We examined the effects of individual versus joint action and racial similarity and dissimilarity on a Simon task using mouse tracking to explore the implicit cognitive dynamics underlying responses. Participants were slower to respond when working with a partner than when working alone, and their mouse movements also differed across conditions. Participants paired with a different-race partner took longer to respond than participants paired with a same-race partner. We argue that, in the joint conditions, participants’ longer responses were the result of automatic inhibitory processes that arise within the social context.

We examined the effects of individual versus joint action on aSimon task using motion tracking to explore the implicitcognitive dynamics underlying responses. In both individual andjoint conditions, participants were slower to respond, and weredifferentially attracted to the distracter response location, whenthe spatial component of the stimulus was incompatible with theresponse location. When two people completed similar twochoice tasks together, the results were not statistically differentfrom the individual condition, even though the magnitude of thestimulus-response compatibility effect was slightly larger.Neither was there an increased effect when the partner had nostimulus-response conflict to resolve. We found no evidence foran action conflict when the responses of the two partners weredifferent. These data imply that the literature regarding the JointSimon task is still in the process of determining the relevantevents that interact with and support joint action.