The marshmallow test: what does waiting really predict?

The marshmallow test cannot tell you a child's future. Waiting for a larger reward has been associated with some later outcomes, but those associations are less simple and less consistent than the popular story suggests. They depend on the children studied, the outcome measured, and what else the analysis takes into account.

Later research has weakened the idea that a few minutes of preschool waiting reveal a powerful, independent cause of lifelong success. At age 26, Sperber and colleagues found little reliable prediction from preschool waiting once their analysis included earlier characteristics. In mid-life, Benjamin and colleagues found that a measure of preschool waiting did not predict 11 adult outcomes, including income and net worth. None of this shows the opposite: that waiting tells you nothing at all.

For parents, teachers, and anyone applying behavioral science, the useful distinction is between predicting an outcome, explaining it, and changing it. The popular marshmallow story often slides between all three without noticing.

One task, several different questions

In the familiar task, a child can take a smaller reward now or wait for a larger one. Researchers record what the child does and, in follow-up studies, check whether it is associated with later characteristics or achievements.

Follow-ups published in 1988 and 1990 by Walter Mischel, Yuichi Shoda and Philip Peake helped establish the connection between preschool waiting and adolescent outcomes. These were longitudinal associations: behavior measured in preschool was related to measures collected years later.

That design leaves several possible explanations. Waiting could reflect something about the child that also affects later performance. It could reflect the child's circumstances. It could involve several influences at once. Seeing that children who wait tend to do better later does not tell you which explanation is correct.

Nor does it show that getting a child to wait longer will produce those later advantages. To answer that question, researchers would need evidence about an intervention and its later consequences. A predictive association is not an instruction manual.

The 2018 replication changed the scale of the claim

Tyler Watts, Greg Duncan, and Haonan Quan revisited the question in a different cohort in 2018. Their main analysis focused on children whose mothers had not completed college. Waiting was associated with later academic achievement, but the relationship was smaller than in the original studies, and it became substantially smaller after accounting for family background, early cognitive ability, and the home environment. Study.

This is not a case of a statistical control making inconvenient evidence disappear. Adjustment changes the question. Instead of asking whether children who wait tend to do better later, it asks whether waiting adds information once those other measured differences are held constant.

Imagine two children who differ in language skills, family circumstances and how long they waited. If they also differ in later school performance, it is hard to pin that difference on waiting alone. Adding the earlier measures to the analysis tests whether waiting carries any extra predictive information.

Adjustment is useful, but what it means still depends on the model. A variable might help cause both waiting and later achievement. Or it might be part of the very developmental process researchers want to understand. Neither adding every available control nor refusing to use controls solves that problem automatically.

The 2018 study itself started a published argument. In 2020, Armin Falk, Fabian Kosse and Pia Pinger argued that the two studies measured waiting differently: waiting times in the newer study were more heavily censored, meaning the task's time limit cut off more of the range, which biases the simple correlations toward zero. They also argued that some controls were not fixed before the task, which makes a drop in the association hard to interpret. When their reanalysis used only background variables determined in advance, it produced estimates closer to the original studies. Falk, Kosse and Pinger, 2020.

Watts and Duncan replied that their achievement correlations were smaller but still a partial replication, and they defended their models as a way to probe what the correlation means. Watts and Duncan, 2020. The exchange shows the previous point at work: how large the association looks depends on how waiting was measured and which variables count as fair controls.

The same data produced a different interpretation

In 2020, Laura Michaelson and Yuko Munakata published a preregistered reanalysis of the same cohort the 2018 paper used. Making different choices about measures and analyses, they found associations between preschool waiting and three of five adolescent outcomes. The associations with problem behavior held across several model forms. Reanalysis.

Their interpretation gave social support a larger role. Waiting might carry information about the child's early social environment rather than serve as a clean measure of self-control. The analysis supported that possibility; it did not experimentally prove that social support was the cause.

This is why a simple “replicated” or “failed” label misleads. The two teams were not just giving different statistical answers to an identical question. They made different decisions about how to measure outcomes, divide the sample, and account for earlier characteristics.

It is also one cohort analyzed more than once. Counting each paper as an independent group of children would make the evidence look more extensive than it is.

What happened when the children reached adulthood?

A 2024 follow-up by Sperber and colleagues looked at 702 participants from that same cohort at age 26. Once the analysis included earlier characteristics, preschool waiting showed little reliable prediction of adult functioning.

One exception stands out. When waiting was scored as passing or failing the full seven-minute task, an association with adult body mass index remained after adjustment. That pass/fail analysis was exploratory and had not been preregistered, so the association needs confirmation. It means you cannot say every adjusted association was zero. It does not make the body mass index result an established exception either.

The study also had a measurement limit. The task stopped at seven minutes, so it could not tell apart children able to wait longer than that. The adult sample was not representative of all children, and age 26 is one stage of adulthood. These details limit how far the finding reaches. They do not restore the much stronger popular promise.

The original cohort, children from Stanford's Bing Nursery School, has also reached middle age. In 2012 and 2013, Daniel Benjamin and colleagues, including Mischel himself, surveyed 113 of them; they averaged 46 years old. The team preregistered its analysis, and the main result was the one it had predicted: a measure built from preschool waiting did not predict 11 mid-life outcomes, including net worth, income, debt and educational attainment (average correlation 0.02). A combined index that added survey measures of self-regulation from ages 17, 27 and 37 predicted 10 of the 11 outcomes in the expected direction, 6 of them significantly (average correlation 0.19). Including preschool waiting in the index did not improve its predictions. Benjamin and colleagues, 2020.

That sample was small, and the authors describe it as well educated and wealthy on average. But it is a different cohort from the 2024 study, and it points the same way on preschool waiting. It also shows what did predict mid-life outcomes in that sample: self-regulation measured later in life. So two adult follow-ups, in two different cohorts, give little reason to use this brief task as a broad forecast of an individual child's adult life.

What parents and practitioners can take from it

Do not turn the marshmallow test into a character test. A child who takes the reward is making a choice in one particular situation. That choice does not reveal a permanent lack of discipline, and a child who waits has not secured a successful future.

Self-control is also much broader than this task. A finding about waiting for a snack does not settle every question about persistence, planning, distraction, or managing impulses. No single measure can carry a whole psychological construct. Research on personality and life outcomes asks related predictive questions with broader trait measures, and keeps the same distinction between an association and one person's future.

If you want to help a child learn, look at the problem more directly. Is the child having trouble understanding the material, starting the activity, or staying with a difficult task? Those are different problems. A preschool waiting score does not tell you which one you are facing or what will help.

A measure can predict something without causing it, and even a useful prediction may offer very little guidance about what to do next. Read with those limits, the marshmallow test is informative. Read as a tiny examination of someone's destiny, it is not.