(PhysOrg.com) -- Wider faced men are less trustworthy and our instincts know it, according to researchers at the University of St Andrews.
A new study by psychologists at the University shows that how trustworthy men are can be seen in their faces.
The study involved inviting men to play a game for money. The game offered players opportunities to trust other participants, but also opportunities to exploit them.
During the game a participant was shown an expressionless photo of a fellow player's face at the start of each game. The participant had then to decide whether to take an immediate pay-off or entrust the money to the person in the snapshot - who, in turn, could decide either to co-operate, and help both players make more money, or take the cash and run.
Lead researcher Michael Stirrat set up the games to investigate whether he could find any measurable relationship between perceptions of trustworthiness from perceptions and behaviour. He found that participants were more likely to entrust money to men with narrower faces.
"We all make instant judgements about strangers - whether to trust him or whether to be wary of her. In my research I have been trying to find a basis for these intuitive judgements.
"From the evolutionary theory of sexual selection we predicted that male faces may signal physical dominance and that more dominant men would be more likely to be exploitative because they can be.
"We found that men with wider faces exploited trust more often to make money for themselves."
By this reasoning, you might trust David Tennant but mistrust Simon Cowell.
However, Michael Stirrat concludes with a word of caution:
"The results are important but we shouldn’t leap to the conclusion that wider-faced men are bad. They were exploitative in our games, but in other games the wider faced men were more likely to sacrifice their money to enforce good behaviour. This is ongoing research and it is difficult to draw any big conclusions, but what is true is that wider faced, more robust men have the capacity to choose to be society's criminals or society's police."
Explore further: Association between parental time pressure and mental health problems among children