Impairment of memory organization in patients with schizophrenia or schizotypal disorder.

Verbal learning and the organization of memory in patients with schizophrenia or schizotypal disorder were compared with normal subjects. Three indices of memory organization (semantic clustering, serial clustering, and subjective clustering) were calculated from participants' responses on the Japanese Verbal Learning Test. Schizophrenic and schizotypal patients showed similar decrements in semantic organization compared with normal subjects. Neither patient group showed any effect of learning on their use of semantic organization, although both groups recalled more items as the number of trials increased. These results suggest that impairment of memory organization is a common characteristic of schizophrenia spectrum disorders.