Lady Macbeth was expressing a deep psychological profound truth when she frantically sought to get imaginary blood off her hands after plotting the murder of the king, Duncan. Clean hands actually do make people feel less guilty, researchers report in tomorrow's issue of Science.
Physical and moral cleanliness have always been closely associated, both in religious practices and in people's minds, as revealed by the words they use--such as "pure" applied either to body or spirit. Chen-bo Zhong, who teaches organizational behavior at the University of Toronto, and management researcher Katie Liljenquist of Northwestern University in Chicago, Illinois, sought to explore the depth of this association. First they asked 30 undergraduates to summon up how they felt from performing an ethical act, such as helping a sick friend, while 30 others were asked to recall an unethical deed, like shoplifting.. All then did took a word completion test.
Those who recalled doing something bad were more likely to fill in a word such as W _ _ H with a cleansing-related word ("wash" rather than "wish"). Similarly, when subjects were offered a choice between an antiseptic wipe and a pencil as a gift, two-thirds of those who recalled the unethical deed took the wipe--twice as many as those who recalled the ethical deed.
Whereas these experiments showed that the association between cleanliness and morality has deep roots, another exercise showed that the two concepts lie so close together as to be almost interchangeable. In this study, 45 participants described an unethical deed from their past. Afterward, 22 were given an antiseptic wipe to clean their hands. All were then asked if they would volunteer for another study to help out a desperate graduate student. Those who felt clean apparently felt less need to expiate for their sins: only 41% agreed to help, compared to 74% who had not wiped their hands.
Psychologist Philip Tetlock of the University of California, Berkeley, says the study is so "clever" he wishes he'd done it himself. It shows that "there is a deep psychological connection between morality and physical cleanliness," he says. "Indeed, our thinking about moral purity appears in some respects to be a metaphorical extension of our deep-rooted aversion to filth and contamination."