From birth onward, the human brain continues to develop and mature. For adolescents, the amount of information they can process continues to increase, but the rate of increase is not as great as it once was during the middle childhood years. Likewise, their overall fund of information continues to build.
Memorization capabilities further expand. Youth can now recall a large amount of detailed information such as lengthy, complicated, driving directions. Likewise, they can remember and apply patterns or formulas such as when solving a complex calculus problem. Youth also use sophisticated memorization strategies such as mnemonics to remember dates (e.g., "Columbus sailed the ocean blue in fourteen hundred and ninety two"), or a musical tune or rhyme to help them to remember lengthy lists (e.g., singing the names of 50 states). Furthermore, as youths' capacity for memorization increases, the brain develops more efficient methods of organizing information allowing for more rapid and accurate information storage, and subsequent retrieval. This enables youth to recall information more easily, and to apply the information in useful ways.
Similarly, adolescents' metacognition continues to strengthen. Metacognition literally means to think about thinking; thus, teens can analyze and evaluate their thoughts and beliefs. Although metacognition began during middle childhood, the difference is that adolescents can now think abstractly. So, when metacognition is coupled with abstract thought, parents may find themselves listening to their teen discuss lofty philosophical issues and challenging their parents' values and beliefs. When teens practice these newly acquired skills it can become quite frustrating but parents may find comfort and solace knowing their teen is simply exercising their "new and improved" metacognitive skills.
The maturing brain is also responsible for advanced language development. Teens' vocabularies continue to grow as they develop an impressive working vocabulary of over 40,000 words. Their improved vocabulary includes the acquisition of words with more abstract meanings, which mirrors their new ability to think in more abstract ways. This expanded vocabulary enables them to verbalize the abstract thoughts they are having. Moreover, teens now understand many more non-literal word meanings, and they begin to use non-literal words to communicate irony and sarcasm. Thus, their ability to think abstractly also allows them to find humor in the world.
Adolescents' grammatical skills also improve to become more refined and sophisticated. Written language becomes more complex and illustrative because adolescents are required to use this form of communication more and more often as a part of their formal schooling. The quality, quantity, and intensity of formal schooling will influence language development. As with all developmental progress, there can be a great deal of variation among youth.
Unfortunately, some brain development proceeds more slowly than others. Recent research suggests the frontal lobes of the human brain are still developing until the early or mid-20's (Stuss, 1992; Thompson, Giedd, Woods, et. al, 2000). The brain's frontal lobes represent the seat of logic and reason and function to enable people to use good judgment when solving problems or making decisions. Therefore, the brain's frontal lobes serve to balance our impulsive, instinctive, emotional reactions with rational thought. Because the frontal lobe is still maturing, youth are more vulnerable to their reactive emotions and therefore may act without thinking about the consequences of their actions. In particular, they may be more likely to react impulsively when experiencing powerful, intense emotions, and seem to lack the ability to pause in order to "think through" their strong feelings.
A mature person is able to inhibit or delay responding to automatic, reactive, emotional impulses long enough to thoughtfully consider the best course of action. This developmental skill is typically acquired during adolescence; however, until this skill is fully developed, parents may become alarmed and frustrated when their teens make poor decisions, or act impulsively. To add to this frustration, parents may believe their teens "know better," and this may indeed be true. But their teens may still lack the ability to utilize this knowledge to temper their emotional impulses because their brains haven't sufficiently matured yet. Sometimes parents will exclaim in frustration, "What were you thinking!?" when in reality, there may have been little thought involved! This is why parental monitoring, guidance, and discipline are so vital throughout the adolescent years.