Table S1.

Study 1: Coded behavior descriptions and inter-rater reliabilities

Behavior	Description/coder instruction	Interrater reliability, r
Expansiveness	Raters used a seven-point scale (−3 “closed” through +3 “expanded”) to code expansive displays once at the beginning of the date and again at the end. Expansiveness scores were averaged across the two time points (α = 0.72).	0.78
Affiliation cues
Smiles	No. of times each participant smiled on each date. All types of smiles (e.g., genuine, range of intensities) were included.	0.81
Laughs	No. of times each participant laughed on each date.	0.95
Nods	No. of times each participant nodded on each date. A nod was counted each time a person’s chin dipped down and then lifted upward.	0.95

Scores for laughing, smiling, and nodding were all standardized and averaged together to create a composite affiliative behavior score for each participant (α = 0.53).