ANN ARBOR—Cleaning your hands removes more than dirt, it also removes residues of the past, such as guilt and doubt, a new University of Michigan study finds.

Spike W.S. Lee, a graduate student in the Department of Psychology, and Norbert Schwarz, a research professor at the Institute for Social Research, say religious rites like baptism make psychological sense.

“Cleansing is about the removal of residues,” Lee said. By washing the hands, taking a shower, or even thinking of doing so, “people can rid themselves of a sense of immorality, lucky or unlucky feelings, or doubt about a decision. The bodily experience of removing physical residues can provide the basis of removing more abstract mental residues.”

In reviewing other studies, the authors found that people asked to judge the moral wrongdoing of others saw them as worse when exposed to an unkempt room or bad odor than when sitting in a clean room.

In another study, participants asked to think of a moral wrongdoing of their own felt less guilty after using an antiseptic hand wipe; they were also less likely to volunteer for a good deed to assuage that guilt. Even imagining yourself either “clean and fresh” or “dirty and stinky” affects your judgments of others’ acts, such as masturbation or abortion, the research showed. The “clean” participants in one study not only judged others more harshly, they judged themselves as more moral than others.

Cleansing works for other mental discomforts, too, such as the doubts one may have after making a difficult decision. To resolve this doubt, people convince themselves that they made the right choice by seeing the chosen alternative in a more rosy light than they otherwise would, a well-known tendency called choice justification.

But if people were given a hand wipe, they no longer justified their choice: They had wiped off their doubt and no longer needed to convince themselves that they had done the right thing. Using soap showed similar results after a bad luck streak in gambling: After washing, participants began to bet higher stakes, suggesting they had “washed away” their bad luck.

Researchers, however, can’t conclude that people who bathe a lot are happier. “Cleansing removes the residual influence of earlier experience,” Lee notes. If that experience was positive, it would go down the drain too. In fact, washing one’s hands after reminiscing about a positive event limits the warm glow of happy memories, leaving people less satisfied.

The findings appear in the new Current Directions, a journal published by the Association for Psychological Science. The weblink is http://cdp.sagepub.com/content/20/5/307

Note: Global Handwashing Day is on Oct 15.

Related Links:

• Global Handwashing Day