Clock Task The "clock task" is an additional reward task that assesses reward learning developed by Michael Frank and colleagues (Moustafa et al., 2008; Frank et al., 2009). For this task, participants observe a clock arm that completes a revolution over the course of 5 seconds, and participants are instructed to press a key to stop the clock at any time in an attempt to win points. The amount of points won varies depending on RT, and participants must use trial-and-error strategies to learn when to stop the clock so as to maximize points received. To prevent subjects form explicitly learning reward values associated with a specific location on the clock face, reward values at any given point along the clock face are randomized within +/- 5 points. At the end of the task, subjects may redeem points for a small amount of additional compensation, each time they complete the task. This task takes approximately 15 minutes to complete.