Are teenagers too rational? That, at least, is the conclusion of a recent study showing that teens overestimate the riskiness of things like unprotected sex and drunk driving, yet choose to do them anyways:
A study by researchers at the University of California, San Francisco, found that teenagers were more likely than adults to overestimate risks for every outcome studied, from low-probability events like contracting H.I.V. to higher-probability ones like acquiring more common sexually transmitted diseases or becoming pregnant from a single act of unprotected sex."We found that teenagers quite rationally weigh benefits and risks," Dr. Reyna said in a recent interview. "But when they do that, the equation delivers the message to go ahead and do that, because to the teen the benefits outweigh the risks."
For example, she said: "The risk of pregnancy from a single act of unprotected sex is quite small, perhaps one chance in 12, and the risk of contracting H.I.V., about one in 500, is very much smaller than that. We're not thinking logically; they are."
I'm not sure I agree. First of all, a one in 12 chance of getting pregnant is not an inconsequential risk. I think you could easily make the case that rational people, even Bayesians, would still choose to wear a condom given those odds. Secondly, I think the "teens are too rational" theory contradicts recent findings about the teenage brain. The problem for teens is that the rational circuits of the frontal cortex are actually the last to develop. (The development of the brain recapitulates its evolution, so that, in general, the brain areas that were last to evolve are the also the last to develop.) While the have fully functional emotional brains, adolescents often lack the mental muscles to hold these emotions in check. A 2006 fMRI study by neuroscientists at Cornell, for example, demonstrated that the nucleus accumbens, a brain area associated with the processing of rewards (like sex, drugs and rock n' roll), was significantly more active and mature than the prefrontal cortex, which helps us resist such temptations. In other words, teens have reckless sex and drink too much and drive dangerously because their rational brain is at a literal disadvantage. It can't argue back against their impulses.
On a related note, I've recently been enjoying the DVD's of My So Called Life, perhaps the greatest teen soap opera ever on television. The verisimilitude of the show is almost painful. (Did I really talk like Angela Chase, with all those ums and likes and maybes stuffed into each of my sentences? Yes, I did.) And the teens on the show definitely aren't rational. (Well, perhaps Brian Krakow is an exception. His frontal cortex seems fully developed...)
Brain & Behavior
Comments (28)
It could be that they are thinking rationally in some regards, but not in others. To an adult, that 1 in 12 chance of pregnancy, with all that entails, doesn't seem worth it to have a sexual intercourse now, especially when preparations can be made for later. To a teenager, later is fraught with uncertainty, sexual intercourse is a more rare and compelling prospect, and the consequences of pregnancy bear mostly on a later, adult self that the teen does not yet know or understand.
Bayesian calculation of benefit relies on utility functions that cannot be calculated. The same problem in different terms besets others trying to assess risk and reward in a rational fashion. The best argument that the way a teenager evaluates such things is irrational is that they will come to agree with us, when they also are adult. I.e., that maturation will recalibrate their utility functions. That argument is not quite as much a syllogism as some people think. A teenager who aced his logic and probability courses might reply, "So? I'm not adult yet, and I'm rationally trying to maximize my current utility functions."
FWIW, convincing people to take greater account of their future selves is not a problem only with teens. There are plenty of adults who are condemning themselves to stroke, because they won't control their current blood pressure, to penury, because they won't control their current spending, and to a variety of morbidity, because they won't control their current diabetes.
Posted by: Russell | December 18, 2007 3:52 PM