Encouraging findings from studies looking at executive function and cognitive control in youth. The results should encourage parents, teachers, and students, and raise questions about how to distinguish normal development from "disorder." In the figure below, a clearly improvement in the accuracy and reaction time of cognitive control tasks occurs at about ages 12-14.
Other neurobiological functions take longer - like antisaccades, the ability to away from a novel visual stimulus. For this, ages 16-20 seem to be what it takes.
But look at how long advantageous decision-making takes to occur- this was defined as being able to choose "good" choices and avoid "bad" ones on a wagering task. This ability doesn't reach adult levels until ages 18-25.
Cognitive Control and Development
Adolescent Brain Development
Eide Neurolearning Blog: Your Brain with Time- What About Teen Brain?