Participants started with a short practice run to get acquainted with the task. After practice, three runs of 200 trials each were performed. In every run, the factors of reward and task difficulty were crossed and shown in randomized order, resulting in 20 trials per condition (high-difficulty reward, low-difficulty reward, high-difficulty no-reward, low-difficulty no-reward) per target side (left vs. right) plus 40 catch trials. This resulted in a total of 60 trials per active-attention condition (120 when combining data for left- and rightward cues), and 120 catch trials. Participants sat in a shielded room and were monitored with a camera. They were asked to sit in a relaxed position, limit blinking, and fixate on the fixation square throughout the task. In each run five 20-seconds breaks were inserted in which participants could move and relax their eyes.
