Reward has a residual impact on target selection in visual search, but not on the suppression of distractors

In the reinforcement learning literature, good outcome following selection of a visual object is thought to bias perception and attention in favour of similar objects in later experience. This impact of reward might be instantiated in two ways: Reward could prime target features or it could act to facilitate suppression of distractors present when reward was received. Here we report results from an experiment in which reward outcome was selectively associated either with the colour defining a visual search target or with the colour defining a salient distractor in the display. Reward's impact on search was evident only when it was tied to the target; reward made it no easier to ignore a distractor when it subsequently reappeared as a distractor. This suggests that reward acts largely to prime target representations, consistent with the idea that objects associated with good outcome become visually salient.