Development of attentional disengagement in typically developing children and children with elevated levels of attentional deficits.

The ability to flexibly disengage and shift attention allows us to successfully interact with our environment and develops across infancy, childhood and adolescence. The aim of the present study was to investigate how attentional disengagement abilities develop. We leveraged a robust longitudinal dataset of the Gap-Overlap task of the YOUth cohort with over 3500 children tested at one or more timepoints to track the maturation of attentional control across infancy, childhood and adolescence (5 months, 10 months, 3 years, 6 years, 9 years, 12 years). While we replicated established group-level developmental patterns showing progressive improvement in saccadic reaction times, the time between the appearance of the target and the initiation of the saccade, our findings revealed individual variation in developmental trajectories of the gap effect that cannot be reliably predicted from performance at earlier timepoints. Although we found no associations between Gap-Overlap performance and (parent-reported) attention-related behaviors (n = 99-734 depending on age and measures), this may reflect the difficulty of identifying early markers in highly heterogeneous neurodevelopmental disorders and could be limited by examining subclinical traits rather than diagnosed conditions. The increased understanding of individual developmental patterns established here is a prerequisite for the identification of atypical patterns in clinical assessment. Future studies could build on this work by investigating atypical attention profiles across development and their relationship to Gap-Overlap task performance, particularly in clinical populations where attentional differences may be more pronounced.