Abstract
Visually guided behaviors are influenced by information obtained in the recent past, even when the information is completely irrelevant to the current goal. For example, studies have found that the report of the current-trial stimulus in a working memory (WM) task is biased away from the previous-trial stimulus. The present study investigated how this repulsive serial dependence might be influenced by the maintenance state of WM representation. We predicted that the 'passively’ maintained stimulus is integrated with the previous-trial stimulus, leading to an attractive serial dependence, while the ‘actively’ maintained stimulus is separated from the previous-trial stimulus, leading to a repulsive serial dependence. To test this hypothesis, participants performed a Stroop task during the retention interval of an orientation delayed estimation task, making the stimulus orientation maintained in a passive manner during the delay (Experiment 1a). We found that the report for the current-trial stimulus was biased toward the previous-trial stimulus (i.e., attractive serial dependence), confirming the hypothesis. The same pattern of results was obtained in a follow-up experiment with a similar task design (Experiment 1b). We next hypothesized that the passive maintenance of the stimulus orientation was driven by the decision-related processes of the Stroop task but not by the perception of the Stroop word or the motor response. In Experiment 2, participants performed a version of Experiment 1a where they were presented with the intervening Stroop stimulus (i.e., controlling the perception of Stroop words) and pressed a button to the stimulus (i.e., controlling motor response), but didn’t make a decision about what button to press. Consistent with our hypothesis, we found a repulsive serial dependence in this experiment. Together, these results demonstrate that the way the visual system relates the new visual information with the past experience depends on the state of WM maintenance for the information.