I have been studying adolescent risk behavior for over 25 years and was intrigued when neuroscientists first starting making claims about the "adolescent brain." Neuroscientists seemed to be making sweeping generalizations about adolescents based essentially on cross-sectional studies of brain structure, the meaning of which seemed speculative. My own longitudinal research on adolescent cognitive development revealed that sensation seeking, the behavioral indicator of risk propensity, was positively related to cognitive development and thus was unlikely to be a pure marker of limbic activation. Instead, it seemed that sensation seeking and cognitive development rise together during adolescence and that there is no imbalance in brain development. There are large individual differences however and some adolescents are likely to have brains that are structurally and functionally imbalanced. But it is a mistake to contend that this is a normative characteristic of all adolescents.
In reviewing the literature that was used to support the imbalance model, my colleagues and I saw more and more evidence that the imbalance model was a simplification that seemed plausible to the public as well as to researchers because of stereotypes about adolescent novelty seeking and exploration rather than lack of control over behavior. This led us to put forth a different model that we feel is consistent with the neuroscience as well as the realities of adolescent risk taking which is the basis for this conversation.