Disorganisation in schizophrenia need not result from a failure to inhibit dominant response tendencies

Schizophrenic disorganisation syndrome is usually considered to be associated with poor performance on frontal lobe tasks, specifically those that require suppression of dominant responses. Two cases are presented who do not fulfil this expectation Despite severe disorganisation of speech and behaviour these patients performed well on several executive tasks in which dominant responses had to be suppressed. One of the patients showed significantly less interference on the Stroop task than normal controls. In contrast, both patients performed badly on a sentence completion task in which production of the dominant response was appropriate. These observations imply that these patients were able to exert ‘‘top-down’’ supervisory control in situations where it was necessary to inhibit dominant response tendencies. We propose that, although many patients with schizophrenia and intellectual deficits do show disorganised behaviour associated with a defective supervisory system, there are others in whom this behaviour is a consequence of the failure of ‘‘bottom-up’’ control by context. Our cases indicate that disorganisation in schizophrenia may be associated with different underlying cognitive deficits.