Impaired speed of information processing in nonmedicated schizotypal patients.

There is increasing evidence that schizophrenia is associated with an attentional or information processing deficit or both. These "early deficit" theories challenge the position that schizophrenia is primarily a disorder of thinking and higher cognitive operations. A tachistoscopic backward masking task was applied in matched groups of 20 schizophrenic, 20 schizotypal, and 20 depressive psychiatric inpatients. Resulting data are an index of visual input factors and speed of information processing. Paranoid schizophrenic and schizotypal subjects had unimpaired visual input thresholds but abnormally slow processing compared with the depressives. Since all the schizotypal subjects were nonmedicated, the data add important support to the hypothesis that impaired speed of information processing in schizophrenia spectrum disorders is due to schizophrenia per se and is not secondary to medication effects. These data also support the theoretical link between schizophrenic and schizotypal patients. The importance of the results is discussed, with emphasis on the hypothesized relationship between information processing dysfunction and symptom formation in the schizophrenias.