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. Author manuscript; available in PMC: 2013 Jan 1.
Published in final edited form as: J Psychiatr Res. 2011 Oct 22;46(1):22–30. doi: 10.1016/j.jpsychires.2011.09.015

Figure 1.

Figure 1

Behavioral paradigm of the Change task. First, a fixation cross is presented for 500ms. Next, participants are instructed to press ‘1’ if an X appears and ‘2’ if and O appears. These constitute prepotent go trials. If a blue background appears, participants are to press a ‘3’ instead of a ‘1’ or ‘2’. These constitute change trials. The onset of the change signal varies from trial to trial. If subjects respond correctly on a change trial, the inhibit delay (the interval between the onsets of the go and change signals) on the next change trial increases by 50 ms, making it more difficult for the subject to change successfully. If subjects respond incorrectly on a change trial, the inhibit delay on the next change trial decreases by 50 ms, making the task easier. A blank screen is displayed during the inter-stimulus interval.