120911 - Changing Choices vs.indd

Su m m ar y summAry Adolescence is a period of physical, psychological and social transitions from childhood to adulthood. It is associated with a unique set of behaviours, resulting in the common view that adolescents are myopic risk-takers, who are unable to plan ahead or envision the long-term consequences of their decisions and actions. It is also a period of continued development of the cognitive and social-emotional systems in the adolescent brain. Changes in the areas of the brain that comprise the social-emotional system make adolescents highly sensitive to rewards, motivational cues and emotional contexts. At the same time, the still developing cognitive control system is often unable to influence the strong impulses of the social-emotional system. This makes adolescence a particularly interesting period to examine decision-making competence. The aim of this thesis was to elucidate how adolescents make decisions and how developmental changes during adolescence may influence this. A general introduction to the thesis is provided in chapter 1. Chapters 2 and 3 examined an important aspect of adolescent decisionmaking, namely the development of delay of gratification abilities, as well as the real life consequences of this ability. Chapter 2 describes how a sample of 622 Dutch adolescents aged 12 -17 years completed a temporal discounting task, which measures the preference for future versus immediate outcomes. Participants were asked to choose between a delayed reward of €50 or an immediate reward of lower value. The delay interval was varied in three blocks (1 week, 1 month, 6 months). Age-related development, as well as the effects of individual differences in level of education and sex, was examined. The frequently used area under the curve (AUC) method for general analysis of the data was combined with an additional examination of the decisions made at each specific delay interval. Results using the AUC method showed that preferences for large delayed rewards over smaller immediate rewards increased with age: late adolescents made more long-term decisions than early adolescents. A higher level of education was associated with an increased preference for longterm rewards. However, analysis of the individual delay intervals showed that the differences in decisions made by the two groups decreased with age for the shorter