The Frontal Cortex

The Teenage Brain

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…)


  1. #1 Russell
    December 18, 2007

    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.

  2. #2 peggy
    December 18, 2007

    Your explanation, that such decisions are made because the part of the brain associated with processing rewards is more developed in teenagers, is certainly plausible. It is also wonderfully illustrated in a scene from the movie Animal House, where Pinto is tempted to have his way with the underage girl when she gets drunk and passes out and an angel and a devil appear over his shoulders to debate the options. Doesn’t he end up taking her home in a shopping cart? That would be the nucleus accumbens talking.

  3. #3 Scott Jensen
    December 18, 2007

    If it is true that their rational brain is at a literal disadvantage, should we focus our parenting to their emotional brains? I was hoping that I could teach my children rational reasons for doing something, instead of having to resort to emotial reasons (fear, shame, ect.)

    Could this argument be used as a reason for religion? Religion is usually not rational, so seems useless to adults. Perhaps it could serve a purpose for teenagers and their fully developed emotional brains? I hate to go there, but I hadn’t thought of current brain development as a factor to the “why does religion exist?” question.

  4. #4 JYB
    December 18, 2007

    I think the author means “rational” in an economic sense rather than a “good judgement” sense.

  5. #5 peggy
    December 18, 2007

    I think Scott just opened up a whole can of worms.

  6. #6 Alan
    December 18, 2007

    According to Robert Sapolsky of Stanford, the frontal cortex is not fully mature until sometime in one’s 20s. He ventures that this fact alone explains a lot of frat/sorority house behavior. So, assuming he is correct, and without getting into the semantic argument of what it means to “mature,” how can use of an undeveloped frontal cortex, that seat of reason (smiling), give rise to more rational decisions? How old was the researcher doing the study?

  7. #7 peggy
    December 18, 2007

    Actually, having just read this article through to the end (and coming away shaking my head), I would reply to Scott that the advice given for dealing with teenagers has nothing to do with appealing to their emotions versus playing to their underdeveloped reason. It is simple: supervise them. Prevent them from having to confront situations in which, although they will weigh the benefits and risks “rationally,” they will come to the conclusion that the benefits outweigh the risks if they really want to do something. In other words, they don’t have enough experience or intuition to “know” how to weigh the two against each other and get the “gist.” (The article says this, or something like it.)
    I guess the idea is that as people’s brains and bodies mature, they need adult supervision so that they can gain experience and acquire intuition. Presumably, at some point they get old enough (let’s call it maturity) not to require adult supervision any more, having presumably figured out how to weigh apples and oranges, I mean risks and benefits.
    So it turns out that we have to mature before we can be trusted to use our reason and trust our intuition (this strikes me as pretty obvious), so parents just better get used to the idea that they need to actually be present to raise their children and must learn to either live with fear (rational or not)during that long in-between period when their children are acquiring intuition but don’t yet have wisdom, or stick close by their growing children at all times to make sure nothing bad happens due to this inability to correctly assess risks versus benefits.
    Is it just me or is this all kind of obvious? What does it suggest about trying to “reason” with very young people?
    And as one poster so astutely noted, some people manage to go from youth to old age without ever acquiring the wisdom of maturity, and continue to incorrectly weigh the risks and benefits. Either that or they weigh them but are unable to choose the beneficial behavior over the risky one. Finally, what about consciously taking a risk knowing full well that you might fail? Isn’t that part of the excitement of being human?

  8. #8 alice
    December 18, 2007

    These kids aren’t being rational, they are rationalizing.

    “Oh baby, just this once, you won’t get pregnant!”

    “Don’t worry, I’ll pull out, I promise.”

    Weighing risks in the heat of passion?….not likely.

