Task Design.

<p>Each trial consisted of a dot motion coherence stimulus displayed for 220 to 3500 milliseconds, with duration determined by the experimenter and defined by a gamma distribution equating the hazard rate across trials (see Methods). The motion coherence of the stimulus was also varied across trials (inset). To indicate that a response was required, the dot motion stimulus disappeared and a green fixation cross was displayed, after which subjects had 350 milliseconds to respond.