A study published in the journal PLOS ONE (through the Public Library of Science) set to find out whether or not eye color influences our perception of trustworthiness. The research team, led by Karel Kleisner of Prague's Charles University, photographed 40 female and 40 male students who had either brown or blue eyes. The researchers then asked 238 participants (mostly students, and two-thirds female) to rate the photographed faces based on perceived trustworthiness, attractiveness, or dominance on a 10-point scale—one meant very trustworthy, attractive, or dominant, and 10 meant very untrustworthy, unattractive, or subordinate.
To see if eye color alone affected trust perception (the main focus of the study), the research team performed a sneaky switcheroo. After digitally swapping blue eyes onto the brown-eyed faces (and vice versa), a second, smaller group of students rated the faces. The eye-opening results: Iris color significantly influenced perceived trustworthiness, with brown-eyed faces being considered more trustworthy than blue-eyed ones.
To their credit, baby-blues were found to be more attractive. Sex mattered too: Female faces were rated more trustworthy than their male counterparts.
Can We Trust It?
Not yet. Before you nix blue-eyed pals from your friends list, or limit yourself to brown-eyed suitors, consider this: The faces rated highest for trustworthiness by the second group pretty much remained the same, even though the eye colors were switched. The researchers then figured there had to be another factor. Kind of.
After measuring facial structure, they found that when it came to people's perception of trust, there was more than meets the eye(s). Faces that rated higher on the trust scale had bigger eyes and broader mouths with upward-turned lips. But why does that matter? The researchers found these facial characteristics are often associated with brown-eyed people, whereas blue-eyed folks tend to be have smaller eyes, longer faces, and eyebrows that are farther apart.
Don't start singing "Brown-Eyed Girl" from the rooftops just yet. While other research may back this study up, it's too small and too limited to be conclusive. Evaluating faces on trustworthiness: an extension of systems for recognition of emotions signaling approach/avoidance behaviors. Todorov A. Annals of the New York Academy of Sciences, 2008, Jun.;1124():0077-8923. Another potentially confounding factor: Blue-eyed people often have longer chins, which may make them look less baby-faced—and research correlates higher ratings of honesty to people with baby faces (not to be confused Grammy Award-winning R&B musician "Babyface").
Moral of the (eye-color) story: The conclusions of this study were just preliminary. As researchers confirmed, further studies are needed on the relationship between eye color, face shape, and trustworthiness in other demographics (and in larger numbers) before we can go trusting the findings fully.
Originally published January 2013. Updated March 2017.