Cognitive and phenomenological characteristics of hallucination-proneness across the lifespan.

Introduction: The impact of age on hallucination-proneness within healthy adult cohorts and its relation to underlying cognitive mechanisms is underexplored. Based on previously researched trends in relation to cognitive ageing, we hypothesised that older and younger adults, when compared to a middle adult age group, would show differential relations between hallucination-proneness and cognitive performance.

Methods: A mixed methods, between-groups study was conducted with 30 young adults, 26 older adults, and 27 from a "middle adulthood" group. Participants completed a source memory task, jumbled speech task, Launay-Slade hallucination scale, unusual experiences schedule, and control measures of delusion-proneness and attitudes to mental health.

Results: Compared to older age-groups, younger participants demonstrated better scores on the source memory task, and reported hearing more words in jumbled speech. Additionally, younger cohorts rated higher on hallucination-proneness and disclosed more unusual experiences on a customised schedule designed to gather further qualitative data. Jumbled speech scores positively correlated with hallucination-proneness scores, particularly for the "middle" age group. Source memory performance unexpectedly correlated positively with hallucination-proneness, although this may be the product of age differences in task performance.

Conclusions: Age differences in hallucination-proneness are evident on self-report and cognitive measures. Implications are discussed for potentially non-overlapping cognitive mechanisms underlying hallucination-proneness in non-clinical groups.