Simon Ciranka: How Brains, Peers, and Environments Fuel Risky Behaviors in Teens

Show Notes for Episode #4 of Unraveling Behavior

March 04, 2025

In this episode, I am joined by Simon Ciranka, a cognitive scientist and developmental psychologist, to explore why teens take risks. Simon explains that parts of the brain that pursue rewards develop early, while parts that control impulses develop later. This imbalance makes teens especially sensitive to rewards like positive feelings and experiences. We also discuss the role of environmental factors. Since severe consequences are rare, teens often experience the rewards of risky behavior without facing immediate negative outcomes. This can foster a false sense of security and diminish caution. Societal guardrails, such as legal age limits for driving or drinking, further shape when and how adolescents take risks. Our conversation extends to peer relationships, which can have both positive and negative effects. While peers can offer valuable lessons from others' mistakes, they can also push teens toward riskier decisions. Teens often think risky behaviors are more common among their peers than they really are, which can lead to more risk-taking. We also explore effective strategies for reducing dysfunctional risk-taking, such as early education and correcting wrong beliefs about how common risky behaviors are. By the end of this episode, listeners will better understand why teens take risks—not as a sign of recklessness, but as a complex interplay of developmental, social, and environmental factors.

Watch the interview on YouTube (curated subtitles: English, Deutsch, Português). Listen to the episode on Spotify, Apple Podcasts, and other players, or subscribe via our RSS feed.

© Max Planck Institute for Human Development

© Max Planck Institute for Human Development

Timestamps

00:00 Introduction
01:04 Brain development in teens and sensitivity to rewards
05:28 Adolescent risk-taking isn’t just about brain imbalances
06:14 Risk-taking in college students
07:15 Laboratory studies vs. real-world findings
10:08 Legal age limits and chances to take risks
13:05 The “Law of Effect” and its role in shaping future behavior
14:40 Teens can feel safer than they really are
18:27 Cumulative risks and severe harms
22:49 Brain imbalances and the environment
23:49 The purpose of risk-taking
27:38 The importance of early education
29:58 Learning from others’ mistakes
32:28 Teens misjudge how often their peers take risks
35:15 Correcting wrong beliefs through school interventions
36:28 Summary

Transcript (edited)

Sofia Morais: Simon, thank you so much for joining us today. It's truly an honor to have you on the podcast.

Simon Ciranka: Hi, Sofia. Yeah, it's nice to be here. Thanks for having me.

Sofia Morais: Many people link adolescents’ tendency to take risks to the fact that their brains are not yet fully developed. What changes are happening in the brain during this stage of development that may contribute to risk-taking?

Simon Ciranka: The easiest or most encompassing definition of risky behavior is doing something where something rewarding, something good, could happen—or something bad might happen—with some probability, and you don’t know for sure which it will be. What’s most pronounced and relevant for risky behaviors is that the incentive or reward-processing regions of the brain are already nearly fully developed at this stage.

Sofia Morais: Can you define reward?

Simon Ciranka: Reward is basically anything that feels good. It’s one of the main motivators of behavior—seeking out experiences that feel rewarding or good makes us want to repeat them. For instance, a reward could be the gummy bears in your desk drawer that you use to stay motivated while working on something complicated. You might give yourself a little treat in between tasks to stay engaged.

Sofia Morais: And could it also be, for instance, a good feeling?

Simon Ciranka: Yeah, absolutely. That’s exactly what it is.

Sofia Morais: Or the approval of other people? Could that also be a reward?

Simon Ciranka: That also feels good. Some researchers even say that reward processing is at the core of forming any kind of behavior. It’s not just that it feels good in the moment—it’s also the anticipation that it will feel good. So the brain processes this prediction of a good feeling. Then there are other brain regions that are responsible for controlling our impulses and projecting ourselves into the future, but these regions develop more slowly. So, what people think drives the propensity of young people to take more risks than older people is that there’s this imbalance. The reward-processing brain regions are already nearly fully developed, but the impulse-control regions take longer to mature, sometimes until the mid-20s.

Sofia Morais: So, you’re saying there’s an imbalance between the parts of the brain that are sensitive to rewards and the parts responsible for thinking about consequences and impulses?

Simon Ciranka: Exactly. Or for controlling our impulses, I think that’s more specific. And that’s why some researchers say adolescents are like someone driving a car, where the gas pedal is fully pressed, but the brakes aren’t working as well. It’s a really nice metaphor to understand how these brain regions work together during this stage of life.

