Social and nonsocial synchrony are interrelated and romantically attractive

Romantic bonding is central to human life and relates to well-being, health, and life satisfaction. While evolutionary perspectives emphasize static traits (e.g., physical features, resources, status), dynamic interactive features like synchrony may also shape attraction. Prior work shows physiological synchrony predicts romantic and sexual attraction during dates, and synchrony has been documented across neural, autonomic, hormonal, and behavioral domains, supporting cooperation and satisfaction. Synchrony is also key in parent-infant bonding and predicts developmental outcomes. Beyond social contexts, synchrony manifests within individuals (sensorimotor control). Evidence suggests potential shared mechanisms between social and nonsocial synchrony; for example, individuals with autism show impaired sensorimotor synchronization and such performance associates with social function. This study asks: (1) Does synchrony elicit attraction (as opposed to being merely a consequence of attraction)? (2) Are individual differences in synchrony interrelated across social and nonsocial domains and linked to attractiveness? Two experiments address these questions: an online manipulation of synchrony in video stimuli (N=144) and a lab speed-dating study measuring electrodermal synchrony during dates, sensorimotor synchrony in a tapping task, and romantic attractiveness (N=48).

Extensive literature reports dyadic synchrony across multiple physiological and behavioral measures and timescales, including brain activity, arousal, heart rate, hormones, motion, and behavior, with links to cooperation, relationship satisfaction, and social well-being. Parent-infant synchrony is a mechanism for bonding and regulation, predicting developmental and social outcomes. Synchrony is not purely social; sensorimotor synchronization (e.g., tapping to a metronome) reflects anticipatory, predictive control and is impaired in certain neurodevelopmental conditions such as autism, where it also relates to social functioning. These bodies of work suggest possible domain-general mechanisms underpinning synchrony across social and nonsocial contexts and motivate testing whether such mechanisms influence romantic attraction and mate selection.

Two complementary studies were conducted. 1) Preregistered online experiment. Design: Between-subjects manipulation of observed synchrony in a 92-second video depicting an actor and an actress on a date. Participants were randomly assigned to view either a high-synchrony or low-synchrony interaction. Sample: 160 recruited; 144 included after exclusions (76 women), ages 18–30 (M=24.89, SD=3.61); Hebrew speakers; preregistered 08/28/2022 (OSF). Power analysis targeted 132 participants (power 0.80, f=0.3, alpha=0.05, r=0.8); 160 recruited. Stimuli: Synchrony manipulated via actor directions; contexts and appearances controlled; physiological verification via electrodermal activity (EDA): high synchrony r=0.614, low synchrony r=-0.097. Procedure: Participants completed demographics, watched the assigned video, then rated (1–10 Likert): attractiveness of the woman, attractiveness of the man, perceived attraction of man to woman, and woman to man. Manipulation check of perceived behavioral synchrony was collected at the end; t-test showed higher perceived synchrony in the synchronous than nonsynchronous condition (Means 5.863 vs 4.338; t=-3.769; p<0.001; Cohen’s d=0.628). Analysis: Repeated-measures MANOVA with synchrony level (high vs low) as IV and attractiveness outcomes as DVs; assumptions verified (Levene’s, Mardia’s, Shapiro–Wilk). 2) Lab speed-dating experiment. Participants: 48 students (24 men, 24 women), ages 19–28 (M=24.72, SD=1.93), heterosexual, single, seeking a romantic relationship. Conducted across seven runs; round-robin 5-minute dates in a homelike lab room. Due to cancellations, some participants completed fewer than four dates; due to technical issues, physiological data were available for 38 participants (20 men, 18 women). Procedure: Before each date, participants reported initial interest (1–5). After each date, they rated attraction to the partner (1–5). EDA was recorded during dates using Empatica E4 wristbands at 4 Hz. Electrodermal Synchrony: For each date, synchrony was computed as Pearson correlation between partners’ EDA time series; motivated by prior work, synchrony was computed for the first two minutes and across the full 5-minute interaction. Individual Electrodermal Synchrony Scores were calculated by averaging synchrony across a participant’s dates. Romantic Attractiveness Scores: For each participant, mean of partners’ post-date attraction ratings across dates. Sensorimotor Synchrony Task: After dates, participants performed a paced finger-tapping task to synchronize taps to an auditory metronome across six 60-second blocks (protocols varied in tempo/structure). Individual Sensorimotor Synchrony Scores were computed as the mean absolute asynchrony (off-beat temporal error, ms) across the task; lower values indicate better synchrony. Analyses: - Initial interest predicting EDA synchrony during dates: multilevel models accounted for non-independence (dates nested within persons and runs), with random intercepts; supplementary Spearman correlations and Bayes factors (JZS priors) reported. - Association between social and nonsocial synchrony: Pearson correlation between Individual Electrodermal Synchrony Scores and Individual Sensorimotor Synchrony Scores (continuous measures). - Association between synchrony and attractiveness: Spearman correlations between Individual Electrodermal Synchrony Scores and Individual Romantic Attractiveness Scores, and between Sensorimotor Synchrony Scores and Romantic Attractiveness Scores. Multiple comparison control via Bonferroni was applied where relevant. Data and code availability provided via OSF.

