At the beginning of each administration of the stop task, the stop delay is set at 200 ms. To ensure that the participants had adjusted their stop-signal delay to the point at which they successfully stopped 50% of the time, we computed the stop RT (and go RT) from the last two blocks of 64 trials. Thus, the procedure provides a measure of the latency in milliseconds to respond to the letter presentation, or the go RT, and the time in milliseconds needed to inhibit a go response, or the stop RT.
