Sunday, March 16, 2003
HealthScout - March 14, 2003
FRIDAY, March 14 (HealthScoutNews) -- While many psychologists believe people use one area of the brain exclusively to recognize faces, a new study suggests they can also use this area to recognize other objects.
"We are trying to understand why we seem to recognize faces in ways that are different from how we recognize other objects," says study co-author Tim Curran, an assistant professor of psychology at the University of Colorado.
Curran notes people recognize faces as a whole, while other objects are recognized piecemeal, with different parts of the brain contributing information to create the image.
"The main reason why faces appear to be different to us is that we are experts with faces, while we are not experts in recognizing other objects," says the study's lead author, Isabel Gauthier, an assistant professor of psychology at Vanderbilt University whose research appears in this week's issue of Nature Neuroscience.
The researchers assumed that if you were an expert in recognizing a class of objects -- cars, for instance -- you would use the same parts of your brain to recognize these objects as you do faces. If this were true, than being an expert in cars would cause the brain to be less efficient in processing information when presented with both a face and car simultaneously, Gauthier says.
To determine if the way people recognize faces might also apply to other objects, the researchers studied 40 men. Twenty of them were car experts, and 20 were not.
The researchers found that when shown pictures that combined faces and cars, the car experts' brain fought to use the same mechanism to identify the car and the face.
"For the car experts, there is some sort of interference that happens within the brain between the recognition of cars and faces, which does not occur if one is a novice in car recognition," Curran adds.
This interference occurs very early in the perceptual process, with both face and car recognition competing to use the same "holistic" recognition process. This result was confirmed by both behavioral and electrophysiological tests of an area of the right brain hemisphere called the fusiform face area.
Similar experiments have shown that people who are experts in a given field, such as bird watchers and dog show judges, also appear to identify these objects in the same holistic way they recognize faces, Curran says.
"It's nothing special about cars," Curran notes. "It seems that when we have more and more experience with a class of objects, we latch on to the same brain mechanism used for identifying faces."
For autistic children who have problems recognizing faces, the study's findings may provide a scientific basis to help teach these children face identification, Curran adds.
Hadyn Ellis, deputy vice chancellor of Cardiff University in Great Britain, disagrees with those conclusions. "The work of Gauthier and her associates is important, but fails to account for well-attested dissociations following brain injury," he says.
Ellis notes there are many reports of patients who have lost the ability to recognize faces yet show superior car recognition ability, or they similarly lose the ability to recognize people but can still identify individual animals.
"Gauthier and her associates must try either to incorporate these data into their model of face processing or explain why they are not relevant," Ellis says.
There is a long history of research and theory on whether faces really are special objects, requiring a specific processing mechanism, Ellis says. "It's not apparent that these researchers have fully consulted the literature and considered all the evidence produced over the last 30 years," he says.
For more on face recognition, visit the Massachusettts Institute of Technology or the Max Planck Institute.
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