Science finds you really can wash hands of it

The discovery may lie behind the phrase "washing your hands of it", referring to a refusal to take the blame for an unhappy outcome.

Hand-washing was most famously performed by Pontius Pilate, the Roman governor who allowed Jesus to be crucified.

But it does more than remove the burden of guilt, according to scientists in the United States.

Researcher Spike Lee, from the University of Michigan in Ann Arbor, said: "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."

Previous research has shown that once people make a choice, they are psychologically driven to stand by it.

A selected item is seen as more attractive than it was before the choice was taken, and a rejected one less attractive but the effect is wiped out by washing hands the research shows.

This was illustrated by a group of student volunteers who were told they were taking part in a consumer survey of CDs.

After browsing through 30 CD covers they picked 10 CDs and ranked them by preference. They were then given a "reward" – the choice of either their fifth or sixth-ranking CD to keep.

Participants then took part in another "survey", this time of liquid soap. Half merely had to examine the soap bottle while the rest washed their hands.

Next, the volunteers were asked to rank the 10 CDs again.

Co-researcher Dr Norbert Schwarz said people who merely examined the soap bottle dealt with doubts about their decision by changing how they saw the CDs "but hand-washing eliminated this classic effect.

"Once participants had washed their hands, they no longer needed to justify their choice when they ranked the CDs the second time around."

The results were reported in the journal Science.