Delayed Goal-Directed Processing Underlies Inhibitory Control Challenges in Adult ADHD

It is well documented that ADHD is associated with challenges in inhibitory control. However, the underlying cognitive mechanisms that give rise to these difficulties are not well established. Here, we employ a novel “forced-response” method with computational modeling to disentangle the time-dependent control of habitual and goal-directed processing in response-conflict tasks in adults with ADHD. We use a converging approach which compares individuals with ADHD against neurotypical individuals and individuals with ADHD off medication against on medication on two conflict tasks (Simon and Flanker). The forced-response method tracks moment-to-moment cognitive processing from stimulus to response, and data from this method was modeled using a computational model that distinguishes the temporal dynamics of habitual and goal-directed processes. Converging results revealed that ADHD was associated with delayed goal-directed processing but not rushed habitual processing when compared to both neurotypical individuals and to the same individuals on medication in both conflict tasks. These findings mark an important step toward elucidating the underlying mechanisms that lead to real-life challenges in inhibiting distracting information in adults with ADHD.