A Treat, a Temptation, and a Theory
In the late 1960s and early 1970s, psychologist Walter Mischel and colleagues at Stanford University conducted an experiment that would become one of the most cited in social science. Preschoolers were brought into a room at Stanford’s Bing Nursery School, seated at a table, and given a simple choice.
They could eat one marshmallow immediately, or wait for 15 minutes while the researcher left the room and receive two marshmallows when the researcher returned. About 90 children, all from families connected to Stanford, took part in the original study.
Long-Term Links and a Famous Reputation
Years later, the researchers followed up with many of the original participants. They found correlations between the ability to wait for the second marshmallow and higher SAT scores, better parent-reported social competence, and lower reported rates of behavioral problems.
These findings were published in the 1980s and 1990s and quickly spread beyond academic circles. The “Marshmallow Test” became a staple example in discussions of willpower and future success. Motivational speakers, educators, and media outlets often used the experiment as evidence that delayed gratification predicts life outcomes.
A Larger Study Brings New Findings
Decades later, researchers revisited the test using a larger and more diverse group of children. In 2018, a study led by Tyler Watts, Greg Duncan, and Haonan Quan analyzed data from over 900 children from various socioeconomic, racial, and ethnic backgrounds.
Published in Psychological Science, the study found that the predictive power of the marshmallow task largely disappeared when family background and home environment were taken into account. Children from wealthier families were more likely to wait for the second marshmallow. Their ability to delay gratification correlated strongly with parental education, household income, and early cognitive skills, rather than uniquely predicting later achievement.
Wealth, Trust, and Timing
The findings suggested that the original results reflected environmental stability more than innate willpower. Children from resource-secure households may have had more reason to trust that a promised reward would actually come.
Those from less stable backgrounds may have chosen the immediate treat not because of weaker self-control, but because immediate rewards were more reliable in their lived experience. The marshmallow task, once thought to measure individual perseverance, turned out to reveal patterns shaped by social and economic conditions.
In a quiet Stanford room in the late 1960s, a child sat before a single marshmallow.
If they waited 15 minutes, they’d get two.
Decades later, this simple setup became one of psychology’s most famous experiments, shaping ideas about willpower, success, and the future…🧵👇 pic.twitter.com/3BPfYwFhrF
— Fascinating True Stories (@FascinatingTrue) October 7, 2025