The Marshmallow Test, Revisited

New research shows the delayed-gratification research at Stanford nearly 50 years ago might be wrong.

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The "Marshmallow Test"—the notion that a quarter of young children who exhibit self control, delay gratification, and wait to eat a marshmallow will also do better in school later in life—is one of the most famous social science experiments of the past generation. It also may be wrong.

A video of the so-called marshmallow test—where preschool children fidget, squirm, and clearly debate whether to eat a marshmallow placed in front of them by an adult or delay gratification until a second marshmallow arrives—has been seen by nearly 2 million people on YouTube.

It's a really funny video. Some kids will nibble away at the marshmallow, squish it, squeeze it, sniff it, roll it around on the plate, and generally torture themselves as they wait, wait, wait for the second marshmallow to arrive. It's the kind of video that people happily pass along—and believe quite earnestly. Those who can wait will be better off later in life.

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The larger social science finding underpinning a series of marshmallow-related research conducted at Stanford University nearly 50 years ago is that preschoolers who delay gratification of the simple task of waiting to eat a marshmallow in order to receive a second marshmallow at some point later correlated strongly with success later in life. Waiting longer was linked to higher SAT scores, less substance abuse, and better social skills.

Over the years, the famous marshmallow studies at Stanford in the late 1960s have been cited repeatedly as evidence that qualities such as self control or emotional intelligence may be more important than more traditional measures of intelligence like IQ.

But it may not be nearly as simple as that, some new research from the University of Rochester that will be published in the journal Cognition shows. And, in fact, things like adult supervision and stable home environments may have a whole lot more to do with your ability to delay gratification and learn than you might think.

In short, some kids may have the innate ability to delay gratification. But many kids may also be just as influenced by whether adults let them down or chaotic environments teach them that waiting just isn't an option.

In fact, the Rochester researchers found, children who experienced reliable, predictable interactions with adults in situations where delayed gratification was expected actually waited four times longer (12 versus 3 minutes) than kids in similar, but unreliable, situations.

The Rochester marshmallow test set up two groups of 28 three- to five-year-olds: those with adults who delivered what they'd promised if the kids waited, and a second group where the adults never delivered anything. They then repeated the famous marshmallow test to the two sets of kids.

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The first set kids—who'd been "trained" by adults that they'd get better, cooler things (more interesting stickers and much better art supplies to replace some used crayons) if they waited did just that—they waited an average of 12 minutes before eating the marshmallow. But the second set of preschoolers—those who never got the better art supplies or fancier stickers because the adults failed to deliver on their promises—ate the marshmallows right away, within an average of three minutes.

The disparity was so large, in fact, that there's almost no need to repeat the experiment with a larger sample group. The meaning is obvious. The kids where adults never delivered what they'd promised had learned that delayed gratification didn't make sense. They ate the marshmallows right away, figuring that a second one wasn't likely to show up.

But the kids in the first group—where adults did, in fact, deliver better art supplies as promised after waiting for a few minutes—learned just the opposite. Waiting did, in fact, lead to better things, so they all waited an average of 12 minutes before eating the first marshmallow.

The message? It's worth waiting in a reliable environment. Not so much in an unreliable one.

"Our results definitely temper the popular perception that marshmallow-like tasks are very powerful diagnostics for self-controlled capacity," said Celeste Kidd, a doctoral candidate in brain and cognitive sciences and the lead author of the study.

"Being able to delay gratification—in this case, to wait 15 difficult minutes to earn a second marshmallow—not only reflects a child's capacity for self control, it also reflects their belief about the practicality of waiting," she said. "Delaying gratification is only the rational choice if the child believes a second marshmallow is likely to be delivered after a reasonably short delay."

It's an example of both nature and nurture at work. "This experiment provides robust evidence that young children's actions are also based on rational decisions about their environment," said co-author Richard Aslin, a brain and cognitive sciences professor at Rochester.

The mean time of waiting—12 versus 3 minutes—between the "reliable" and "unreliable" environments is significant. "I was astounded that the effect was so large," Aslin said. "I thought that we might get a difference of maybe a minute or so. You don't see effects like this very often."

What the research clearly shows, the authors concluded in their Cognition study, is that the wait times actually reflected a rational decision-making process by the kids. Uncertainty over the promise of future rewards or unstable environments where future rewards might not be possible or even feasible will logically teach a kid that waiting isn't really a rational option.

In other words, if you've learned that waiting for a future reward isn't likely to be fruitful, why wait? "If you are used to getting things taken away from you, not waiting is the rational choice," Kidd said.

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