After reading this article, you may go easy on the deodorant... But before talking about smells, let's take a quick look at vision. It's a well-known fact that smiling and laughing are contagious. When someone smiles, you smile back. Vision thus comes into play in triggering a brain process: emotion. What if odors also had this same effect?

Because they realized that negative emotions such as fear or disgust could be transmitted from one individual to another through the smell of sweat, Gün Semin and his team at Utrecht University in the Netherlands examined the transmission of positive emotions through this same mechanism.

The experiment took place in two phases: sweat was first sampled and then tested for smell. In the beginning, the natural secretions of twelve men were sampled using an adhesive pad placed on clean, dry armpits. Prior to the experiment, the researchers verified that none of the participants smoked, took medication, or suffered from psychological disorders, nor had they recently consumed alcohol or fragrant foods. They were then asked to watch a video that induced either a positive or negative emotion, or no emotion at all. They then carried out an implicit emotional measurement test in which they were asked to rate Chinese ideograms as being pleasant or unpleasant. The pad was then removed and placed in a beaker.
During the second phase, 36 women were recruited. In order to avoid influencing responses, the task was double blinded, meaning that neither the subjects nor the experimenters knew which samples were given to whom. The female volunteers smelled each beaker (positive, negative, and neutral) separated by 5-minute breaks, while experimenters measured their facial expressions. Finally, they also took part in the implicit emotional measurement test.

As a result, and using the Chinese ideograms, the scientists were able to observe that the men involved in the first experiment experience the expected emotions, induced by the different videos. As for the transmission of these emotions to the female subjects, the effects appear to be mixed. On the one hand, the researchers saw a behavioral synchronization between the "giver" and the "receiver." The facial expressions of the female participants mirror the emotions felt by the male participants. The frontalis muscles of the forehead, which are involved in fear reactions, contract when subjects smelled the "fear" pad, while Duchenne smile (involuntary smile) muscles were activated by the "joy" pad. It is in fact these chemical compounds present in sweat that play a role in the mechanism. They are transmitted through the smell of sweat of those around you.

However, the odors smelled had no impact on the results of the ideogram test, indicating that the chemical signals in the sweat did not condition subjects' implicit emotional state.

For Gün Semin, the results suggest that someone who is happy brings happiness to others around them. In some ways, "happy" sweat is much like a smile; it's contagious.