Scientists Find How Our Brains Recognize Faces
January 10, 2012

Scientists Find How Our Brains Recognize Faces

A new study by Massachusetts Institute of Technology (MIT) shines new light on how the human brain can recognize faces, as well as how it can discern actual faces from face-like images or objects.

According to an MIT press release, our minds are often able to see things that resemble faces, such as the New Hampshire's "Old Man of the Mountain." Yet at the same time, rarely do we have difficulty telling the difference between these and actual faces, and Professor of Brain and Cognitive Sciences Pawan Sinha and colleagues sought to discover the biological mechanics behind this ability.

Sinha, lead author Ming Meng (now an assistant professor at Dartmouth College), and associates found that activity on the left side of the brain, in the fusiform gyrus, is responsible for determining how "facelike" the thing a person is looking at truly is. The right fusiform gyrus, which is located on the underside of the brain, then uses that information to quickly determine whether or not an object or image is actually a face.

The Institute's media release says that, although the mind's different hemispheres have divided tasks in dealing with linguistic or spatial perception functions, this is "one of the first known examples of the left and right sides of the brain taking on different roles in high-level visual-processing tasks."

Previous research has illustrated that neurons in the fusiform gyrus have shown a positive response to faces, but in order to study how the brain can discern between faces and face-like objects, they created a series of images of various face-like qualities.

"By doing a series of one-to-one comparisons, the human observers rated how face-like each of the images were. And while the subjects sorted out the photographs, functional magnetic resonance imaging (fMRI) was used to scan their brains and look for activity," Mark Brown of Wired UK wrote in a Tuesday article, adding that they discovered different patterns of activity on each side of the brain.

"On the left, the activity patterns changed very gradually as images became more like faces and there was no clear distinction between faces and non-faces. The left side would flare if someone was looking at a human or an eerily face-like formation of rocks," he added. "But on the right side, activation patterns in the fusiform gyrus were completely different between genuine human faces and face-like optical illusions.  There was no fooling the right side of the brain."

The conclusion, the Wired reporter says, is that the left side of the brain was the part that would rank how face-like something appeared to be, while the right side would make the actual determination as to whether or not the object in question was a person's face.

Their findings were published January 4 in the journal Proceedings of the Royal Society B.


Image Caption: Old Man of the Mountain on 26 April 2003, 7 days prior to the collapse. A late spring snow occurred the night before. Credit: Jeffrey Joseph/Wikipedia


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