The famous marshmallow test said kids who waited would do better in life, but a larger study found family background explained much of it
In the late 1960s and early 1970s, psychologist Walter Mischel offered preschoolers at a Stanford University nursery a simple choice: eat one treat now, such as a marshmallow, or wait alone in a room for several minutes and get two.
Years later, follow-up studies reported that children who had waited longer tended to do better as teenagers, including on the SAT. A 1990 study by Yuichi Shoda, Mischel and Philip Peake linked longer waiting to higher scores and better coping skills, and the marshmallow test became a famous symbol of self-control as a key to success.
The original sample, however, was small and drawn mostly from the children of Stanford faculty and graduate students, a far from typical group.
In 2018, Tyler Watts, Greg Duncan and Haonan Quan revisited the question using a larger and more diverse group of more than 900 children from a national US study. They gave a version of the test to children at age 4 and looked at their academic achievement at age 15.
They did find a link: children who waited longer tended to do somewhat better later. But the association was about half as large as in the earlier studies. And once the researchers accounted for family background, early cognitive skills and home environment, it shrank by about two-thirds and was no longer statistically reliable for most measures.
In other words, much of what the marshmallow test seemed to predict may reflect the circumstances children grow up in. A child from a stable home with reliable adults may have good reason to trust that a promised reward will actually come. A child used to promises not being kept may sensibly take what is on the table.
Mischel himself had long argued that self-control is a skill that can be taught, not a fixed trait, and that the strategies children used, such as distracting themselves, mattered. The newer research does not say self-control is unimportant. It says that one short test at age 4 tells us less about a child’s future than popular retellings suggested.
For parents, the takeaway is reassuring. A preschooler who grabs the marshmallow is not doomed, and the environment adults provide matters as much as any trait a child is born with.
Sources
Shoda Y, Mischel W, Peake PK. “Predicting adolescent cognitive and self-regulatory competencies from preschool delay of gratification.” Developmental Psychology, 1990.
DOI: 10.1037/0012-1649.26.6.978
Watts TW, Duncan GJ, Quan H. “Revisiting the marshmallow test: A conceptual replication investigating links between early delay of gratification and later outcomes.” Psychological Science, 2018.
DOI: 10.1177/0956797618761661
