Figure 2.

Eye movement task. (A) Participants fixated on a disc displayed on a desktop monitor linked to an infrared eye tracker. At the beginning of each trial participants heard an auditory cue (‘0p/10p/50p maximum’) informing them the maximal amount they could win on that trial. Following a delay of 1400–1600 ms the central disc disappeared and concurrently a target disc appeared on one side, cueing a saccade to this location. Participants were rewarded with a proportion of the maximum amount available based on the time taken to reach the target. (B) Although the absolute amount of reward varied with reaction time, this was dynamically adjusted according to the mean reaction time of the last 20 trials. Therefore, difficulty level was maintained across the experiment and overall participants received equal reward amounts. Adapted from Muhammed et al. (2016) with permission.