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This next story is about a group of researchers who tried to change the behavior of aggressive teenagers by changing the way they looked at faces. The researchers explored how we judge expressions when they're hard to read.
NPR's Alix Spiegel tells us what they found.
ALIX SPIEGEL, BYLINE: All day long we're surrounded by faces. We pass them on the street, nod to them in the elevator. But according to psychologist Marcus Manafoe, most of those faces don't convey strong emotions.
MARCUS MANAFOE: People don't go around the world just smiling or grimacing or frowning. I think the majority of the facial expressions that you come into contact with - people walking past you in the street, for example - will be ambiguous to some extent.
SPIEGEL: And this ambiguity, he says, means that there is plenty of room for interpretation. Does the expression of the man coming towards you have the smallest tinge of threat around the eyes or is that just surprise?
MANAFOE: When you see someone just looking relatively neutral, then it's really down to you which of those interpretations you choose.
SPIEGEL: And research has found that different groups of people see different things. When depressed people look out at the ambiguous faces around them, they see sadness in those faces more often than people who are not depressed. People with anxiety see fear. But it's people with aggression that particularly interested Manafoe and his colleagues.
MANAFOE: People with aggression show a tendency to interpret ambiguity as reflecting hostility.
SPIEGEL: Was there some way to change what aggressive people saw when they looked out at the world? That's what Manafoe and his colleagues wondered. It's not that this tendency to interpret facial expressions as hostile isn't adaptive, Manafoe says. It some ways, it makes a lot of sense.
MANAFOE: If you've grown up in a tough environment where actually a lot of the time people are out to get you, then that default assumption is probably a relatively safe assumption to make. The problem arises when you take that assumption into a more benign environment - into the wider world, if you like - and start responding inappropriately to people who have no hostile intent.
SPIEGEL: Then the strategy that you developed to help you survive becomes a kind of prison. You see aggression everywhere and respond aggressively, which causes the people around you to actually be aggressive even if they didn't begin that way. It's a vicious cycle.
MANAFOE: The question is to what extent can you re-tune or recalibrate people's perceptual biases to better fit the environment that they now find themselves in.
SPIEGEL: So Manafoe and his colleagues went to a youth program for troubled teens - kids whose aggression had already caused problems.
MANAFOE: About two-thirds already had some kind of criminal conviction.
SPIEGEL: And they tried to retrain the way that those kids interpreted faces - that very small simple intervention. To begin with, kids were placed at computers, and asked to identify the emotions in a series of faces that flashed on the screen. Some of the faces were clearly happy, some were clearly angry. But most were somewhere in the middle.
MANAFOE: There were 15 faces along the continuum. They were presented one at a time very briefly, and people were simply asked to judge whether that face was happy or angry.
SPIEGEL: In this first round, the goal of all this was simply to identify the point on the continuum where each teen stopped seeing happiness in an ambiguous face and started seeing anger - their set point. After that, the researchers divided the teens into two groups. One essentially got no treatment. In the other, the researchers attempted to shift the point on the continuum where they started seeing angry faces.
They did this by showing the kids the same faces in the same way. Only, this time after each face, they were given feedback. And here's the trick.
MANAFOE: For two of the faces that they previously would have described as angry, if they called them angry again, the feedback told them, no that wasn't an angry face - that was a happy face.
SPIEGEL: For a week, day after day, the kids looked at the faces over and over, relearning which were angry and which were happy. Then the researchers tracked the number of aggressive incidents the kids were involved in. They followed both the kids who got the treatment and the kids who didn't for weeks, had staff at the program evaluate each teen without knowing whether or not the kids had been retrained. And what they found surprised them.
The kids who had been trained to visually see differently interacted with the world in a different way - came at the world with less aggression.
MANAFOE: There was a 30 percent difference between the two groups.
SPIEGEL: In fact, researchers have been trying this approach of modifying visual biases in other groups, as well - people with anxiety and depression - and have gotten similar results.
Ian Penton-Voak, another psychologist, says the value of the work is clear.
IAN PENTON-VOAK: It demonstrates that the way you see the emotional world around you affects your behavior in a kind of causal way.
SPIEGEL: An insight, he says, which ultimately might lead to new interventions.
Alix Spiegel, NPR News, Washington.
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