A child who resists one marshmallow now is destined for success later.
Verdict: contested
The link to later outcomes shrinks sharply once family background is accounted for.
What the evidence shows
In Walter Mischel's classic studies, preschoolers who waited longer for a second treat later had, on average, better test scores and life outcomes. The story became a parable about the power of self-control — and a target for early-intervention programmes.
A larger, more representative replication by Watts, Duncan & Quan (2018) confirmed a correlation, but found it roughly halved once the child's family background and home environment were controlled, and further weakened when accounting for early cognitive ability. In other words, the marshmallow test partly measures a child's circumstances — affluence, stability, trust that the promised treat will actually arrive — not just an inner trait. Delay of gratification matters, but it is not the near-magical predictor the popular version claims.
Sources
Mischel, W., Shoda, Y., & Rodriguez, M. L. (1989). Delay of gratification in children.
Science, 244(4907), 933–938
Preschoolers who delayed gratification longer showed better adolescent outcomes in the original small samples.
DOI: 10.1126/science.2658056 →Watts, T. W., Duncan, G. J., & Quan, H. (2018). Revisiting the marshmallow test: A conceptual replication investigating links between early delay of gratification and later outcomes.
Psychological Science, 29(7), 1159–1177
In a larger, diverse sample the predictive link roughly halved after controlling for family background and largely faded with further controls.
DOI: 10.1177/0956797618761661 →