To test the concept further, Nestor and Tarr used an androgynous image compiled from the average of the 200 initial faces. Trial by trial, they randomly clouded the face with "visual noise" that either included more red or green. The "noise" was not unlike static that can appear on a television screen with no signal.
Subjects were then asked to decide on the gender of the image, using nothing more than the random shape and color patterns over the sexually ambiguous face as a guide. Tarr describes the effect as a "superstitious hallucination," similar to being in the shower and hearing the doorbell or telephone even when neither rings.
Three Brown University students participated in the experiment for pay, and they all had normal or corrected vision with no color blindness. Each observer handled about 20,000 trials spread across 10 one-hour sessions.
Once the study was complete, the images identified by subjects as male or female were divided into two piles according to gender.
Each pile of images was then analyzed to determine the average color content across various locations in the images.
Across much of both sets of face images, Nestor and Tarr found that the "male" piles were redder and the "female" piles greener.
Such differences are not absolute some women's faces are much redder and some men's faces are much greener but overall, across this and related studies, Tarr has determined that observers use the color of a face when trying to identify its gender. That is particularly true when the shape of the given face is ambiguous or hidden.
Another study found, for example, that observers are quite sensitive to the color of faces when the facial images are blurred to the point where
|Contact: Mark Hollmer|