Fig. 1. Sequence of events in 3-armed bandit task.

After familiarization, participants were asked to choose one of the three pictures. Images were presented at randomized positions that changed on each trial. Unfamiliar and familiar pictures appeared during the test. Participants were told that each picture had some probability of winning 20p and participants should pick the rewarded picture as many times as possible. Visual and acoustic feedback was given immediately after each trial.