Auditory false perceptions are mediated by psychosis risk factors

INTRODUCTION: Auditory hallucinations exist in psychotic disorders as well as the general population. Proneness to hallucinations, as measured by positive schizotypy, predicts false perceptions during an auditory signal detection task (Barkus, Stirling, Hopkins, McKie, & Lewis, 2007). Our aim was to replicate this result and extend it by examining effects of age and sex, both important demographic predictors of psychosis.

METHOD: A sample of 76 healthy volunteers split into 15-17 years (n=46) and 19 years plus (n=30) underwent a signal detection task designed to detect propensity towards false perceptions under ambiguous auditory conditions. Scores on the Unusual Experiences subscale (UE) of the O-LIFE schizotypy scale, IQ, and a measure of working memory were also assessed.

RESULTS: We replicated our initial finding (Barkus et al., 2007): High scores on positive schizotypy were associated with false perceptions. Younger participants who scored highly on positive schizotypy reported significantly more false perceptions compared to other groups (p=.04). Older participants who had had an imaginary friend reported more false perceptions during the signal detection task (p<.01).

CONCLUSIONS: Younger participants seem most vulnerable to the effects of positive schizotypal traits in terms of a signal detection deficit that underlies auditory hallucinations. Schizotypy may have greatest impact closer to the risk period for development of psychotic disorders.