Fig 1. Trial structure of the VMAC task.

Participants had to respond to the orientation of the line segment within the diamond (target); on the majority of trials, one of the circles in the display was a colour-singleton distractor. Only the feedback screens differed between phases of the procedure. During the reward phase (A) faster responses earned more points and the colour of the distractor signalled whether or not these points would be multiplied by 10 (bonus trials, as depicted here). During the unrewarded test phase (B) feedback simply informed participants whether or not they had responded correctly.