The Stanford marshmallow experiment[1] was a series of studies on delayed gratification in the late 1960s and early 1970s led by psychologist Walter Mischel, then a professor at Stanford University. In these studies, a child was offered a choice between one small reward provided immediately or two small rewards if they waited for a short period, approximately 15 minutes, during which the tester left the room and then returned. (The reward was sometimes a marshmallow, but often a cookie or a pretzel.) In follow-up studies, the researchers found that children who were able to wait longer for the preferred rewards tended to have better life outcomes, as measured by SAT scores,[2] educational attainment,[3] body mass index (BMI),[4] and other life measures.[5]

Original experiment[edit]

Origins[edit]

The experiment has its roots in an earlier one performed in Trinidad, where Mischel noticed that the different ethnic groups living on the island had contrasting stereotypes about one another, specifically the other's perceived recklessness, self-control, and ability to have fun.[6] This small (n= 53) study focused on male and female children aged 7 to 9 (35 Black and 18 East Indian) in a rural Trinidad school. The children were required to indicate a choice between receiving a 1¢ candy immediately, or having a (preferable) 10¢ candy given to them in one week's time. Mischel reported a significant ethnic difference, large age differences, and that "Comparison of the "high" versus "low" socioeconomic groups on the experimental choice did not yield a significant difference".[6] Absence of the father was prevalent in the African-descent group (occurring only once in the East Indian group), and this variable showed the strongest link to delay of gratification, with children from intact families showing superior ability to delay.

Stanford experiment[edit]

The first “Marshmallow Test” was a study conducted by Walter Mischel and Ebbe B. Ebbesen at Stanford University in 1970.[7]

The purpose of the original study was to understand when the control of deferred gratification, the ability to wait to obtain something that one wants, develops in children. The original experiment took place at the Bing Nursery School located at Stanford University, using children age four to six as subjects. The children were led into a room, empty of distractions, where a treat of their choice (Oreo cookie, marshmallow, or pretzel stick) was placed on a table, by a chair.[1] The children could eat the marshmallow, the researchers said, but if they waited for fifteen minutes without giving in to the temptation, they would be rewarded with a second marshmallow.[1] Mischel observed that some would "cover their eyes with their hands or turn around so that they can't see the tray, others start kicking the desk, or tug on their pigtails, or stroke the marshmallow as if it were a tiny stuffed animal," while others would simply eat the marshmallow as soon as the researchers left.[1]

In over 600 children who took part in the experiment, a minority ate the marshmallow immediately. Of those who attempted to delay, one third deferred gratification long enough to get the second marshmallow.[1] Age was a major determinant of deferred gratification.

Method[edit]

Subjects[edit]

Test subjects were 16 boys and 16 girls attending the Bing Nursery School of Stanford University. Three other subjects were run, but eliminated because of their failure to comprehend the instructions. The children ranged in age from 3 years, 6 months to 5 years, 8 months (with a median age of 4 years, 6 months). The procedures were conducted by two

male experimenters. Eight subjects (four male and four female) were assigned randomly to each of the four experimental conditions. In each condition each experimenter ran two boys and two girls in order to avoid systematic biasing effects from sex or experimenters.[7]

The conditions[edit]

1. Both the immediate (less preferred) and the delayed (more preferred) reward were left facing the subject and available for attention[7]

2. Neither reward was available for the subject’s attention, both rewards having been removed from his/her sight[7]

3. The delayed reward only was left facing the subject and available for attention while he or she waited[7]

4. The immediate reward only was left facing the subject and available for attention while he or she waited[7]

Procedure[edit]

On the table in the experimental room there were five pretzels and an opaque cake tin. Under the cake tin were five pretzels and two animal cookies. There were two chairs in front of the table, on one chair was an empty cardboard box. On the floor near the chair with the cardboard box on it were four battery operatedtoys. The experimenter pointed out the four toys; before the child could play with the toys, the experimenter asked the child to sit in the chair and then demonstrated each toy briefly and in a friendly manner, saying that they would play with the toys later on. Then the experimenter placed each toy in the cardboard box and out of sight of the child. The experimenter explained to the child that the experimenter sometimes has to go out of the room but if the child eats a pretzel the experimenter will come back into the room. These instructions were repeated until the child seemed to understand them completely. The experimenter left the room and waited for the child to eat a pretzel – they did this four times.

Next the experimenter opened the cake tin to reveal two sets of reward objects to the child: five pretzels and two animal crackers. The experimenter asked which of the two the child liked better (preferred reward), and after the child chose, the experimenter explained that the child could either continue waiting for the more preferred reward until the experimenter returned, or the child could stop waiting by bringing the experimenter back. If the child stopped waiting, then the child would receive the less favored reward and forgo the more preferred one.

Depending on the condition and the child’s choice of preferred reward, the experimenter picked up the cake tin and along with it either nothing, one of the rewards, or both. The experimenter returned either as soon as the child signaled him to do so or after 15 minutes. [7]

Follow-up studies[edit]

In follow-up studies, Mischel found unexpected correlations between the results of the marshmallow test and the success of the children many years later.[5] The first follow-up study, in 1988, showed that "preschool children who delayed gratification longer in the self-imposed delay paradigm, were described more than 10 years later by their parents as adolescents who were significantly more competent."

