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. Author manuscript; available in PMC: 2011 Jan 1.
Published in final edited form as: Neuropsychologia. 2009 Oct 29;48(2):541. doi: 10.1016/j.neuropsychologia.2009.10.015

Figure 1.

Figure 1

Task design. A. Go trials. The cue “Maybe Stop Left” or “Maybe Stop Right” (or, in the no foreknowledge condition, “Maybe Stop XXX”) is presented for 1 second followed by a blank screen for 1 second, after which time the imperative go stimulus is presented as two blue colored circles (either outer or inner). Participants initiate left and right index finger presses if the blue circles are on the outside, or left and right index finger presses if the blue circles are on the inside. Limited hold refers to the time period during which the circles are displayed if there is no response. ITI is the inter-trial-interval. B. Stop trials. These make up one-third of trials and are identical to go trials, except that a stop signal is presented with a variable stop-signal delay subsequent to the go stimulus. If a stop signal occurs, the subject must try to stop the indicated hand while completing a key press with the other (‘alternative response’) as quickly as possible. C. Probe trials. 25% of stop trials were probe trials. For these, the stop signal appeared in the middle of the screen, probing the participant‘s knowledge of the cue. The participant tries to stop the hand indicated by the cue and to respond with the other hand. The percent of trials for which this was performed correctly provides the cue recall accuracy measure. The stop signal delay on all probe trials was 50 ms.