The study, published in Science, found that people who recall acting unethically are more drawn to cleansing products than those who remember behaving ethically.
Chen-Bo Zhong, who works for the Rotman School of Management at Canada's University of Toronto, and Katie Liljenquist, a graduate student at Northwestern University's Kellogg School of Management in Chicago, did the research.
"Daily hygiene routines such as washing hands, as simple and benign as they might seem, can deliver a powerful antidote to threatened morality, enabling people to truly wash away their sins," the researchers write.
They call the phenomenon the "Macbeth effect," after Lady Macbeth, who plotted King Duncan's murder in Shakespeare's play, Macbeth.
"Lady Macbeth's desperate obsession with trying to wash away her bloodied conscience while crying, 'Out, damned spot! Out, I say,' may not have been entirely in vain," the researchers write.
The researchers did four short studies on cleanliness and conscience. The studies included 119 Northwestern University undergraduates.
The first study included 60 students. In private conversations, a researcher randomly asked each student to describe an ethical or unethical deed from their past.
Next, the students completed the blanks in these unfinished words:
- W - - H
- SH - - ER
- S - - P
Those who had recalled past unethical deeds were the most likely to jot down "wash," "shower," and "soap," instead of words like "wish," shaker," and "step."
"Participants who recalled an unethical deed generated more cleansing-related words than those who recalled an ethical deed," the researchers conclude.
The finding suggests that unethical behavior tends to bring cleansing to mind, note Zhong and Liljenquist.
Good, Bad Behavior
The second study included 27 different students. They were asked to read a short story in which the main character either behaved ethically or unethically.
The story was set in an imaginary, prestigious law firm. The main character finds a document a colleague needs for a case.
In one version of the story, the main character gives the document to the colleague, saving the colleague's case.
In another version, the main character shreds the document to sabotage the colleague's career.
Afterwards, the students rated the desirability of cleansing products, snacks, batteries, or CD cases.
Those who had read the backstabbing story went for the cleansers. Those who read the save-the-day story didn't prefer any particular type of product.
The third study, which included 32 students, used the same stories. This time, the students chose between a free gift of a pencil or an antiseptic cleansing wipe after reading the stories.
Two-thirds of those who read the unethical story chose the wipe, compared with a third of those who read the ethical story.
Cleansing the Conscience
The last study included 45 students who described an ethical or unethical deed from their past.
Afterwards, the researchers randomly gave an antiseptic wipe to some, but not all, of the students.
Lastly, the students were asked to volunteer for another study that desperately needed participants.
Nearly three-quarters of those who hadn't gotten the antiseptic wipes volunteered, compared with 41% of those who had gotten wipes.
"Presumably," the researchers write, "participants who had cleansed their hands before being solicited for help would be less motivated to volunteer because the sanitation wipes had already washed away their moral stains and restored a suitable moral self."
That's the researchers' interpretation. Their study doesn't show why the students decideto volunteer or not.
"It remains to be seen whether clean hands really do make a pure heart, but our studies indicate that they at least provide a clean conscience after moral trespasses," write Zhong and Liljenquist.
SOURCES: Zhong, C. Science, Sept. 8, 2006; vol 313: pp 1451-1452. Zhong, "Supporting Online Materials for Threatened Morality and Physical Cleansing." News release, Science.
By Miranda Hitti
Reviewed by Louise Chang