Time-on-task analysis using wavelet networks in an event-related potential study on attention-deficit hyperactivity disorder

Objective: The aim of this event-related potential (ERP) study was to test time-on-task analysis at the level of single sweeps in a clinical trial. Since inattentiveness is one of the main symptoms of attention-deficit hyperactivity disorder (ADHD), this child psychiatric disorder was chosen as an exemplary application. Methods: Twenty-four healthy and 24 ADHD boys, aged 9–15 years, performed an auditory selective attention task for about 5 min. ERP single trials were analyzed using wavelet networks. Time-on-task analysis was applied to omission errors, reaction time and slow ERP components (frontal negativity, parietal positivity), represented by a low-frequency wavelet component. Results: Both performance and ERP measures showed distinct temporal dynamics. Time-on-task effects were not only linear, but also of higher order and started after less than 1 min. For ADHD children, earlier time-on-task effects, i.e. an earlier increase of omission errors and frontal negativity, resulted. Healthy children could allocate more attentional resources during the course of the experiment. Conclusion: Time-on-task analysis at the level of single trials revealed phenomena probably reflecting ADHD childrenʹs attentional deficits. Thus, a more differentiated ERP analysis may provide a better understanding of the pathophysiological background in neuropsychiatric disorders.