How the Brain Reacts to Angry Expressions

The way your brain reacts when you see someone who is scared or angry depends largely on whether that person is looking at you.

But it's not what you'd expect, according to new research.

An angry face looking away from you and a fearful face staring right at you trigger the highest activity in the amygdala, the part of the brain that regulates emotional behavior, says a study in the latest issue of Science.

"Where someone else is looking when they're expressing emotion affects how our brain processes that info," says the study's lead author, Reginald Adams, a postdoctoral fellow at Harvard University in Boston. Adams completed this research while he was at Dartmouth College in Hanover, N.H.

"The amygdala might be useful in detecting a threat and making sense of that threat," he explains. And, he says, if someone is angry and looking away from you, or frightened and looking straight at you, it's hard for you to know where the threat is coming from.

"That uncertainty might add to the threat value. The amygdala just has to work harder to figure it out," he says.

Uncertainty Fuels More Active Response

Adams and his colleagues asked 11 people to undergo functional magnetic resonance imaging, or fMRI. The device allows researchers to see which parts of the brain become active during the test.

The volunteers were shown several different pictures of a man. Sometimes his face was angry and looking right at them. Sometimes he was scared and looking at them. Other times, he made the same faces, but his gaze was directed off to the side. Adams says the researchers actually manipulated the gaze using computer software, so the expression of fear or anger didn't change.

Adams says the researchers said the amygdala was most active for the angry face looking away and the fearful gaze looking directly at the study participants.

He believes the higher response was due to the uncertainty of the situations. If someone is looking right at you with an angry face, you can assume he's angry at you. Likewise, if someone is looking away and he's fearful, you can assume the threat is coming from that direction.

But, if someone is looking directly at you and he's scared, or he's looking away and angry, you probably can't immediately identify the source of those emotions.

"In situations where the potential threat is not as direct, such as with averted anger, there seems to be more response in the amygdala," says Dr. Kenneth Skodnek, chair of the departments of psychiatry and psychology at Nassau University Medical Center in East Meadow, N.Y.

Skodnek says the reason may be that when the threat is immediate, the brain acts reflexively, "without involving conscious thought or any sophisticated processing of the information." As an example he says, if another car pulls out in front of you while you are driving, you instantly jam on your brakes without consciously thinking about it.

But if there's no instantaneous need to react to a threat, such as when someone is angry and looking away from you, Skodnek says it gives your brain more time to process and analyze the threat.

"My understanding of the amygdala is that it is involved in assessing situations in terms of past experience. So the less clear a situation is, the more there would be a focus on going to past memories to try to understand or make sense out of what's perceived as a threat," he says.

Adams says the only immediate practical implication from his finding would be for brain-damaged patients in helping them to understand potential impairments in brain function if the amygdala were damaged.

Skodnek adds that this is another study that shows how complex the human mind is.

More information

To read more about the inner workings of the brain, visit HowStuffWorks.com. To learn more about the amygdala specifically, go to the University of Idaho Web site.

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