    Jonah, you use the word verisimilitude more than any writer on the planet

  9. #9 jonah
    December 18, 2007

    but isn’t it a great word! thanks a lot for the tip, alice. i get in weird word ruts, but o promise not to use for the rest of the month…

  10. #10 TJ
    December 19, 2007

    It seems to me that teenagers aren’t actually thinking rationally –they are actually “overestimating risks”, but in the end, they are acting rationally. The study, i think, is an outcome-oriented evaluation of rationality rather than a process-oriented evaluation. The nucleus accumbens might overpower cues from the prefrontal cortex, but the balance of influence results in an outcome that happens to be an accurate assessment of risk, at least in the case of something like sex. I don’t think the study, as i see it, is off the mark.

  11. #11 Gyan
    December 19, 2007

    Jonah, your rebuttal puts the cart before the horse

    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.

    If teenagers indeed act more rationally, then the neurological schema of rational cognition needs to adapt to that instead of treating itself as a fixed reference point i.e. circuit X controls rationality, and since circuit X isn’t mature in teenagers, ergo they can’t be as rational.

  12. #12 peggy
    December 19, 2007

    It is interesting from a sociological perspective to look at the purpose and claims of the article itself.

    1. Starting with the title: Teenage risks and how to avoid them. The article is aimed at parents and the goal is to prevent their teens from exposure to risks that are rightly or wrongly associated with this sub-population (specifically, unwanted pregnancy, irresponsible drinking and driving). Question: Are teens more exposed to these risks than other groups? This is not documented in the article, which begins with an anecdote. It mentions teens, cars, excessive speed and death. It also mentions that one of the dead is a 68-year old van driver who was killed by the speeding teens. He was exposed to this “teenage risk” but could not avoid it.
    2. Following from 1, risky behavior is more common among teens. Is this true? Again, this assumption is never questioned or backed with any evidence, except the anecdotal, in this article anyway.
    3. Teens overestimate risks. This claim is suposed to be “scientifically proven,” so let’s accept it as true. But what about benefits? Maybe they overestimate those too, by an even greater margin, which is why they say the benefits outweigh the risks. And maybe they are right most of the time, some of the time or once in awhile. The article does not say.
    4. Following from 2 and 3, the psychologist claims that an analytic approach doesn’t work with teens because it leads them to believe that the risks their parents and educators want them to avoid are acceptable. The psychologist even says it’s a bad idea to give them the real numbers on the risk of certain behaviors because then they’ll know these behaviors are not as dangerous as they mistakenly believe. In other words, teens should not have the facts if these facts could be used to do things adults don’t want them to do. Don’t confuse these addled risk-takers with the facts!
    5. Following from 2, 3 and 4: Teens must be protected from themselves.
    6. Therefore, parents (and presumably other qualified adults) must supervise them at all times to ensure that they have no opportunities to drink, drive or have sex.

    We can talk about brain development, which is certainly a more fruitful way to approach the subject, but the fact remains that all this article (and the psychology it is based on) does is mirror our current social reality and play on fear. American parents may be the ones who are overestimating the risks their teenage and other children are exposed to. Maybe that’s why they drive them everywhere, overschedule “safe” activities, and monitor their whereabouts at every moment. The sociological/psychological research here is basically reassuring them that their approach to parenting, the 24/7 supervisory approach driven by the belief that the world is a terrible and dangerous place, is the right one.

  13. #13 Scott Jensen
    December 19, 2007

    Thanks Peggy for the reaffirming comments. You expressed my thoughts so much better than I could.

  14. #14 alice
    December 19, 2007

    How’s about this?

    Teens are at the beginning fo their sexual career. If our society were not set up the way it is… with universities to go to and careers to attend to and houses to buy before ever considering having a child, these teens would be right on track to want to screw their brains out and have as many kids they could before some famine came or some big beastie killed them off or they died a natural death at age thirty.

    We’re trying to hold back the tide of nature. And we, for the most part, do a pretty good job of it.

  15. #15 peggy
    December 19, 2007

    I knew there had to be some good explanation for why our society is set up the way it is.

    Lions and tigers and bears, oh my!
    Degrees and houses and jobs, oh my!

