Missing referents, psychotic symptoms, and discriminating the internal from the externalized.

The communicative efficacy of the speech of schizophrenia patients is compromised by the presence of references for which there are no referents. There is evidence that this kind of error is positively associated with the genetic substrate of schizophrenia. The present study was an effort to identify a cognitive process source of these errors by looking at their association with performance on an internal source memory task assessing the ability to remember what one has said out loud versus only thought. Their relationship to psychotic symptoms also was examined. A sample of 110 schizophrenic/schizoaffective outpatients, and 23 nonpsychiatric controls provided 10-min speech samples and completed a battery of memory tests. Patients' symptoms also were rated for severity. Patients performed more poorly than controls on the memory tests, and their speech contained much more frequent references without referents. Frequency of missing referents was associated with scores on the test of internal source memory, even after scores on tests of immediate memory, working memory, and external source memory were regressed out. Missing referents were also related to severity of hallucinations and delusions, and internal source memory performance was related to hallucinations. The findings of this study support the idea that missing referents, hallucinations, and delusions have some common process underpinnings. Impairment in internal source memory appears to be one such process.