Although neuroscientists have known for many years that the brains of young children change and develop considerably in their first few years of life, studies on adolescence brain development weren't done until recently. When scientists began to study the teenage brain, they were surprised to discover that some areas of the brain affecting social cognition are still changing and developing during the teenage years.
Theory of Mind
Theory of mind is the ability to realize that other people have thoughts and feelings of their own, to guess what those thoughts and feelings might be and to predict how they might behave in a certain circumstance based on those thoughts and feelings. It takes most children until about age 5 to develop a theory of mind. In a lecture from 2007 reprinted in "The Psychologist," neuroscientist Sarah-Jayne Blakemore described the results of research showing that teenagers do not yet have theory of mind as fully developed as adults do.
Blakemore's research into adolescent social cognition found that younger teenagers had more difficulty switching from a first-person perspective to a third-person perspective than adults did. Both groups could imagine how they would feel in a particular circumstance and how another person might feel, but the teenagers took longer to answer the question about how another person would feel. This result suggests that theory of mind is not yet completely developed in younger teenagers.
Another study, described by Blakemore and neuroscientist Stephanie Burnett in a 2009 research paper, found that younger teenagers had less ability to resist peer pressure than older teenagers. When asked to assess their likelihood of going along with the group in an imaginary scenario, younger teens rated themselves as more likely to do so even when the group was doing something wrong or socially unacceptable. Older teens rated themselves as less likely to go along with the group in the same circumstance. Blakemore and Burnett point out that the ability to go against the group sometimes is an important aspect of social maturity.
A 2011 study by Blakemore and neuroscientist Jennifer H. Pfeifer found that teenagers used the same part of their brain to assess what they thought about themselves as they used to assess how other people might think of them. Adults used separate areas of the brain for those different tasks. This implies that teens have less ability to distinguish between what other people think about them and how they feel about themselves, which might explain the vulnerability of teens to peer pressure. With less ability to correctly assess the perspectives of others, a stronger tendency to go along with the crowd and a limited ability to distinguish social judgment from self-esteem, teenagers appear to think about social interactions very differently from adults.