TABLE 2.

Mirroring activities, video sampling, and rating.

Video type	Activity	Video sampling method	Quantitative and qualitative data collected	Raters
Leading	Leading the partner when instructed to mirror each other	Systematic sampling: 30 s taken from the middle of the activity	All scales rated Short descriptions of participant’s movement and interaction written by all raters	Three interaction quality raters for all video clips One primary synchrony rater for all segments, a second synchrony rater on 20% of the video clips
Following	Following the partner when instructed to mirror each other
Open-ended dance	Open-ended dance with instructions to “stay in contact with your partner,” not assigned leading or following role		All scales rated Short descriptions of participant’s movement and interaction written by all raters Additional page with movement characteristics of interest completed by synchrony scale raters	Three interaction quality raters for all video clips Two synchrony raters for all video clips
Interactive behaviors	Any of the above mirroring tasks	Purposive sampling: 30 s selected for most interactive behaviors