The Marshmallow Test, Re-run
In 1972, waiting for a second marshmallow seemed to predict children’s futures. When researchers re-ran the test with ten times the children, the story changed.
Based on: Watts, T. W., Duncan, G. J., & Quan, H. (2018). “Revisiting the Marshmallow Test: A Conceptual Replication Investigating Links Between Early Delay of Gratification and Later Outcomes.” Psychological Science, 29(7). doi.org/10.1177/0956797618761661
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In 1972, a few dozen preschoolers were left alone in a room with one marshmallow. Wait fifteen minutes, and you get two.
Years later, the children who had waited scored higher on the SAT. For decades, self-control looked like destiny.
In 2018, researchers ran the test again. Nine hundred children this time, ten times the original sample, and a far more diverse one.
The link was still there. But about half as strong. And once they accounted for the family's income and the mother's education, most of what was left disappeared.
Waiting still predicted a little. But the marshmallow was mostly measuring the kitchen it came from.
Two lessons. Small samples make big stories. And the finding everyone remembers is usually the first one, not the best one.
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