Stereotyped responding by schizophrenic outpatients: cross-cultural confirmation of perseverative switching on a two-choice task.

Some theoretical implications from amphetamine-based models of psychosis were tested during a study of stereotyped responding by schizophrenic patients. Non-institutionalized Danish schizophrenic outpatients (N = 17) and their matched normal controls were asked to guess on which side (R or L) a cross (+) would appear on a computer screen. The sequence of cross positions was random. Multiple analyses of the patients' responses revealed a significantly greater number of single alterations (RLRL), while the matched controls displayed no such tendency. Controls showed instead, significantly more right side repetitions (RRRR) and more frequent double alterations (RRLL and LLRR). The patient response sequences were similar to those seen in an earlier study by Frith and Done (Psychol Med, 13, 779-786, 1983), but some control group differences emerged. Parallels are drawn between the development of perseverative response switching in schizophrenics and predictions derived from the Lyon-Robbins theory of amphetamine-induced stereotypy.