Why do teenagers sometimes make outrageous, risky choices? Do they suddenly become reckless, or are they just going through a natural phase? To find out, Kashfia Rahman, winner of the Intel International Science and Engineering Fair (and a Harvard freshman), designed and conducted an experiment to test how high school students respond to and get used to risk, and how it changes their still-developing brains. What she discovered about risk and decision-making could change how we think about why teens do what they do. Kashfia is a psychology researcher. She studies cognitive science and global health policy at Harvard University.