what were the results of the stanford marshmallow experiment

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The Stanford Marshmallow Experiment: How Self-Control Affects Success in Life

The  Stanford marshmallow experiment was a psychological study conducted in the late 1960s to early 1970s , in which children were placed in a room with some tasty snack, such as a marshmallow, and told that if they could wait for a short while before eating it then they will get an extra snack as a reward. Follow-up studies on the experiment found that children’s ability to exercise self-control in this situation, by waiting before eating the snack, was correlated with a large range of positive outcomes later in life, such as academic success and physical health.

This experiment received much attention in popular media, and was used to demonstrate the importance of self-control, a concept which was supported by other studies on the topic .

However, later studies criticized the Stanford marshmallow experiment for various issues with its methodology. Furthermore, the results of a large replication study cast doubt on the predictive abilities of the marshmallow test, especially when controlling for relevant background factors such as family background and home environment.

Nevertheless, despite these criticisms, the Stanford marshmallow experiment remains of interest, due to the notable influence it had on psychological research of self-control and on people’s perception of the topic.

As such, in the following article you will learn more about the Stanford marshmallow experiment and about related research on the importance of self-control, see the main criticisms of this study, and learn how you can use a few simple techniques in order to strengthen your own self-control when necessary.

The procedure and results of the Stanford marshmallow experiment

The initial data collection for the Stanford marshmallow experiment took place between 1968 and 1972, using toddlers and preschoolers around the age of 4, who attended Stanford University’s Bing Nursery School.

The main procedure for the experiment was as follows:

• First, a child was taken into a room and allowed to pick a snack that they would like to eat, such as a marshmallow, a pretzel, or a cookie.
• Then, the child was then told that the researcher has to leave the room for a few minutes, and that if they could wait until the researcher came back without eating the snack, then they would get another snack of their choice as a reward.

The children’s ability to delay gratification was measured by seeing whether they were able to wait until the researcher returned without eating the snack, and if not, then by seeing how long it took before they ate the snack or called the researcher back into the room.

Even though the experiment was short and simple, the researchers found that the children’s performance on this test at an early age predicted their long-term success in various ways. Specifically, kids who were able to wait longer before eating the snack were:

• More likely to be rated by their parents as academically and socially competent, verbally fluent, attentive, and rational, when they were older.
• Better able to deal with frustration and stress as adolescents.
• More likely to have  higher SAT scores as adolescents.
• Less likely to be overweight 30 years later.

Note : the main researcher associated with the Stanford marshmallow experiment is psychologist Walter Mischel, who, together with his colleagues, published the initial studies on the experiment in 1970 and 1972 , as well as the later follow-up studies. Two other notable researchers associated with this experiment are Ebbe B. Ebbesen, who was involved with the initial studies, and Yuichi Shoda, who was involved with the follow-up studies.

Other studies using the marshmallow test

Several studies used the marshmallow test in order to examine the factors that affect children’s performance on it.

For example, studies found that trust plays a significant role in children’s decision to wait on the marshmallow task. This was the case both when it came to specific trust in the person conducting the experiment , who promised the reward to the children if they could wait, as well as when it came to children’s generalized trust in unfamiliar people . Furthermore, similar results regarding the influence of social trust were also found in delayed-gratification tests conducted on adults.

In addition, one study found that children delayed gratification for longer if they believed that members of their ingroup , which is the social group that they identify as being a part of, also waited, while members of their outgroup did not, compared to if they believed that the opposite was true.

Finally, another study compared children’s performance on the marshmallow test when it came to three birth cohorts, from the late 1960s, 1980s, and 2000s, and found that, contrary to people’s expectations, children’s ability to delay gratification has been increasing over time, a finding that has been replicated in other studies.

