It's weird, if you think about it. An arched eyebrow, a tense mouth, and we usually know what the person across from us is feeling. How, though? Researchers at Ohio State University think they've located the part of the brain that recognizes these subtle facial changes - "a very tiny, small region that is specifically dedicated exclusively to this task," said Ohio State scientist Aleix Martinez.
It's weird, if you think about it. An arched eyebrow, a tense mouth, and we usually know what the person across from us is feeling.
Researchers at Ohio State University think they've located the part of the brain that recognizes these subtle facial changes — "a very tiny, small region that is specifically dedicated exclusively to this task," said Aleix Martinez, a cognitive scientist and professor of electrical and computer engineering at Ohio State.
Their paper, published today in the Journal of Neuroscience, pinpoints that region as behind the right ear in an area called the posterior superior temporal sulcus. That part of the brain was activated as test subjects evaluated expressions on the faces of more than 1,000 images.
It's more than just fascinating: Martinez said the results might help research into the evolution of language and grammar and could prove useful for those who don't pick up on facial cues, including some people with autism.
"I think it's fundamental for our social life," Martinez said. "Without this region, we would not be able to function normally in society. From the very beginning, we would have such tremendous difficulty understanding what's going on."
Loads of research has been done on facial expressions, what they convey and how quickly people can read them. Movies and TV shows have been made about experts finding meaning in pressed lips or squinted eyes.
"There's a very specific set of facial expressions that have been studied to death," Martinez said.
But finding the part of the brain that identifies those expressions has proven more elusive.
"This is the first study to pinpoint a part of the brain responsible for encoding facial 'action units' — for example, the raising of an eyebrow or curling of a lip," study co-author Julie Golomb, an assistant professor of psychology and director of the Vision and Cognitive Neuroscience Lab at Ohio State, said in an email.
"The idea is that different combinations of action units form different emotional expressions (for example, a happy face versus a surprised face)."
The OSU researchers used MRIs of the brains of college students who looked at photographs of people whose facial expressions indicated that they were disgusted, happily surprised, happily disgusted, angrily surprised, fearfully surprised, sadly fearful or fearfully disgusted.
Those expressions were conveyed through one or a combination of facial features including raised eyebrows and stretched or pulled lips.
The students had two seconds to choose from two of those categories for each picture they were shown. All students showed increased activity in a certain part of the brain, and the researchers mapped that activity and built an algorithm based on nine students.
A 10th student looked at the same images, and about 60 percent of the time the algorithm was able to identify the facial expression the student was viewing based solely on his or her brain activity.
Both Golomb and Martinez were surprised by how similar the brain activity was across the students and how well the algorithm worked.
"This tells us we're probably tapping into something pretty important about how the brain functions," Golomb wrote.