Proactive inhibition of goal-directed movements involves explicit changes to movement planning

Inhibition can be implemented reactively, withholding movement in response to a stop-signal, or by proactive changes to movement planning when a stop-signal is expected. Previous studies have typically employed simple button presses, finding proactive delays to movement onset when a stop-signal might appear. Here, we consider inhibition in the context of more complex, goal-directed movements, such as the swing of a bat. Thus, we observe two additional dimensions of movement planning under proactive control, movement duration and end-point error. We found, in addition to onset delay, movements were briefer and arrived later when a stop-signal might appear. This challenges a classical theoretical dichotomy, suggesting proactive inhibition is underlay by both response suppression and delayed facilitation. Moreover, participants were aware of delays to onset and arrival, but reported magnitudes were smaller than observed. This suggests proactive inhibition operates as an explicitly retrievable compensatory strategy whose finer details are implicitly tuned.