  16. #16 M.L.
    December 19, 2007

    I’m sorry to waste comment space, as this is really replying to the comments, and not the post, but . . .

    alice, you are horribly disconnected from teenage life. While I am glad that so many teenagers are concentrated on going to universities and doing well, there is so much emphasis placed on this in the wrong way. We’re a generation that’s afraid of paper. If a teacher likes a banal style of writing, the student usually adheres to it in order to get the best grade. If a student knows they can get a better grade by reading CliffNotes than by reading the actual book, they’ll do it. And don’t get me started on cheating. Indifference is rampant because they see no freedom in the future. Most of my peers don’t read books or newspapers or even blogs. To them, nothing matters, nothing can change. Still wondering why the “emo” culture has flourished?

    They drink, smoke, and have sex because they want to escape. Most who abstain are just afraid of repercussions. Very few do for the best reason, because they posess a rich intellectual life and a good circle of friends. I am not convinced that this happens solely because the brain has not completed its growth. If I wasn’t lucky enough to know people who are beyond trivialities, I would, but this is not the case.

    I’m not against universities, or houses for that matter. A “good” job is subjective, I want a job that will make me happy. What I am against is not having a choice of whether or not I want those staples of modern “happiness”. So give us a choice. A clear cut path is only stifling our youth.

    We may not have all our logical screws in place, but locking us up in cinderblock prisons isn’t the answer. I go to an all-girl’s school, and all I see are Lydias, very few Elizabeths. It’s a shame, because I also see so much potential.

  17. #17 M.L.
    December 19, 2007

    I forgot to thank peggy for her lovely comments.

  18. #18 alice
    December 19, 2007

    “Oh Lord, please don’t let me be misunderstood!”

    ML, what the heck are you talking about?

    My comment had nothing to do with universities, houses or careers. It had to do with the humor I find in wondering about the sexual proclivities of teenagers.

    My point is that if it weren’t for our societal rules which have emerged rather lately in the history of our species, the unprotected sexual activity of our teenage population would be no cause for comment or concern.In fact, it would be accepted and encouraged.

    Put another way, we are living in a world which we weren’t designed to live in, but ironically is of our design.

    I am sorry that your angst is so intense. You live in the freest place on earth. Hopefully some day you’ll appreciate it and quit whining.

    Sorry, no lovely comments to thank me for.

  19. #19 alice
    December 19, 2007


    I fear I may have answered you in an unkind way and now that I realize you are just a kid and don’t have the tough hide of an old broad like me, I would like to say just a few things which may make you know I’m not as out of touch as I may have seemed.

    First, I hope you now understand what I was saying about teenage sex being the most natural thing in the world and that it is only our current societal restraints which make it “a problem”. This is not to say that I think teenage pregnancy is a good thing…..much better to wait.

    But more than that….all the stuff you are experiencing at school, in your peer group and with your teachers is NORMAL.

    It has always been this way, even back in ancient Chicago, where I attended all girl’s schools.

    Life sucks, but you learn your way around it and you get stronger and pretty soon you get to smile because you are wise.

    Hang in there.

  20. #20 M.L.
    December 20, 2007

    Thank you for your response, alice. I’m sorry if I misunderstood your comment initially.

  21. #21 FairEconomist
    December 20, 2007

    The article doesn’t go into the science, but “rational” in the economic sense really just means “consistent”. Somebody who enjoys russian roulette is “rational” if they’re willing to pay twice as much, or endure twice as much of some privation, to play it twice as often. Probably all it means to say that the teens are “rational” is that they really want to get laid and so a 1 in 12 chance of pregnancy or a 1 in 500 chance of HIV is “worth it”. Not really a big surprise.

    It’s true that in times past having children early was perfectly reasonable in many circumstances. What’s disturbing is that although in our society it’s worse for people to have children early it’s better for their genes. Because pretty much everybody survives to reproduce in the developed world, genes that induce their carriers to have more babies make more copies and become more common. This reduces quality of life for the carriers, but genes don’t “care” about that. Our safe secure lives will breed us into baby machines, probably including increasingly reckless teenagers.