A second follow-up study, in 1990, showed that the ability to delay gratification also correlated with higherSAT scores.[5]

A 2006 paper to which Mischel contributed reports a similar experiment, this time relating ability to delay in order to receive a cookie (at age 4) and reaction time on a Go/no go task.[8]

A 2011 brain imaging study of a sample from the original Stanford participants when they reached mid-life showed key differences between those with high delay times and those with low delay times in two areas: the prefrontal cortex (more active in high delayers) and the ventral striatum (an area linked to addictions) when they were trying to control their responses to alluring temptations.[9][10]

A 2012 study at the University of Rochester (with a smaller N= 28) altered the experiment by dividing children into two groups: one group was given a broken promise before the marshmallow test was conducted (the unreliable tester group), and the second group had a fulfilled promise before their marshmallow test (the reliable tester group). The reliable tester group waited up to four times longer (12 min) than the unreliable tester group for the second marshmallow to appear.[11][12] The authors argue that this calls into question the original interpretation of self-control as the critical factor in children's performance, since self-control should predict ability to wait, not strategic waiting when it makes sense. Prior to the Marshmallow Studies at Stanford, Walter Mischel had shown that the child's belief that the promised delayed rewards would actually be delivered is an important determinant of the choice to delay, but his later experiments did not take this factor into account or control for individual variation in beliefs about reliability when reporting correlations with life successes.[13][14][15][16]

What the Marshmallow Test Really Teaches About Self-Control

One of the most influential modern psychologists, Walter Mischel, addresses misconceptions about his study, and discusses how both adults and kids can master willpower.

Maryam Abdulghaffar/Flickr

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JACOBA URIST

 

 SEP 24, 2014

The image is iconic: A little kid sits at a table, his face contorted in concentration, staring down a marshmallow. Over the last 50 years, the “Marshmallow Test” has become synonymous with temptation, willpower, and grit. Walter Mischel’s work permeates popular culture. There are “Don’t Eat the Marshmallow!” t-shirts and Sesame Street episodes where Cookie Monster learns delayed gratification so he can join the Cookie Connoisseurs Club. Investment companies have used the Marshmallow Test to encourage retirement planning. And when I mentioned to friends that I was interviewing the Marshmallow Man about his new book,  The Marshmallow Test: Mastering Self-Control ,   nobody missed the reference.

It began in the early 1960s at Stanford University’s Bing Nursery School, where Mischel and his graduate students gave children the choice between one reward (like a marshmallow, pretzel, or mint) they could eat immediately, and a larger reward (two marshmallows) for which they would have to wait alone, for up to 20 minutes. Years later, Mischel and his team followed up with the Bing preschoolers and

found that children who had waited for the second marshmallow generally fared better in life. For example, studies showed that a child’s ability to delay eating the first treat predicted higher SAT scores and a lower body mass index (BMI) 30 years after their initial Marshmallow Test. Researchers discovered that parents of “high delayers” even reported that they were more competent than “instant gratifiers”—without ever knowing whether their child had gobbled the first marshmallow.

But there’s been criticism of Mischel’s findings too—that his samples are too small or homogenous to support sweeping scientific conclusions and that the Marshmallow Test actually measures trust in authority, not what he says his grandmother called sitzfleisch, the ability to sit in a seat and reach a goal, despite obstacles. I met with Mischel in his Upper West Side home, where we discussed what the Marshmallow Test really captures, how schools can use his work to help problem students, why men like Tiger Woods and President Bill Clinton may have suffered “willpower fatigue”—and whether I should be concerned that my five-year old devoured “the marshmallow” (in his case, a small chocolate cupcake) in 30 seconds.

Jacoba Urist: I have to tell you right off, my son is in kindergarten and he flunked the Marshmallow Test last night.

Walter Mischel: First, it’s important that I say “the test” in quotes, because it didn’t start out as a “test” but a situation where we were studying the kinds of things that kids did naturally to make self-control easier or harder for them. Four-year-olds can be brilliantly imaginative about distracting themselves, turning their toes into piano keyboards, singing little songs, exploring their nasal orifices.

"It’s really not about candy. The studies are about achievement situations and what influences a child to reach his or her choice."

Urist: The problem is, I think he has no motivation for food. In our house, dessert isn’t a big deal. Could the kids who wait for the marshmallow just not care that much about treats? Maybe their families didn’t use food as a reward system so they didn’t respond to it as a motivator?

Mischel: You have to understand, in the studies we did, the marshmallows are not the ones presented in the media and on YouTube or on the cover of my book. They were these teeny, weeny pathetic miniature marshmallows or the difference between one tiny, little pretzel stick and two little pretzel sticks, less than an inch tall. It’s really not about candy. Many of the kids would bag their little treats to say, “Look what I did and how proud mom is going to be.” The studies are about achievement situations and what influences a child to reach his or her choice. In some cases, we even used two colored poker chips versus one.  

