Subjects are presented with a sequence of three numbers in ascending order (20, 40, and 80). Each number is displayed onscreen for one second and, if the subject presses a button while that number is displayed, he/she receives that number of points along with immediate positive visual and auditory feedback. When a 40 or 80 appears, however, there is a chance that it will appear in an alternate color, along with immediate negative feedback signaling a loss of 40 or 80 points, respectively. When this occurs, the trial ends immediately (i.e. the subject may not make a response).
Definition contributed by BGregory about ten months ago.