Working Memory Load and Inhibition Performance Among Children With ADHD

Inhibition is a critical executive function for stopping routine responses and facilitating planned behaviour. Although the results are mixed, individuals with ADHD are reported to have poorer inhibition performance; however, this remains a subject of ongoing debate. Findings in the literature suggest that the central executive component of working memory and resource allocation could play a role. The present study investigated whether varying maintenance demands would influence inhibition performance among children with and without ADHD.

The study sample comprised 80 children aged between 7 and 11 years (60 males and 20 females; M_age = 9.01). For the first time in the literature, participants completed a Go/no-go Task with four levels of gradually increased working memory load. The data was analysed using mixed repeated measures ANOVA.

A significant main effect of group, load and interaction were obtained. There was no significant difference in inhibition performance between the two groups when there was no working memory load. However, in the presence of a load, the ADHD group consistently scored lower across all load conditions. Their inhibition performance declined as the load increased. Under the heaviest load condition, the ADHD group obtained the worst scores, whereas the control group's performance improved. In conclusion, introducing a working memory load has a large negative impact on the inhibition performance of the ADHD group but not the control group. These results suggest that children with ADHD struggle to allocate enough resources to meet the increased task demand for optimal inhibition performance.