As health educators never tire of reminding us, washing our hands helps stop the spread of disease. But a growing body of research suggests this routine activity has deep metaphorical connotations, and triggers surprising psychological side effects.
Two newly published studies look at this phenomenon from different perspectives. One links physical cleanliness with harsh moral judgments, while the other suggests hand-washing impacts the way we view past decisions on matters unrelated to ethics or values.
The connection between physical cleanliness and moral purity dates back at least as far as William Shakespeare: Lady Macbeth cries, “Out, damn spot” as she attempts to wash away the metaphorical blood stains on her hands. Over the past two decades, social psychologists have been both theorizing about its origins (it is probably an evolutionary adaptation dating from an era when physical cleanliness literally meant survival) and studying its political implications (Jonathan Haidt finds the association is particularly pronounced among social conservatives).
University of Toronto psychologist Chen-Bo Zhong presents some uncomfortable implications of this pairing in the Journal of Experimental Social Psychology. “Given the association between cleanliness and moral purity,” he and two colleagues write, “we suggest that a clean person may not only feel dirt-free, but also morally untainted. This elevated sense of moral self can in turn license severe moral judgment.”
Zhong and his colleagues conducted an experiment in which 58 University of Toronto undergraduates were seated in a brand-new laboratory. At the outset, half of them were asked to clean their hands with an antiseptic wipe before touching the keyboard or mouse. All were then asked to rate six issues — smoking, illegal drug use, pornography, profane language, littering and adultery — on an 11-point scale ranging from very moral to very immoral.
“Participants who cleansed their hands before rating the social issues judged these issues to be more morally wrong compared to those who did not cleanse their hands,” the researchers report.
To see if those findings would hold for a larger, more diverse sample, Zhong and his colleagues conducted an online experiment featuring 323 participants. One-third began the experiment by visualizing an unhygienic scenario and typing a set of short sentences, including “My hair feels oily and heavy. My breath stinks. I feel so dirty.” One-third visualized an alternative scenario emphasizing cleanliness, typing sentences such as “My breath is fresh. My clothes are pristine and like new.” The other third did not take part in this task.
Afterward, all the participants rated 16 issues on the 11-point morality scale: The six from the earlier test, plus 10 additional items including abortion and homosexuality. The results were consistent: Those who held a self-image of cleanliness and purity rendered harsher moral judgments than those in the other two groups.
According to Zhong, these experiments provide fresh evidence that some moral judgments are “not based on rational reasoning,” but rather are the results of unconscious “metaphorical thinking that confuses physical purity with moral purity.”
What else does an aura of cleanliness do, besides heightening our sense of moral superiority? A separate study published in the journal Science suggests it metaphorically washes away doubts regarding choices we have made.
University of Michigan psychologists Spike W.S. Lee and Norbert Schwarz conducted an experiment in which 40 undergraduates chose 10 CDs they would like to own, ranking them in order of preference. They were then offered a choice between their fifth- and sixth-ranked CDs as a gesture of appreciation.
Afterward, they participated in an ostensibly unrelated product survey. Half examined a bottle of liquid soap, while the others actually used it to wash their hands. Finally, all were asked to rank their top 10 CDs a second time.
Those who merely looked at the soap bottle ranked their chosen CD higher and their rejected one lower than their original ordering. This is consistent with previous research finding that, after the fact, people convince themselves they made the right call by suddenly perceiving a big difference between their choice and the rejected alternative.
But among those who washed their hands, this well-documented effect disappeared: Their CD preference lineup remained pretty much the same. These surprising results were confirmed by a second study utilizing antiseptic hand wipes and jars of jam.
“Much as washing can cleanse us from traces of past immoral behavior, it can also cleanse us from traces of past decisions, reducing the need to justify them,” Lee and Schwarz write.
So the psychological effects of hand washing apparently extend beyond the linkage of cleanliness and Godliness. Under some circumstances, it appears that wiping our hands of a situation truly does allow us to move on. But under different conditions, it appears to convince us of our own purity and lead us to judge others more harshly.
Something to think about the next time you’re working up a lather.