When you talk with a friend, the timing of your gestures and movements may naturally fall into step. Such bodily synchrony offers one clue to how people relate to each other. Would adding a pleasant scent to the room make their movements more synchronized?
In 2025, M. R. Coeugnet and colleagues studied 25 pairs of same-sex friends, 50 people in total, to examine how conversational goals and peppermint scent affect bodily synchrony. They measured not only mood during conversation but also, separately, how much people moved and how closely their movements corresponded over time.
Cooperating, competing, and being playful together
Each pair completed three tasks. In the cooperative task, they received arguments for and against a social or political topic and worked together to formulate a shared position. The competitive task also involved debate, but participants were asked to defeat their partner rather than compromise.
A third task aimed to create a fun atmosphere. Together, participants devised either a five-course meal made entirely of dishes they both disliked or a five-song playlist of songs they both disliked. Rather than sharing favorites, they deliberately created combinations that did not suit their tastes.
They performed all three tasks both with peppermint scent and without added scent. Each condition included a two-minute preparatory period and a five-minute conversation, for six conditions in total. The order of scented and unscented conditions was counterbalanced across pairs to account for effects of repeating the tasks.
Moving a lot is not the same as moving in sync
The researchers filmed the two participants facing each other and quantified movement from changes in the image regions occupied by each person’s body. They then analyzed how closely increases and decreases in their movement corresponded, allowing for short time lags.
Synchrony here does not mean adopting the same pose. If one person’s movement increases when the other’s does, that is in-phase synchrony. If one person’s movement increases while the other’s decreases, their movements correspond in opposite directions. It does not refer to moving an arm to the left or right.
They also used comparison data generated by shuffling combinations of movement data to distinguish synchrony from chance correspondence. After each conversation, participants rated their feelings of pleasure and arousal.
The conversational setting, rather than scent, made the difference
In-phase movement synchrony was higher in the fun task than in either the cooperative or competitive task. The fun task also showed clear synchrony relative to the chance baseline.
The greatest amount of movement, by contrast, occurred in the competitive task. Animated debate with plenty of gestures did not necessarily align the timing of the two people’s movements. Competition also tended toward opposite-direction correspondence, but the difference from chance was not clear.
Peppermint scent did not produce a detectable clear increase in synchrony. Nor were there clear scent-related changes in movement quantity, pleasure, or arousal.
Pleasure ratings were higher for the fun task than for the competitive task, but the difference from cooperation was not clear. The results do not show that a fun task improves mood more than every other kind of conversation.
Noticing a scent does not necessarily connect it to the conversation
The scent was presented at an intensity perceptible to many participants, and 65% identified it as mint. The result therefore cannot simply be explained by saying nobody noticed the smell.
One possibility considered by the authors concerns the relationship between scent and conversation. For people concentrating on debating or playing, mint in the room may have been treated as task-irrelevant background. In this view, whether a scent naturally fits a setting or activity may determine how it directs attention and influences behavior.
This mechanism was not directly tested; it is a hypothesis for future work. The authors call for comparisons involving context-appropriate scents, body odors, and unpleasant odors in more everyday-like situations.
The participants were friends, and 20 of the 25 pairs were female. Only one scent was tested. Moreover, the presence of synchrony and pleasure in the fun conversations does not establish that synchronized movement necessarily deepens friendship or improves mood.
Summary
This experiment did not confirm that simply adding peppermint scent synchronizes friends’ movements. Changing the purpose of conversation, however, changed both how people moved and how their movements synchronized. Moving a lot and having movements that correspond to another person’s were distinct phenomena.
The authors see understanding these bodily exchanges as a foundation for thinking about everyday relationships and communication in helping professions. To determine whether scent can be useful, research must go beyond adding a pleasant smell and consider who encounters it and what they are doing at the time.
References
Coeugnet, M. R., Delevoye-Turrell, Y. N., Tschacher, W., & Coutinho, J. (2025). The effect of social settings and olfactory environments on spontaneous movement synchrony. Scientific Reports, 15, 8229. DOI: 10.1038/s41598-025-92318-9 (Full original article).
The study received support through French research institutions and National Research Agency programs, and from the Portuguese Foundation for Science and Technology. The authors declared no competing interests. Original article: © The Author(s) 2025, CC BY-NC-ND 4.0.
