Do Inhibitory Deficits in ADHD Reflect Both Controlled and Automatic Mechanisms?

Background: The present study investigated automatic and intentional inhibitory control processes in children with Attention-Deficit/Hyperactivity Disorder (ADHD) within the framework of the dual-process theory, comparing their performance with that of typically developing children in ocular motor tasks. The aim was to determine whether deficits in ADHD involve both controlled and automatic inhibitory mechanisms. Methods: 104 children (M = 10.92, SD = 1.97) divided into three groups (ADHD-Inattentive, ADHD-Combined, and control) were tested using the Delayed Ocular Response (DOR) task, which measures intentional inhibitory control by requiring the suppression of reflexive saccades toward peripheral stimuli, and the Saccadic Interference (SI) task, which evaluates automatic inhibitory control by assessing susceptibility to distractor interference during goal-directed saccades. Results: In the DOR task, ADHD groups exhibited a higher number of premature saccades, fewer correct saccades, and lower accuracy compared to controls, with no differences between ADHD subtypes, indicating an impairment in intentional inhibitory control. Performance on the SI task did not differ significantly among groups, suggesting preserved automatic inhibitory control in children with ADHD. Conclusions: These findings indicate that ADHD is characterized by deficits in intentional inhibitory processes rather than in automatic inhibitory mechanisms, contributing to a more differentiated understanding of inhibitory control dysfunctions in this disorder.