We should have guessed blue-eyed Texan Lance Armstrong was a cheat

Men with blue eyes and thin faces are seen as inherently less trustworthy than brown-eyed males with wider faces, a study has found.

Research from scientists in the Czech Republic suggests that the colour of a man's eyes does not in itself alter their perceived trustworthiness, but it can have that effect when combined with certain facial features.

The study was based on the perceptions of 238 volunteers as they looked at the facial photographs of 40 male and 40 female students. Men with blue eyes and long, narrow faces were seen as the least trustworthy, although the effect was not significant with female faces.

To test whether it was eye colour in itself that caused the suspicion, the scientists, led by Jaroslav Flegr from Charles University in Prague, artificially changed the eye colour of the male photographs so that the blue-eyed men had brown eyes and vice versa. Eye colour now had no effect on whether they were perceived as trustworthy, indicating that it was the combination of blue eyes and facial shape that was important.

Previous research suggested that the shape of a person's face affects the way they are perceived and that brown eyes tend to be associated with the kind of facial shape that many people perceive to be trustworthy.

Professor Flegr and his colleagues found a link between eye colour and facial type, although the link was only statistically significant in men.

"Blue-eyed male faces were characterised by a more angular and prominent lower face, a longer chin, a narrower mouth and downward-pointing corners, relatively smaller eyes and rather distant eyebrows. This was also the pattern of an untrustworthy face," Professor Flegr said.

"In contrast, brown-eyed faces tended to have a rounder and broader chin, a broader mouth with upward-pointing corners, relatively bigger eyes, and eyebrows closer to each other. This was also the pattern of a trustworthy face," he said.

The research was reported in the online journal PlosOne.