In both the stop-signal and go/no-go tasks, subjects are required to make frequent, speeded motor responses to a “go” signal. On a smaller subset of trials, subjects are presented with a “stop” signal, and failures to suppress responding are measured. One key difference between stop signal and go/no-go tasks is the time at which the stop signal is presented.18 In go/no-go tasks, stop signals are either presented in combination or in lieu of the go signal; conversely, in the stop-signal task, stop signals are presented after the go signal is presented, such that subjects must stop and/or inhibit an already initiated response. By parametrically varying the time between the presentation of the go and stop cues, one can create a quantitative, individualized estimate of the time required to inhibit an ongoing response, referred to as the individual’s stop signal reaction time.59 Both procedures have been used extensively in both human and animal research.18