Other research on the importance of self-control

“People who have better control of their attention, emotions, and actions are better off almost any way you look at it. They are happier and healthier. Their relationships are more satisfying and last longer. They make more money and go further in their careers. They are better able to manage stress, deal with conflict, and overcome adversity. They even live longer. When pit against other virtues, willpower comes out on top. Self-control is a better predictor of academic success than intelligence… a stronger determinant of effective leadership than charisma…. and more important for marital bliss than empathy…” — Kelly McGonigal in “ The Willpower Instinct: How Self-Control Works, Why It Matters, and What You Can Do to Get More of It “

Other research on the topic of self-control, which used different methods than the Stanford marshmallow experiment, supports the idea that self-control, as measured early in life, is associated with a range of positive outcomes later on.

For example, one study found that childhood self-control predicts employment rates at adulthood, with individuals who are low in self-control being more likely to be unemployed.

Similarly, another study found that self-control at childhood predicts factors such as financial status, physical health, substance dependence, and criminal offending at adulthood, with higher levels of self-control leading to better outcomes. This remained the case even when the researchers controlled for background factors such as intelligence and familial socioeconomic status, though these factors did play a crucial role in children’s development. A later study replicated these findings, though its results emphasized, to a greater degree, the role that relevant background factors play in children’s development.

Furthermore, research on self-control found that this factor also plays an important role in predicting people’s success when measured directly during adulthood.

For example, a study conducted on people participating in a weight-loss program found that higher levels of self-control were associated with increased weight loss during the program, as a result of eating less and exercising more.

Similarly, a study conducted on university students showed that higher levels of self-control are correlated with “a higher grade point average, better adjustment (fewer reports of psychopathology, higher self-esteem), less binge eating and alcohol abuse, better relationships and interpersonal skills, secure attachment, and more optimal emotional responses”.

Overall, these studies, together with other studies on the topic, demonstrate that self-control measured both during childhood as well as at later stages of life , is associated with a range of positive outcomes, which suggests that it’s an important ability to have.

Related concepts and terms

The marshmallow experiment focused on people’s ability to delay gratification, a facet of self-control that’s sometimes referred to as “patience”. However, the experiment has been found to be a good predictor of self-control in general, meaning that it can be used to predict people’s ability to exercise control in other ways, such as by bringing themselves to do something that they feel anxious about.

In general, self-control is crucial to people’s ability to self-regulate their behavior in pursuit of their goals. This ability is also affected by their executive functions , which are the cognitive processes and abilities, such as task-switching and behavioral inhibition, that are used to control one’s behavior.

A notable, related concept in psychology is conscientiousness , which is the trait of being disciplined, achievement-oriented, organized, and focused, since this trait is one of the strongest predictors of people’s ability to delay gratification.

Note: the term ‘willpower’ is  sometimes used in place of the term ‘self-control’, though it’s also possible to view willpower as something that people use while they’re exercising self-control.

Criticism and replications of the Stanford marshmallow experiment

Though the Stanford marshmallow experiment gained much positive attention in the research community and the press, it has also been heavily criticized by various groups. The main criticisms of the Stanford marshmallow experiment include the following :

• The initial sample for the experiment was highly selective, as it consisted of children from the Stanford University community.
• The samples used in the longitudinal studies on the experiment were small and even more selective than the initial sample, since they contained only the children examined in the original experiment that the researchers were able to reach later.
• The analyses of the data didn’t always account for potential confounding factors, such as family socioeconomic status and general cognitive abilities.

In light of these criticisms, a large replication study was conducted to assess the validity of the findings from the Stanford marshmallow experiment. This replication examined how well preschooler’s ability to delay gratification on the marshmallow test predicted a variety of academic and behavioral outcomes at age 15.

The researchers considered their study to be “a conceptual, rather than traditional, replication of Mischel and Shoda’s seminal work”, since there were some notable differences between their replication and the original work on the topic. These differences included a larger sample, a focus on children born to mothers who had not completed college, and the use of a modified version of the original marshmallow experiment.

The replication did find that the ability to delay gratification at the age of 4 predicted increased achievement at the age of 15. However, the effect size of this association was only half as big as in the original studies, and was reduced by two thirds when the researchers controlled for relevant factors, such as family background, home environment, and early cognitive ability.