  22. #22 alice
    December 20, 2007

    “genes that induce their carriers to have more babies make more copies and become more common.”

    See now that’s a statement that makes sense evolutionarily and theoretically, but several questions emerge.

    1)Since any living thing has genes which come from parents who had genes which induced it to have babies what makes a difference? The “more”?

    2)Are you saying that big families are genetic?

    3) and is there a gene for “more”?

    It seems that the condition of abundance would tell the living thing that it is OK to have “more” offspring.The condition of abundance also allows more offspring to survive. So is it genetic or environmental?

    Ironically, it is the third world countries that have “more” babies.

    I am only an amatuer at understanding this stuff (obviously), but I figure the best way to learn is to jump
    right in.

    And from what I understand about science, one must learn to ask the right questions.

  23. #23 EANMDPHD
    December 20, 2007
    Tannhäuser’s Dilemma
    A Study in Rational Choice Hermeneutics

    Perhaps Tannhauser was a teen-ager, with an ulterior motive:

    At first sight Tannhäuser’s behaviour in the song contest is indeed puzzling. Departing from
    all courtly rules he interrupts the songs of his fellow knights, harshly attacking their views of
    the nature of love. As such this would already be disturbing but Tannhäuser goes one step
    further: He praises Venus, the goddess of erotic love, and confesses to having spent time at
    her grotto of sin, the Venus mountain, upsetting the entire court and deeply hurting Elisabeth.

    This apparently self-damaging behaviour is attributed to Tannhäuser’s high-rising emotions,
    his inability to exert self-control. Yet, a few minutes later this stir of emotions seems to have
    subsided and Tannhäuser falls in line with the verdict of the court and, calmly accepting his
    fate, decides to go on a pilgrimage to Rome. This sudden change of heart has been viewed as
    inexplicable and some authors (as we shall discuss in more detail below) have argued that
    Wagner’s libretto simply does not make sense here.

  24. #24 peggy
    December 20, 2007

    I was attending a charity event (ironically, to raise money for distressed young people) and therefore missed the exchange of views above until now. I have a few random thoughts on the comments.
    First, intuitively I agree with ML that teenage life in America today is highly constricted, and that we are placing the wrong emphasis on education and success. Collectively, we as a nation are driving our children everywhere, literally and figuratively. We are fearful, and we are teaching them to be afraid. We are teaching them that money and success are the only things that matter. We are increasingly drawn to churches which teach us that greed is good. As Oscar Wilde said, in defining the cynic, we know the price of everything and the value of nothing.
    I graduated from a public high school in 1974. It was (and still is) considered to be one of the “worst” in its school district, but the substandard level we were exposed to did not stop my brother from getting a full scholarship to Harvard and me from getting full ride offers from several excellent schools. Today, this would be unthinkable. To go anywhere but the local community college, one has to start early by getting into the right kindergarten. I remember when Americans used to laugh when told this about the Japanese.
    Last night at the charity event, a woman told me that she had to go home and write an essay as part of her daughter’s application to an elite private middle/high school whose annual tuition is more than what a year at Harvard cost when my brother was there. Her daughter is in the sixth grade!
    Second, I can understand ML’s consternation as she looks around her, and I think I would feel it too if I were a teenager today. If it’s any consolation ML, it sounds to me like you have identified what really matters (a rich intellectual life and a good circle of friends). I don’t like to give advice, but mine to you would be this: stay focused on that goal all your life and remain open to possibility. According to the article, your brain is supposed to be a few years away from “delivering” this message to you.
    Speaking of which, I know nothing about the science of brain development, but it seems logical that this development would be gradual and not off/on like a switch. I found the article very reductive in its approach to the brain in general and the teenage brain in particular.
    Third, I disagree with the statement that we live in the freest place on earth. We love to think so and say so, but this is open to debate. And even if we accept it at face value, I think that what we as a nation have done with our freedom, particularly in the past six years or so, is appalling. That is just my opinion and this is not the forum for debate on the topic of freedom, but there are some very good reasons why America does not score the highest marks on the human rights watch front.
    Finally, I don’t know enough about genetics to weigh in about the “selfishness” of genes and the proliferation of those that “induce” people to have more sex and make more babies. But it sounds pretty fishy to me!

