Intra-individual variability among children with ADHD on a working memory task: an ex-Gaussian approach

Abstract

Intra-individual variability on a computer-based working memory task was examined among 25 children/adolescents with ADHD and 24 typically developing peers. Participants completed the Visual Serial Addition Task (VSAT) and reaction time data were fit to an ex-Gaussian distribution. ADHD participants demonstrated significantly more variable performance than controls, and effects of working memory load were observed. Event rate, however, had no influence on group differences in performance. Follow-up correlations revealed associations between VSAT performance and ADHD symptomatology. This study supports intra-individual variability as a hallmark feature of ADHD beyond the domain of response inhibition and reinforces the need to consider variability in ADHD more broadly.

Figures

Figure 1

The Visual Serial Addition Task (VSAT). Schematic demonstrates example of the first three screens presented during the task.

Figure 2

Mean VSAT performance (±SE) of participants with ADHD (grey bars) and control participants (white bars) across increasing WM loads.