Furthermore, the researchers found that most of the achievement boost from the early ability to delay gratification came from the ability to wait for only 20 seconds. This calls into question the hypothesis proposed by the original researchers, that the relationship between the ability to delay gratification and later academic achievement is driven primarily by the ability to utilize relevant metacognitive strategies, since such strategies are unlikely to have played a significant role in children’s ability to wait only 20 seconds.

The findings of this replication were supported by another replication , which found that the ability to delay gratification at age 4.5 did  not predict children’s academic achievement at age 15, once relevant background variables were controlled for.

In addition, a  different replication of the original study , which followed the original protocol more closely but used a smaller sample, found that the ability to delay gratification at the age of 4 did  not predict children’s performance, more than a decade later, at a task requiring cognitive control. However, the children’s ability to direct their attention away from the rewarding stimuli was associated with increased efficiency at the task, in terms of being able to perform it at greater speed without reduced accuracy.

Moreover, a follow-up study on the original sample from the Stanford marshmallow experiment found that there is no significant relationship between people’s delay of gratification at preschool age and their economic outcomes in their late 40s. Nevertheless, the study did find that there is an association between more comprehensive measures of self-regulation at later ages and people’s economic outcomes in their 40s.

Finally, however, it’s important to note that some of the research criticizing the Stanford marshmallow experiment has also been criticized in itself. For example, the main replication on the topic has been criticized for various reasons , as evident, for instance, in a paper on the topic , which argues that “many of the variables in their models should not have been included as confounds because they likely captured factors that measure fundamental processes supporting delay of gratification”.

Overall, the criticisms and replications of the Stanford marshmallow experiment cast doubt on its validity. Nevertheless, given the large body of supporting evidence on the topic, research suggests that self-control does play an important role when it comes to success in life, both when measured during childhood as well as when measured during adulthood. This suggests that the main issues with the marshmallow experiment are its methodology, which is simple and appealing, but not sufficiently robust.

The cognitive mechanisms of self-control

Based on the findings of the Stanford marshmallow experiment, researchers suggest  that we engage two cognitive systems when faced with a situation that requires self-control:

• Hot system. The hot system is our impulsive, emotional system. Hot behaviors, which rely on this system, include things such as fixating on rewards (e.g. imagining what a marshmallow will taste like). These behaviors undermine our self-control, and make it more difficult for us to resist temptation.
• Cool system. The cool system is our rational, emotionally-neutral system. Cool  strategies, which rely on this system, include things such as successful self-distraction (e.g. playing a game which is unrelated to potential temptations). These strategies help us exercise self-control, and successfully delay gratification.

Based on these mechanisms, we can say that our self-control is affected by our ability to inhibit the occurrence of hot behaviors, by utilizing cool  strategies.

Lessons from the marshmallow experiment on exercising self-control

Though the marshmallow test is primarily known for illustrating the importance of self-control, it also provides several insights into how people can learn to better exercise their self-control.

For example,  one of the original studies on the Stanford marshmallow experiment describes several factors that affected the children’s ability to exercise self-control during the test:

• Children who were told to distract themselves by playing with a toy or by thinking about playing with one were able to delay gratification for longer.
• Children who were told to think about “fun things” were able to wait for significantly longer than those who were told to think “sad thoughts”.
• Children who were told to spend their time thinking about the rewards of the test generally struggled to delay gratification.

Furthermore, the studies on the topic also demonstrate how the children coped with temptation, even when they weren’t instructed how to do so by the researchers. As the first study on the topic states:

“One of the most striking delay strategies used by some subjects was exceedingly simple and effective. These children seemed to facilitate their waiting by converting the aversive waiting situation into a more pleasant nonwaiting one. They devised elaborate self-distraction techniques through which they spent their time psychologically doing something (almost anything) other than waiting. Instead of focusing prolonged attention on the objects for which they were waiting, they avoided looking at them. Some children covered their eyes with their hands, rested their heads on their arms, and found other similar techniques for averting their eyes from the reward objects. Many seemed to try to reduce the frustration of delay of reward by generating their own diversions: they talked to themselves, sang, invented games with their hands and feet, and even tried to fall asleep while waiting—as one child successfully did… These observations, while obviously inconclusive, suggest that diverting one’s attention away from the delayed reward (while maintaining behavior directed toward its ultimate attainment) may be a key step in bridging temporal delay of reward. That is, learning not to think about what one is awaiting may enhance delay of gratification, much more than does ideating about the outcomes.”

