Stop-Signal Task¶
The Stop-Signal Task (SST) is a widely used experimental paradigm in cognitive neuroscience and psychology to study response inhibition—the ability to suppress prepotent or ongoing actions. First formalized by Logan and Cowan in the 1980s, the SST builds on the horse-race model, which conceptualizes response execution and inhibition as two independent processes competing in time.
In a typical SST, participants respond to go stimuli (e.g., left/right arrows), but must withhold their response when a stop signal (usually a tone or visual cue) appears shortly afterward. The delay between the go and stop signal—called the stop-signal delay (SSD)—is dynamically adjusted to estimate the stop-signal reaction time (SSRT), a key measure of inhibitory control.
Over time, numerous variants of the SST have been developed, including versions with emotional or motivational cues, modified timing strategies, and neurophysiological adaptations using EEG or fMRI. The SST remains a gold standard for probing executive control across both healthy and clinical populations.