  25. #25 Alan
    December 20, 2007

    ML’s viewpoints echo those of some kids I know, and I find myself intuitively in agreement. Many teenagers today reject the prefab model of jumping on a hedonic treadmill desperately pursuing a life of overwork and overconsumption, in order to afford the best retirement money can buy. Is this an attractive model of living one’s life? Some people can reasonably answer, no.

    These kids are also coming of age during some of the most cynical times we have ever experienced. Does it help to tell anyone, essentially, life is not worthwhile, but get over it because you’re free, and then you’ll learn to gloat internally over the (illusory?) sense of satisfaction that you’ve achieved wisdom? Interesting ….really?

    The objective of cultivating a rich intellectual life and close circle of friends demonstrates a substantial degree of emotional intelligence, and seems a very positive outlook. ML is making very good sense and does not deserve condescension.

  26. #26 alice
    December 20, 2007

    I have been thinking a lot about my “conversation” with ML and I am moved to say a few more things to her.

    I am probably most interested in you for a couple of reasons. One is that I remember very clearly what it was like to be a teenager. I also have a daughter who has made it through those high school years relatively recently and relatively unscathed so your situation seems close to home. I realized only after I pushed the “post” button that you were a high school student. Bad reading on my part.

    Your complaints about the world, which apparently Peggy and Alan agree with, are very common in the young. At that age we see all kinds of things we don’t agree with and don’t understand. As one matures, it seems to me, you begin to realize that there will always be things you don’t agree with and don’t understand and that this is just the way life is and you have choices about how you will respond to those things. As far as “not agreeing”, as an adult you will have opportunities to walk away or try to change or maybe you can choose to just complain. As far as “not understanding” you can educate yourself.

    As for you, I think you have guts and curiosity, two characteristics which are very valuable in this world. These characteristics are evidenced by the fact that you entered this forum and voiced your opinion.

    I think this is a great learning opportunity and I encourage you to do more of it. It will help your to hone your debating skills so that you can take on both your teachers and your peers and encourage them to listen to you and take your well chosen thoughts seriously and it will also teach you that just because someone doesn’t agree with you that it is not the end of the world.

    And to Alan, I didn’t actually say that life is not worthwhile nor do I believe that.

    I also never intimated that university, career and big house are the way to happiness nor do I believe that.

  27. #27 peggy
    December 20, 2007

    To Alice,
    I don’t mean to quibble, but you did state quite clearly that life sucks (not the same as life is not worthwhile, but a fairly gloomy assessment nonetheless), and that is actually another statement I disagree with.
    I also think that ML’s criticisms–not complaints–are very specific and detailed. In fact, they are related to her experience as a young person at this time. While there may be some truth to the notion that people of her age see lots to not like in the world, I think it is a little unfair to dismiss what may be very real concerns about values with a dismissive “that’s how people your age have always felt.” Of course we learn as we mature how to choose the battles worth fighting and not letting the others eat away at us, and we spend time figuring out how we want to live, love and be in the world. As I read ML’s post, it seemed to me that she was doing just that.
    The world I lived in at 18 was different in many respects from the one we live in now, just as the world my mother lived in at 18 was very different from mine. Personally, I find it refreshing and inspiring that someone who is about that age today is critical of some of our current values. I guess that’s ultimately why I would not dismiss ML’s distress and observations as typical of an age or level of maturity.

  28. #28 sARAH c. dEMPSEY
    September 29, 2008


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