Sofia Morais: What are the names of these brain regions?

Simon Ciranka: The most relevant brain region for reward processing is the nucleus accumbens. It’s deep in the brain and very old evolutionarily because it plays such a big role in shaping behavior. For impulse control, we have regions like the prefrontal cortex and the dorsolateral prefrontal cortex, which is right in front of our forehead—‘pre’ meaning ‘before’ the front. And when you think about brain development, the parts that are evolutionarily older develop earlier, while the prefrontal regions came much later in evolution, so they take longer to mature.

Sofia Morais: So, mid-20s you were saying?

Simon Ciranka: Yes, mid-20s is what they say.

Sofia Morais: Some research suggests that adolescent risk-taking isn't just about brain imbalances. What findings challenge this idea?

Simon Ciranka: If it were only about brain imbalances, we’d expect risky behavior to peak during the time when the imbalance is greatest, which is usually between ages 14 and 16. That’s when we see a lot of activity in the reward-processing regions, and not enough in the prefrontal brain regions. But that’s not actually when we see the most risk-taking. The biggest risk-takers in Western societies seem to be college students in their early 20s, when the maturational imbalance should already be leveling out. So, there has to be another explanation for risky behavior.

Sofia Morais: And in the case of college students, what sort of actions are we talking about? Is it dangerous driving? Drinking?

Simon Ciranka: Yes, those are common examples. When we talk about risky behavior in the real world, we often mention things like unprotected sex, binge drinking, or substance abuse. More generally, thrill-seeking behaviors are involved—things like risky driving, but also in some of the assessments, riding a bike without a helmet could be considered a risky behavior. It’s a very broad range of behaviors.

Sofia Morais: And when scientists do studies on risk-taking behavior in the lab, do they also find that this group—college students—are the biggest risk-takers?

Simon Ciranka: In the laboratory, what you actually find is that younger people—perhaps even younger than the age range where this imbalance we've been talking about occurs—are the biggest risk-takers. In the samples we've been collecting, we defined childhood as being before 12 years old, mostly 8 to 12 years old. And within that group, the youngest—so the 8-year-olds—are actually the ones taking the most risks. So, that doesn't quite align with the idea of a peak in extreme risk-taking that is often assumed to occur during adolescence.

Sofia Morais: Do scientists know what kinds of factors might explain the differing conclusions between, you know, studies that look into real world behaviors and studies that look at risk-taking in the lab?

Simon Ciranka: One explanation I really like, because it helps you think about what you’re actually measuring in the lab, is that experience differs between age groups, and opportunities to take risks also differ. For young people and adolescents, they usually have a set time to be home. They usually have teachers and parents looking out for them. So the opportunities to engage in risky behaviors are much more limited compared to young adults, who don’t have those societal barriers. That’s one thing. In the experiments, you put everyone in the same situation, give everyone the same task, and the same constraints for behavior. So, the environment is the same for everyone. This risky behavior we’re interested in with young people may be related to this maturational imbalance in the brain, but also to the environments that individuals are in. These environments change as we grow. So, the environment that a 10-year-old lives in is very different from the one a 14-year-old experiences, and that’s really different from the one that older people experience.

Sofia Morais: This brings us nicely to an article you published in 2023 with Ralph Hertwig in Trends in Cognitive Sciences. In this paper, you argue that people's willingness to take risks as they grow isn’t just about brain imbalances, but also how they interact with their environments. You identify two environmental factors that might lead to greater risk-taking. One of them, as you’re saying, is greater opportunities to take risks. Can you explain how this works in the real world?

Simon Ciranka: In this article, we use an example of driving, and also binge drinking behavior, because these are things where opportunities are different in different countries. We can ask the question: how much does the environment actually influence our conclusions about age trends in risky behavior? For instance, with risky driving. In Germany, people are allowed to drive when they’re 18. In other countries, people are allowed to drive at 16, and sometimes even earlier. You can look at accidents as a manifestation of risky driving behavior and see how accident statistics differ across age groups. It becomes clear that as soon as young people are novices—adolescents doing something for the first time with little experience—they get the opportunity to engage in risky behavior, and accidents happen more often. That’s one way to look at it. You can also look at behavior directly. For alcohol consumption, there are similar regulations in different countries. In Germany, young people can drink at 16, in other countries at 18, and some countries at 21. You can look at alcohol consumption by these groups and see that once people reach the legal drinking age, their alcohol consumption goes up. It doesn’t matter if they’re 16, 18, or 21—it increases. This shows how societal guardrails and opportunities for risky behavior in an environment shape the outcomes we see in the real world.

