DISCRIMINATION LEARNING AND HYPOTHESIS SAMPLING BY SUBJECTS WITH UNILATERAL FRONTAL-LOBE LESIONS.
Item
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Title
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DISCRIMINATION LEARNING AND HYPOTHESIS SAMPLING BY SUBJECTS WITH UNILATERAL FRONTAL-LOBE LESIONS.
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Identifier
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AAI8319751
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identifier
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8319751
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Creator
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CICERONE, KEITH DOUGLAS.
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Contributor
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Max Pollack
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Date
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1983
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Language
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English
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Publisher
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City University of New York.
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Subject
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Psychology, Physiological
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Abstract
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Thirty-two subjects with unilateral, supratentorial cerebral tumors were assessed for the use of hypotheses and response strategies during a visual discrimination learning task. Subjects with either anterior or posterior lesions utilized hypotheses at the outset of discrimination learning, and were able to maintain a confirmed hypothesis, suggesting that these two cerebral regions were equipotential for this aspect of the task. Subjects with frontal-lobe lesions attained fewer correct solutions and used fewer appropriate hypotheses than subjects with posteriorly located lesions. The impairment of subjects with frontal-lobe tumors was most evident following disconfirming outcome trials, and was characterized by reduced ability to shift to a new hypothesis and perseveration of the preceding hypothesis. Neither the overall levels of performance nor the types of errors differentiated subjects with left- or right-hemisphere frontal-lobe lesions. Neither clinical evidence of aphasia nor verbal comprehension scores were related to hypothesis sampling; reduced verbal fluency was correlated with the use of fewer appropriate hypotheses and increased perseveration among the subjects with frontal-lobe lesions.;The results of hypothesis sampling and a second discrimination task suggested that the subjects with frontal-lobe lesions, especially those subjects for whom perseveration was the dominant error tendency, were attending to fewer aspects of the informing stimuli. Further analyses indicated two principle sources of this deficit: (1) the complexity of the stimulus, which produces a need to direct attention to several aspects of the stimulus, and (2) the degree to which feedback serves to disconfirm existing response preferences and increase cue-reward variability. The findings were discussed in regard to the neurophysiological processes which may underlie associative learning.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Psychology