This means that, in order to help yourself exercise self-control in the face of temptation, you want to avoid obsessing about the potential reward that you’re tempted by or fixating on the difficulty of resisting it. Instead, as soon as you recognize yourself starting to fall into one of these negative thought patterns, you need to mentally “exit” it as quickly as possible.

You can do this by distracting yourself and taking part in unrelated positive experiences, such as reading a book, playing a game, or talking to a friend. The more positive the experience, and the more it can distract you from the potential reward, the more it will help you exercise restraint and self-control.

This may sound difficult to accomplish, but studies show that self-control training can be beneficial  in the long term , and that you can strengthen your self-control through the regular practice of small acts of self-control. As the main book on the topic states:

“…the ability to delay immediate gratification for the sake of future consequences is an acquirable cognitive skill.” — Walter Mischel in “ The Marshmallow Test: Why Self-Control Is the Engine of Success “

This is important, since it means that doing something such as reducing your snacking behavior can later help you exercise self-control in unrelated areas, such as pushing yourself at the gym or fighting against your procrastination tendencies when it comes to doing work.

Note : the book written about the marshmallow test discusses other techniques that you can use to improve your self-control, such as increasing your connection to your future self and creating if-then implementation plans .

Summary and conclusions

• The  Stanford marshmallow experiment was a psychological study conducted in the late 1960s to early 1970s, in which children were placed in a room with some tasty snack, such as a marshmallow, and told that if they could wait for a short while before eating it then they will get an extra snack as a reward.
• Follow-up studies on the experiment found that children’s ability to exercise self-control in this situation, by waiting before eating the snack, was correlated with a large range of positive outcomes later in life, such as academic success and physical health.
• The validity of the marshmallow experiment has been questioned by a number of studies, but also supported by related research on the topic, and overall, it appears that while the marshmallow test is flawed in some ways, self-control nevertheless plays an important role in people’s development.
• The researchers who conducted the Stanford marshmallow experiment suggested that the ability to delay gratification depends primarily on the ability to engage our cool , rational cognitive system, in order to inhibit our hot , impulsive system.
• Therefore, to improve your ability to exercise self-control, you can focus on using relevant cool strategies, such as distracting yourself from tempting rewards, in order to inhibit hot behaviors, such as obsessing about the difficulty of resisting a certain temptation.

If you found this concept interesting and you want to learn more about it, read the main book on the topic, which was written by the primary researcher involved with the study: “ The Marshmallow Test: Why Self-Control Is the Engine of Success “.

Other articles you may find interesting:

• The Empathy Gap: Why People Fail to Understand Different Perspectives
• Authority Bias: Lessons from the Milgram Obedience Experiment
• The Napoleon Technique: Postponing Things to Increase Productivity

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The Marshmallow Test: Delayed Gratification in Children

• Archaeology

• Ph.D., Psychology, Fielding Graduate University
• M.A., Psychology, Fielding Graduate University
• B.A., Film Studies, Cornell University

The marshmallow test, which was created by psychologist Walter Mischel, is one of the most famous psychological experiments ever conducted. The test lets young children decide between an immediate reward, or, if they delay gratification, a larger reward. Studies by Mischel and colleagues found that children’s ability to delay gratification when they were young was correlated with positive future outcomes. More recent research has shed further light on these findings and provided a more nuanced understanding of the future benefits of self-control in childhood.

Key Takeaways: The Marshmallow Test

• The marshmallow test was created by Walter Mischel. He and his colleagues used it to test young children’s ability to delay gratification.
• In the test, a child is presented with the opportunity to receive an immediate reward or to wait to receive a better reward.
• A relationship was found between children’s ability to delay gratification during the marshmallow test and their academic achievement as adolescents.
• More recent research has added nuance to these findings showing that environmental factors, such as the reliability of the environment, play a role in whether or not children delay gratification.
• Contrary to expectations, children’s ability to delay gratification during the marshmallow test has increased over time.

