Slight variations in how an individual face is viewed can lead people to develop significantly different first impressions of that individual, researchers said.
"Our findings suggest that impressions from still photos of individuals could be deeply misleading," said psychological scientist and study author Alexander Todorov of Princeton University.
Previous research has shown that people form first impressions about someone's personality after viewing their face only briefly.
But much of this research has rested on the assumption that an image offers a single, true representation of what a person is like.
The results of a series of studies conducted by Todorov and colleague Jenny Porter, of Columbia University, suggest that there really isn't a static link between face and personality.
"This research has important ramifications for how we think about these impressions and how we test whether they are accurate," said Todorov.
"The findings suggest that the images we post online can affect us in unexpected, and undesired, ways, subtly biasing other people's decisions," Todorov said.
For their study, Todorov and Porter asked participants in an online survey to view and rate target faces on various characteristics, including attractiveness, competence, creativity, cunning, extraversion, meanness, trustworthiness,
The images were all straight-on headshots, taken in similar lighting. There were, however, slight differences across photos of the same individual, reflecting natural variation in facial expression.
Examining participants' ratings of the photos revealed that there was just as much variability in trait ratings based on different photos of the same individual as there was in trait ratings across photos of different individuals.
In other words, different images of the same individual led to noticeably varied first impressions. Moreover, participants tended to favour certain headshots for certain contexts.
So, for example, they tended to prefer one shot of an individual when they were told the photo was for an online dating profile, but they preferred another shot when they were told the individual was auditioning to play a movie villain, and yet another shot when they were told he was running for political office.
The research was published in Psychological Science, a journal of the Association for Psychological Science.