Adolescence may seem like a period during which the brain goes offline, but it is anything but that. All-consuming relationships, capricious decisions, radical mood swings, and an addiction-like compulsion to risk-taking all offer tremendous insight into a time when the brain is shifting, changing, and ultimately determining who we will become as adults.
For Sarah-Jayne Blakemore, adolescent behavior is not only fascinating to study, it is central to understanding our experience. In her new book, Inventing Ourselves: The Mysterious Working of the Teenage Brain, Blakemore – who was one of only four scientists on the Sunday Times 100 Makers of the Twenty-First Century – applies her scientific rigor to parse the conjecture from the provable. She delivers a solid understanding of adolescence and, perhaps more importantly, fosters a healthy appreciation for it.
Adolescence is not an aberration, and it’s not new.
“Aristotle described ‘youth’ as ‘lacking in sexual self-restraint, fickle in their desires, passionate and impulsive,” writes Blakemore.
The sense of self that emerges through adolescence is affected by multiple factors including genetic material inherited from our parents, the way in which these genes interact with the environment, and the social-environmental factors that are present when we enter adolescence.
“In California, where I was living independently for the first time, I became aware that many people had preconceptions of what women should be doing with their lives, and that the career I wanted to enter was not viewed as particularly ‘feminine’,” writes Blakemore.
Self-reflection and intentional causality, or the ability to think about what we might do in a given situation, are both important skills for regulating our behavior in pro-social ways. These skills differ greatly between adolescence and adulthood. Blakemore references her own study, which found that when performing intentional causality the adolescent brain uses more of the medial-prefrontal cortex, a part of the brain that also becomes active when people feel self-conscious.
Adolescents are also much more sensitive to social exclusion than adults – an outcome that has also been found in animal studies – which often leads to lasting consequences in brain development.
“The consequences of social instability in adolescence – in both rats and humans – can be so detrimental that mechanisms and behaviors promoting peer acceptance can be considered adaptive,” writes Blakemore.
Making decisions with sensitivity to their social implications and the possibility of social exclusion then becomes an act of adolescents’ weighing the pros and cons of each choice – something Blakemore calls the see-saw model. This model can apply to almost any choice a teenager makes.
“Even though adolescents understand the health risks of experimenting with drugs, there is also the social risk to consider: saying no to a drug when all of your friends are taking it, and potentially being ostracized by your social group as a consequence, might be perceived as more risky than accepting the tablet,” writes Blakemore.
The choices that adolescents consistently make also influence the growth of related areas of the brain. Blakemore points to a study where introspective ability was associated with the size of the right rostrolateral prefrontal cortex, which influenced people’s ability to judge their own performance.
And while plasticity of the brain applies to both adolescent and adult brains, there is a critical difference: Experience-dependent plasticity allows us to adapt to new information and underlies learning at any age. Experience-expectant plasticity, on the other hand, is the readiness of the brain to respond to sensory input at critical “sensitive periods.”
Adolescents are more concerned with social interactions, but as studies done by Blakemore and others show, these interactions are also more cognitively expensive.
“Echoing the findings of other developmental mentalizing studies, our results showed that activity in the dmPFC when reading about social emotions was higher in the adolescent group than in the adult group,” writes Blakemore.
Brain development also helps explain the risk-taking behavior of adolescents. With a limbic system that is already mature and primed for reward-seeking behavior, and a prefrontal cortex – which helps us weigh the consequences of our actions and inhibit behavior that is too risky – that is not yet fully developed, adolescents are not always able to stop themselves from acting on impulses.
Impulsive risk-taking, mood swings, and excessive experimentation, however, all serve an adaptive purpose on the journey to adulthood. With education, practicing cognitive skills, and becoming aware of cultural and environmental influences, adolescent brains can be supported in this process.
One important shift Blakemore encourages readers to make is in how we think about adolescents. While poor behavioral choices can describe adolescents, so too can creativity, divergent thinking, and originality.
An eye-opening book, Inventing Ourselves takes a deep look at the adolescent brain, from the studies that give us revealing insights, to the practical implications that play out in everyday life. In doing so, Blakemore encourages us all to rethink adolescence.
Inventing Ourselves: The Mysterious Working of the Teenage Brain
Softcover, 256 Pages