FIGURE 1.

Task details. (A) Instrumental stage. Trials started with the appearance of the instrumental stimulus at the top center of the screen and a dot at the bottom of the screen. In approach trials, the dot appeared either on the left or on the right bottom of the screen. From left to right: Participants could choose to do nothing (approach-no-go), in which case the dot would move past the instrumental stimulus. Alternatively, they could press the button repeatedly to steer the dot through the instrumental stimulus (approach-go). In withdrawal trials, the dot started centrally beneath the instrumental stimulus. Participants could choose to press the button repeatedly to avoid moving through instrumental stimulus (withdrawal-go) or to do nothing (withdrawal-no-go). If the dot entered the target region, then the instrumental stimulus was ‘collected’. The vertical line to one side of the instrumental stimulus could not be crossed by the dot. (B) Pavlovian conditioning. Participants were presented with different stimuli that were followed by juice delivery. (C) PIT stage. The PIT stage paralleled the instrumental training, except that Pavlovian CS tiled the background. The effect of interest is how the Pavlovian CS changed instrumental behavior (mean proportion of go-actions and the average number of button presses over the go-actions). Note that the trials involving the appetitive CS were omitted from this figure, because this particular paradigm has been shown to be insensitive to detecting appetitive PIT (see Supplementary material) and our hypotheses concern aversive PIT.