Researchers from Princeton and Columbia created an online survey containing a series of straight-on headshots of 20 individuals making a number of expressions. The 800 participants were instructed to record their instinctual reactions to each photo, rating the people depicted on characteristics like intelligence, attractiveness, cunning, meanness, and extraversion.
They found that the participants developed completely different opinions of each person depending upon precisely which photo they were shown. In fact, the reactions varied as much between photos of the same individual as they did among photos of entirely different people.
A second experiment asked subjects to choose their favorite photo of each individual for use in distinct situations. In a thoroughly un-shocking twist, the data showed that the respondents' reactions changed when they were provided with context about how each picture would be used. For example, participants preferred one photo when they were told it was for an online dating profile, while they chose an alternate image for uses pertaining to running for political office.
For anyone who maintains any sort of internet presence, these findings are no surprise — after all, you choose your profile pic with the same dedication and consideration you'd use to pick a job-interview outfit. But, knowing that others make split-second decisions about you based on that image — that go way beyond #hotornot — you shouldn't take the choice any less seriously.