When they were younger, children tended to make moral choices pretty much along the value system that they were given by their important adults: parents and teachers primarily. Pleasing these significant adults is essential to most young children. However, as they reach adolescence, the influence of peers and the peer culture becomes much stronger (especially, among children who have not been able to please overly-critical adults). Counter-balanced against values acquired earlier are newer values reflecting his/her adolescent society.
There are four basic themes from the adolescent struggle that help define the adolescent's response to choices in his/her life. These four themes are RESPECT, IDENTITY, POWER & CONTROL, & SECURITY. When any of these themes are activated either positively or negatively, they strongly direct the adolescent towards his/her eventual choice.
In many ways, adolescents do not feel respected by adults: parents and teachers. Adults are always criticizing them as bad, amoral, stupid, and/or strange. Whether they feel invalidated by adults or not, with the rise of the importance of peers whether or not they are respected by peers becomes more and more important.
Respected adults (who are usually the ones who the adolescent feels gives them respect) are still influential as to the adolescents choices; their respect of the adolescent's behavior remains important- conversely, their disagreement is also meaningful. However, as they make choices in life, their perception of their choice being respected or disrespected- accepted or not accepted by the significant peers who they admire or wish to emulate, will often be their primary guide.
As adolescents make the transition from being and seeing themselves as children to becoming and defining themselves as adults, they will tend (if conscious of the opportunity) to move toward any behavior or activity that supports their successful identification as a autonomous, competent, and powerful adult. They will, conversely, resist any behavior or activity that interferes with their identification as an adult.
At the same time, while adolescents often have insecurities about being immature ("kids"), accusing an adolescent of being immature is experienced as disrespectful- it is not a effective or useful intervention. While adolescents still have a strong instinct to be child-like (playful, desirous of instant gratification), they will behave predictably more "maturely" if they are aware of these identification issues (and other issues, especially Power & Control if they are not in conflict).
POWER & CONTROL
Adolescents, like all individuals are very interested in gaining more power and control in their lives. Unlike children who usually accept their lesser power and control due to adult management, adolescents no longer are willing to accept lesser power and control due to social considerations. Unlike adults who usually (and hopefully) are secure enough to accept the limitations to their power and control, adolescents often strongly resist any indication or threat of loss to their power and control whether real or imagined. Adolescents may engage in self-defeating and self-harming behavior to maintain their sense of power and control.
While it may seem contradictory that such negative choices seem to be against the desire to affirm a more adult-like identity, being in power and having control is such a fundamental part of the adolescent's identity needs, that "immature" choices that give the illusion of power and control are more predictable over "mature" choices that seem to cause a loss of power and control (especially from an adult perspective and in the long term).
As adolescents make the transition into adulthood, they are leaving the relatively secure world of childhood with its easy going lack of accountability and moving into an adult world of responsibility. And, they do so without the clear rites of passage and apprenticeships from prior generations, and without solid guidance from their parents who themselves may be struggling to deal with current societal demands.
Adolescents will tend to move toward any behavior or activity that supports their greater sense of security. However, as young people still, the security that is more tangible is in the short-term and not necessarily in the long-term. As a result, behaviors or activities that support immediate security needs tend to be favored over those that sacrifice the present for long-term needs or security.
*Of these Power & Control and Respect are the most important. Of these two, Power & Control is the most important to the teen (keeping even just the illusion of Power & Control is important enough to take being disrespected by adults).