The differential responses to affective and neutral stimuli in the visual-motor performance of schizophrenics and normals
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Investigators studying the perceptual functions of schizophrenics believe that schizophrenics sensitivity to affective stimuli is related to deficit, the so-called stimulus-meaning hypothesis. Since deficit is, partially, a function of task difficulty, the failure of previous studies to include neutral stimuli of visual complexity comparable to that of the affective stimuli confounds the conclusion that deficit is a function only of affective stimuli. To test the stimulus-meaning hypothesis, a size estimation task was chosen in order to present affective and neutral stimuli to a group of schizophrenics and normals. The behavior required by the task was analyzed by two measures generated by the method of limits: accuracy of judgment (upper limen/2 /lower limen/2) and efficiency in discrimination (upper limen -lower limen). A distinction was made between accuracy and efficiency in order to obtain more sensitive estimates of the effects of the two types of stimuli. An analysis of the effects of sequence indicated that schizophrenics were significantly less accurate on neutral pictures preceeded by thematic pictures than on those preceeded by other neutral pictures. Thus the apparently inconsistent finding regarding the neutral control for heterosexuality can be interpreted as a function of sequence. This finding of sequence effect also gives added strength to the stimulus-meaning hypothesis. Based on the data, one could infer that deficit in schizophrenia is a function of a complex interaction among the disease process, the type of performance required by the task, and the nature of the stimuli. Since a discussion of results indicated that deficit in performance may be related to the degree of affective meaning, ways for intensifying the impact of the affective stimuli in future research were suggested• [TRUNCATED]
Dissertation (Ph.D.)--Boston University
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