Reduced sensitivity to curvature in adolescents diagnosed with ASD

Background: Research on visual perception in individuals diagnosed with autism spectrum disorder (ASD) has generated conflicting results. Studies on low-level perception among individuals with ASD show mixed results, and while some report reduced performance in this level, others present superior or typical low-level processing. Interestingly, despite the difficulties in social perception in this population, these studies usually do not implement social cues or context in these paradigms. Using a two-alternative forced-choice psychophysics task, we aim to integrate these results by assessing the perception of low-level stimulus presented either on its own or served as a local feature within a context. Methods: Thirty-one adolescents diagnosed with ASD and 27 typically developed adolescents were asked to judge whether an arc, a low-level stimulus, was convex or concave. We measured the individual perceptual thresholds and biases under three conditions: face-like stimuli (where the arc was the mouth inside a circle with two dots), scrambled (same visual features as the former, in a scrambled location), and arc-only stimuli. Results: Our results show that compared to TDs, adolescents with ASD were less sensitive to changes in the curvature of the arc across conditions and contexts. Our results also validate the known high heterogeneity in ASD, as we point to a subset of ASD participants who displayed reduced perceptual abilities. Conclusions: By showing that adolescents diagnosed with ASD had difficulties during curvature perception, our results contribute to the growing knowledge base on low-level perception in ASD. Moreover, these findings highlight the importance of using multi-level paradigms composing of both low and local-level stimuli to fully understand visual perception in ASD.