Attitudes to risk (known probabilities) and attitudes to ambiguity (unknown probabilities) are separate constructs that influence decision making, but their development across adolescence remains elusive. We administered a choice task to a wide adolescent age-range (N = 157, 10-25 years) to disentangle risk- and ambiguity-attitudes using a model-based approach. Additionally, this task was played in a social context, presenting choices from a high risk-taking peer. We observed age-related changes in ambiguity-attitude, but not risk-attitude. Also, ambiguity-aversion was negatively related to real-life risk taking. Finally, the social context influenced only risk-attitudes. These results highlight the importance of disentangling risk- and ambiguity-attitudes in adolescent risk taking.

It was examined how ventral striatum responses to rewards develop across adolescence and early adulthood and how individual differences in state‐ and trait‐level reward sensitivity are related to these changes. Participants (aged 8–29 years) were tested across three waves separated by 2 years (693 functional MRI scans) in an accelerated longitudinal design. The results confirmed an adolescent peak in reward‐related ventral striatum, specifically nucleus accumbens, activity. In early to mid‐adolescence, increases in reward activation were related to trait‐level reward drive. In mid‐adolescence to early adulthood decreases in reward activation were related to decreases in state‐level hedonic reward pleasure. This study demonstrates that state‐ and trait‐level reward sensitivity account for reward‐related ventral striatum activity in different phases of adolescence and early adulthood.

This study tested the pathways supporting adolescent development of prosocial and rebellious behavior. Selfreport and structural brain development data were obtained in a three-wave, longitudinal neuroimaging study (8-29 years, N = 210 at Wave 3). First, prosocial and rebellious behavior assessed at Wave 3 were positively correlated. Perspective taking and intention to comfort uniquely predicted prosocial behavior, whereas fun seeking (current levels and longitudinal changes) predicted both prosocial and rebellious behaviors. These changes were accompanied by developmental declines in nucleus accumbens and medial prefrontal cortex (MPFC) volumes, but only faster decline of MPFC (faster maturity) related to less rebellious behavior. These findings point toward a possible differential susceptibility marker, fun seeking, as a predictor of both prosocial and rebellious developmental outcomes.

Although many neuroimaging studies have investigated adolescent risk taking, few studies have dissociated between decision-making under risk (known probabilities) and ambiguity (unknown probabilities). Furthermore, which brain regions are sensitive to individual differences in task-related and self-reported risk taking remains elusive. We presented 198 adolescents (11-24 years, an age-range in which individual differences in risk taking are prominent) with an fMRI paradigm that separated decision-making (choosing to gamble or not) and reward outcome processing (gains, no gains) under risky and ambiguous conditions, and related this to task-related and self-reported risk taking. We observed distinct neural mechanisms underlying risky and ambiguous gambling, with risk more prominently associated with activation in parietal cortex, and ambiguity more prominently with dorsolateral prefrontal cortex (PFC), as well as medial PFC during outcome processing. Individual differences in task-related risk taking were positively associated with ventral striatum activation in the decision phase, specifically for risk, and negatively associated with insula and dorsomedial PFC activation, specifically for ambiguity. Moreover, dorsolateral PFC activation in the outcome phase seemed a prominent marker for individual differences in task-related risk taking under ambiguity as well as self-reported daily-life risk taking, in which greater risk taking was associated with reduced activation in dorsolateral PFC. Together, this study demonstrates the importance of considering multiple risk-taking measures, and contextual moderators, in understanding the neural mechanisms underlying adolescent risk taking.