Adaptation to the Running Speed of Biological Motion in Autistic Children/Adolescents

Background:

Adaptation is a ubiquitous property of perception, a form of experience-dependent plasticity in which our current sensory experience is intimately affected by how we viewed the world only moments before. Previous research has demonstrated that autistic individuals often present reduced adaptation to a range of social and non-social sensory stimuli, relative to non-autistic individuals. Here, we examined adaptation to the processing of biological motion – a higher-level visual attribute important for a range of social competences, such as inferring other people’s emotions, mood, and intentions.

Objectives:

We sought to compare adaptation to the speed of biological motion in autistic and typical children and adolescents.

Methods:

We tested 19 autistic children and adolescents (6 girls) aged between 8;8 and 19;5 years and 19 typically children of similar age and verbal and non-verbal reasoning abilities. Each participant received a child-friendly dual-task paradigm adapted from an existing study (Arrighi, Orsi & Burr, 2010) and based on point-light-display (PLD) representations of running silhouettes. The paradigm included a primary speed-discrimination task, which provided a measure of precision in the discrimination of running speed and a measure of adaptation to the running speed. We also included a secondary change-detection task, which motivated participants to attend to centre-screen and provided an implicit measure of attention (accuracy in change-detection). Reaction times and eye-movement data were also collected.

Results:

Unexpectedly, analyses showed that autistic and typical participants performed similarly in both tasks – both in terms of their precision in the speed-discrimination task and their adaptation to speed. Autistic and typical participants also showed similar patterns of attention during the task – as indexed by similarly high performance in the change-detection task and the scatter of fixation preferences around a centrally-located fixation point.

A secondary correlational analysis revealed no systematic relationship between the magnitude of adaptation and age, cognitive ability or autistic symptomatology. Interestingly, adaptation was less pronounced in participants (autistic and non-autistic) who presented more scattered fixations around the centrally-located fixation point.

Conclusions:

Contrary to our prediction, we found that adaptation to the speed of biological motion was comparable in our autistic and typical children/participants. This finding could not be attributed to group differences in attention or fixation patterns. Our results suggest that limitations in adaptive coding are not pervasive in autistic perception. More nuanced accounts of adaptation in autism are warranted, which would also consider the role of attention and looking preferences.