Liars, cheats, philanderers(1) and murderers are not renowned for exquisite(2) personal hygiene(3), but then no one has studied their showering habits.
They may scrub extra hard after a con(4) job, use $40 hyacinth shampoo after a secret tryst or book a weekend at a spa after a particularly ugly hit(5). They are human beings, after all, and if a study published in the journal Science is any guide, they feel a strong urge to wash their hands - literally(6) - after a despicable act in an unconscious effort to ease their consciences.
And it works, at least for minor guilt stains(7). People who washed their hands after contemplating an unethical act were less troubled by their thoughts than those who didn't, the study found.
The researchers at the University of Toronto and Northwestern University call this urge to clean up the "Macbeth effect," after the scene in Shakespeare's tragedy in which Lady Macbeth moans, "Out, *ed spot(8)! Out, I say!" after bloodying her hands when her husband, at her urging, murders King Duncan.
In one of several experiments among Northwestern undergraduates, the researchers had one group of students recall an unethical act from their past, like betraying a friend, and another group reflect on an ethical deed, like returning lost money. Afterward, the students had their choice of a gift, either a pencil or an antiseptic(9) wipe. Those who had reflected on a shameful act were twice as likely as the others to take the wipe.
In another experiment, the researchers found that students who had been contemplating an unethical deed rated the value of cleaning products significantly higher than peers who had been thinking about an ethical act.
Psychologists have known for years that when people betray their values, they feel a need to compensate. Christians who have read a blasphemous story about Jesus express a desire to go to church more frequently. "It's sometimes called symbolic cleansing, or moral cleansing, and it's an attempt to repair moral identity," said Dr. Philip Tetlock, a professor of organizational behavior at the University of California, Berkeley.
Sure enough, researchers found that students who had been thinking about past sins were very likely to agree to volunteer their time to help with a graduate school project - unless they had been allowed to wash their hands, which cut their willingness to volunteerroughly in half.
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撒谎者，骗子，花花公子和杀人犯不是以精致的个人卫生而著称，但也从来没人研究过他们洗浴的习惯。
他们可能在行骗后使劲搓洗，在秘密幽会后用昂贵的40美圆一瓶的风信子浴液或者在犯罪后在周末安排一次水疗。毕竟他们也是人。如果发表在《科学》杂志上的一份研究报告可以提供些许参考，这种在干完卑劣勾当后想洗手的强烈愿望其实是他们无意识中想减轻内心谴责的努力。
至少对于小恶这么做管用。研究发现，那些在图谋不轨之后洗手的人所受的自我困扰比不洗手的人少。
加拿大多伦多大学和美国西北大学的研究人员称这种想洗清罪恶的强烈愿望为"麦克白效应"，该名字源于莎翁笔下的悲剧里的一个场景，其中麦克白夫人唆使丈夫谋杀了顿肯王，手上沾满鲜血后，呻吟道，"洗掉，该死的污点！洗掉，我说了。"
有一项试验是在美国西北大学的在校生中进行的。研究人员让一组学生回忆自己以前做过的不道德的事，例如背叛朋友，同时让另一组回忆做过的好事，例如拾金不昧。之后，学生们可以在铅笔和消毒湿巾之间任选一个作礼物。回忆起不体面行为的学生选择湿巾的可能性是其他人的两倍。
另一项试验中，研究人员发现有不良企图的学生给清洁用品定的价格远远高于他们想着做好事的同学。
心理学家多年前就发现当人们背叛了自己的价值观，他们感到需要去补偿。基督徒在读了亵渎耶稣的故事后会有更频繁地去教堂的渴望。"这种行为有时叫象征性清洁，或道德清洁，它是一种重建道德观的努力。"位于伯克利的加州大学的组织行为学教授菲利普.泰特劳克博士说。
当然，研究人员发现回想以往不齿行径的学生更可能答应贡献他们的时间帮忙研究生院做一个课题 - 除非他们被允许先去洗手，洗手之后他们想当志愿者的热情就锐减了一半。

2006-10-16