A version of the “stop-signal” Go/NoGo task was then administered to measure response inhibition. Subjects were asked to discriminate between letters “X” and “O” as quickly and accurately as possible. One third of the time they were told to withhold their responses for the “NoGo” trial when they heard a “stop” signal tone (a clear sound) presented at a variable delay after the letter was displayed. A staircase variation of the stop-signal-delay was used to keep the commission error (CE) rate at ∼50% for the “stop” trials, in line with previous studies [23], [24]. Stop-signal reaction time (SSRT), the mean length between the stop signal tone and the mean reaction time, measured the capacity of response inhibition.
