Figure 1. Task design.
(A) Schematic of a single trial. At the start of each trial, 3 stimuli were presented on the screen in one of four spatial configurations. Monkeys chose a stimulus by touching its location on the screen. Once selected, the alternative options disappeared and reward was or was not delivered according to a pre-determined schedule (note that the red box is shown for illustration only, but was not presented during testing). Following an intertrial interval, the next trial would begin. (B) Schematic of two varying schedules, 'Stable' (upper panel) and 'Variable' (lower panel), showing the running average probability (across 20 trials) during a session that selecting that option would result in reward.