Skip to main content
. Author manuscript; available in PMC: 2012 Aug 1.
Published in final edited form as: J Cogn Neurosci. 2012 Mar 8;24(6):1371–1381. doi: 10.1162/jocn_a_00225

Figure 1.

Figure 1

Experimental task. (A) Diagram of the experimental task. (1) Upon the start of a trial, a fixation light located straight ahead was turned on, and the subjects were expected to look at it and maintain fixation until it was extinguished. (2) During fixation, a 100-msec visual target was presented. (3) The time between the onset of the target and the offset of the fixation light, the delay period, was varied randomly from trial to trial (1–6 sec). (4) The subjects were required to withhold response to the target until the fixation light was turned off, which was their instruction to respond. (B) Percent success as a function of the number of delays presented in a session. The average duration of the delays was kept constant (e.g., one delay of 3 sec; three delays of 2, 3, and 4 secs). As the number of delays randomly intermixed within a session increased, performance decreased as a result of the increased level of difficulty and cognitive/attentional demands. This study used six delays, 1–6 sec in steps of 1 sec, thereby preventing subjects from anticipating the timing of the response and requiring them to attend for the signal to respond.