The latest school shooting has renewed calls for gun control laws and security measures. But the age of the boy who killed a teacher before he shot himself -- 12 -- also raises questions about the brain’s development: How could a young boy portray such seeming lack of empathy?

Recent research helps explain what seems so unimaginable. Psychologists talk about two types of empathy, cognitive and affective. Simply put, cognitive empathy is the intellectual ability to understand others’ points of view, whereas affective empathy is the emotional capacity to respond to the mental states of others.

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Although girls seem to develop more cognitive empathy at age 13, most boys don’t show signs of it until age 15. Boys also experience a dip in affective empathy between the ages of 13 and 16, according to a six-year study published recently in Developmental Psychology.

In her lab at the University of Oregon, assistant professor of psychology Jennifer Pfeifer has noted something else related to empathy: a link between experiencing a rejection and subsequently taking more risks than usual. She watches the activity of teens’ brains as they play a computerized game of catch. At some point, the computer-generated images stop throwing the ball to the subject and continue playing catch on their own. The neural indices of distress appear when the subjects realize they have been excluded. Next, the rejected teens play a game, believing the “people” they were rejected by are watching them. The teens who were rejected take more risks than those who weren’t.

The neural basis for empathy may be a system of mirror neurons. These nerve cells are activated both during an action and observing someone else performing the action.

“It’s hotly debated, but there’s some evidence suggesting that the mirror system functions atypically in autism,” Pfeifer said.

Researchers are just beginning to explore methods of repairing the system when it appears to be dysfunctioning.

“There’s also pretty good evidence that there are wide individual differences in how much systems are engaged in response to seeing someone else in distress,” Pfeifer said.

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Roger Griffin, a professor at Oxford Brookes University in England and expert on terrorism, understands the challenges in understanding empathy from both a personal and professional standpoint.

As the author of "Terrorist's Creed: Fanatical Violence and the Human Need for Meaning," he knows that fanatical violence and sociopathic killing usually involve a dysfunction in empathy. And, from the way boys of his son's age (14) behave with their peers and parents, he sees that even those who seem well-adjusted, socially well-integrated, and academically successful occasionally have lapses in which empathy is replaced by violent verbal outbursts and threatening physicality -- a pattern he believes is fueled by video games that celebrate violence and criminality.

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“The capacity for empathy is suspended at least temporarily in that moment of violence,” he said. “Human beings have a disturbing capacity for creating a space within their imagination where a category, or part, of the world is replaced by a symbolic consciousness. So you’re not killing the person -- you’re killing the symbol of what you hate. So if you hate school, you might kill a schoolteacher.”

This plays out across many mass killings and acts of terrorism, he points out: the Twin Towers, for example, symbolizing the West and capitalism, overshadowing the real human beings in the buildings.

“It’s a very powerful tribute to the complexity of human imagination,” he said. “But when it goes wrong it’s terrifying.”

Research may not only help understand how extreme violence occurs, but it could be used in figuring out ways to teach empathy.

“We may have to teach kids in different ways," Pfeifer said. "Systems may be plastic at different periods."

Of course, teaching empathy and emotional intelligence is just one part of solving an extremely complex puzzle of violence.

“All schoolteachers and parents should be proactively educating kids about empathy, but at the end of the day there are limits to how much you can prevent,” Griffin said.