Auditory verbal hallucinations (AVH) are a cardinal symptom of psychosis but are also present in 6-13% of the general population. Alterations in sensory feedback processing are a likely cause of AVH, indicative of changes in the forward model. However, it is unknown whether such alterations are selective for voices and similar along the psychosis continuum. By directly comparing psychotic and nonclinical voice hearers (NCVH), in our first experiment we probed whether and how AVH proneness modulates sensory feedback processing for voices and tones (N1, P2) with event-related brain potentials (ERPs). In a second experiment, we manipulated the emotional quality of the self-voice and examined whether unexpected changes in one’s voice feedback engage attentional resources distinctly as a function of hallucination proneness.
In the first experiment, groups differed in sensory feedback processing of expected and actual feedback: NCVH displayed an atypically enhanced N1 to self-initiated voices, while N1 suppression was reduced in psychotic patients. In our second experiment, we observed that the increased N1 response to self-generated voices with higher hallucination proneness did not depend on voice quality. Moreover, hallucination proneness was associated with a reduced N2 response to unexpected voice quality in sensory feedback.
These findings suggest that selective changes in sensory feedback processing in self-voice production are a core feature of AVH. They additionally suggest a link between hallucination proneness and an altered response to unexpected change or error awareness. The results provide partial support for continuum models of psychosis.