The Original Marshmallow Test

The original version of the marshmallow test used in studies by Mischel and colleagues consisted of a simple scenario. A child was brought into a room and presented with a reward, usually a marshmallow or some other desirable treat. The child was told that the researcher had to leave the room but if they could wait until the researcher returned, the child would get two marshmallows instead of just the one they were presented with. If they couldn’t wait, they wouldn’t get the more desirable reward. The researcher would then leave the room for a specific amount of time (typically 15 minutes but sometimes as long as 20 minutes) or until the child could no longer resist eating the single marshmallow in front of them.

Over six years in the late 1960s and early 1970s, Mischel and colleagues repeated the marshmallow test with hundreds of children who attended the preschool on the Stanford University campus. The children were between 3 and 5 years old when they participated in the experiments. Variations on the marshmallow test used by the researchers included different ways to help the children delay gratification, such as obscuring the treat in front of the child or giving the child instructions to think about something else in order to get their mind off the treat they were waiting for.

Years later, Mischel and colleagues followed up with some of their original marshmallow test participants. They discovered something surprising. Those individuals who were able to delay gratification during the marshmallow test as young children rated significantly higher on cognitive ability and the ability to cope with stress and frustration in adolescence. They also earned higher SAT scores.

These results led many to conclude that the ability to pass the marshmallow test and delay gratification was the key to a successful future. However, Mischel and his colleagues were always more cautious about their findings . They suggested that the link between delayed gratification in the marshmallow test and future academic success might weaken if a larger number of participants were studied. They also observed that factors like the child’s home environment could be more influential on future achievement than their research could show.

Recent Findings

The relationship Mischel and colleagues found between delayed gratification in childhood and future academic achievement garnered a great deal of attention. As a result, the marshmallow test became one of the most well-known psychological experiments in history. Yet, recent studies have used the basic paradigm of the marshmallow test to determine how Mischel’s findings hold up in different circumstances.

Delayed Gratification and Environmental Reliability

In 2013, Celeste Kidd, Holly Palmeri, and Richard Aslin published a study that added a new wrinkle to the idea that delayed gratification was the result of a child’s level of self-control. In the study, each child was primed to believe the environment was either reliable or unreliable. In both conditions, before doing the marshmallow test, the child participant was given an art project to do. In the unreliable condition, the child was provided with a set of used crayons and told that if they waited, the researcher would get them a bigger, newer set. The researcher would leave and return empty-handed after two and a half minutes. The researcher would then repeat this sequence of events with a set of stickers. The children in the reliable condition experienced the same set up, but in this case the researcher came back with the promised art supplies.

The children were then given the marshmallow test. Researchers found that those in the unreliable condition waited only about three minutes on average to eat the marshmallow, while those in the reliable condition managed to wait for an average of 12 minutes—substantially longer. The findings suggest that children’s ability to delay gratification isn’t solely the result of self-control. It’s also a rational response to what they know about the stability of their environment.

Thus, the results show that nature and nurture play a role in the marshmallow test. A child’s capacity for self-control combined with their knowledge of their environment leads to their decision about whether or not to delay gratification.

Marshmallow Test Replication Study

In 2018, another group of researchers, Tyler Watts, Greg Duncan, and Haonan Quan, performed a conceptual replication of the marshmallow test. The study wasn’t a direct replication because it didn’t recreate Mischel and his colleagues exact methods. The researchers still evaluated the relationship between delayed gratification in childhood and future success, but their approach was different. Watts and his colleagues utilized longitudinal data from the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development, a diverse sample of over 900 children.

In particular, the researchers focused their analysis on children whose mothers hadn’t completed college when they were born—a subsample of the data that better represented the racial and economic composition of children in America (although Hispanics were still underrepresented). Each additional minute a child delayed gratification predicted small gains in academic achievement in adolescence, but the increases were much smaller than those reported in Mischel’s studies. Plus, when factors like family background, early cognitive ability, and home environment were controlled for, the association virtually disappeared.

