Message disruptions during syntactic processing in schizophrenia.
Twenty-four schizophrenics and 24 nonschizophrenic psychiatric patients were given the Hunt test, which requires the subject to use syntactic strategies to synthesize an extended multisentence text on the basis of a controlled set of input propositions. This syntactic processing task induced many more meaning misrepresentations of input propositions in the schizophrenic group compared to the control group. These group differences could not be accounted for by confounding variables such as level of psychopathology, medication, and verbal skills. An error analysis indicated that schizophrenics were highly likely to produce meaning errors when the rewritten proposition assumed a passive syntactic form. Conceptually complex sequences of propositions also resulted in a high frequency of message errors among schizophrenics; this second factor did not account, however, for the high association of errors and passive rewrites. These data are interpreted as indicating that schizophrenics suffer from a multilevel language-production disturbance that includes higher-level message errors that are reflexively induced by lower-level syntactic processing disturbances.