Long before oxytocin was the miracle spray that could make people feel more trusting, our ancestors used lavender. Unsurprisingly, it still works today, according to a new psychology paper.

Nederlandse Vereniging voor Psychonomie member psychologists Roberta Sellaro and Lorenza Colzato investigated whether the calming olfactory fragrance of lavender has a positive effect on mutual trust. Aromatherapists already knew that aromatic compounds can alter mood and even claim cognitive, psychological or physical wellbeing effects. “Mutual trust is the social glue of society,” says Sellaro. “Interpersonal trust is an essential element for social co-operation bargaining and negotiation.”

Trust Game

To determine the effect of fragrances, the researchers exposed one group of test persons to the aroma of lavender, while a second group to the aroma of peppermint. Subsequently, the test persons played a trust game, a task that is often used to measure how much one test person trusts the other. A trustor was given 5 euros and was free to decide how much of that money he would give to a trustee in each round of the game. The trustor would then receive extra money, but only if the trustee gave him enough money in return. The money transferred to the trustee by the trustor served as an indicator of mutual trust.

The Dutch won't miss any opportunity to use weird puppets in a video. 

Subjects gave significantly more money to the other person when they were exposed to the aroma of lavender, compared to persons who had been exposed to the fragrance of peppermint. 

Sellaro says, “Our results might have various serious implications for a broad range of situations in which interpersonal trust is an essential element. Smelling the aroma of lavender may help a seller to establish more easily a trusting negotiation to sell a car, or in a grocery store it may induce consumers to spend more money buying products. The smell of lavender may also be helpful in sport psychology to enhance trust and build team spirit, for example in the case of team games such as soccer and volleyball.”

So the new time you go to a used car dealership and smell flowers...

Citation: Sellaro R, van Dijk W, Rossi Paccani C, Hommel B and Colzato LS (2015). A question of scent: lavender aroma promotes interpersonal trust. Front. Psychol. 5:1486. doi: 10.3389/fpsyg.2014.01486