Faces everywere, obsession??

More than a decade ago, Diana Duyser of Hollywood, Fla., received a religious message through an unlikely medium: a grilled cheese sandwich she had made herself. As she gazed at the brown skillet marks on the surface of the bread, a familiar visage snapped into focus.

Golden Palace.com; Oyster shell: Denis Balibouse/Reuters
A grilled cheese sandwich, top, with an image of what some see as the Virgin Mary sold for $28,000 on eBay. Jesus Christ is seen in an oyster shell, a frying pan and a pirogi.
“I saw a face looking up at me; it was the Virgin Mary staring back,” she told reporters in 2004. “I was in total shock.”
After holding onto the stale relic for 10 years, Ms. Duyser put it up for sale on eBay. The auction generated so much excitement that the sandwich eventually sold for $28,000, proving that she was not alone in seeing a face where none should reasonably exist. (Efforts to locate her to comment for this article were unsuccessful.)
Such faces made headlines again near the end of 2006, when Mars Express, an orbiter from the European Space Agency, captured the highest-quality three-dimensional images to date of what looks like a face in the Cydonia region of Mars. The photos reignited conspiracy theories that governments on Earth are trying to hide the existence of intelligent life on Mars.
Why do we see faces everywhere we look: in the Moon, in Rorschach inkblots, in the interference patterns on the surface of oil spills? Why are some Lay’s chips the spitting image of Fidel Castro, and why was a cinnamon bun with a striking likeness to Mother Teresa kept for years under glass in a coffee shop in Nashville, where it was nicknamed the Nun Bun?
Compelling answers are beginning to emerge from biologists and computer scientists who are gaining new insights into how the brain recognizes and processes facial data.
Long before she had heard of Diana Duyser’s grilled-cheese sandwich, Doris Tsao, a neuroscientist at the University of Bremen in Germany, had an inkling that people might process faces differently from other objects. Her suspicion was that a particular area of the brain gives faces priority, like an airline offering first-class passengers expedited boarding.
“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.”
Dr. Tsao used functional magnetic resonance imaging to record which areas of the brain were activated when macaque monkeys were presented with stimuli including fruits, gadgets, scrambled patterns — and faces. She discovered almost immediately that groups of cells in three regions of the brain’s temporal lobe seemed to be strongly attuned to faces.
“The first day we put the electrode in, it was shocking,” Dr. Tsao said. “Cell after cell responded to faces but not at all to other objects.” Her results were published in October in the journal Science.
Dr. Tsao’s investigation yielded a surprising related finding: areas of the brain she had identified as face-specific occasionally lighted up in response to objects that bore only a passing resemblance to faces.
“Nonface objects may have certain features that are weakly triggering these face cells,” she said. “If you go above a certain threshold, the monkeys might think that they’re seeing a face.” In the same way, she said, objects like cinnamon buns, rocky outcroppings and cloud formations may set off face radar if they bear enough resemblance to actual faces.
Pawan Sinha, a cognitive scientist at the Massachusetts Institute of Technology, has devoted years of research to figuring out just what attributes touch off these face-specific pings. Security software that is being developed for identifying potential terrorists or detecting intruders must be able to reliably recognize faces. In teaching the software to do this, Dr. Sinha and his colleagues have arrived at unexpected insights into the question of why we sometimes see a cinnamon bun as a cinnamon bun, and other times as the earthly incarnation of a sainted nun.
To develop detector software optimized to pick out any human face, even in less-than-ideal surroundings, Dr. Sinha began by putting into his computer hundreds of faces as varied as those in a Benetton advertisement famous for its diversity.
As the computer amassed the information, it was able to discover relationships that were of great significance to almost all faces, but very few nonfaces. “These turn out to be very simple relationships, things like the eyes are always darker than the forehead, and the mouth is darker than the cheeks,” Dr. Sinha said. “If you put together about 12 of these relationships, you get a template that you can use to locate a face.”