Based on this data, the scientists found that humans make split-second judgments on faces on two major measures -- whether the person should be approached or avoided and whether the person is weak or strong.
From there, using a commercial software program that generates composites of human faces (based on laser scans of real subjects), the scientists asked another group of test subjects to look at 300 faces and rate them for trustworthiness, dominance and threat. Common features of both trustworthiness and dominance emerged. A trustworthy face, at its most extreme, has a U-shaped mouth and eyes that form an almost surprised look. An untrustworthy face, at its most extreme, is an angry one with the edges of the mouth curled down and eyebrows pointing down at the center. The least dominant face possible is one resembling a baby's with a larger distance between the eyes and the eyebrows than other faces. A threatening face can be obtained by averaging an untrustworthy and a dominant face.
Using the program and the ratings from subjects, the scientists could actually construct models of how faces vary on these social dimensions. Once those models were established, the scientists could exaggerate faces along these dimensions, show them to other test subjects to confirm that they were eliciting the predicted emotional response, and find out what facial features are critical for different social judgments.
"If you can think of an emotion being communicated by the face as a kind of signal, you can understand that we can amplify that signal into what was almost a caricature to see if we get the
|Contact: Kitta MacPherson|