Eye vergence (EV) is a fixational, binocular eye movement involved in depth perception that recently has also been linked to cognitive processing and symptoms of ADHD. More specifically, weaker EV responses to visual cues have been reported in children with ADHD compared to typically developing peers or children with a mental health condition but no ADHD diagnosis (Sole Puig et al., 2015; Varela Casal et al., 2018). This study aims to evaluate the utility of eye vergence and pupil dilation (PD), measured using computerised eye-tracking tasks, as indicators of visuo-spatial attention processing in children and adolescents. We will compare behavioural, EV and PD responses on two eye-tracking tasks (Oddball and Gap-overlap paradigms) between four groups of children: 3 neurodivergent groups (ADHD, autistic, ADHD+autistic) and a neurotypical group. The tasks are designed to measure specific attentional processes, namely sustained attention and inhibitory control (Oddball task) and orienting and disengaging attention (Gap-overlap task). The Oddball paradigm is a continuous performance test. Our version is based on the classic oddball paradigm, where subjects identify infrequent ‘target’ stimuli within a series of rapidly presented distractor stimuli (Huettel & McCarthy, 2004). This is a 3-stimulus task requiring participants to respond via a button press to an infrequent target presented amongst frequently and infrequently occurring distractors. Response to the infrequent target stimulus provides a measure of sustained attention and vigilance. Response to the infrequent distractor assesses executive control (inhibition of response). Our Gap-overlap task is adapted from a paradigm developed by Elsabbagh and colleagues (Elsabbagh et al., 2013; Elsabbagh et al., 2009). The participant is required to fixate on a central spinning stimulus and to shift their gaze to a peripheral stimulus as soon as it appears. There are three task conditions: gap, overlap and baseline. In the gap condition the central stimulus (CS) disappears and there is a short gap before the peripheral stimulus (PS) appears. In the overlap condition the animated PS appears while the CS remains displayed and animated. In the baseline condition the CS is extinguished, and the PS simultaneously appears. We will calculate the difference in saccadic reaction time between the gap and the overlap condition and between the baseline and the overlap condition for measures of attentional disengagement. References Bustos-Valenzuela, P., Romeo, A., Boxhoorn, S., Helfer, B., Freitag, C. M., Asherson, P., & Supèr, H. (2022). Atypical cognitive vergence responses in children with attention deficit hyperactivity disorder but not with autism spectrum disorder in a facial emotion recognition task. Psychiatry Research Communications, 2(2), 100045. https://doi.org/https://doi.org/10.1016/j.psycom.2022.100045 Elsabbagh, M., Fernandes, J., Webb, S. J., Dawson, G., Charman, T., Johnson, M. H., & British Autism Study of Infant Siblings, T. (2013). Disengagement of visual attention in infancy is associated with emerging autism in toddlerhood [Research Support, Non-U.S. Gov't]. Biological Psychiatry, 74(3), 189-194. Elsabbagh, M., Volein, A., Holmboe, K., Tucker, L., Csibra, G., Baron-Cohen, S., Bolton, P., Charman, T., Baird, G., & Johnson, M. H. (2009). Visual orienting in the early broader autism phenotype: disengagement and facilitation [Comparative Study Research Support, Non-U.S. Gov't]. Journal of Child Psychology & Psychiatry & Allied Disciplines, 50(5), 637-642. Huettel, S. A., & McCarthy, G. (2004). What is odd in the oddball task? Prefrontal cortex is activated by dynamic changes in response strategy. Neuropsychologia, 42(3), 379-386. https://doi.org/10.1016/j.neuropsychologia.2003.07.009 Sole Puig, M., Perez Zapata, L., Puigcerver, L., Esperalba Iglesias, N., Sanchez Garcia, C., Romeo, A., Canete Crespillo, J., & Super, H. (2015). Attention-Related Eye Vergence Measured in Children with Attention Deficit Hyperactivity Disorder. PLoS One, 10(12), e0145281. https://doi.org/10.1371/journal.pone.0145281 Varela Casal, P., Lorena Esposito, F., Morata Martinez, I., Capdevila, A., Sole Puig, M., de la Osa, N., Ezpeleta, L., Perera, I. L. A., Faraone, S. V., Ramos-Quiroga, J. A., Super, H., & Canete, J. (2018). Clinical Validation of Eye Vergence as an Objective Marker for Diagnosis of ADHD in Children. J Atten Disord, 1087054717749931. https://doi.org/10.1177/1087054717749931