File drawer report: Testing for spontaneously perceived joint affordances in an object-based compatibility task

Evidence from joint action research suggests that a suite of spontaneous cognitive and perceptual processes underpins our ability to coordinate with others. We tested whether people spontaneously perceive affordances (or action possibilities) for the dyad when a co-actor is present. To test this hypothesis, we asked participants to complete an object-based response time task either alone (individual condition) or while seated next to a partner who completed the complementary task (joint condition). Participants in both conditions made unimanual go/no-go keypresses to objects that afforded either a bimanual (e.g., a laundry hamper) or unimanual (e.g., a bucket) grasp. In total, we conducted seven experiments (total N =293). An initial experiment revealed an affordance × task interaction effect on response times, such that responses to bimanually graspable objects were faster in the joint than in the individual condition. However, several follow-up experiments failed to replicate this finding, providing no overall evidence for spontaneously perceived joint affordances.