What Happens in Initial Interactions Forecasts Relationship Development: Showcasing the Role of Social Behavior

We do not know what happens in initial interactions to spark platonic or romantic relationships. This requires data on relationships from their inception, tracked over time. Building on theory about relationship promotion, we identified three exemplar behaviors to test novel hypotheses about relationship development. When starting college, a greenhouse for relationship initiation, first-year undergraduates ( N = 143) reported initial interactions with potential friends and romantic partners, and then 129 of them reported back about those 591 people over the semester. As predicted, reports of each behavior—affectionate touch, shared laughter, and partner’s gratitude expression—were associated with immediate interest in affiliating with the new person, beyond their perceived warmth, competence, and attractiveness; theoretically derived social perceptual mechanisms explained these links. Critically, although not all potential connections blossomed into relationships, these behavioral precursors to relationship promotion predicted relationship development via post-interaction interest in affiliating. Findings are contextualized within attraction literature with implications for relationship development.