What prompts trust?

Is it a reassuring smile, saintly eyes or mere sex appeal that prompts one to trust? New research says - none.

According to psychologist Lisa DeBruine, who works with the University of Aberdeen, one instinctively trusts faces that most resemble our own physically, according to the Scotsman newspaper.

But look-alikes are trustworthy, not 'lustworthy', she says.

According to DeBruine, men and women appear to have a physical aversion to members of the opposite sex who look like themselves - because subconsciously, one is defending oneself against the taboo of incest and the possibility of inbreeding.

The study is based on examining the reactions of 144 students - 66 male and 78 female - who were asked to 'judge' a series of paired faces of the opposite sex.

Unknown to the students, one of the paired faces had been electronically manipulated to subtly resemble their own. The other photograph was a complete stranger.

When asked which of the two faces looked trustworthy and which was sexually attractive, the students chose the stranger for sex appeal and the look-alike for trustworthiness.

DeBruine said: 'It was surprising. I found that while they have preferences for the same-sex faces that look like your own, they have a more sophisticated learning process when it comes to opposite sex faces.

'They were averse to faces that looked like their own in a sexual context; they disliked them.

'Everybody knows about 'inbreeding avoidance'. You shouldn't be mating with brothers and sisters. This study shows that we find people, who are closely 'related' to us unattractive in a sexual sense.'

Earlier research has shown that people trust certain groups more than others.

A recent study in the US and Britain revealed that more than 80 per cent of people trust clergymen and doctors; 79 per cent will listen to scientists and judges, and a marginally smaller percentage believe what the police tell them.

However, people are least likely to trust politicians and, for some reason, journalists.