The effect of social settings and olfactory environments on spontaneous movement synchrony

The materials are shared openly as part of the publication of the article. The statistical data can be obtained on request to Yvonne N. Delevoye-Turrell (yvonne.delevoye@univ-lille.fr), but the raw camera data cannot be shared due to the ethical difficulty of giving open access to non-anonymous video clippings.
Interpersonal synchrony refers to the temporal coordination between two individuals, signaling the coupling of their behaviors. Optimal movement synchrony in dyads is linked to more affiliative behavior, cooperation, and trust. However, there is limited research on how the sensory environment impacts interpersonal synchrony. One significant environmental factor influencing human behavior and social interactions is ambient odors. This study aimed to examine the effect of ambient odor on interpersonal synchrony, particularly in-phase movement synchrony. Motion energy analysis and windowed cross-correlations were used to measure synchrony levels between participants during video-recorded interactions. Twenty-five same-sex friend dyads performed three interaction tasks designed to create fun, cooperative, or competitive atmospheres. These tasks were conducted with a pleasant, stimulating peppermint odor or in a control condition without odor. Consistent with previous studies, higher synchrony levels were observed in fun atmospheres compared to competitive and cooperative ones. No significant effects of odor stimulation were found. Overall, the results confirm that social context significantly influences movement synchrony and affiliation, while ambient odor might not affect interpersonal synchrony, at least when the odor is irrelevant to the task.
This research was suported by the Research Federation FR CNRS 2052 Visual Sciences and Cultures and by French government funding managed by the National Research Agency under the Investments of Future Program (PIA) grant ANR-21-ESRE-0030 (Equipex+ Continuum). This work was partially conducted at CIPsi, School of Psychology, University of Minho, supported by the Portuguese Foundation for Science and Technology (FCT; UID/01662: Centro de Investigação em Psicologia) through national funds.