The Role of Affect and Priors in the Generation of Hallucinations in Early Psychosis

Timothy Friesen; Philomène Labilloy; Deven Parekh; Maia List; Youcef Barkat; Victoria Fisher; Camille Jacquet; Jed Burde; Ivy Guo; Eva Hammer; Parnia Akhavansaffar; Dylan Hamitouche; Martin Lepage; Chris Mathys; Jai Shah; Al Powers; David Benrimoh

arXiv · 2512.14743

The Role of Affect and Priors in the Generation of Hallucinations in Early Psychosis

Timothy Friesen·Philomène Labilloy·Deven Parekh·Maia List·Youcef Barkat·Victoria Fisher·Camille Jacquet·Jed Burde·Ivy Guo·Eva Hammer·Parnia Akhavansaffar·Dylan Hamitouche·Martin Lepage·Chris Mathys·Jai Shah·Al Powers·David Benrimoh

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Abstract

Background: Stress and negative affect play significant roles in developing psychosis. Bayesian analyses applied to the conditioned hallucinations (CH) task suggest that hallucinations arise when maladaptive prior beliefs outweigh sensory evidence. Prior weighting is linked to hallucination severity, yet the nature of these priors remains unclear. Negative affect may influence the strength of maladaptive priors. We hypothesized that, under stress, participants will show increased CH rates and prior weighting, with this effect more pronounced in patients. Methods: This study employs a modified CH task using valenced linguistic stimuli and stress and non-stress affective manipulations. The sample for this pilot study included those at risk for psychosis and patients with first episode psychosis (N=12) and healthy controls (N=15). The objective of this study was first to validate this affective version of the CH task and then to demonstrate an effect of affect on CH rates and prior weighting. Results: Replicating past results, patients had higher CH rates (b = 0.061, p < 0.001) and prior weighting (b = 0.097, p < 0.001) for session 1 compared to controls (n=15) across conditions. Further, runs with stress manipulations had higher prior weighting across patients and controls compared to runs with non-stress manipulations (b = 0.054, p = 0.033). Conclusions: This study validates this affective version of the CH task and provides preliminary evidence of a relationship between affective state and prior weighting. Future work will be aimed at confirming and extending these findings, with the objective of developing biomarkers of early psychosis. Key words: Schizophrenia, Affect, Priors, Computational Psychiatry, Clinical High Risk Population, Psychotic Symptoms

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Timothy Friesen, Philomène Labilloy, Deven Parekh, Maia List, Youcef Barkat, Victoria Fisher, Camille Jacquet, Jed Burde, Ivy Guo, Eva Hammer, Parnia Akhavansaffar, Dylan Hamitouche, Martin Lepage, Chris Mathys, Jai Shah, Al Powers, David Benrimoh. 2025-12-12. The Role of Affect and Priors in the Generation of Hallucinations in Early Psychosis. https://arxiv.org/abs/2512.14743

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