Sofia Morais: Another way the environment shapes risk-taking is through the so-called law of effect. What exactly is the law of effect, and how does it influence our behavior?

Simon Ciranka: The principle of conditioning, and the law of effect, is what we’ve been talking about before. If something feels good or leads to rewarding experiences, if my behavior has an effect on the world that I like, I will do it again. This can generate very complex reward-seeking behaviors from a very simple principle: if I do something nice, I will do it again.

Sofia Morais: And negative experiences would increase caution?

Simon Ciranka: They would increase caution. That’s the hot stove effect. Psychologists like to have funny names for these effects. The hot stove is like a cat sitting on a hot stove for the first time, realizing, "Ouch, that hurts," and then avoiding it. The same law of effect applies here.

Sofia Morais: For example, if you have a car accident.

Simon Ciranka: Yeah, exactly. So negative experiences that follow your risky behavior could make you avoid the risky behavior next time. For instance, let’s say I go to a party and I stay longer than I had planned, I get drunk, and then I can't find a way to get home. That's a very negative experience—so I won't do it again.

Sofia Morais: In this paper, you also discuss how learning about risks through personal experience can sometimes create a false sense of security. How does that work?

Simon Ciranka: This is related to statistics in an environment. If you think about an environment, we need to describe how it interacts with an individual. When we say that environments, opportunities, and everything around us are important, we need to figure out the interface between the environment and the individual. It's here that statistics really come into play. So, for instance, if I’m at a party and engaging in binge drinking behavior, I may not know what consequences will result, but there is some likelihood that good things will happen and some likelihood that bad things will happen. For example, there might be a 10% chance that I won’t make it home, but a 50% chance I’ll find my crush at the party or meet someone cool with whom I feel a connection. With these experiences, the bad outcomes that could occur are less likely than the good things that happen. If you think about it more abstractly, it’s similar to a lottery. The outcome of a risk-taking behavior is probabilistic—something that could occur but doesn’t have to. The simplest example is a lottery: imagine I have a bag of marbles with 20 marbles inside, 19 of which are blue and 1 is red. The red marble represents the bad experience. If you draw the red marble, you have to give me €20, for example. If you draw a blue marble, I’ll give you €1. You don't know the exact distribution of the red and blue marbles, but I’m handing you the bag, essentially giving you a sample of the consequences of your behavior. You draw one marble and get blue—you're happy, and you think, “Oh, this is really nice.” You draw again, and again, and again...

Sofia Morais: And it's always blue!

Simon Ciranka: Exactly. So the statistics—the distribution of experiences—is heavily skewed towards the positive. You don't realize how bad it could be to draw the one red marble.

Sofia Morais: Except that one day, you might draw the red one. It might just take you a few attempts.

Simon Ciranka: And the problem is, if you don't know how many red and blue marbles are in the bag, how can you possibly know? Only experience can tell you. That’s where the law of effect becomes important in shaping our future behavior. If I keep making these experiences where nothing bad happens, I may think, "Nothing really bad is going to happen. Sure, I know there’s a red marble somewhere in there, but maybe it’s not for me. I haven’t drawn it 100 times before, so I’ll keep doing it."

Sofia Morais: So, what you're saying, if I understand correctly, is that since really bad, severe harms are rare...

Simon Ciranka: Oftentimes with these risky behaviors.

Sofia Morais: ...they’re often rare, adolescents get to enjoy the rewards from risky behaviors without realizing the dangers, right? Without experiencing a bad outcome. And over time, they come to underestimate the risks.

Simon Ciranka: That’s right. I think the particularly insidious example is substance use, like drinking alcohol or using other drugs. It feels good initially but can lead to really bad consequences later on. That’s another example we discuss in the paper.

Sofia Morais: Cumulative risks.

Simon Ciranka: Exactly. At first, drinking one or two beers at a party might not seem to make much of a difference. But if you repeatedly follow this pattern, the law of effect kicks in, and eventually, you will experience bad outcomes. Similarly, having unprotected sex once may have a higher chance of being lucky and avoiding sexually transmitted diseases or an unwanted pregnancy. But the more you engage in these behaviors, the probability of a negative outcome becomes nearly certain. Initially, for most of these behaviors, it’s really unlikely that something bad will happen, which can create a vicious cycle of risky behavior.

