Researchers at the California Institute of Technology have found people make negative judgements about people pictured in close-up photos, compared with those who appear in more standard shots.
"It turns out that faces photographed quite close-up are geometrically warped compared to photos taken at a larger distance," graduate student Ronnie Bryan said.
"What you're left with is a warping effect that is so subtle that nobody in out study actually noticed it. Nonetheless. It's a perceptual clue that influenced their judgements."
People pictured in close-up photos looked less trustworthy, according to study participants.
They were also judged to be less attractive and less competent.
"This was a surprising and surprisingly reliable effect," psychology professor Ralph Adolphs said.
The researchers ran several experiments using photos of 18 people - each had one photograph taken from a range of 60cm and another from about 2.1m.
The distances were chosen because one is within 'personal space' - which is on average 90cm to 1.2m from the body - and one was outside it.
In one experiment, people were asked to invest real money with unfamilar people they saw as a measure of how much they trusted them. Another was run online.
The researchers plan to build on their findings by using machine-vision techniques that automatically analyse data in images.
One application would be for a computer program to have the ability to evaluate any facial image in a magazine or online and estimate the distance at which the photo was taken.
"The work might also allow us to estimate the perceived trustworthiness of a particular face image," electrical engineering professor Pietro Perona said.
"You could imagine that many people would be interested in such applications - particularly in the political arena."
The study appears this week in the journal PLoS One.
- Online ODT
