Paradigm and behavioral data.

<p>(A) In Stop-relevant blocks, a choice-reaction stimulus (a green German traffic-light symbol oriented to the left or right) was either presented for the entire stimulus duration of 800 ms (Go-trial) or replaced by a red Stop-stimulus (Stop-trial) after a variable SOA set trial-to-trial by a tracking algorithm. The Stop-stimulus indicated that the response to the Go-stimulus was to be cancelled, yielding successful (SSTs) and unsuccessful Stop-trials (USTs). (B) In Stop-irrelevant blocks the visual stimulation was identical, but the Stop-stimuli were all irrelevant, i.e. responses were required for all the Go-trials regardless of whether they were followed by a Stop-stimulus. (C) Response times were slowest for Stop-relevant (SR) Go-trials but similar for unsuccessful Stop-trial, Stop-irrelevant (SI) Stop-trials, and Stop-irrelevant Go-trials. The Stop-signal reaction time (SSRT) was calculated to be 230 ms (grand-average data + standard error of the mean (SEM)).