If there’s anything we’ve learned from the coronavirus pandemic, it’s that washing our hands is one of the best ways to protect ourselves from the dangers of contagion. But hand washing does much more than cleanse us physically; sometimes it can wipe our mental slate clean. Here are some examples of what a bit of soap can do for our psyches.
1. It can remove our guilt
Washing our hands can rid us of remorse, according to a now-classic 2006 study in which psychologists Chen-Bo Zhong and Katie Liljenquist asked volunteers to recall something bad that they had done before giving half of them an antiseptic wipe to use as “part of the hygiene protocol for using public computers.” The researchers then asked the participants to report their emotions and found that those who cleansed their hands after recalling their unethical deeds felt less remorseful and ashamed. Then, knowing that people who feel guilty about past transgressions normally try to make made amends by doing something good, the scientists asked everyone whether they would help with another experiment. Three-quarters of those who had not wiped their hands offered their time whereas only four in 10 of those who had been given the chance to wipe their hands did.
The researchers concluded that a threat to our moral purity makes us want to get clean and called it “the Macbeth effect,” after the Shakespearean character Lady Macbeth who, after assisting her husband in a murder, feels so guilty that she starts compulsively washing her hands in an effort to cleanse them of imaginary blood. Watching someone else wash their hands produces a similar, if slightly weaker, effect.
2. It can affect our moral judgments
We are more likely to judge other people’s “dirty” behaviors harshly when we are feeling squeaky clean. In a 2010 study, participants who were instructed to clean their hands before judging vignettes depicting social issues like using drugs and committing adultery were less forgiving than those who had not cleaned their hands. Cleaning their hands had given them an inflated sense of self-righteousness, and the resulting moral high ground made them more judgmental.
3. It can help us justify our decisions
Hand washing has been shown to help us justify our purchase decisions. In one study, participants were asked to rank 10 CDs and were then allowed to choose either their fifth- or sixth-ranked CD as a gift to take home with them. Then they took part in a bogus product test of hand soap. Half of them just got to examine the bottle of hand soap, and the other half were asked to test it by washing their hands. Then they were asked to provide a final evaluation of the CDs. Those who had merely examined the soap bottle showed the usual post-decision justification: their preference for the CD they had chosen was stronger after they made their choice than it was before. However, this was not the case for people who had washed their hands after making their choice. A second study, in which a new set of participants were asked to choose between fruit jams before judging an antiseptic wipe, replicated these results. Simply cleaning our hands seems to eliminate our need to justify our choices to ourselves.
4. It can help us recover our optimism
People who wash their hands after failure tend to feel more optimistic. This was demonstrated in a study in which people who washed their hands after failing an anagram task showed more optimistic expectations about their future performance on a second anagram task than those who did not wash their hands. That said, their actual performance was even worse on the second task, possibly because they didn’t try as hard.
5. It can encourage risk-taking
Cleanliness encourages us to take risks, according to a study in which business students were either asked to recall an incident in which they had been lucky financially or one in which they had had bad financial luck. Those who had recalled a good financial outcome tended to take more risk on a subsequent financial decision task than people who had recalled a bad financial outcome. However, cleaning their hands with an antiseptic wipe as part of a bogus product test seemed to effectively remove the influence of either good or bad luck in the past. After wiping, those who had thought about a good outcome took less risk, whereas those who had recalled a bad outcome took more risk.
6. It can strengthen cognitive control
Hand washing can help us to strengthen our executive function — the set of cognitive skills we need for self-control and goal-directed behavior, often described as “the management system of the brain” — by freeing our minds from ruminating about moral failures. In this study, participants were asked to write a detailed description of an unethical deed they had done before being asked to complete a computer questionnaire. Half were told that the “Research Protection Board recommended that everyone should wipe their hands before using public computers,” and half were not. They then went on to take several cognitive tests. Those who had used an antiseptic wipe performed much better than those who had not and whose performance was described as approximating a level “commonly found only in young children.”
7. It can remove the endowment effect
The endowment effect is a bias that makes us assign more value to an object that we own simply because we own it, and often results in sellers asking for more money for a product than buyers are prepared to offer. Hand washing can lessen or eliminate the effect, as shown by a study in which participants who washed their hands were more likely to exchange a previously endowed chocolate bar or drink for a different one than participants who merely evaluated a liquid soap or had their height measured.
8. It can reduce prejudice
The world was a dangerous place for our ancient ancestors, with parasites, pathogens, and other disease-causing organisms constantly challenging their survival. So they evolved mechanisms — a behavioral immune system — to help them minimize their exposure to disease-related threats, which included strangers and people who were not kin. To this day, a fear of germs underlines prejudice toward social groups that are associated with unfamiliar cultural practices.
As it happens, we may be able to clear the prejudice away with an antiseptic wipe. In one study, undergraduates were split into two groups, seated in front of a computer, and asked to rate a hand wipe. The experimental group was asked to use it to wipe the keyboard and their hands, whereas the control group just examined it. Then they were asked to read a passage about the seasonal flu that emphasized the use of antibacterial hand wipes as a protective measure against contamination, before being asked to rate their impressions of certain social groups — such as crack addicts, illegal immigrants, Muslims, and the homeless. Those who had been given an opportunity to clean their hands had less negative attitudes toward those groups than those who had not.
- “Washing Away Your Sins: Threatened Morality and Physical Cleansing” by Chen-Bo Zhong and Katie Liljenquist, 8 September 2006, Science.
- “Washing the guilt away: effects of personal versus vicarious cleansing on guilty feelings and prosocial behavior” by Hanyi Xu, Laurent Bègue and Brad J. Bushman, 28 February 2014, Frontiers in Human Neuroscience.
- “A clean self can render harsh moral judgment” by Chen-BoZhong, Brendan Strejcek and Niro Sivanathan, 27 April 2010, Journal of Experimental Social Psychology.
- “Washing Away Postdecisional Dissonance” by Spike W. S. Lee and Norbert Schwarz, 7 May 2010, Science.
- “Washing One’s Hands After Failure Enhances Optimism but Hampers Future Performance” by Kai Kaspar, 10 April 2012, Social Psychological and Personality Science.
- “Washing away your (good or bad) luck: Physical cleansing affects risk-taking behavior” by A. J. Xu, R. Zwick and N. Schwarz, Journal of Experimental Psychology.
- “Washing away your sins will set your mind free: physical cleansing modulates the effect of threatened morality on executive control” by Eyal Kalanthroff, Chen Aslan and Reuven Dar, 21 September 2015, Cognition and Emotion.
- “Detaching the ties of ownership: the effects of hand washing on the exchange of endowed products” by Arnd Florack, Janet Kleber, Romy Busch and David Stöhr, 5 October 2013, Journal of Consumer Psychology.
- “Immunizing Against Prejudice: Effects of Disease Protection on Attitudes Toward Out-Groups” by Julie Y. Huang, Alexandra Sedlovskaya, Joshua M. Ackerman and John A. Bargh, 4 November 2011, Psychological Science.