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Poster C88 in Poster Session C - Friday, August 9, 2024, 11:15 am – 1:15 pm, Johnson Ice Rink
Prior-variance-dependent alterations in perceptual inference relate to hallucination severity in schizophrenia
Andra Mihali1,2, Florian Ragalmuto1,2,3,4, Emeline Duhamel1,2,5, Najate Ojeil1,2, Guillermo Horga1,2; 1Columbia University, Department of Psychiatry, 2New York State Psychiatric Institute, 3Berliner FortbildungsAkademie, 4Vrije Universiteit Amsterdam, 56Hospitalier Universitaire de Rouen, Department of Psychiatry
Bayesian models of hallucinations in psychosis posit that this symptom arises when people’s perceptual representations are excessively biased towards prior expectations. But where do these variations in prior reliance come from? It is an open debate whether prior overreliance results from impaired sensory resolution arising from alterations at lower levels of processing or from alterations in the prior representation itself at higher levels. Following our work in healthy controls, we extended our investigation to a group of 36 patients with schizophrenia and 29 matched healthy controls. We aimed to disentangle the effects of hallucination severity and sensory resolution on prior biases in the perceptual estimation of time intervals. Among patients, we critically found that hallucination severity related to decreased ability to represent or use prior variance, but not to decreased sensory resolution or increased sensitivity to sensory noise.
Keywords: perceptual inference hallucinations prior biases magnitude estimation