They base this hypothesis on the fact that the brain’s ventral striatum mediates reward processing. In other words, as brain activity in the area increases, so does the ability to resist peer pressure. For example, a young teenager is offered a cigarette by his or her friends, and must consider the consequences and benefits. Because this teenager does not have a developed ventral striatum, he or she wouldn't process the risks of smoking cigarettes as thoroughly as an older teenager. A younger teenager has a less developed ventral striatum, and as a result, is unable to resist peer pressure as effectively.