The marshmallow test, redone with ten times as many children, found that a four-year-old's willpower mostly stopped predicting teenage success once family background was taken into account

June 16, 2026 - 01:30

A landmark 2018 study has cast new doubt on the famous marshmallow test, the classic experiment that seemed to prove a child's ability to delay gratification predicted their future success. The original work, conducted in the late 1960s and 1970s, suggested that a four-year-old who could resist eating one marshmallow for a promised second one tended to have better SAT scores and social outcomes as a teenager.

But a much larger replication, involving ten times as many children and a far more diverse sample, tells a different story. Researchers found that the link between a preschooler's willpower and their teenage achievement was weak. More importantly, that link largely disappeared once the researchers accounted for the child's family background, including factors like household income, parental education, and the overall stability of the home environment.

The new data suggests that the original test may have been measuring something less about innate self-control and more about the resources and security a child grew up with. A child from a stable, well-off home might find it easier to wait for a second treat, knowing that the promise is likely to be kept and that food is not scarce. The study does not argue that willpower is meaningless, but it strongly indicates that the simple act of waiting for a marshmallow is not a powerful predictor of a child's life trajectory once you account for the economic and social advantages they were born into.