“…According to the activation–suppression hypothesis, the engagement and build up of selective suppression of direct response activation can be observed by plotting the interference effect as a function of the entire RT distribution (i.e., delta plots). In particular, the modulation of the interference effect at the slowest segments of the distribution, where inhibition is expected to be fully engaged, is sensitive to group differences in the efficiency of inhibitory control (Bub, Masson, & Lalonde, 2006; Ridderinkhof, Scheres, Oosterlaan, & Sergeant, 2005; Wylie, Ridderinkhof, Eckerle, & Manning, 2007). Guided by this framework and the proposed role of the basal ganglia during action selection, we predicted that PD patients would show reduced selective suppression of incongruent responses when instructions emphasized speed of responding.…”