Joint spatial-temporal association of response codes (STEARC) effect: Mental timelines embodied interpersonally

A co-action task was used to explore the effect of social interactions on temporal judgements, in comparison with an individual-task condition. In Experiment 1, the co-actors sat either individually (individual condition) or alongside a partner (joint condition) in front of a monitor and then responded to time-related words (e.g. yesterday, tomorrow). In Experiment 2, co-actors sat separately in front of two monitors and categorized the words either individually or jointly. Participants' response times to past- and future-related words in the individual conditions of both experiments had no significant difference. However, in the joint conditions, the responses were faster when the past-time words were mapped toward the participants on the left than when future-time words were mapped toward them. Our data support the existence of a specific mapping between past-time-left space and future-time-right space. This suggests that the two cooperators probably shared a similar mental timeline.