Bridging Lab and Life: A Dual-Person Paradigm for Social Interaction Research.

Interpersonal synchrony, the spontaneous coordination of actions, emotions, and physiological processes, plays a crucial role in social bonding. While existing research has significantly advanced our understanding of interpersonal synchrony, many studies rely on either artificial paradigms that may limit ecological validity or naturalistic approaches that can pose challenges for achieving sufficient statistical power. To address this, we developed and validated a semi-naturalistic verbal social interaction paradigm, in which two individuals talk about a variety of standardized neutral and autobiographical emotional topics. Sixty-nine dyads (N = 138) participated and reported valence, arousal, connectedness, and dominance after each trial. Results confirmed the paradigm's reliability and validity by showing that emotional conversations, especially when sharing one's own autobiographical event, elicited higher arousal, more valence, and increased heart rate than neutral ones, with relatively stable affective responses across trials. Participants also felt more connected during emotional conversations, particularly with closer friends. In conclusion, we are optimistic that our social interaction paradigm is a useful tool for studies of dual person neuroscience by balancing experimental control and ecological validity. Its flexible design allows for adaptation across research contexts and supports broad application. This validation establishes the paradigm's reliability, enabling future hypothesis testing regarding interpersonal synchrony.