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Abstract
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Aims: ASD and ADHD are disorders with neurodevelopmental aetiology which share analogies across various domains, despite phenotypic differences. It remains unclear whether similarities express overlapping or different developmental courses. Given that cognitive deficits are central in the pathophysiology of both disorders, we will explore cognitive processes during a visual search task. Evidence from the literature relies mostly on manual reaction time and calls for a typical ASD and an atypically slow ADHD performance.
Methods: In an ongoing cross-sectional study we have tested so far N=251 participants (8,9-17,9 years old) (N=118 typically developing (TD), N=91 ADHD und N=42 ASD) during a visual search task while eye movements were being recorded. Dependent variables are mean and standard deviation (SD) of: (1) Initiation of search (latency of the first saccade), (2) Time until target (time between the first saccade offset on the search grid and the first fixation onset on target), (3) Time on Target (time between first and last fixation on target) (4) Manual Reaction time (time between first saccade onset and manual response).
Results and Conclusions: In comparison to TD, ASD showed a smaller proportion of correct answers, a larger mean but a typical SD of manual reaction time. ADHD did not differ from either TD or ASD. Concerning Initiation of Search, ASD and ADHD shared larger mean and SD of the first saccade than TD. As for Time until target, ASD needed more time and showed a larger SD in the time until they first looked at the target, compared to TD and ADHD. ASD and ADHD shared larger mean and SD of Time on target than TD.
Results from the literature could not be replicated, as ASD, not ADHD, were overall slower and more variable than TD in finding the target. The slower and more variable Initiation of search in ASD and ADHD could express common deficits in planning search, while the slower and more variable Time on target could call for impaired identification processes in both clinical groups.
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