Student Study Finds Instinct To Wash After Poor Behavior

Ryan Wenzel

By Mike CherneyThe Daily Northwestern

Washing hands or taking a shower can make one feel subconsciously better about bad deeds, according to a new study released earlier this month that was co-authored by a Northwestern graduate student.

The study, published in the journal Science, called the phenomenon the “Macbeth effect.” The study is named for Lady Macbeth, the Scottish noblewoman in Shakespeare’s “Macbeth” who washes her hands in an attempt to absolve herself of the treacherous murder of the Scottish king.

“We weren’t too surprised to find initial confirmation for the ‘Macbeth effect,'” said Katie Liljenquist, a graduate student at the Kellogg School of Management. “People certainly aren’t realizing they’re doing things; it’s all happening at a subconscious level.”

Liljenquist, and her co-author, Chen-Bo Zhong of the University of Toronto, designed several experiments to test their theory. They asked participants to recall ethical or unethical deeds and then rate the desirability of certain consumer products. The participants who recalled bad deeds rated hygiene products higher.

“It’s an amazing find,” said Nicholas Epley, an assistant professor of behavior at the University of Chicago Graduate School of Business, who was not connected to the study. “It’s a very impressive scientific contribution.”

Epley said the subconscious desire to wash after bad deeds is similar to the desire to clean one’s mouth after eating something gross.

The find is important because it shows that humans’ morality might be less a development of large brain sizes and more of a connection to basic physical emotions of disgust, he said.

“It joins a line of research that suggests a strong link between moral emotions and more basic kinds of physical states,” he said.

In another experiment in the study, participants who recalled bad deeds were more likely to favor a sanitary wipe over a pencil.

Participants who recalled bad deeds and washed their hands were also less likely to offer to volunteer for another unpaid survey than participants who did not wash their hands. This indicated that those who washed their hands had felt better about their bad deed and were less motivated to volunteer, according to the study.

Liljenquist said the implications for future research could be huge. Nearly every religion in the world has purifying cleaning rituals, so it would be interesting to study the connection between religiosity and good – or bad – behavior, she said.

Another line of further study could be to determine if clean environments promote better behavior or license bad behavior.

“It would be cool to find that it can regulate people’s behavior,” Liljenquist said.

Reach Mike Cherney at [email protected]