Humans use their senses to continually adapt to different social contexts. Several studies highlight the capacity of humans to communicate negative emotions such as fear, stress, and anxiety to others via the emission of volatile chemical compounds from their bodies. However, the transmission of positive emotions remains to be understood. In one of the very few studies on this topic, we have previously shown that women (receivers) had a decreased heart rate and better performances on behavioral tasks in response to body odors of male donors collected during a positive mood induction (positive BO) compared to BO collected in a neutral state. These findings suggest that BO emitted during positive emotional states have a distinctive chemical signature that is produced rapidly and induces physiological and behavioral changes in another individual indicating emotional contagion (transfer of the donor’s emotional state to the receiver).

The current study investigated this chemical communication of positive emotions by looking for modulating factors. We tested the hypothesis that the transfer of positive emotional states between humans could be influenced by the type of relationship (couples/roommates), the duration of the relationship (short, i.e. <2 years, versus long, i.e. >2years) and the level of sociability (low/high). Also, by comparing responses to BO alone and with perfume added, we investigated how fragranced cosmetics interact with this chemical communication. The Covid-19 crisis prevented participants from coming to the laboratory due to safety concerns, and thus we created an innovative at-home method. A package containing a complete set of material and instructions needed for the experiment was delivered to the dyad’s home and a web interface was developed to collect their answers. Both members of the dyad served as donor and as receiver. A positive state was created in the donors by a video mood induction procedure (MIP), while BO was collected on a cotton t-shirt. Then the other member of the dyad, the receiver, was asked to position the t-shirt close to their face and to perform two series of tasks, first without perfume and second after having sprayed perfume on the t-shirt. The behavioral tasks assessed creativity. As a control, the same procedure using another t-shirt was carried out with donors watching neutral videos. The members of the dyad smelling the BO from positive MIP were expected to achieve a higher creativity score relative to the neutral MIP BO. In addition, several questionnaires were filled out by the dyad members to determine their level of sociability (based on self-reports in extraversion and emotional intelligence scales) and the characteristics of their relationship (nature, duration).

Analysis of the results will confirm if chemical communication of positive emotion is possible in this new naturalistic setting, and what, if any, factors affect this communication. For instance, it may be that responses to positive emotion signals are learned and are stronger in dyads who have been living together longer. It may also be that the physical proximity (higher in couples than in roommates) increases this form of non-verbal communication. Higher sociability may also be associated with more intensive experience of, but also greater propensity to respond to chemical signals. Finally, we will examine whether perfume has a synergistic, a disruptive or no effect on chemical communication. Our preliminary results suggest that positive emotions were treated differently depending on the type of relationship, with a transmission of positive emotional state likely to be more efficient in couples than in roommates. This experiment offers interesting possibilities in terms of formulation of new cosmetic products with emotional benefits and of new ways to development personalized beauty routines. The innovative at-home method also opens new approaches to test products with emotional benefits in a less stressful and more ecological environment.