Language medium and schizophrenic thought disorder.

Ten selected schizophrenic patients and 10 control subjects were assessed in their home language and in a second language for evidence of formal thought disorder. The performance of the schizophrenics was significantly poorer in their home language, while that of control subjects did not differ between the two languages. The results are compatible with Bannister's serial invalidation hypothesis of schizophrenic thought disorder. Of more immediate importance, they indicate that careful attention must be paid to the language used in assessing psychiatric patients in a multilingual society.