Competition for Guidance of Attention by Visual Working Memory and Long-term Memory

How do visual working memory (VWM) and long-term memory (LTM) interact to guide attention? Here, we examined attention guidance when the two mechanisms operate on different values within a feature dimension, placing them in direct competition for establishing priority. Participants completed two sessions: a Learning Session followed by a Main Session. In the first session, they searched for a small target feature within arrays of colored disks. Of the four possible colors, one color was disproportionately likely to contain the target (frequent color, 50% of trials). In the second session, the task was identical (including the color-target probabilities), except participants also completed a color VWM task. The search array could include a match to the frequent color and/or the VWM color as either the target or a distractor. Critical trials included both types of match, with the target either the frequent color or the VWM color. This design allowed us to 1) assess guidance from LTM and VWM independently and 2) assess whether guidance to a LTM- or VWM-matching target was impaired by the presence of a distractor engaging the competing guidance mechanism. Participants showed a robust LTM validity effect in the first session, indicating that they learned the frequent color. In the second session, the LTM validity effect remained in the absence of VWM competition. However, the introduction of a VWM-matching distractor produced a substantial cost in guidance from LTM. For VWM guidance, participants showed a robust validity effect in the absence of LTM competition. In contrast with the LTM results, the introduction of a LTM-matching distractor produced no observable cost in guidance from VWM. This pattern was replicated in an experiment using shape as the guidance dimension rather than color. In sum, guidance from VWM is prioritized when the two modes of guidance are placed in competition.