Science, Tech & Environment

Research suggests a new reason for teens' risky behavior

Neuronal_activity_DARPA.jpg

Neuronal activity in a human brain.

Credit:

Defense Advanced Research Projects Agency (DARPA)

According to current research, teenagers make bad decisions and take too many risks because the prefrontal cortex, the decision-making center, is still developing until around age 25. Now, new research suggests this may not be the case.

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Dr. Dan Romer and his colleagues at the University of Pennsylvania took a look at the research and didn’t see sufficient evidence for the "structural deficit" theory in the literature. Yes, the brain’s not fully developed in teens, they say, but that’s not the problem behind bad decision making.

Dr. Romer says most teens actually aren’t impulsive. In fact, they’re sort of hyper-rational. Their risky behavior is a choice teens make that is driven by a desire to explore the risk in favor of gaining experience. So, it’s not a structural deficit that’s causing this. Instead, it’s a desire to gain experience.

The conventional wisdom seemed to make a great deal of sense: The underdeveloped pre-frontal cortex creates an imbalance between the decision-making center and the regions in charge of motivation and reward, which have already matured. Researchers used this to explain why teens have poor impulse control or why they take risks that adults probably wouldn’t, the theory being that the reward center is motivating the teen and the prefrontal cortex just isn’t prepared to put the brakes on, so to speak.

But Dr. Romer points out that if risky behavior in teens was simply a function of biology, then more teens would probably have this problem. But, in reality, only a handful of teens are making the impulsive decision to drink and drive, for example, or to have unprotected sex. If this behavior were solely based in biology, there really should be a higher prevalence of it. 

What’s more, Romer says, if a "brain imbalance" was the issue, then one would expect teens to be worse at controlling their urges than younger kids. But this, too, is not actually the case. When teens are given a mature version of the classic marshmallow test — the one in which kids can choose between eating one marshmallow now or two marshmallows in five or 10 minutes — teens are pretty good at weighing their choices.

In the teen version, kids are told they can have $2 now or there’s a 50/50 chance they will later get either $4 or nothing. When the probability of an outcome is clearly laid out, either a reward or the risk of punishment, they are better able to use the information to make a successful decision than younger kids.

The bad news, of course, is that teens are still going to make risky decisions, even if it’s not due to an underdeveloped prefrontal cortex. This is especially true when teens don’t have sufficient information available to them. When they’re making a decision under ambiguous circumstances, they’re going to take more risks than adults because they’re going to want the experience.

But as almost any parent will tell you, a scientific explanation is small comfort when you hand over the keys to the car, because the bottom line is this: Teens are going to be teens, no matter how the science explains it.

This article is based on a story that aired on PRI's Science Friday with Ira Flatow.