Broca patients.

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PubMed1987

Effects of flow cytometric analysis on morphology and viability of fragile phytoplankton.

We assessed damage done to especially delicate marine phytoplankton cells by passage through a Coulter Epics V flow cytometer. The cells did not distort or lyse after exposure to fluidics or to laser light to 1,000 mW. The cells did sustain damage evidenced by temporary growth rate depressions. The four clones tested eventually resumed control growth rates after growth lags to 48 h.

Journal Article↗
PubMed1986

Processing open and closed class-headed nonwords: left hemisphere support for separate vocabularies.

Evidence from studies of sentence production and comprehension points to a distinction between the open and closed class vocabularies. Data from the neurologically impaired suggest the left hemisphere selectively supports this distinction. This study further examines the vocabulary distinction by presenting to the different visual hemifields nonwords embedded with open or closed class portions, and asking normal subjects to make lexical decisions. Results indicate the vocabulary distinction is evident with RVF, but not LVF, presentations. This is discussed in terms of the use to which open and closed class words are put in sentence processing and also bears on the issue of the distinct cognitive styles associated with the different cerebral hemispheres.

Adult↗