The experiment consisted of a practice phase and an experimental phase. The practice phase consisted of 20 stimuli, 5 of each type, while the experimental phase consisted of 100 stimuli, 25 of each type. Subjects were instructed to press a key with the index finger of their right hand whenever a white triangle pointed either up or down (Go stimulus) and refrain from pressing the key whenever the triangle pointed towards the right or left (NoGo stimulus). If subjects responded correctly to the Go stimulus by pressing the key within 100-500 ms of stimulus onset, or successfully refrained from pressing the key to the NoGo stimulus within 1200 ms of stimulus onset, a dollar sign ($) appeared on the screen for 200 ms at 1200 ms after stimulus onset. However, if subjects responded incorrectly, i.e., either pressed the key for a NoGo stimulus within 1200 ms from stimulus onset or did not press the key hard enough and/or within 100-500 ms of stimulus onset for a Go stimulus, a cross sign (X) appeared on the screen for 200 ms at
