Figure 1. Schematic diagram of the reward learning task.

Participants are instructed to press a button on the keyboard to indicate whether a long or short mouth is presented (100 ms) within a schematic face. Following some, but not all correct responses, participants received a monetary reward of 5 cents. One stimulus (rich) was rewarded 3 times more than the other (lean). Figure adapted from (Pizzagalli et al., 2005).