## 2 Dataset
### Odour Stimuli  
BO were samples of armpit sweat from 10 healthy women and nine healthy men (henceforth \"donors\") collected across three individual sessions (separated by at least one week). To avoid odour contamination, donors were asked to follow a strict hygiene, dietary, and behavioural protocol in the two days before BO collection (e.g., avoid sites with intense odours, avoid eating excessive flavoured food, use odours-free hygiene products), similar to previous studies (e.g., [16; 17; 18]). Each session included a 5-min neutral film clip (Baseline), which was followed by a 30-min set of film clips from comedy movies (to induce happiness: positive BO), horror movies (to induce fear: negative BO), or documentaries about nature and space (to induce a neutral state: neutral BO). The order of film clips presented in each set was fixed, from the least intense to the most intense clip (in case of the fearful and happy sets), to keep a constant state of activation. All film clips were previously shown to induce the expected emotion (e.g., [41; 42; 43]); this was also confirmed in the current dataset based on the analysis of the donors' subjective emotional state. Donors were not aware of emotional induction (single-blind experiment), and the order of the sessions was randomised for each donor. Armpit sweat was collected during film-clips visualisation using sterilised absorbent pads ([PERSON], Germany), which were placed under each armpit and secured with an additional pad and a hypoallergenic tape. To avoid sweat contamination, a strict protocol for BO collection was implemented (e.g., use of steristerilizedes by the researcher handling the sweat samples, and sterilisation of reusable laboratory material). After film clips, each pad was carefully removed and saved in individual vials ([PERSON], Germany). Vials were labelled and kept in a freezer at \(-21^{\circ}\) until the day of the experimental session. At the end of their participation, each donor was fully debriefed about the purposes of the sweat collection and given 10\(\mathrm{\SIUnitSymbolCelsius}\) per hour.  
Concerning CO, positive, negative, and neutral CO were selected based on the literature (e.g., [44; 45]) and experts' consensus. The positive CO was rose, 2-phenylethanol alcohol (28.16% \(v/v\) in propylene glycol, Sigma-Aldrich, Germany). The negative CO was faeces, skatole (0.04% \(w/v\) in propylene glycol, Sigma-Aldrich, Germany). The neutral CO was grass, cis-3-Hexen-1-ol (3.61% \(v/v\) in propylene glycol, Sigma-Aldrich, Germany). Volume percentage was defined through pilot testing to ensure that all COs were similar in terms of perceived intensity [30].  
Before odour exposition, all stimuli were placed in individual amber vials (63 mm of height by 46 mm of diameter, Bauchlueten, Germany). In the case of BO, four pad pieces of distinct donors (same-sex and valence) were randomly combined to create a \"super-donor\", thus reducing inter-individual variability (e.g., [16; 17]), with two coming from left armpts and two coming from right armpts. Each super-donor was prepared one hour before the first experimental session of the day. Each receiver was exposed to the same two super-donors (one female and one male) across the three emotion conditions. Concerning CO, 150 \(\mathrm{\SIUnitSymbolCelsius}\) of each CO was applied to an absorbent pad to mimic BO presentation approximately one hour before the first experimental session of the day. Each pad was cut into four pieces, and the four pieces were placed in an amber vial. Lastly, a \"no odour\" condition was created, containing four pieces of an absorbent pad, which were also placed in an amber vial.