Chen-Bo Zhong, of 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, conducted 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.
The phenomenon was called the "Macbeth effect," after Lady Macbeth, who conspired 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.
4 short studies on cleanliness and conscience were carried out on 119 Northwestern University undergraduates by the researchers.
The first study was carried out on 60 students. Each of these students were randomly asked tell the researcher about an ethical and an unethical act from their past, in confidential conversations.
The students were subsequently asked to complete the blanks in these unfinished words:
W - - H, SH - - ER, S - - P.
"wash," "shower," and "soap," were the words written by those who recollected past unethical acts, 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.
The next study was conducted on 27 different students. The students read a short story in which the lead character either behaved ethically or unethically. In the story, there is a prestigious law firm. The lead character gets a document that a colleague requires for a case.
The main character gives the document to the colleague in one form of the story, saving the colleague's case. While in the other form, the document is shredded by the lead character to sabotage the colleague's career. Subsequently, the students rated their attraction for cleansing products, snacks, batteries, or CD cases.
The students who read the sabotaging version went for the cleansing products while those who read the other version didn't prefer any particular type of product.
The third study was conducted on 32 students using the same story. After reading the story, the students were given a choice of a free gift of a pencil or an antiseptic cleansing wipe. The wipe was chosen by two-thirds of the students who read the unethical version, compared with one-third of those who read the ethical version.
The final study was conducted on 45 students who were asked to describe an ethical or unethical deed from their past. The wipes were given to some of them. Subsequently, the students were asked to volunteer for another study. Almost 75% of those who had not got the 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."
"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.