While baby-blue peepers might seem pretty, blue-eyed people can be perceived as less trustworthy compared to brown-eyed people, a new study shows.

Researchers from Charles University in Prague and Laval University in Canada asked 238 university students to rate photographs of 80 of their classmates -- 40 men and 40 women. The photos were either of blue- or brown-eyed individuals, all maintaining neutral expressions. Subjects were asked to rate the faces for trustworthiness based on two main factors: eye color and face shape.

One of the first trends the scientists found was that people with brown eyes seemed to be rated more trustworthy than the blue-eyed photos, according to their paper published in the journal PLoS ONE.

But the researchers suspected that facial traits associated with eye color, rather than the eye color alone, could be a determining factor. In a second experiment, the researchers used Photoshop to switch eye colors, changing blue to brown and vice versa, and asked another group of 106 students to rate the recolored photos.

Their analysis showed the hunch held up.

“We concluded that although the brown-eyed faces were perceived as more trustworthy than the blue-eyed ones, it was not brown eye color per se that caused the stronger perception of trustworthiness but rather the facial features associated with brown eyes,” the authors wrote.

The blue-eyed male faces in the researchers’ sample tended to be more angular, with a longer chin, narrower mouth, smaller eyes and more distant eyebrows. In contrast, brown-eyed faces tended to have rounder and broader chins, broader mouths with upward-pointing corners, and eyebrows that were slightly closer together.

Since trust lies at the heart of so much human interaction, from business to mating, studying the link between face attributes and perceived trustworthiness is worth studying, according to the authors.

Other recent research on trust from a Northeastern University-led team looks for cues elsewhere and takes it a step further by actually connecting trust cues to real situations.

The group’s paper, published in the journal Psychological Science in November, had people interact face-to-face with each other or online before playing a game. When subjects interacted with a partner face-to-face, they were better able to predict if the other person would adopt a selfish or cooperative strategy.

Nonverbal cues seemed to be the key. Video records of the interactions showed that selfish players tended to touch their hands and faces, cross their arms and lean away from their partners.

“According to these researchers, we are like robots, programmed to move in particular ways if we are honest,” Scientific American writer Piercarlo Valdesolo wrote. “To know who to trust, one simply needs to be able to read the patterns.”

In a second experiment, the researchers had subjects interact with a robot, Nexi, that was programmed with the nonverbal cues of either selfishness or cooperativeness that were observed in the first study. As with human partners, subjects tended to accurately predict that Nexi would cheat them if the robot showed the subtle signs of untrustworthiness.

Perhaps, while on a business meeting or a date, you might be able to save yourself some grief if you happen to notice the other party appears to be leaning back a lot or crossing their arms.

SOURCE: Kleisner et al. “Trustworthy-Looking Face Meets Brown Eyes.” PLoS ONE 8: e53285, 9 January 2013.