Lady Macbeth desperately attempted to wash away a spot of blood after the murder of Duncan. Scientists at Northwestern University have put the “Macbeth effect” to the test and found that, unconsciously at least, people can wash away their sins. Volunteers described an ethical or unethical action they had undertaken in their lives. Then they saw six word fragments, three of which—W_ _ H, for example—could be completed in a cleansing way (WASH) or an unrelated way (WISH). Those who recollected an unethical deed were more likely to produce a cleansing word; moreover, they often chose an antiseptic wipe over a pencil when given the choice. A need to be clean might drive behavior, too. Among those who recalled dirty deeds but were not allowed to wash up, 74 percent later offered to help in another project, versus only 41 percent of those who had cleaned up, according to the September 8 Science.
This article was originally published with the title "Washing Hands to Remove Moral Taint" in Scientific American 295, 5, 37 (November 2006)