Perceptual Biases as the Side Effect of a Multisensory Adaptive System: Insights from Verticality and Self-Motion Perception

Abstract

Perceptual biases can be interpreted as adverse consequences of optimal processes which otherwise improve system performance. The review presented here focuses on the investigation of inaccuracies in multisensory perception by focusing on the perception of verticality and self-motion, where the vestibular sensory modality has a prominent role. Perception of verticality indicates how the system processes gravity. Thus, it represents an indirect measurement of vestibular perception. Head tilts can lead to biases in perceived verticality, interpreted as the influence of a vestibular prior set at the most common orientation relative to gravity (i.e., upright), useful for improving precision when upright (e.g., fall avoidance). Studies on the perception of verticality across development and in the presence of blindness show that prior acquisition is mediated by visual experience, thus unveiling the fundamental role of visuo-vestibular interconnections across development. Such multisensory interactions can be behaviorally tested with cross-modal aftereffect paradigms which test whether adaptation in one sensory modality induces biases in another, eventually revealing an interconnection between the tested sensory modalities. Such phenomena indicate the presence of multisensory neural mechanisms that constantly function to calibrate self-motion dedicated sensory modalities with each other as well as with the environment. Thus, biases in vestibular perception reveal how the brain optimally adapts to environmental requests, such as spatial navigation and steady changes in the surroundings.

How much I moved: Robust biases in self-rotation perception

“…This means that the slightest deviation from it would be swiftly detected and corrected. For this reason, inherent perceptual biases are interpreted as the consequence of a system that attempts to optimize behavioral performance in daily life, also taking advantage of prior experiences (Cuturi, 2022 ; Knill & Pouget, 2004 ; MacNeilage et al, 2007 ). In this sense, the fine-tuning of the vestibular system to movements away from a preferential direction is likely to reflect the attempt to maintain efficient spatial navigation and locomotion.…”

“…This means that precision in discriminating low-frequency stimuli is poor. Although we did not directly investigate whether the chosen frequency affected observed results in accuracy, we can speculate the potential outcomes with other movements frequencies by considering the Bayesian perspective in interpreting biases (Crane, 2012a;Cuturi, 2022;Cuturi & MacNeilage, 2013a;Cuturi & MacNeilage, 2013b;De Vrijer et al, 2009). According to this model, the perception of a stimulus is based on combining prior information (previous knowledge and experiences) and the available sensory information encoded by our sensors (e.g., the semicircular canals in the vestibular system).…”