Source monitoring and memory confidence in schizophrenia

Background. The present study attempted to extend previous research on source monitoring deficits in schizophrenia. We hypothesized that patients would show a bias to attribute self-generated words to an external source. Furthermore, it was expected that schizophrenic patients would be over-confident regarding false memory attributions. Method. Thirty schizophrenic and 21 healthy participants were instructed to provide a semantic association for 20 words. Subsequently, a list was read containing experimenter- and self-generated words as well as new words. The subject was required to identify each item as old/new, name the source, and state the degree of confidence for the source attribution. Results. Schizophrenic patients displayed a significantly increased number of source attribution errors and were significantly more confident than controls that a false source attribution response was true. The latter bias was ameliorated by higher doses of neuroleptics. Conclusions. It is inferred that a core cognitive deficit underlying schizophrenia is a failure to distinguish false from true mnestic contents.