Perceptual size constancy in chronic schizophrenia.

The influence of symbolic stimulus value on perceived size in chronic schizophrenia.

“…Cooper (I960) recently reported a decrease in accuracy and an increase in variability on simple size comparison tasks. These results are in disagreement with a recent study by Leibowitz and Pishkin (1961), in which no differences were found between normals and schizophrenics on a simple task of judging sizes of wooden dowels under well lighted conditions. The conclusions reached on the basis of that study were, "whatever disorders of perception, thinking, or behavior they (chronic schizophrenics) suffer from, their size constancy is unaffected" (p. 198).…”

“…For example, Sanders and Pacht (1952) used outpatients, while Cooper (1960) used a schizophrenic population which was predominantly composed of patients of less than 2 years' hospitalization. Neither of these groups is comparable to the population used by Leibowitz and Pishkin (1961) which had an average length of hospitalization of close to 9 years.…”

“…Zahn (1959) has also stressed the utility of size judgment technique in evaluation of affective variables' influences on schizophrenics' behavior. In the earlier study (Leibowitz & Pishkin, 1961) the experimental stimuli were simple wooden dowels, which presumably have no symbolic or emotional connotation for the patients. It is possible that when stimuli become emotionally charged the result is a deficit in the performance of schizophrenics.…”

“…The tech-nique involved required the subject to indicate whether a human shaped plywood silhouette is larger, smaller, or the same size as a three-dimensional clothed dummy figure. The patient population was essentially the same as that of the previous study (Leibowitz & Pishkin, 1961). They were all chronic schizophrenics who had demonstrated marked withdrawal symptoms.…”

The Effect of Informational Feedback on Size Judgements of Schizophrenic Patients

“…* A n analysis of variance of transformed variability scores (log variance) showed the same significance are equivocal (Lovinger, 1956;Rausch, 1952;Weckowicz, 1957). Differences in mean equality judgements between schizophrenics and normals have generally been found only with reduction of viewing conditions (Lovinger,, not under maximal conditions (Leibowitz & Pishkin, 1960). The maximal conditions used in this experiment showed no difference in the mean equality settings for the four groups but showed significantly larger intra-subject variability for the schizophrenics under verbal instructions.…”