Urist: How important is trust then? Some critics claim that a 2012 University of Rochester study calls the Marshmallow Test into question. Children in a reliable environment (where they could trust that the delayed reward would materialize) waited four times longer than children in the unreliable group. Were the kids in your test simply making a rational choice and assessing reliability? And wouldn’t that factor be outside the scope of the original Marshmallow Tests?

Mischel: This is another thing the media regularly misses. Before the marshmallow experiments, I researched trust in decision-making for adults and children. Trust is a tremendous issue. Therefore, in the Marshmallow Tests, the first thing we do is make sure the researcher is someone who is extremely familiar to the child and plays with them in the playroom before the test. It’s also important to realize, it’s not a matter of if somebody will come back with the two little marshmallows. They are all right there on the tray. It’s all out in the open, so there’s no trust issue about whether the marshmallows are real.

Urist: When it comes to correlations between the Marshmallow Test and indicators of success later in life, some

people say the marshmallow tests are based on too small a sample to draw meaningful conclusions, that you originally studied over 500 children, but you only tracked down 94 of the participants’ SAT scores?   

Mischel: We didn’t want parental reports of SAT scores. We actually wanted to be able to contact the organization that administered the SAT at the time and therefore had to use a subset of the children. But the correlations were sufficiently strong that the smaller sample size isn’t relevant. To me, the real problem was that we were dealing with an incredibly homogenous sample, either children of Stanford faculty or Stanford graduate students—and we still saw strong correlation. But it was an unbelievably elitist subset of the human race, which was one of the concerns that motivated me to study children in the South Bronx—kids in high-stress, poverty conditions—and yet we saw many of the same phenomena as the marshmallow studies were revealing.

Urist: Are some children who delay responding to authority? Could waiting be a sign of wanting to please an adult and not a proxy for innate willpower? Presumably, even little kids can glean what the researchers want from them.

Mischel: Maybe. They might be responding to anything under the sun. But it’show they respond. The most interesting thing, I think, about the studies is not the correlations that the press picks up, but that the marshmallow studies became the basis for testing all kinds of adults and how adults deal with difficult emotions that are very hard to distance yourself from, like heartbreak or grief.

[Ed. note: Mischel’s book draws on the marshmallow studies to explore how adults can master the same cognitive skills that kids use to distract themselves from the treat, when they encounter challenges in everyday life, from quitting smoking to overcoming a difficult breakup.]

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The Chocolate-and-Radish Experiment That Birthed the Modern Conception of Willpower

Urist: I have to ask you about President Clinton and Tiger Woods, both mentioned in the book. I’ve heard of“decision fatigue”—are their respective media scandals both examples of adults who suffered from “willpower fatigue?” Men who could exercise enormous self-discipline on the golf course or in the Oval office but less so personally?

Mischel: No question. People experience willpower fatigue and plain old fatigue and exhaustion. What we do when we get tired is heavily influenced by the self-standards we develop and that in turn is strongly influenced by the models we have. Bill Clinton simply may have a different sense of entitlement: I worked hard all day, now I’m entitled to X, Y, or Z. Confusion about these kinds of behaviors [tremendous willpower in one situation, but not another] is erased when you realize self-control involves cognitive skills. You can have the skills and

not use them. If your kid waits for the marshmallow, [then you know] she is able to do it. But if she doesn’t, you don’t know why. She may have decided she doesn’t want to.

Urist: So for adults and kids, self-control or the ability to delay gratification is like a muscle? You can choose to flex it or not?

Mischel: Yes, absolutely. That’s a perfectly reasonable analogy.

Urist: In the book, you advise parents if their child doesn’t pass the Marshmallow Test, ask them why they didn’t wait. What should I be trying to elicit from my son about why he grabbed the first little cupcake? When I asked, he just shrugged and said, “I don’t know.”

Mischel: It sounds like your son is very comfortable with cupcakes and not having any cupcake panics and I wish him a hearty appetite. Whether the information is relevant in a school setting depends on how the child is doing in the classroom. If he or she is doing well, who cares? But if the child is distracted or has problems regulating his own negative emotions, is constantly getting into trouble with others, and spoiling things for classmates, what you can take from my work and my book, is to use all the strategies I discuss—namely making “if-then” plans and practicing them. Having a whole set of procedures in place can help a child regulate what he is feeling or doing more carefully.

Urist: One last question. After all these years, why a book now?  

Mischel: Well, there are two reasons. First, so much research has exploded onexecutive function and there have been so many breakthroughs in neuroscience on how the brain works to make it harder or easier to exercise self-control. It’s an enormously exciting time within science for understanding in a much deeper way the relationships between mind, brain, and behavior and to ask the important questions: How can you regulate yourself and control yourself in ways that make your

life better? Second, there have been so many misunderstandings about what the Marshmallow Test does and doesn’t do, what the lessons are to take from it, that I thought I might as well write about this rather than have arguments in the newspapers.