Individuals with autism show non-adaptive relative weighting of perceptual prior and sensory reliability

Abstract

Modulation in sensory-perceptual processing is a known characteristic of autism, although the underlying mechanism is debated. A prevailing account is formulated in Bayesian terms, where either a reduced prior or reduced noise in the measurement (sensory input) may account for the modulated perception as expressed by the posterior distribution. However, research has shown that individuals with autism use priors in some conditions, and to the same extent as neurotypicals, while other studies fail to show enhanced sensory sensitivity in these individuals. We asked whether the modulated prior effects on perception may arise from non-adaptive relative weighting of priors to sensory reliability. We employed a Two-alternative forced choice (2AFC) width discrimination task, using the width–height illusion, which is based on a long-term acquired bias, where a taller rectangle is typically perceived as thinner than a shorter one. The measurement was manipulated by adding Gaussian blur on the vertical edges of the rectangles. Typically developed individuals displayed the expected increase in bias as a function of noise in the measurement. High-functioning individuals with autism exhibited typical perceptual resolutions and similar susceptibility to the illusion. However, the relative weighting of the perceptual bias and the sensory input differed in their effect on the two groups. Individuals with autism showed a non-adaptive, consistent bias across the different degrees of sensory noise, while typically developed individuals displayed monotonically increasing biases. Cluster analyses showed that this difference in the relative weighting between the groups was preserved regardless of the overall illusion magnitude displayed by individuals in each cluster. Lay abstract Unique perceptual skills and abnormalities in perception have been extensively demonstrated in those with autism for many perceptual domains, accounting, at least in part, for some of the main symptoms. Several new hypotheses suggest that perceptual representations in autism are unrefined, appear less constrained by exposure and regularities of the environment, and rely more on actual concrete input. Consistent with these emerging views, a bottom-up, data-driven fashion of processing has been suggested to account for the atypical perception in autism. It is yet unclear, however, whether reduced effects of prior knowledge and top-down information, or rather reduced noise in the sensory input, account for the often-reported bottom-up mode of processing in autism. We show that neither is sufficiently supported. Instead, we demonstrate clear differences between autistics and neurotypicals in how incoming input is weighted against prior knowledge and experience in determining the final percept. Importantly, the findings tap central differences in perception between those with and without autism that are consistent across identified sub-clusters within each group.

Is she still angry? Intact learning but no updating of facial expressions priors in autism

“…These findings suggest that autistic people can learn the statistics of the environment and implement them as prior knowledge. This is consistent with results from previous research that showed intact construction and utilization of prior in autism using simple visual and auditory stimuli such as visual judgment of size (Sapey-Triomphe et al, 2021;Binur et al, 2022) and weight , duration judgment (Karaminis F I G U R E 2 (a). Accuracy rates (mean ± SEM) for "switch stimuli" across groups in the two segments of the study.…”

“…These findings suggest that autistic people can learn the statistics of the environment and implement them as prior knowledge. This is consistent with results from previous research that showed intact construction and utilization of prior in autism using simple visual and auditory stimuli such as visual judgment of size (Sapey‐Triomphe et al, 2021; Binur et al, 2022) and weight (Hadad & Schwartz, 2019), duration judgment (Karaminis et al, 2016), and pitch discrimination (Lieder et al, 2019). The acquisition of priors in the present study with facial expressions extends previous research on social priors and show priors can be implicitly formed based on accumulated social information without explicit knowledge.…”

“…Another option is that reduced effects of the priors may arise from narrower likelihoods (i.e., more precise sensory representations; see illustration Brock, 2012). However, autistic people are shown to use both preexisting priors and learned priors in a manner similar to that of nonautistic people in several perceptual tasks involving discrimination of simple features such as size and weight (Binur et al, 2022; Hadad & Schwartz, 2019), suggesting no attenuated priors or enhanced sensory sensitivity in autism (Hadad & Yashar, 2022). Instead, recent studies have proposed that autistic people can form priors and integrate them with sensory information; yet, they tend to rely less on recent experiences, and are less flexible in adjusting their priors (Lieder et al, 2019; Sapey‐Triomphe et al, 2021; Vishne et al, 2021).…”

Decision-making in autism: A narrative review

“…Similarly, on a probabilistic visual search task, autistic participants performed as well as comparison participants, except that reaction times were longer in the autism group when the target followed a distractor in a rare region of the search space (Allenmark et al, 2021). Binur et al (2022) found that autistic participants showed an equivalent width-height bias to comparison participants, but the blur effect on perceived width was attenuated in the autism group. Two trait-based studies also fell into this category.…”

Neural response and representation: Facial expressions in scenes

“…This aids the rapid generation of largely accurate perceptual experiences (Press et al, 2020). To test this hypothesis, we refer to previous studies to reduce this relative reliability by blurring stimuli (Binur et al, 2022; Fourtassi & Frank, 2020; Rohlf et al, 2020). If the above framework holds, we expected facial expression clarity to modulate the effect of the scene on facial expression representation.…”