• Hyojeong Kim (Department of Psychology, the University of Colorado, Boulder)
• Jae-Yoon Lee (Department of Psychology, Yonsei University)
• Do-Joon Yi (Department of Psychology, Yonsei University, [email protected])

As a social being, we need to understand others’ actions as quickly and accurately as possible. Action understanding can occur at many levels. We sometimes grasp others’ intentions unintentionally. Other times, however, we have to effortfully draw inferences about their goals. In the context of joint action, the Joint Simon Effect (JSE) demonstrates that actors are influenced by the unintended representation of co-actor’s actions. This effect has been described to be quasi-automatic, but it is not known if the effect is automatic enough to be immune to cognitive load. Thus, we asked participants to do a joint Simon task with or without a concurrent working memory (WM) task. One group of participants maintained a single digit in their mind during WM load blocks (low-load group) while the other group maintained five digits (high-load group). As a result, the low-load group showed JSE both during no-load and low-load blocks. In contrast, the high-load group did not show any SSE during either no-load or high-load blocks. These results suggest that JSE is not an automatic phenomenon given that it requires cognitive resources. Actors in a joint task may represent co-actor’s actions in their task-set only when cognitive resources are available. (Science of Emotion & Sensibility, 25(2), 11-22, 2022)