Katy Hill and David E.J. Linden, in Renaud Jardi, et al. (eds.), The Neuroscience of Hallucinations (Springer, 2013, 21-41).
Abstract: It is now widely recognised that some people hear voices in the absence of distress or a need for psychiatric care. Although there have been reports of such individuals throughout history, until relatively recently there was little empirical research on this population. The consensus from interview and questionnaire-based research is that non-clinical voice-hearers hear voices that are more positive in content, less frequent, less disruptive, and less distressing. Influenced by cognitive models of psychosis, the literature has focused on the appraisals that voice-hearers make of their voices, to the exclusion of other variables such as content. There is growing evidence that clinical voice-hearers have more negative beliefs about their voices and that these are influenced by their more negative beliefs about people in general, formed in the context of negative life experiences. Initial fMRI data suggests that non-clinical voices are underpinned by similar neural mechanisms as clinical voices but as yet it is unclear from these studies why they are experienced so differently. The current chapter reviews these findings and suggest avenues for future research.