For the controlled poses, the observers accurately judged extraversion and self-esteem. When participants looked at the naturally expressive shots, which revealed dynamic non-verbal cues, they were nearly spot-on, getting nine out of the 10 traits correct (everything but political orientation).
For instance, both the neutral and expressive photos garnered about a 70 percent success rate.
"Extraversion is one of those things that's probably the easiest trait to judge," Naumann told LiveScience. "Even without seeing whether someone is smiling or not people can pick that up."
But when judging likeability, observers got it right on average for 55 percent of the photos with neutral poses and 64 percent of the expressive photos. Similar results were found for agreeableness, with participants judging correctly 45 percent of the time for neutral poses compared with 60 percent in the expressive images.
Beyond pure science, the researchers say the results, which will be detailed in the December issue of the journal Personality and Social Psychology Bulletin, have practical implications.
For example, if you want to come off as an extravert, try to smile more, stand in energetic and less tense ways, and gear your overall appearance to look healthy (as opposed to sickly), neat and stylish, the study found. For those interested in seeming open to new experiences, it'd be best to show off a distinctive style of dressing rather than a healthy, neat appearance.