Fig. 1.

The process of “slip of action test”. a, During the instrumental training stage, participants saw fruits on the outside of the box first, and then had to learn whether press left or right key to collect the fruit inside the box to establish and reinforce the stimulus-action-outcome association. Faster and correct responses led to higher point gains. In this example, the cherry stimulus is paired with the apple outcome, and the pear stimulus paired with the grape. b, During the outcome devalued stage, at the beginning of each block of trials, two certain fruit outcomes were devalued (indicated by two red crosses), signifying that participants should no longer respond to those outcomes, as doing so would lead to subtraction of points. Participants were instructed to respond the stimulus when the associated fruit outcome was not devalued and withhold respond to the devalued fruit (e.g., the apple is devalued so no response should be made to the cherry).