Mirror game is an improvisation exercise for two people, where one person moves and the other acts as their mirror. We extended this game to four people, and are investigating it as a) a method for studying group dynamics in movement coordination, and b) a measure of intersubjectivity. We used optical motion capture to record four participants mirror each others' hand movements. e overall average speed of the participants (¯) body parts was calculated and correlated to investigate overall movement coordination. Finger accelerations were cross-correlated for all pairwise combinations of participants, to assess the dynamics of following and leading, and mutual adaptation and innuence in the group. In the pilot, we compared two games, played before and aaer another group improvisation exercise. e laaer game produced more group syn-chrony, and facilitated the introduction of larger movements. e four-person game gives rise to " connicts " where a performer must quickly decide which other player to match, leading to a mismatch with the other two. e game can be used to investigate the aaec-tive and social eeects of these decisions, and the factors leading to these choices.