Verbal self-monitoring and auditory verbal hallucinations in patients withschizophrenia

Background. Contemporary cognitive models of auditory verbal hallucinations propose that they arise through defective self-monitoring. We used a parad igm that engages verbal self-monitoring to investigate this theory in patie nts with schizophrenia. Methods. Ten patients with auditory verbal hallucinations and delusions (ha llucinators), eight patients with delusions but no hallucinations (non-hall ucinators), and 20 non-psychiatric control subjects were tested. Participan ts read single adjectives aloud, under the following randomized conditions: reading aloud; reading aloud with acoustic distortion of their own voice; reading aloud with alien feedback (someone else's voice); and reading aloud with distorted alien feedback. Immediately after articulating each word, p articipants identified the source of the speech they heard ('self' / 'other ' / 'unsure'), via a button press. Response choice and reaction time were r ecorded. Results. When reading aloud with distorted feedback of their own voice, pat ients in both groups made more errors than controls; they either misidentif ied its source or were unsure. Hallucinators were particularly prone to mis attributing their distorted voice to someone else, and were more likely to make errors when the words presented were derogatory. Both patient groups m ade faster decisions than controls about the source of distorted or alien s peech, but faster responses were only associated with errors in the former condition. Conclusions. Impaired verbal self-monitoring was evident in both hallucinat ors and non-hallucinators. As both groups had delusions, the results sugges t an association between delusions and impaired judgements about ambiguous sensory stimuli. The specific tendency of hallucinators to misattribute the ir distorted voice to someone else may reflect impaired awareness of intern ally generated verbal material.