Fig. 1.

a Data collection. Two participants sat approximately 1.5 m apart on small stools. A wooden frame between the participants held the picture (for description) and the Polhemus transmitter box. Polhemus motion sensors were placed on the upper back and forehead of each participant. A projector screen beside the participants provided instructions, timing cues, and video synchronization. b Trial structure. Each trial had 30 s of monologue by one participant, designated Leader, followed by 60 s of dialogue with the Follower, marked by beep sounds. Participants completed 16 trials, alternating turns as Leader or Follower. c Possible patterns of behavior. Four possible patterns of interpersonal coordination are illustrated schematically