Sofia Morais: Some of our audience might be wondering: If severe harms are rare, why should we be concerned?

Simon Ciranka: Because those severe harms are rare only in the small window of experience. But as I said earlier, if you continue engaging in risky behaviors like reckless driving, risky sexual encounters, or drug abuse, the bad consequences will eventually happen—and they are often really severe. The problem is that it’s a matter of individual experience. In the beginning, the probability of positive outcomes outweighs the probability of bad outcomes, which leads to a reinforcement of these risky behaviors. With substance abuse, the issue is even more complex because substances alter our brain chemistry and make us literally dependent on them. At some point, it’s not just about risky behavior anymore, but about substance dependency, which is a qualitatively different problem. That’s also one of the risks that the law of effect presents to young people.

Sofia Morais: What I was also thinking is that the severity of the risk might also play a role, right?

Simon Ciranka: Yes, absolutely.

Sofia Morais: How bad the consequences could possibly be. Because when we talk about risk, we should consider both the probability of the bad consequence happening, which we’ve discussed, and how damaging or impactful the outcome could be. If we’re talking about life-changing consequences—permanent changes to our lives—then even a rare harm can represent a significant risk, right?

Simon Ciranka: Yes, absolutely.

Sofia Morais: For instance, if there's a risk of incurring a permanent disability from a certain behavior.

Simon Ciranka: Exactly. That’s basically what substance addiction can do.

Sofia Morais: At this point, I think we should perhaps go back to the beginning of our conversation. We talked about the brain imbalances observed during this stage of development. How does the rarity of risks in the environment or their delayed nature interact with these brain development dynamics that you mentioned earlier?

Simon Ciranka: There’s this imbalance in reward processing. It doesn’t necessarily mean young people are totally crazy, but when combined with an environment that facilitates rewarding experiences, where there could also be really bad consequences, these two factors can lead to maladaptive behaviors.

Sofia Morais: If brain development dynamics, along with environmental conditions, create a situation where adolescents are likely to underestimate risks, you might wonder: Why did evolution shape humans in this way?

Simon Ciranka: It seems paradoxical, right?

Sofia Morais: Yes.

Simon Ciranka: Different developmental stages come with different milestones. For young children, milestones like saying their first words or learning to walk are crucial for healthy development. For adolescents, the developmental task is to become an adult—gaining an adult role in society, developing their own identity, and becoming independent from their parents. They need to develop the ability to lead a sustainable life. It wouldn’t work if they never dared to leave the nest. I like to use the example of a penguin. There’s a great book that tells the story of a penguin named Ursula, who grows up in South Georgia. At one point, this penguin leaves its parents’ nest, jumps into the Arctic Sea, and swims around for 16 days, facing dangers from seals, whales, and other predators. Afterward, the penguin returns, having learned how to avoid predators and become mindful of potential dangers. This process of leaving the nest and facing risks allows young animals, like penguins, to gain the experience they need for survival. Similarly, these neurodevelopmental changes in young humans (and other species) help them gain the courage to make important experiences, which help them discover who they are, clarify what they want, and determine how they should lead their lives as adults.

Sofia Morais: This also connects well to our previous podcast episode with Tomás Lejarraga. His research also shows that risk-taking can be a way for younger siblings to differentiate themselves from their older siblings, in order to get parental attention and resources.

Simon Ciranka: Yeah, so risk-taking isn't necessarily a bad thing. In fact, for adolescents, taking risks—whether academic risks, sports-related, or identity exploration—can be related to their mental health. If young people don’t have these opportunities or don’t engage in risks, they may not feel good about themselves. So, not allowing them to take any risks at all wouldn’t be the solution. As a society, we need to find a way to enable young people to have these valuable formative experiences while striking a balance and helping them avoid the worst pitfalls of risky behaviors. It’s a really tough task.

Sofia Morais: What are the implications for how risk warnings should be delivered to adolescents? I’m thinking of warnings about substance abuse or sexual health.

Simon Ciranka: This is the easiest intervention we can make as a society: we can tell young people, “This is not good. Don’t do it.” The problem with the law of effect is that when someone already has the experience of something feeling really good, warnings about all the bad things that could happen don’t work so well. This is because the warnings contrast with their rich, personal experience of the reward.

Sofia Morais: There’s a disconnect between what they read and what they experience.

