Task structure and participants’ behaviour.

(A) Schematic of the go/no-go learning task. On each trial, a fixation cross was presented for 1000–1600 ms. Then, participants were presented with one stimulus for 500 ms and had 1000 ms to decide whether to perform a go (button press) or no-go (no button press) response. Blocks of reinforced trials alternated with probe blocks (illustrated in the timeline). On reinforced trials (cyan), a go response resulted in reward or punishment (monetary win or loss, indicated by a smiley or frowny, respectively), depending on whether the stimulus was a go or no-go stimulus. No-go responses resulted in no feedback, and in neither reward nor punishment. A progress bar at the bottom of the screen displayed cumulative reward (rewards increased the bar, punishments shrank it). On probe block trials (purple), participants were required to respond as during reinforced blocks, but no feedback following responses was provided. (B) Sensitivity index d’, separately for reinforced (cyan) and probe trials (purple). (C) Time course of go-response probabilities, P(Go), for go trials (green) and no-go trials (red). Darker shades of green and red indicate probe trials. Solid lines in B and C represent mean, shaded areas SEM across participants.