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Out, damn’d decision: Hand washing helps us live with our choices

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hand washing choice decisionShakespeare’s Lady Macbeth could never wash away the guilt of murder from her hands, but research has shown that the simple act of hand washing—or even using a wipe—can in fact help people clean their conscience of dirty deeds. A new study, published online May 6 in Science, reveals the power of hand washing to ease people’s minds about even mundane decisions.

Often, when people make decisions—no matter how big or small—they tend to justify them, rationalizing often beyond reason that their choice was by far the best.  Resolving the sense of cognitive dissonance vastly decreased in subjects who washed their hands after having to make a simple choice.

In an experiment, 40 subjects had to pick and rank 10 of 30 CDs that they would like to own as if they were completing a consumer survey. They were then given the choice of the fifth- and sixth-ranked CDs. Afterward, as part of an unrelated task, subjects took a survey about liquid soap. Half of the participants were given a soap bottle to assess, and the other half were instructed to try the soap out by washing their hands. Last, the participants were asked to rerank the 10 CDs.

"People who merely examined the soap bottle dealt with their doubts about their decision by changing how they saw their CDs," Norbert Schwarz, of the Department of Psychology at the University of Michigan in Ann Arbor and a co-author on the study, said in a prepared statement. "They saw the chosen CD as much more attractive than before and the rejected CD as much less attractive." Those who had washed their hands, however, appeared to have reduced cognitive dissonance and rated their chosen and rejected CDs about as they had before having to choose between them. 

In a similar experiment, the researchers asked 85 participants to predict how good four different fruit jams would taste and then complete a survey about antiseptic wipes—some people being asked to use them and others only to examine the box. Again, those who had just looked at the wipe boxes later showed typical cognitive dissonance, expecting "the taste of the chosen jam to far exceed the taste of the rejected one," said lead author Spike Lee in a prepared statement. Lee is a graduate researcher in social psychology at the University of Michigan. Those who had used the wipes were more likely to stick to their original ratings.

These findings show that the hand-washing effect is not limited to intense, morally profound situations, but that it "reduces the influence of past behaviors and decisions that have no moral implications whatsoever," Lee noted.

Image courtesy of AAAS/Science





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  1. 1. candide 3:11 pm 05/6/2010

    Is this a joke? "lead author Spike Lee" ?

    "to try the soap out by" – this fails even Jr. High School English classes.

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  2. 2. eecummings 4:43 pm 05/6/2010

    Not to mention the spurious comma in the second sentence of the second paragraph.

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  3. 3. Derick in TO 4:49 pm 05/6/2010

    Get a life candide. Spike is a real name, not just one film director’s handle. I actually know a guy named Spike – and he’s a researcher (different guy though).

    "to try the soap out" – the whole rule about not ending a clause with a preposition hasn’t been taught in a lot of schools for many years. There is no meaningful difference between "try out the soap" and "try the soap out", and adhering to a meaningless rule that 90% of the population ignores in their colloquial speech is just silly.

    How about if you try making a comment about the science?

    Here’s mine – wow, how cool a finding is that! Who would have thought that the idea of physical cleanliness would be related in our minds to the way in which we assign value and make decisions?

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  4. 4. Wayne Williamson 8:17 pm 05/6/2010

    very interesting study….
    does it mean that if i use the clorox wipes i have all over the house that i’ll be more biased in my decisions?…

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  5. 5. Wayne Williamson 8:20 pm 05/6/2010

    sorry…really meant to say that the last paragraph really didn’t fit in with the rest of the article….

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  6. 6. Herod 12:57 am 05/7/2010

    I wash my hands of this topic

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  7. 7. ea 4:34 am 05/7/2010

    How do they know that the effect is due to the cleaning of the hands, as opposed to the reassurance of being able to use the hand-cleaning product when asked to assess it?

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  8. 8. Johnay 11:13 am 05/7/2010

    Because the post-wipe follow-up question was about the CDs, not the wipes. Actually using the product would certainly make you more sure of your opinion of it, but presumably would not affect your confidence in an unrelated assessment. That it does is psychologically significant.

    It would be interesting to repeat the experiment with crackers instead of wipes/soap, allowing half the subjects to taste them. This would help show if the effect is due to the cleaning, or the subsequent more-assured decision.

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  9. 9. Heinrich 1:15 pm 05/7/2010

    The effect is more likely to do with performing a physical activity(washing hands) versus a mundane intellectual activity (inspecting consumer product). Very different parts of the brain are used. Try it again and have one group chop wood, while the other inspects the log.

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  10. 10. 23rdtehXX 2:43 am 05/9/2010

    hmm.. i know as a woman, i make a lot of silly decisions, and most while doing the dishes… maybe pms isn’t to blame for the irrationalities of my sex.

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  11. 11. bijou 9:01 am 05/9/2010

    To wipe or not to wipe, that is the question? Whether is it nobler in the mind to make decisions based upon ablutions or to caste away such soap as appears before thee, that is the question! I fear thy vain imaginings are but clouds before thee.

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