Simon Ciranka: Exactly. And we want to avoid this disconnect by giving warnings before young people have these experiences. One study from Ethiopia found that education about condom use led to higher adoption rates among people who had never had sex before. Similarly, a campaign in Germany in my youth, "Keine Macht den Drogen" ("Don’t Give Drugs the Power"), was successful for those who hadn’t yet engaged in drug use. Similarly, during the AIDS epidemic in the 1980s, campaigns by the US Surgeon General to educate young people about safer sexual practices were more effective for those who hadn’t engaged in sexual behavior yet. Age didn’t play a role. It’s really about being new to a behavior that makes a difference.

Sofia Morais: But you can’t talk about risk-taking in adolescence without discussing peers. Peer influence is often seen as a reason why adolescents take risks. But in this paper you wrote with Ralph Hertwig, you argue that peer influence can also be helpful.

Simon Ciranka: Often, peers are seen as a bad influence. Early studies investigating the neuroscience behind this narrative suggested that being around peers worsens the developmental imbalance, making reward processing even more pronounced in young people. That’s a narrative that has been around for a very long time. But peers also have a positive influence. They help establish social norms. A social norm can be divided into two different aspects: first, "Am I supposed to do this?" and second, "What is everybody else doing?" If many people are engaging in risky behaviors, this provides an opportunity for vicarious experience. Essentially, you don’t need to go through all the hoops and face all the negative consequences yourself. Sometimes, it’s enough to observe how these consequences unfold within your peer group. That becomes a vicarious experience, helping you gain a clearer understanding of the potential outcomes of your own risky behaviors. For example, if you know someone who got into an accident, or someone who ended up in the hospital, or even someone who contracted a sexually transmitted disease, those instances give you insight into what might happen. So that's the force of vicarious experience—other people can shape our knowledge of the statistics of our environment. They can help us form a more holistic view of what's really out there and what's really at risk without having to rely on direct experience or the law of effect—where one learns everything from one’s own actions.

Sofia Morais: And peers also influence risk-taking through the approval they give. Adolescents might engage in behaviors that they perceive as social norms to gain approval from their peers. In a paper you published in 2021 with Wouter van den Bos, you explore adolescents’ sensitivity to these perceived social norms.

Simon Ciranka: We were mainly interested in how often young people think others in their social networks—people they know—are engaging in risky behaviors.

Sofia Morais: The question was: "How many of your peers have engaged in this behavior?"

Simon Ciranka: Exactly. That’s the understanding of the social norm. We then explored the relationship between participants’ conception of the social norm and their own propensity to engage in a risky behavior. Interestingly, this relationship was surprisingly stable across age groups. When young people believe that a certain risky behavior is the social norm, it increases their likelihood of engaging in that behavior. What I found particularly exciting was that, for adolescents aged 14 to 18 (though I’m not sure of the exact range), they reliably overestimated how often their peers were engaging in these risky behaviors.

Sofia Morais: And what did you observe regarding their tendency to recommend risky behaviors to others?

Simon Ciranka: We don’t think of adolescents—or anyone, really—as just passive recipients of social information. They actively contribute to it as well. So we also asked them, "Would you tell your friends that it’s a good idea to engage in this behavior?" It seemed that because they believed everyone was doing it, they were more likely to reinforce the behavior by suggesting to others, "Well, yeah, you should really go skiing" or "You should really try that."

Sofia Morais: So, in a way, this creates a vicious cycle, right? Because if adolescents overestimate how frequently their peers are engaging in risky behaviors, and they are more likely to recommend those behaviors, plus they are seeking approval from others who recommend them, it sets up a mechanism that spreads risky behaviors throughout the adolescent population.

Simon Ciranka: Yes, absolutely. But it can also be an entry point for intervention. We tend to estimate social norms based on our own perceptions, but we don't always know what the actual norms are. No one is explicitly telling us what those norms are. We have to figure them out ourselves. That’s why telling young people what the true peer norms are can be incredibly powerful. Adjusting their understanding of peer norms becomes a potential entry point for interventions that could help shape their behavior.

Sofia Morais: Simon, as we come to a close, I want to sincerely thank you for taking the time to join us and share your insights. It was truly a pleasure to have you on the podcast.

Simon Ciranka: It was a pleasure for me as well. Thanks so much.

[End of transcript]

Simon Ciranka: How Brains, Peers, and Environments Fuel Risky Behaviors in Teens

Links

Timestamps

Transcript (edited)