Reduced weighting of short-term perceptual priors during auditory perceptual decision-making in psychosis-prone individuals.

backgroundSerial dependencies in perceptual tasks have been suggested to reflect implicit perceptual priors derived from short-term perceptual history. A reduced weighting of perceptual priors has been proposed as a mechanism underlying psychotic experiences such as delusions and hallucinations. Here, we sought to characterize the effects of implicit and explicit perceptual priors on auditory perceptual decision-making and their modulation by psychosis proneness.

resultsAcross two online experiments, 197 healthy participants completed an auditory two-alternative forced-choice task and standard questionnaires assessing psychosis proneness. In experiment 1, we assessed serial dependence by quantifying the influence of previous on current perceptual choices. Participants revealed a tendency to repeat previous choices, suggesting they formed implicit priors based on recent choice history. The weighting of these implicit priors correlated negatively with psychosis proneness. In experiment 2, we additionally manipulated explicit perceptual priors by providing probabilistic cues before each trial. We found significant effects of both implicit (i.e., choice history) and explicit (i.e., probabilistic cues) prior information, but only the latter correlated negatively with psychosis proneness. In both experiments, reliance on sensory information was increased with higher psychosis proneness. Using hidden Markov models, we found no conclusive evidence for a modulation of temporal dynamics of serial dependencies by psychosis proneness.

conclusionsOur findings support the notion of a shift in perceptual inference away from perceptual priors and towards sensory information as a mechanism facilitating psychosis. However, the degree to which different types of perceptual priors are modulated by psychosis proneness seems to depend on experimental context.