Rapid motor inhibition as a mechanism to prevent outdated movements.

Sudden changes in the environment can drastically change the utility of planned hand movements. Instead of executing outdated actions, a general inhibition of motor responses upon salient changes in the environment could delay movements just long enough for alternative movement plans to be evaluated. While such a mechanism has been demonstrated for eye movements, it is not clear if it generalizes to hand movements. Here, we report data from three behavioral online experiments tailored to investigate key features – significant inhibition, temporal precedence, movement update, and saliency dependence – of such an inhibitory mechanism in hand movements. Participants executed sequential hand movements by tapping on movement targets. At an unpredictable time, a behaviorally relevant change (a displacement of the movement targets) or an irrelevant change (a bright flash) appeared. We compared the rate of hand movement onsets after relevant and irrelevant changes to a baseline condition, where changes were absent. Movement rates showed significant inhibition after both relevant and irrelevant changes. The inhibition temporally precedes a movement update that is completed at the time of the response. Across experiments, we find evidence that more salient changes result in stronger inhibition. This research highlights that the rapid inhibition of movements after salient changes is a sufficient mechanism to prevent inadequate actions across motor systems.