The historic “marshmallow test” has tied young children’s ability to delay gratification to their long-term success, but a new, larger study replicating the famous study puts those long-term results in doubt.
Using a significantly larger and more diverse group of children than the original study, researchers from New York University and the University of California, Irvine, compared 4-year-olds’ ability to delay gratification to their academic and behavioral progress in 1st grade and at age 15. They found, in a study in the journal Psychological Science, children’s early ability to delay gratification was linked to their later academic achievement, but not to later behavior, impulsivity, or attention control.
In the wake of Walter Mischel’s original findings in 1990, schools across the country have sought to use the experiments to teach students about the importance of delayed gratification to self-control and self-regulation—some even going so far as to have older students try out the experiment themselves. (The original study found the ability to delay gratification increases naturally as children age.)
“As people have become interested in the marshmallow experiments again over the last 15 years, they say, do these findings mean that we should think about programs that can promote the ability to delay gratification in younger kids?” said Tyler Watts, the lead author of the replication study and a research assistant professor of applied psychology at New York University’s Steinhardt School of Education. “You may expect, based on the older studies, that there would be this cascade of benefits that would be unlocked by raising the ability to delay gratification early in life. And I think our findings probably pour some cold water on that.”
The researchers used data from a nationwide longitudinal study by the National Institute of Child Health and Human Development, which tested children’s ability to delay gratification by using a version of Mischel’s original waiting task. In the task, each child was offered one food treat immediately, or twice the amount if the child could wait seven minutes. The study tracked 910 children, as well as a subset of about 550 children of mothers who had not completed college. By contrast, only about 50 children participated in the original “marshmallow test” study.
On average, children waited a little less than four minutes before eating the treat, and more than half of the children could hold out the full seven minutes for a second treat. However, 68 percent of the children whose mothers had completed a college degree could wait, compared to only 45 percent of those whose mothers did not finish college.
The researchers found that waiting did predict children’s later math and reading achievement. For every additional minute a child was able to wait at age 4, he had math and reading achievement that was about a tenth of one standard deviation higher. That was significant, but only about half the difference in achievement found in the original study.
Moreover, when researchers looked at other outcomes that could reasonably be associated with delayed gratification—students’ behavior in school, their parents’ observations, their performance on tasks that required attention and persistence—"We just found nothing there” Watts said.
“We were sort of surprised,” Watts said, but noted that even the original study, found a strong correlation between preschoolers’ ability to delay gratification and their general cognitive ability. “So even at preschool, it looks like what’s driving success at the marshmallow test could be cognitive skills,” he said.
The results do not mean that educators should not try to improve students’ self-control or attention skills, the study concludes, but they do suggest programs that do so should be more comprehensive.
“I think our study probably suggests that if you want to intervene in a way that’s going to produce long-term effects later on, that it’s going to have to change more than just one narrow skill. It is probably going to have to change a lot about the kid or about their circumstances,” Watts said.
A version of this news article first appeared in the Inside School Research blog.