The English language is full of metaphors linking moral purity to both physical cleanliness and brightness. We speak of "clean consciences", "pure thoughts" and "dirty thieves". We're suspicious of "shady behaviour" and we use light and darkness to symbolise good and evil. But there is more to these metaphors than we might imagine. The mere scent of a clean-smelling room can take people down a virtuous road, compelling them to choose generosity over greed and charity over apathy. Meanwhile, the darkness of a dimmed room or a pair of sunglasses can compel people towards selfishness and cheating.
These new results are the latest from psychologist Chen-Bo Zhong. Back in 2006, he showed that people who brought back memories of past wrong-doings were more likely to think of words related to cleaning, or to physically crave cleaning products. He called this the "Lady Macbeth effect". Subsequently, another group found that it works the other way too. People judge moral transgressions more leniently if they had previously washed their hands or if they had been primed with words related to cleanliness, like 'pure' or 'immaculate'.
Now, Zhong, together with Katie Liljenquist and Adam Galinsky, have expanded on these studies by showing that clean smells can make people behave more virtuously. They ushered 28 volunteers into a room that was either unscented or that had been lightly sprayed with a citrus air freshener. In either case, they had to play a trust game, where a "sender" has a pot of money and chooses how much they want to invest with a "receiver". The investment is tripled and the receiver decides how much to give back.
