Perceptual organization in schizophrenia.

A report of numerosity task was used in 2 experiments to examine the effect of inherent stimulus organization on the report accuracy of 2 S groups. Ss in each experiment were 10 schizophrenics and 10 drug abusing inpatients (controls). In both experiments, displays containing from zero to 6 lines were presented tachistoscopically. In Exp I, the lines appeared either alone or with noise elements (circles). When the lines appeared alone, schizophrenics and controls performed comparably. Their report accuracy decreased with increases in the number of lines. In the noise condition, the level of performance dropped only for schizophrenics. In Exp II, the stimulus arrays did not contain noise elements. Ss were given the task of reporting all the lines they saw. The perceptual organization of the arrays was manipulated by varying the similarity and proximity of the line elements. The performance of controls deteriorated as the organization of the arrays became more complex; schizophrenics were not affected by the organization. In fact, their average performance was significantly better than that of controls. Results of the 2 experiments are interpreted as evidence that schizophrenics' perceptual deficit lies in a failure to organize information at an early stage in processing. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)