Action inhibition revisited: Stopping is not faster than going

Abstract

We often need to swiftly abort a prepared response at the last moment before it is initiated. Our ability to abort a planned response is thought to be a fundamental facet of action control, which is distinguished by being more rapid than initiating an action, and has been suggested to be enabled by specialized neural mechanisms. This narrative has, however, largely been established based on experiments in which there is much greater urgency to abort an action than there is to generate an action. Here, we demonstrate that, under conditions of matched urgency, the speed at which participants are able to abort an action is comparable to the speed at which they can initiate an action. Our results challenge the prevailing view that reactive stopping behaviors have a privileged status over action initiation. Instead, action initiation may be systematically delayed to allow time to abort an action if needed. We propose that action cancellation and action initiation may reflect two opposing states of a single process supporting a decision about whether to act or not.