Process Analysis of Visual Search in ADHD, Autism and Healthy Controls - Evidence from Intra-Subject Variability in Gaze Control

Increased Intra subject variability, i.e. moment to moment fluctuations in performance, is a candidate endophenotype of Attention Defecit Hyperactivity Disorder (ADHD. In light of potential etiological overlap between ADHD and Autism Spectrum Disorder (ASD) (Biscaldi et al., 2015; Rommelse et al., 2011), it is important to study ISV, in both aforementioned disorders simultaneously. Here, we broaden the study of ISV from reaction time tasks with manual responses to the ISV of gaze control. Children and adolescents with ADHD, ASD and healthy controls, aged 10-13 years (N = 90; all native German speakers) were invited for an oculomotor testing session. Participants were presented a visual search task. The task required participants to find a Portuguese target word shown above a grid with multiple Portuguese German word pairs and indicate its position by pressing response keys matching the search array. Preliminary analysis have been calculated with moment-to-moment fluctuations in eye movements for the period of search. Preliminary results suggest increased ISV in the ADHD group. Our study extends the ISV finding to the ocular-motor domain, proposes methods to study ISV in gaze movement, and highlights its relationship with ASD.