So that's why Pontius Pilate washed his hands - it can help ease niggling doubts about decisions

By Fiona Macrae
Last updated at 11:32 PM on 6th May 2010

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If you have made a difficult decision and want to stick to it, go and wash your hands.

A study has revealed that hand washing, long associated with absolving the mind of guilt, can also erase any doubts about everyday choices.

The latest research, reported in the journal Science, looked at whether the phenomenon extends to decisions with little or no moral implications by asking a set of volunteers to pick between two CDs or two jams.

Scientists found the 40 volunteers were less likely to try to justify their choice if they washed their hands just after making it.
Christ before Pilate

Pontius Pilate: Washed his hands after condemning Jesus in the Bible

University of Michigan researcher Spike Lee said that hand washing appears to erase doubts, 'wiping the slate clean'.

He added: 'When people make decisions, they are often faced with choosing between two very attractive options.

'Let's say they are choosing a vacation spot - Paris or Rome. After choosing, let's say, Paris, they justify their choice by thinking to themselves it is the right one because French cuisine is better and the art museums are fantastic.

They are justifying their choice by focusing on the positive features.

'What our study showed was that after people washed their hands they no longer felt they had to justify their choice.
Helen Baxendale as Lady Macbeth

Shakespeare's Lady Macbeth (here Helen Baxendale) attempted to wash away her guilt after committing murder

'They had washed away the compulsion to justify the choice they had made.' The researchers added: 'It's not just that washing your hands contributes to moral cleanliness as well as physical cleanliness.

'Our studies show that washing also reduces the influence of past behaviours and decisions that have no moral implications whatsoever.'

Previous research by the team has established a link between washing hands and the absolving of guilt. The idea that it is possible to wash away our sins is deep rooted in many cultures and religions, including Christianity.

Water is a cornerstone of baptism ceremonies and, in the Bible, Pontius Pilate washed his hands after condemning Jesus to death.

Shakespeare also subscribed to the idea, making Lady Macbeth attempt to wash away her guilt of plotting King Duncan's murder.

But it took scientists until 2006 to show that the theory holds water.

A team at the University of Toronto asked volunteers to either dwell on something they were ashamed of having done or think happy thoughts. They were then asked to play a word game and given a choice of a free gift.

Those recalling an unethical deed were more likely to pick the words 'soap' and 'shower' in the word game. Similarly, guilty thoughts led to an antiseptic wipe proving more popular as a gift than a pencil.

The research team concluded that the areas of the brain that deal with physical cleanliness likely overlap with those that process psychological purity.