Evidence for Reduced Sensory Precision and Increased Reliance on Priors in Hallucination-Prone Individuals in a General Population Sample

TL;DR

This study shows that individuals prone to hallucinations in the general population tend to rely more on prior beliefs and have reduced sensory precision, especially in processing complex linguistic auditory stimuli, as demonstrated by a hierarchical Bayesian model.

Contribution

It introduces a linguistic version of the conditioned hallucinations task and demonstrates that hallucination-prone individuals exhibit reduced sensory precision alongside increased prior reliance.

Findings

Higher hallucination-proneness correlates with increased prior weighting.

Hallucination-prone individuals show higher stimulus thresholds and lower sensitivity.

Reduced sensory precision is linked to increased hallucination susceptibility.

Abstract

There is increasing evidence that people with hallucinations overweight perceptual beliefs relative to incoming sensory evidence. Much past work demonstrating prior overweighting has used simple, non-linguistic stimuli. However, auditory hallucinations in psychosis are often complex and linguistic. There may be an interaction between the type of auditory information being processed and its perceived quality in engendering hallucinations. We administered a linguistic version of the Conditioned Hallucinations (CH) task to an online sample of 88 general population participants. Metrics related to hallucination-proneness, recent auditory hallucinations, stimulus thresholds, and stimulus detection were collected; data was used to fit parameters of a Hierarchical Gaussian Filter model of perceptual inference to determine how latent perceptual states influenced task behavior. Replicating past results, higher CH rates were associated with measures of higher hallucination-proneness and recent hallucinatory experiences; CH rates were positively correlated with increased prior weighting; and increased prior weighting was related to recent hallucinatory experiences. Unlike past results, participants with recent hallucinatory experiences as well as those with higher hallucination-proneness had higher stimulus thresholds, lower sensitivity to stimuli presented at the highest threshold, and tended to have lower response confidence, consistent with lower precision of sensory evidence. We show that hallucination-prone individuals in the general population have increased conditioned hallucination rates using a linguistic version of the CH task, and replicated the finding that increased CH rates and recent hallucinations correlate with increased prior weighting. Results support a role for reduced sensory precision in the interplay between prior weighting and hallucination-proneness. *contributed equally