by: Jon Hamilton
A brain area that recognizes faces remains functional even in people who have been blind since birth, researchers say. The finding, presented at the Society for Neuroscience meeting this week, suggests that facial recognition is so important that evolution has hardwired it into the human brain. “It’s all inborn,” says Josef Rauschecker, a professor of neuroscience at Georgetown University Medical Center. “The structures are all there because nature has put them there.”
Rauschecker was part of a team that studied the brains of six blind people, including Jeannette Gerrard, a retired government worker who lives in Washington, D.C. Gerrard has always relied on voices to identify people, and says that faces were never that important to her. “I knew what my face looked like by touch,” she says, “and I figured a face was a face.”
So she was intrigued when researchers from Georgetown asked her to take part in an experiment that would eventually allow her to see faces using sound. First, the scientists had Gerrard learn to use a special headset fitted with a small camera. By moving her head, Gerrard could make the camera scan across a drawing. The device produced sounds. And as lines or curves came into the camera’s view, those sounds would change. The concept is a bit like tapping your way along a wall to find a stud behind the plaster.
With practice, Gerrard was able to interpret more complex sound patterns that revealed more complicated shapes. Eventually, “I could identify a face by listening to those sounds,” Gerrard says. To find out how Gerrard was doing this, the Georgetown scientists put her in a brain scanner. The idea was to watch Gerrard’s brain while she was using sounds to recognize a simplified drawing of a face, says Paula Plaza, who was in charge of the experiment. “Our interest was looking into the brain,” she says. “What part of the brain is responsible for this perception?”