Two Minds in Adolescence and Young Adulthood

The commonly accepted model of adolescents’ and young adults’ (AYA) thinking goes like this: Adolescents don't always think clearly because their brains aren't fully developed yet. Brain development goes on through the early teens, especially in the prefrontal cortex (PFC: the part of the brain right behind the eyes), which is responsible for executive control of behavior. Because they don't have good control over their behavior yet, AYA are prone to doing risky or foolish things, which can result in negative consequences. As long as they don't mess up too badly, they will eventually outgrow the risk-taking phase and become normal, healthy, risk-averse adults. Is this model familiar?

A major line of research with AYA does show that the brain continues to generate new synapses in the PFC region well into young adulthood, for instance to age 24 or later. Based on an understanding of the PFC as the seat of executive control functions in the brain, this neurological finding has been interpreted to mean that AYA are less reasonable than adults, and that the timeframe of unreasonableness extends well beyond traditional conceptions of adolescence that end at 18 or 21. (We might further remember that in an earlier era the “age of reason” at which people could be held responsible for their actions was seven years old!) The neurological evidence is consistent that the brain is developing new connections much longer than was previously believed, and that this is especially true in the PFC region of the brain. There is also strong evidence, reviewed in a previous blog post, to show that people with damaged or inhibited PFC regions exhibit more impulsive behaviors. So isn’t the clear conclusion that adolescents have less self-control?

Let's look at AYA’s behavior a different way. Put aside what you think about other people you knew in adolescence or young adulthood, or what you think about the AYA in your life right now. Ask yourself instead about your own experiences at that age. Maybe you remember taking some risks you now would avoid, or you made some mistakes that you now regret. At the time, did you take those chances or make those mistakes in the full knowledge that they were risky decisions? Or did they seem like a good idea at the time? Many people would say the latter. Those who say the former are probably still risk-takers as adults. One recent study actually found no change in AYA's risk-taking preferences over the course of 6 years starting at age 9-13: Those who valued the present over the future at the start of the study had higher rates of substance use and overweight as time went on. But adolescents' preferences for the present vs. the future didn't change on average with the passage of time, and those who still had high levels of discounting the future at the end of 6 years were simply those who already showed this tendency at the start of the study.

Despite our cultural stereotypes, AYA are not unreasonable people. In fact, when we take time to talk with them, we find that AYA do have a well-developed capacity for logical thought. For instance, they are not more influenced by social considerations or emotions when discussing possible decisions in the abstract, and often express (apparently sincere) intentions to do the right thing. As AYA grow into adulthood, they may be able to develop more sophisticated and accurate narratives about the world. If you ask them to give advice to a friend, AYA often provide thinking of great insight and sensitivity. The problem is just in applying those insights to their own behavior — in TMT terms, a classic intention-behavior gap. Kohlberg’s popular theory of moral development suggests that as we get older we develop general narratives that then we then also apply to ourselves (formal operations), instead of personal narratives that only look at consequences from our own perspective (preconventional or conventional morality). This gap between the personal and the universal is one potential explanation for AYA’s risky behaviors.

The neurocognitive evidence is similarly ambiguous. In a recent post I presented evidence from the research of Benjamin Libet that suggests a “veto” function for the PFC rather than a self-directive decision-making role. Impulsivity may not result from flawed decision making, but simply from a failure to delay behavior long enough for the Narrative system to explore how the decision might play out. Some research with AYA suggests that this is a developmental or personality difference, in which some AYA have a greater capacity for mindfulness that also correlates with healthier behavior. Other research shows that AYA’s capacity for effective self-management can vary from one day to another, and that on days when they feel more in control they are more successful in maintaining healthy behaviors. All of this suggests that the ability to put off behavior is a learned or developmental skill. In a recent article, we argued that training the Intuitive system to engage in a slight delay as its first response is an effective way to bring the Narrative system to bear on their problems. According to this view, it isn’t that AYA don’t know the right answer or have the right intention, it’s that their Intuitive system jumps the gun by immediately producing behavior with no time for a veto by the PFC. The apparent impulsivity of adolescent behavior may simply result from lack of practice with a key behavioral skill for adult life, taking a few deep breaths to delay one’s initial response. 

Finally, the PFC shows strong neural connections with areas of the brain involving social roles and perceptions of other people. This accords well with what we know about AYA’s typical concern for peer relationships. (A friend once said, “in my twenties I worried what others were thinking about me. In my thirties I decided that I didn’t care what others thought of me. And in my forties I realized nobody else was really thinking about me that much.”) TMT suggests that one of the major roles of the Narrative System (and its agent the PFC) is social perception, specifically running mental models of how others might react to our behavior. Humans are social animals, and getting along with others is essential for our survival. So it’s no surprise that young humans learning to operate in society would devote a great deal of their cognitive resources to understanding and predicting others’ behavior. It’s also no surprise that humans who are still new at this skill aren’t very good at it yet! In fact, those who live or work with adolescents sometimes observe that AYA can be too rational, inflexibly applying an abstract rule in a situation that adult “common sense” would tell us is more nuanced. For instance, declaring one’s undying love may be a natural reaction to feelings that one is experiencing, but doing so out-of-context and without consideration for how the recipient of those feelings will react is likely a social mistake. The ongoing development of neurons in the PFC and adolescents’ high attentiveness to social interactions might both be explained by simple lack of experience with social interactions. Perspective-taking therefore may be another skill that AYA are developing along with neural connections in the PFC.

Instead of viewing AYA as “naturally impulsive” and waiting for them to grow out of it, TMT suggests that AYA might simply lack life experience and practice in three crucial areas: (a) applying insights about the general consequences of behavior to themselves, (b) delaying their own response through mindfulness or other techniques, and (c) taking others’ perspective to better predict social reactions to their behavior. These are skills that one can develop through practice or vicarious experience (e.g., using virtual reality, or by reading 19^th-century novels of manners). Additional techniques like sensor-based biofeedback might help AYA to develop mindfulness skills, or classic behaviorist strategies could be employed like providing a peer “coping model” who demonstrates how to delay reactions and consider others’ perspectives. Even a simple intervention that asks AYA to advise others can be powerful, especially if they are then asked how they are modeling the target behavior for their peers. Clinicians can likely devise many clever ways to capitalize on these three key areas of cognitive development to help AYA become more “self-controlled” without simply waiting for their brains to finish developing.