The Marshmallow Experiment

Last updated: 2026-08-17

The marshmallow experiment (Stanford Marshmallow Experiment) and its long-term follow-ups

It is one of the most cited studies in developmental psychology, carried out mainly by Walter Mischel at Stanford University in the late 1960s and early 1970s. It is known as a “long-term experiment” because what was interesting was not only what the children did at the moment, but the correlations that were found decades later.

The original procedure

Children of approximately 4 years of age (at the Bing Nursery School at Stanford) were offered a simple deal:

They could eat one marshmallow (or another attractive prize) immediately.
Or they could wait for the experimenter to return (normally up to 15 minutes) and receive two.

The child was left alone in the room with the prize in sight. How many seconds he managed to resist before eating it or ringing the bell to call the adult was measured.

Mischel was not interested only in “willpower.” He observed that the children who waited longer used cognitive strategies: looking away, singing, imagining that the marshmallow was something inedible, covering their eyes, etc. The capacity to redirect attention turned out to be more important than a simple “holding out.”

The long-term follow-ups (what made it famous)

In the 1980s and 1990s, Mischel and collaborators (especially Yuichi Shoda and Philip Peake) located some of those children already as adolescents and young adults. In small samples they found that those who had waited longer at age 4 tended to:

Have better SAT scores.
Be described by their parents as more competent academically and socially, more able to plan, concentrate, and handle frustration.
Show, in some later studies, better health indicators (lower BMI) and lower substance use.

These correlations were what popularized the idea that the capacity to delay gratification at age 4 predicted life success decades later.

What the modern replications show (2018 onward)

Later studies with much larger and more diverse samples (especially Watts, Duncan, and Quan, 2018, using NICHD data, and follow-ups to age 26 published in 2024) strongly qualified the original finding:

The bivariate correlation with later academic achievement was approximately half of what Mischel reported.
When family socioeconomic status, mother’s education, quality of the home environment, and early cognitive ability were controlled for, most of the predictive power disappeared or became very weak.
In the follow-up into adulthood (around age 26), wait time on the marshmallow did not reliably predict outcomes such as income, wealth, health, impulsive behaviors, or educational achievement once background factors were controlled for.

In short: the original experiment measured something real, but it overestimated how much of that “something” was a pure, innate individual capacity for self-control.

A more precise interpretation (and its connection with Austrian time preference)

From an Austrian and evolutionary-psychology standpoint, what the experiment captures is a behavioral manifestation of Time Preference, but one deeply mediated by the environment:

In stable, predictable, high-trust environments (where promises are kept and future resources are reliable), waiting makes sense. Low time preference is adaptive.
In unstable, scarce, or low-reliability environments (broken promises, institutional uncertainty, chaotic homes), eating the marshmallow now is the rational strategy. High time preference is adaptive.

That is why children from more disadvantaged or less reliable environments tend to wait less: not necessarily from “lack of character,” but because they have learned that the future is less secure. This fits perfectly with the point we had been discussing: institutions and culture that erode the reliability of the future (chronic inflation, legal insecurity, clientelism, broken state promises) systematically raise the average time preference of the population.

The marshmallow experiment, properly interpreted, does not show that “willpower at age 4 determines destiny.” It shows that the capacity to orient oneself toward the future is real, measurable, and valuable, but is deeply conditioned by the reliability of the environment in which the individual develops.

Categories: Home -> Psychology

Last updated: 2026-08-17

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