Circular inference in bistable perception

Abstract

When facing fully ambiguous images, the brain cannot commit to a single percept and instead switches between mutually exclusive interpretations every few seconds, a phenomenon known as bistable perception. Despite years of research, there is still no consensus on whether bistability, and perception in general, is driven primarily by bottom-up or top-down mechanisms. Here, we adopted a Bayesian approach in an effort to reconcile these two theories. Fifty-five healthy participants were exposed to an adaptation of the Necker cube paradigm, in which we manipulated sensory evidence (by shadowing the cube) and prior knowledge (e.g., by varying instructions about what participants should expect to see). We found that manipulations of both sensory evidence and priors significantly affected the way participants perceived the Necker cube. However, we observed an interaction between the effect of the cue and the effect of the instructions, a finding incompatible with Bayes-optimal integration.In contrast, the data were well predicted by a circular inference model. In this model, ambiguous sensory evidence is systematically biased in the direction of current expectations, ultimately resulting in a bistable percept.

Hallucinations Under Psychedelics and in the Schizophrenia Spectrum: An Interdisciplinary and Multiscale Comparison

“…Importantly, different loops result in different types of aberrant percepts: while ascending loops induce unimodal hallucinations (eg, AH in SCZs), descending loops give rise to multisensory phenomena (eg, synesthesia-like experiences; MMH induced by DMT). 151 Although the former link between ascending loops and SCZs has already been empirically established, 152 the latter between descending loops and psychedelics remains purely theoretical and still needs experimental support.…”

A Review of Multimodal Hallucinations: Categorization, Assessment, Theoretical Perspectives, and Clinical Recommendations

“…Evidence linking CI and MMHs comes from work on synesthesia, a perceptual phenomenon whereby stimulation of one modality leads to experiences in another modality 77 and which has been linked to disinhibited feedback from association cortex to sensory cortex. 78 Ongoing research using simulations of drug-induced synesthesia 79 has shown that reverberation of information descending the cortical hierarchy (descending loops) could induce audio–visual experiences in the absence of clear sensory input (cross-modal hallucinations) but also a contamination of one modality by another in the presence of a unimodal stimulus (synesthesia). These 2 features were retained as good candidates for modeling psychedelic-induced subjective experiences using probabilistic approaches.…”

Within-object element ambiguity allows for a strange illusion of alternating facial expression and structure

“…A conceivable experiment could use biasing by creating expectation of either a face with low facial height-to-width ratio or with high value of this ratio. (The often used selective, physically produced emphasis of some parts of the face can be used as an experimental control-e.g., Leptourgos et al, 2020. ) In the Gestalt tradition there are different types of cues for perceptual organization and object formation (Wagemans et al, 2012).…”