The results of the replication study have led many outlets reporting the news to claim that Mischel’s conclusions had been debunked. However, things aren’t quite so black and white. The new study demonstrated what psychologists already knew: that factors like affluence and poverty will impact one’s ability to delay gratification. The researchers themselves were measured in their interpretation of the results. Lead researcher Watts cautioned , “…these new findings should not be interpreted to suggest that gratification delay is completely unimportant, but rather that focusing only on teaching young children to delay gratification is unlikely to make much of a difference.” Instead, Watts suggested that interventions that focus on the broad cognitive and behavioral capabilities that help a child develop the ability to delay gratification would be more useful in the long term than interventions that only help a child learn to delay gratification.

Cohort Effects in Delayed Gratification

With mobile phones, streaming video, and on-demand everything today, it's a common belief that children's ability to delay gratification is deteriorating. In order to investigate this hypothesis, a group of researchers, including Mischel, conducted an analysis comparing American children who took the marshmallow test in the 1960s, 1980s, or 2000s. The children all came from similar socioeconomic backgrounds and were all 3 to 5 years old when they took the test.

Contrary to popular expectations, children’s ability to delay gratification increased in each birth cohort. The children who took the test in the 2000s delayed gratification for an average of 2 minutes longer than the children who took the test in the 1960s and 1 minute longer than the children who took the test in the 1980s.

The researchers suggested that the results can be explained by increases in IQ scores over the past several decades, which is linked to changes in technology, the increase in globalization, and changes in the economy. They also noted that the use of digital technology has been associated with an increased ability to think abstractly, which could lead to better executive function skills, such as the self-control associated with delayed gratification. Increased preschool attendance could also help account for the results.

Nonetheless, the researchers cautioned that their study wasn’t conclusive. Future research with more diverse participants is needed to see if the findings hold up with different populations as well as what might be driving the results.

• American Psychology Association. "Can Kids Wait? Today's Youngsters May Be Able to Delay Gratification Longer Than Those of the 1960's." 25 June, 2018. https://www.apa.org/news/press/releases/2018/06/delay-gratification
• Association for Psychological Science. "A New Approach to the Marshmallow Test Yields Complicated Findings." 5 June, 2018. https://www.psychologicalscience.org/publications/observer/obsonline/a-new-approach-to-the-marshmallow-test-yields-complex-findings.html
• Carlson, Stephanie M., Yuichi Shoda, Ozlem Ayduk, Lawrence Aber, Catherine Schaefer, Anita Sethi, Nicole Wilson, Philip K. Peake, and Walter Mischel. "Cohort Effects in Children's Delay of Gratification." Developmental Psychology , vol. 54, no. 8, 2018, pp. 1395-1407. http://dx.doi.org/10.1037/dev0000533
• Kidd, Celeste, Holly Palmeri, and Richard N. Aslin. "Rational Snacking: Young Children's Decision-Making on the Marshmallow Task is Moderated By Beliefs About Environmental Reliability." Cognition, vol. 126, no. 1, 2013, pp. 109-114. https://doi.org/10.1016/j.cognition.2012.08.004
• New York University. "Professor Replicates Famous Marshmallow Test, Makes New Observations." ScienceDaily , 25 May, 2018.  https://www.sciencedaily.com/releases/2018/05/180525095226.htm
• Shoda, Yuichi, Walter Mischel, and Philip K. Peake. "Predicting Adolescent Cognitive and Self-Regulatory Competencies from Preschool Delay of Gratification: Identifying Diagnostic Conditions." Developmental Psychology, vol. 26, no. 6, 1990, pp. 978-986. http://dx.doi.org/10.1037/0012-1649.26.6.978
• University of Rochester. "The Marshmallow Study Revisited." 11 October, 2012. https://www.rochester.edu/news/show.php?id=4622
• Watts, Tyler W., Greg J. Duncan, and Haonan Quan. "Revisiting the Marshmallow Test: A Conceptual Replication Investigating Links Between Early Delay of Gratification and Later Outcomes." Psychological Science, vol. 28, no. 7, 2018, pp. 1159-1177. https://doi.org/10.1177/0956797618761661
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