mind & bodyWikipedia1970 · Stanford University, California, USA
Stanford marshmallow experiment
The Stanford marshmallow experiment, run in 1970 by psychologist Walter Mischel, offered children a choice between one treat now or two if they could wait. The researcher left a child alone with a marshmallow for about 15 minutes, and those who waited got a second reward. In follow-up studies, children who waited longer tended to have higher SAT scores, more education and better measures of life outcomes. The result became famous as evidence that self-control in childhood predicts future success. Later work complicated this. A replication with a far larger and more diverse sample found only about half the original effect, and it suggested that family economic background explained much of the rest. A 2020 study challenged its predictive power further, and work in 2018 and 2024 concluded that the test does not reliably predict adult functioning.
Children had to resist an immediate reward by distracting themselves, such as covering their eyes or singing, while the reward stayed in view. Mischel's team interpreted sustained waiting as delayed gratification, a skill that could help people pursue long-term goals. Later analyses suggested that home environment and trust in adults also influenced how long children waited.
The experiment shaped decades of thinking about willpower, but its replications show how a striking result can shrink under scrutiny. It is a good example of why economic circumstances and not only personal discipline may shape life outcomes.
Long-running studies of childhood traits often find strong correlations that weaken when samples are broadened and methods are repeated. The marshmallow test is a well-known case where a famous result was narrowed by replication, a pattern that has prompted many psychology findings to be retested.
Adapted from Wikipedia, the free encyclopedia · CC BY-SA 4.0
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