Disgusting stuff turns us into liars and cheats, and cleanliness makes us honest again

Study reveals the subconscious impact of emotions on decision making

Ewan McGregor in the 'Worst Toilet in Scotland' scene from the film Trainspotting, 1996 (REX/Moviestore Collection)

Feeling physically disgusted can make us prone to deceive others, whereas cleanliness prompts us to play fair again, say scientists behind a newly published study.

The decisions you make are often highly influenced by seemingly innocent objects and events around you, whilst you remain completely oblivious to the effect. Seeing an ad for a burger chain and choosing to stop for food is an obvious example, but some of the ways in which our minds are guided by the outside world are less self-evident. Would you have guessed, for example, that watching the toilet scene from ‘Trainspotting’ would make you more likely to lie and cheat?

That infamous scene was shown to one group of participants in a new study published in the journal ‘Organizational Behavior and Human Decision Processes’, which aimed to uncover the effects of disgust on unethical behaviour. And lo and behold, those who had just watched Ewan McGregor slide through the ‘Worst Toilet in Scotland’ were more likely to lie in order to get two dollars than those who had been spared this ordeal.

Vikas Mittal, professor of marketing at Rice University in Houston, Texas, co-authored the paper and explains the mechanism behind the seemingly bizarre connection.

"As an emotion, disgust is designed as a protection. When people feel disgusted, they tend to remove themselves from a situation. The instinct is to protect oneself. People become focused on 'self' and they're less likely to think about other people. Small cheating starts to occur: If I'm disgusted and more focused on myself and I need to lie a little bit to gain a small advantage, I'll do that.”

Another group of subjects was asked to evaluate products with a high ick factor, such as anti-diarrheal medicine, diapers, cat litter, and adult incontinence pads. Again, compared to a control group, these people were more likely to cheat directly after completing their task.

As happens in daily life, the participants were unaware that the revulsion they felt had anything to do with their subsequent decision. In fact, the researchers had purposely chosen the supermarket products as examples of innocuous items that could easily influence a person’s mind as they go about their business.

In a second set of experiments, the researchers examined whether the effects of disgust could be reduced by asking people to assess cleaning products, such as disinfectants and body washes. Sure enough, those who were exposed to the cleansing goods after feeling revolted were well behaved afterwards, indicating that thinking about soap cancelled out the morally corrupting effects of disgust.

The implications of these effects seem clear. "At the basic level, if you have environments that are cleaner, if you have workplaces that are cleaner, people should be less likely to feel disgusted," Mittal said. "If there is less likelihood to feel disgusted, there will be a lower likelihood that people need to be self-focused and there will be a higher likelihood for people to cooperate with each other."

Outside of the workplace, it may be advisable to tidy up your dirty socks before having a heart-to-heart with anyone close to you.