Cross-modal auditory priors drive the perception of bistable visual stimuli with reliable differences between individuals

Kinga Farkas,Zsófia Pálffy,Gábor Csukly,Szabolcs Kéri,Bertalan Polner

doi:10.1038/s41598-021-96198-7

Kinga Farkas, Zsófia Pálffy + Show 3 more

Open Access

https://doi.org/10.1038/s41598-021-96198-7

Copy DOI

Abstract

It is a widely held assumption that the brain performs perceptual inference by combining sensory information with prior expectations, weighted by their uncertainty. A distinction can be made between higher- and lower-level priors, which can be manipulated with associative learning and sensory priming, respectively. Here, we simultaneously investigate priming and the differential effect of auditory vs. visual associative cues on visual perception, and we also examine the reliability of individual differences. Healthy individuals (N = 29) performed a perceptual inference task twice with a one-week delay. They reported the perceived direction of motion of dot pairs, which were preceded by a probabilistic visuo-acoustic cue. In 30% of the trials, motion direction was ambiguous, and in half of these trials, the auditory versus the visual cue predicted opposing directions. Cue-stimulus contingency could change every 40 trials. On ambiguous trials where the visual and the auditory cue predicted conflicting directions of motion, participants made more decisions consistent with the prediction of the acoustic cue. Increased predictive processing under stimulus uncertainty was indicated by slower responses to ambiguous (vs. non-ambiguous) stimuli. Furthermore, priming effects were also observed in that perception of ambiguous stimuli was influenced by perceptual decisions on the previous ambiguous and unambiguous trials as well. Critically, behavioural effects had substantial inter-individual variability which showed high test–retest reliability (intraclass correlation coefficient (ICC) > 0.78). Overall, higher-level priors based on auditory (vs. visual) information had greater influence on visual perception, and lower-level priors were also in action. Importantly, we observed large and stable differences in various aspects of task performance. Computational modelling combined with neuroimaging could allow testing hypotheses regarding the potential mechanisms causing these behavioral effects. The reliability of the behavioural differences implicates that such perceptual inference tasks could be valuable tools during large-scale biomarker and neuroimaging studies.

Highlights

It is a widely held assumption that the brain performs perceptual inference by combining sensory information with prior expectations, weighted by their uncertainty
Perception can be understood as an unconscious inferential process that estimates the state of the environment by combining prior expectations with incoming sensory data, weighted by their u ncertainty[1,2,3,4]: the less informative sensory data becomes, the more observers will rely on their prior expectations that are influenced by their previous experiences[5,6,7,8]
Such prior expectations may have multiple s ources[1]: one may distinguish between lower-level expectations based on frequency statistics of the environment and higher-level expectations based on conditional probabilities

Summary

Introduction

It is a widely held assumption that the brain performs perceptual inference by combining sensory information with prior expectations, weighted by their uncertainty. The influence of prior beliefs on perception is implemented by top-down feedback signals arriving from higher-level multimodal association areas to sensory areas, mirrored by the modulation of posterior alpha by frontal delta[18] or parietal beta activity[19] These signals seem to carry information as prior expectations induced by sensory conditioning activate featurespecific stimulus representations in the human primary visual c ortex[20]. As mentioned a bove[3], prior expectations have a stronger weight when sensory input is uncertain and at the neural level, increased frontal theta and fronto-parietal and occipital-parietal beta power have been observed when processing ambiguous s timuli[21], while the precision of lower-level priors in the primary visual cortex was reduced if the environment was inconsistent[22]. Carefully designed paradigms that reliably capture individual differences are needed to provide mechanistic explanations for hallucinations and delusions in the psychosis spectrum

Objectives

Methods

Results

Discussion

Conclusion