The marshmallow test

In the late 1960s a Stanford researcher put a marshmallow in front of a four year old and made a deal: eat this one now, or wait fifteen minutes alone with it and get two. Then he left the room. Some children caved instantly. Some covered their eyes, sang, or turned around to resist. Years later came the famous part. The children who had waited were doing better in school, scored higher on tests, seemed more successful in life. The lesson spread everywhere. Willpower in childhood predicts success. Then in 2018 a much larger study tried to reproduce it, with hundreds of children instead of a few dozen, and something important emerged. Once family background, early cognitive ability and the home environment were taken into account, about two thirds of the effect faded. One explanation, supported by a separate 2013 study, is that the children who waited were often the ones who had learned to trust that the second marshmallow would really come.

When you see a single trait that seems to predict success, ask what sits underneath it. The marshmallow story felt like proof that character causes outcomes, when much of it was that stable circumstances produce both the patience and the outcomes. Carry that into how you judge people, including yourself. The person who seems disciplined and the person who seems impulsive may mostly be showing you the conditions they came up in, not the ceiling of what they can become. And be wary of any process that scores someone on one dimension. The traits that actually predict performance show up across several behaviours, not one.

Source: Mischel and colleagues, original studies from 1972. The reckoning: Watts, Duncan and Quan, Revisiting the marshmallow test, Psychological Science, 2018.

The Marshmallow Test

Walter Mischel, 2014

From the researcher who ran the original studies. Worth reading with the 2018 replication in mind, because the book predates it.