Department of Psychiatry, Columbia University, New York State Psychiatric Institute, New York, New York 10032.
Department of Psychiatry, Centre Hospitalier Universitaire de Rouen, 76031 Rouen, France.
J Neurosci. 2023 Jul 19;43(29):5365-5377. doi: 10.1523/JNEUROSCI.0692-22.2023. Epub 2023 Jun 21.
Bayesian models of perception posit that percepts result from the optimal integration of new sensory information and prior expectations. In turn, prominent models of perceptual disturbances in psychosis frame hallucination-like phenomena as percepts excessively biased toward perceptual prior expectations. Despite mounting support for this notion, whether this hallucination-related prior bias results secondarily from imprecise sensory representations at early processing stages or directly from alterations in perceptual priors-both suggested candidates potentially consistent with Bayesian models-remains to be tested. Using modified interval timing paradigms designed to arbitrate between these alternative hypotheses, we show in human participants (16 females and 24 males) from a nonclinical population that hallucination proneness correlates with a circumscribed form of prior bias that reflects selective differences in weighting of contextual prior variance, a prior bias that is unrelated to the effect of sensory noise and to a separate index of sensory resolution. Our results thus suggest distinct mechanisms underlying prior biases in perceptual inference and favor the notion that hallucination proneness could reflect direct alterations in the representation or use of perceptual priors independent of sensory noise. Current theories of psychosis posit that hallucination proneness results from excessive influence of prior expectations on perception. It is not clear whether this prior bias represents a primary top-down process related to the representation or use of prior beliefs or instead a secondary bottom-up process stemming from imprecise sensory representations at early processing stages. To address this question, we examined interval timing behaviors captured by Bayesian perceptual-inference models. Our data support the notion that excessive influence of prior expectations associated with hallucination propensity is not directly secondary to sensory imprecision and is instead more consistent with a primary top-down process. These results help refine computational theories of psychosis and may contribute to the development of improved intervention targets.
贝叶斯感知模型认为，感知是新感觉信息和先验期望最佳整合的结果。反过来，精神病学中感知障碍的突出模型将类似幻觉的现象框定为过度偏向感知先验的感知。尽管越来越多的证据支持这一观点，但这种与幻觉相关的先验偏差是源自早期处理阶段不准确的感觉表示，还是直接源自感知先验的改变——这两种可能性都与贝叶斯模型一致——仍有待检验。我们使用经过修改的间隔时间计时范式来对这些替代假设进行裁决，在来自非临床人群的人类参与者（16 名女性和 24 名男性）中，我们发现易产生幻觉与一种特定形式的先验偏差相关，这种偏差反映了对上下文先验方差的加权存在选择性差异，而这种先验偏差与感觉噪声的影响以及与感觉分辨率的单独指标无关。因此，我们的结果表明，在感知推理中的先验偏差存在不同的机制，并支持这样一种观点，即易产生幻觉可能反映了感知先验的直接改变，而与感觉噪声无关。当前的精神病学理论假设，易产生幻觉是由于先验期望对感知的过度影响所致。目前尚不清楚这种先验偏差是代表与先验信念的表示或使用有关的主要自上而下的过程，还是源自早期处理阶段不准确的感觉表示的次要自下而上的过程。为了解决这个问题，我们检查了贝叶斯感知推理模型所捕获的间隔时间行为。我们的数据支持这样一种观点，即与易产生幻觉倾向相关的先验期望的过度影响不是直接源自感觉不准确，而是更符合主要的自上而下的过程。这些结果有助于完善精神病学的计算理论，并可能有助于开发改进的干预目标。
