Abstract
The language performance of hospitalised manic (n = 12) and schizophrenic (n=15) patients was compared in order to test hypotheses based on previous models of communication disorder in these patient groups. It was hypothesised that the derailments of manic and schizophrenic patients were discriminable by virtue of differences in the level of connectedness of the speech during this type of language disorder. Previous hypotheses have suggested that manics derail because they discuss multiple concurrent topics and schizophrenics derail as a pattern of general vagueness and poorly interconnected speech. These hypotheses were supported by the finding that manic patients manifested a higher level of overall discourse connectedness during derailments, even when the overall increased amount of speech was accounted for. M anics were not simply more competent overall, because they failed to differ from schizophrenics in their discourse connectedness during nondisordered segments. These results are discussed in terms of their implications for clinical and linguistic differentiation of the language of psychotic patients.