You can eat your mallow: debunking the marshmallow test

The Stanford marshmallow experiment is probably the most famous study in delayed gratification. In 1972, a group of kids was asked to make a simple choice: you can eat this marshmallow now, or wait 15 minutes and receive a second treat.

In the paper, the researchers highlighted two significant findings. First, not physically seeing the bigger reward made it easier for the children to wait longer. Second, using distraction strategies also had a positive impact on how long the children managed to wait. “They made up quiet songs, hid their head in their arms, pounded the floor with their feet, fiddled playfully and teasingly with the signal bell, verbalised the contingency, prayed to the ceiling, and so on. In one dramatically effective self-distraction technique, after obviously experiencing much agitation, a little girl rested her head, sat limply, relaxed herself, and proceeded to fall sound asleep.”

While this first study was interesting, what made it famous was the follow-up studies conducted in the 80’s and 90’s, where another group of researchers found some correlations between the results of the original marshmallow test, and the success of children many years later. In particular, children who showed higher levels of self-control during the marshmallow test tended to have higher SAT scores as teenagers.

Because of these follow-up studies, many people think that kids who show self-restraint will turn out to be more successful adults, and teaching patience to a kid may help them achieve similar benefits. But there are many problems with these studies.

Correlation is not causation

The researchers from the original studies themselves have been unhappy about the way their work was interpreted. “The idea that your child is doomed if she chooses not to wait for her marshmallows is really a serious misinterpretation,” said Walter Mischel, who pioneered the concept of the marshmallow test.

A more serious issue? The study fails the replication test. To their credit, Mischel and his colleagues made the fragility of the study very clear in their 1990 paper, citing a small sample size, low variance, and the potential importance of many other factors—such as home environment—which were not accounted for in the study.

Marshmallow test limitations

So it’s surprising it took more than thirty years for another team to put these studies to the test. Tyler Watts, a psychology professor at NYU, worked with his team to analyse data collected by the US National Institutes of Health in the 1990s with more than 900 four-year-old kids. While the marshmallow test used with the NIH sample was shorter—7 minutes instead of 15 minutes—the principles were the same.

There are two aspects which make this data more interesting, though. First, the sample size: almost a thousand kids versus fewer than a hundred with the older studies. Second, the diversity of the sample itself. While the older studies were conducted with kids from wealthy and educated families—the children’s parents were professors at Stanford—the new study focused on kids whose mothers did not attend college.

The results are a blow to the original marshmallow studies. Once the researchers controlled for factors such as family background, the correlation between self-control at age 4 and SAT scores at age 15 completely vanished.

In the words of the researchers: “If you have two kids who have the same background environment, they get the same kind of parenting, they are the same ethnicity, same gender, they have a similar home environment, they have similar early cognitive ability, then if one of them is able to delay gratification, and the other one isn’t, does that matter? Our study says, probably not.”

Abundance breeds patience

So why are some kids able to delay gratification, and others just eat the marshmallow? The new study suggests a simpler explanation. “It suggests that the capacity to hold out for a second marshmallow is shaped in large part by a child’s social and economic background—and, in turn, that that background, not the ability to delay gratification, is what’s behind kids’ long-term success,” writes Jessica Calarco.

First, from the child’s perspective: when you’re not even sure the one marshmallow you have been given won’t disappear, why take the risk to wait for a second marshmallow? Children growing in poorer households are more likely to have this thought process.

Second, from the parent’s perspective: why not indulge my kid when I can? While wealthier parents will tend to teach their children to wait for the bigger reward, lower income parents may use any opportunity to make their kid happier in the short term.

A kid’s capacity to delay gratification is not a predictor for success as an adult. It’s their socio-economic background instead which has the largest impact on their future. We should stop scolding children who seem to be impatient—impatience is a sign of uncertainty about the future.

Willpower is overrated

For the longest times, scientists thought self-control was a measure of willpower. The more willpower, the easier to resist temptations. But recent studies make the case against using willpower as a means to achieve one’s goals.

In a study which followed more than 200 people during one week, researchers administered a survey to measure self control (with statements such as “I am good at resisting temptations” or “I can easily keep a secret”), then reported on their in-the-moment desires, temptations, and self-control levels throughout the week.

The findings were surprising: the people who were the best at self-control according to the initial survey reported fewer temptations throughout the week. To put it another way, the people who said they had excellent self-control didn’t need to use it as much.

If willpower is not the answer, how can you increase your self-control as an adult?

  • Turning “have to” into “want to.” Whether your goal is to eat healthy, exercise, or study, make it fun so it doesn’t feel like a chore. Some people use gamification, others pair up with a buddy. Experiment to figure out what makes these tasks more enjoyable. Turn your push goals into pull goals.
  • Building better habits. That’s why habits are so powerful: they become automatic. Which can be bad, when we have developed habits such as snacking all day long, or smoking, or can be good, such as the habit of drinking water, or meditating. Instead of relying on willpower, design better habits, routines, and rituals.
  • Managing temptations. Finally, make it easier to stick to these goals. Trying to eat healthy? Stock up on healthy foods. Trying to exercise? Put your running shoes right next to your door and put the TV remote away so it’s not in plain sight. Trying to read more? Put books around the house: on your bedside table, in the living room, in the bathroom. Tempt yourself into achieving your goals.

Acknowledge that you are human: your willpower is both extremely limited and a terrible tool to achieve your goals. Instead, design an environment and build habits which will make it much easier to stick to your resolutions. And if yourself or a child sometimes fails at delaying gratification, don’t beat yourself up. A temporary lack of self-control is not predictive of future success. Let it go and just get back on track.

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