Cognitive flexibility is the ability to switch between different ideas, rules and points of view during problem solving, or even completing multiple tasks at the same time. Switching between rules and tasks makes us a little “slower” since this is a much more difficult thing to do than focusing on just one thing at a time. In this study, we examine the development of flexible thinking in adolescence. We do this using 2 tasks (10 minutes each) where the participant looks at simple pictures on a monitor and makes decisions based on rules that keep changing throughout the task.