Implicit learning in psychotic patients

Abstract

Implicit verbal learning of psychotic patients ( n = 59) and non-psychotic control patients ( n = 20) was studied using stem completion and association tasks in lexical and semantic priming paradigms. Performance on these tasks was contrasted with explicit memory on Rey's verbal learning test. Furthermore, correlations of these aspects of memory with positive and negative symptoms of psychosis were examined. Symptom ratings were based on an interview by a psychiatrist using the CPRS and SANS. As expected, the lexical and semantic priming effects in both patient groups were not significantly different, whereas the psychotic patients compared to the controls were impaired in explicit learning. None of the memory variables was significantly correlated with negative or positive symptoms. These findings are explained by the fact that priming effects, as opposed to explicit learning, depend on automatic memory processes, which do not require conscious effort. Moreover, the findings suggest the intactness of posterior cortical functions in psychotic patients.