Children with autism spectrum disorder show reduced adaptation to number

Abstract

Autism is known to be associated with major perceptual atypicalities. We have recently proposed a general model to account for these atypicalities in Bayesian terms, suggesting that autistic individuals underuse predictive information or priors. We tested this idea by measuring adaptation to numerosity stimuli in children diagnosed with autism spectrum disorder (ASD). After exposure to large numbers of items, stimuli with fewer items appear to be less numerous (and vice versa). We found that children with ASD adapted much less to numerosity than typically developing children, although their precision for numerosity discrimination was similar to that of the typical group. This result reinforces recent findings showing reduced adaptation to facial identity in ASD and goes on to show that reduced adaptation is not unique to faces (social stimuli with special significance in autism), but occurs more generally, for both parietal and temporal functions, probably reflecting inefficiencies in the adaptive interpretation of sensory signals. These results provide strong support for the Bayesian theories of autism.utism is a heritable, lifelong neurodevelopmental condition with striking effects on social communication. The condition, however, is also associated with a range of nonsocial symptoms, including both hypersensitivity and hyposensitivity to perceptual stimuli, and sensory-seeking behaviors such as attraction to light, intense looking at objects, and fascination with brightly colored objects. These sensory atypicalities, which now form part of the diagnostic criteria for autism (1), can have debilitating effects on the lives of autistic people (2) and their families (3).We have recently proposed a Bayesian account of autism (4), suggesting that it is not sensory processing itself that is disrupted in individuals with autism, but the interpretation of the sensory input. The Bayesian class of theories, including predictive coding and other generative models (5-7), assumes that perception is an optimized combination of external sensory data (the likelihood) and an internal model (the prior). We suggested that this process may be atypical in autism, in that the internal priors are underweighted and less used than in typical individuals. Our theory has been followed by several others along similar lines (8-11).The suggestion of underutilization of priors leads to several specific predictions. One strong prediction is that autistic individuals should show reduced adaptation aftereffects. Adaptation, which occurs throughout sensory systems, represents a form of experience-dependent plasticity in which our current sensory experience is intimately affected by how we viewed the world only moments before. It is widely held to pose numerous functional advantages (12-16), including serving to autocalibrate perceptual systems to their environment by dynamically tuning its responses to match the distribution of stimuli to make maximal use of the limited working range of the system (12-16). It achieves this by reducing the transm...

Distinctive Role of Symbolic Number Sense in Mediating the Mathematical Abilities of Children with Autism

“…Given that performance on this task improves rapidly in the 6–7 age range studied (Halberda and Feigenson 2008), we might have expected the older ASD group to perform better than their younger TD peers. Our findings align with the recent study by Turi et al (2015) who found reduced adaptation for non-symbolic quantity in children with ASD. Although non-symbolic number sense itself could not be adequately determined from their experimental paradigm, their findings nevertheless suggest weakness in integration of complex visuo-spatial quantity information.…”

“…Instead, we found that children with ASD were significantly impaired on a non-symbolic comparison task relative to their TD peers. This pattern is broadly consistent with previous studies on non-symbolic number sense in ASD which also failed to find superior quantity estimation in individuals with ASD (Meaux et al 2014; Titeca et al 2014; Turi et al 2015). While attention to local features may be beneficial in tasks requiring identification of individual items, such as the Navon Task (Muth et al 2014; Navon 1977), our results suggest that this skill does not translate to enhanced non-symbolic quantity processing in children with ASD.…”

Perceptual Averaging in Individuals with Autism Spectrum Disorder

“…These patterns of results suggest that both groups were similarly affected by the vertical line cues to perspective, but ASD observers did not rely on the prior knowledge that the projected stimulus was actually a circle to the same extent as controls. A similar failure to rely on prior information has been linked to findings that ASD participants show reduced levels of perceptual adaptation to facial identity (e.g., Pellicano et al, 2007) and numerosity (Turi et al, 2015) compared to controls. A decreased reliance on prior knowledge could also account for findings that ASD observers fail to perceive impossible figures (e.g., Mottron and Belleville, 1993; Mottron et al, 1999).…”

“…Along these lines, our results also have important implications for theories that posit impairments in predicting or integrating prior information in ASD (e.g., Pellicano and Burr, 2012; Sinha et al, 2014). For example, previous studies have reported that observers with ASD are less susceptible to adaptation to facial identity (Pellicano et al, 2007) and numerosity (Turi et al, 2015). However, the present results demonstrating susceptibility to mean size adaptation strongly suggest that ASD observers nonetheless rely on statistical redundancies in the external environment to some extent.…”

Disentangling signal and noise in autism spectrum disorder

“…Hence, weaker (i.e., lower precision or less confidence in) top-down predictions would also lead to increased reliance on bottom-up information as in the ''weak priors" account (Pellicano & Burr, 2012). The importance of relative precisions, however, also implies that studies that find reduced adaptation in behavior or reduced repetition suppression in fMRI responses in ASD (or high autism traits) (e.g., Ewbank et al, 2014;Molesworth, Chevallier, Happé, & Hampton, 2015;Turi et al, 2015) cannot simply be considered evidence for the weaker priors thesis, even though both adaptation and repetition suppression are thought to be the result of (top-down) predictive activity (Chopin & Mamassian, 2012;Summerfield, Trittschuh, Monti, Mesulam, & Egner, 2008).…”