child that he was going to leave the room. If they wanted to eat the marshmallow, they only had to ring the bell. But, as Mischel informed them, if they waited for his return, he would bring them more marshmallows. Mischel took out his stopwatch and recorded how long each child waited before ringing the bell. Some children rang the bell almost immediately, leaving Mischel no time to leave the room. Others waited. This isn’t surprising. Some children are impulsive, others are impatient, and this shows up early in life. What is surprising is that these early appearing personality types held steadfast, impacting later life decisions and actions. The more impatient types were more likely to be involved in juvenile delinquency, have poor grades, abuse drugs, get divorced, and lose their jobs. For women who developed eating disorders, those who were more patient were more likely to be anorexic, whereas those who were more impulsive were more likely to be bulimic. When the American developmental psychologist B.J. Casey put these now 40-somethings inside a brain scanner, the patient ones showed stronger activation in the prefrontal areas of the brain when viewing happy and fearful faces, revealing stronger self-control over their feelings. In contrast, when the impatient ones viewed the same stimuli, not only was there a weaker response in the prefrontal region but a stronger response in the ventral striatum when viewing happy faces. The striatum, as noted earlier, is involved in the experience of reward. For the impatient types, seeing something positive is like eating candy, something that is hard to ignore. The patient types regulate this feeling, transforming the heat of the moment into a cool experience. The impatient types are overwhelmed by this feeling, giving into temptation. This work adds to the genetic evidence reviewed earlier, showcasing both the importance of individual differences in self-control, and the stability of these differences as distinctive person