The marshmallow test is one of the most famous pieces of social-science research: Put a marshmallow in front of a child, tell her that she can have a second one if she can go 15 minutes without eating the first one, and then leave the room. Whether she’s patient enough to double her payout is supposedly indicative of a willpower that will pay dividends down the line, at school and eventually at work. Passing the test is, to many, a promising signal of future success.
But a new study, published last week, has cast the whole concept into doubt. The researchers—NYU’s Tyler Watts and UC Irvine’s Greg Duncan and Haonan Quan—restaged the classic marshmallow test, which was developed by the Stanford psychologist Walter Mischel in the 1960s. Mischel and his colleagues administered the test and then tracked how children went on to fare later in life. They described the results in a 1990 study, which suggested that delayed gratification had huge benefits, including on such measures as standardized test scores.
Watts and his colleagues were skeptical of that finding. The original results were based on studies that included fewer than 90 children—all enrolled in a preschool on Stanford’s campus. In restaging the experiment, Watts and his colleagues thus adjusted the experimental design in important ways: The researchers used a sample that was much larger—more than 900 children—and also more representative of the general population in terms of race, ethnicity, and parents’ education. The researchers also, when analyzing their test’s results, controlled for certain factors—such as the income of a child’s household—that might explain children’s ability to delay gratification and their long-term success.