• Online experiment: Inducing synchrony between an actor and actress increased perceived attractiveness. Overall MANOVA indicated a significant effect of synchrony (F(1,142)=6.073, p=0.003). Actor attractiveness was higher in the high-synchrony condition (F(1,142)=5.034, p=0.026; M=8.507, SE=0.493; 95% CI [7.542, 9.475]; N=73) than low-synchrony (M=7.070, SE=0.406; 95% CI [6.291, 7.860]; N=71). Perceived mutual attraction between actors was also higher when synchronized (F(1,142)=11.92, p<0.001; M=11.411, SE=0.421; 95% CI [10.590, 12.230]; N=73) than when not (M=9.282, SE=0.451; 95% CI [8.404, 10.512]; N=71). Manipulation check confirmed greater perceived synchrony in the high-synchrony video (t=-3.769, p<0.001; Cohen’s d=0.628). - Initial interest does not drive physiological synchrony: Multilevel models showed no significant association between initial interest and electrodermal synchrony during dates (e.g., p=0.464 without covarying age; p=0.513 with age; N=64 dates). Supplementary correlations were non-significant for men (Spearman r=-0.105, p=0.41; BF01=2.44; N=64) and women (Spearman r=0.059, p=0.466; N=64), with Bayesian analyses providing at least weak-to-moderate evidence for the null. - Social and nonsocial synchrony are interrelated: Individual Electrodermal Synchrony Scores (social) correlated with Individual Sensorimotor Synchrony Scores (nonsocial) (Pearson r=0.494; p=0.008; 95% CI [0.148, 0.732]; N=28). - Synchrony predicts attractiveness: Higher individual electrodermal synchrony during dates was associated with higher romantic attractiveness ratings (Spearman r=0.415; p=0.018; 95% CI [0.080, 0.746]; N=32). Better sensorimotor synchrony (lower tapping error) was also associated with higher attractiveness (Spearman r=0.413; p=0.005; 95% CI [0.176, 0.648]; N=44). - Some participants showed consistently higher synchrony across contexts ("Super Synchronizers"), and these individuals were rated as more romantically attractive.

The findings address the causal direction and generality of synchrony in romantic attraction. First, experimentally increasing synchrony in an interaction increases third-party perceived romantic attractiveness, suggesting synchrony can elicit attraction rather than solely reflect it. Second, initial interest before a date does not predict subsequent physiological synchrony during the date, providing no support for attraction driving synchrony. Third, individual differences in synchrony appear to be domain-general: social physiological synchrony during dates correlates with nonsocial sensorimotor synchrony in a tapping task, consistent with shared predictive-control and sensorimotor integration mechanisms. Finally, individuals who synchronize more effectively—across both social and nonsocial contexts—are rated as more attractive, indicating that dynamic interactive capacities play a role in mate preferences. Potential mechanisms include improved physiological co-regulation and more rewarding, adaptable interactions when engaging with high-synchrony partners. These results underscore synchrony as a meaningful determinant of romantic appeal and suggest broader implications for understanding the neurobehavioral bases of social bonding.

This research demonstrates that synchrony can causally enhance perceived romantic attractiveness and that individual abilities to synchronize are interrelated across social physiological and nonsocial sensorimotor domains. Individuals who are "Super Synchronizers"—showing high synchrony across partners and tasks—are perceived as more romantically attractive, suggesting that human mate selection incorporates dynamic interactive traits. Future work should: (1) test causal effects of manipulating synchrony during actual dates on immediate mutual interest and long-term outcomes; (2) assess the temporal stability of individual synchrony to evaluate trait-like properties; (3) investigate neural and developmental mechanisms underlying synchrony; and (4) extend findings to diverse populations, including homosexual relationships.

• Trait stability: Although synchrony correlated across social and nonsocial tasks, longitudinal stability was not tested; thus, the extent to which synchrony is a stable individual trait remains unknown. - Causality in real interactions: While video-based manipulation increased perceived attractiveness, synchrony was not experimentally manipulated during actual dates; causal effects on partners’ real-time romantic feelings and long-term outcomes remain to be established. - Sample and generalizability: The speed-dating sample included heterosexual, cisgender young adults; applicability to other ages, cultures, and sexual orientations (e.g., homosexual couples) requires further study. - Measurement and sample size constraints: Technical malfunctions reduced physiological data availability; some analyses involved modest subsamples (e.g., N=28–44), which may limit precision. - Analytical notes: Some reported Bayesian factors and descriptive inconsistencies warrant cautious interpretation, though the primary conclusions were supported across analyses.