In the 1960s, Walter Mischel conducted an experiment with preschoolers where they were given a marshmallow and told they could eat it immediately, but if they waited 15 minutes without eating it they would get two marshmallows. The experiment studied children's ability to delay gratification and how it impacted their future success and behavior. The study found that children who were able to wait longer for the second marshmallow tended to have better life outcomes, including higher SAT scores, educational attainment, and healthier relationships.