Abstract
To systematically measure perceptual capacity for autistic, ADHD, autistic people with ADHD (AuDHD), and neurotypical adult populations, and to examine whether increased perceptual capacity represents a specific feature of autism or extends to other neurodivergent groups.
UK-based adults (n = 270: 69 autistic, 66 ADHD, 65 AuDHD, and 70 neurotypical), aged 18 to 40 years of age, took part in an online, computer-based perceptual capacity paradigm. Participants performed a target detection task with various levels of perceptual load (set size) and distractor congruency.
Pre-registered Analysis of Variance and Generalized Linear Models/Linear Mixed-Effects Models indicated a significant group by set size interaction for reaction time. This was driven by a plateau in reaction time from set size 4 for the neurotypical group. There were no significant main effects of group for accuracy or reaction time. Exploratory analyses showed autistic participants demonstrated significantly stronger congruency effect (greater slowing from incongruent distractors) at moderate load levels than neurotypical participants, with a similar trend for those with AuDHD, but not ADHD.
These findings suggest that increased perceptual capacity might be a unique aspect of autistic cognition. This offers important insight into the differing cognitive underpinnings that may give rise to attentional challenges experienced by autistic people and those with ADHD and consequently, alternative recommendations regarding individualised approaches to support.