Friday, February 16, 2007

A Face in a Crowd, a Face in a Cloud, a Face in a... Photo Array?

An interesting article appeared in the New York Times this week, on the human tendency to extract facial features from our surroundings. The Virgin Mary in a grilled cheese sandwich, Mother Teresa in a cinnamon bun, and Jesus Christ on a pierogi. Besides revealing a curious cultural bias, this tendency to see faces -- and, interestingly, specific faces -- led researchers to investigate the cognitive underpinnings of this phenomenon.

Dr. Doris Tsao, a neuroscientist in Germany, has been exploring the manner in which humans process faces for some years:

"Some patients have strokes and are then able to recognize everything perfectly well except for faces," Dr. Tsao said. "So we started questioning whether there really might be an area in the brain that is dedicated to face recognition."

Upon further research, it began to become clear to Dr. Tsao and her research team that there is a specific region in the human brain that is particularly attuned to the recognition of faces. But not exactly in the sense that we might expect: it appears that this unique adaptive trait is just as good at finding a familiar face where none is present, as it is at finding true "matches."

...people have gotten so used to seeing faces everywhere that sensitivity to them is high enough to produce constant false positives. This tendency to become hyperattuned to common stimuli may represent a survival advantage. "If you lived in primeval times, for instance," Dr. Watanabe said, "it would be good to be very sensitized to tigers."

Coupled with our ability to instantly spot a face against a backdrop of non-face stimuli, there appears to be an equally strong tendency to impose familiar faces where no familiar face exists, perhaps a residual side-effect of an evolutionary survival strategy. What does this say for the ability of a traumatized witness to pick her assailant's face from a photo array -- particularly when it isn't there to begin with?

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