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resistance is futile

New twist on marshmallow test shows power of a promise

Younger children were slightly more likely to successfully delay gratification than older children.

Jennifer Ouellette – | 56
For decades, Walter Mischel's "marshmallow test" was viewed as a key predictor for children's future success, but reality is a bit more nuanced. Credit: Igniter Media
For decades, Walter Mischel's "marshmallow test" was viewed as a key predictor for children's future success, but reality is a bit more nuanced. Credit: Igniter Media

You've probably heard of the infamous "marshmallow test," in which young children are asked to wait to eat a yummy marshmallow placed in front of them while left alone in a room for 10 to 15 minutes. If they successfully do so, they get a second marshmallow; if not, they don't. The test has become a useful paradigm for scientists interested in studying the various factors that might influence one's ability to delay gratification, thereby promoting social cooperation. According to a paper published in the journal Royal Society Open Science, one factor is trust: If children are paired in a marshmallow test and one promises not to eat their treat for the specified time, the other is much more likely to also refrain from eating it.

As previously reported, psychologist Walter Mischel's landmark behavioral study involved 600 kids between the ages of four and six, all culled from Stanford University's Bing Nursery School. He would give each child a marshmallow and give them the option of eating it immediately if they chose. But if they could wait 15 minutes, they would get a second marshmallow as a reward. Then Mischel would leave the room, and a hidden video camera would tape what happened next.

Some kids just ate the marshmallow right away. Others found a handy distraction: covering their eyes, kicking the desk, or poking at the marshmallow with their fingers. Some smelled it, licked it, or took tiny nibbles around the edges. Roughly one-third of the kids held out long enough to earn a second marshmallow. Several years later, Mischel noticed a strong correlation between the success of some of those kids later in life (better grades, higher self-confidence) and their ability to delay gratification in nursery school. Mischel's follow-up study confirmed the correlation.

Mischel himself cautioned against over-interpreting the results, emphasizing that children who simply can't hold out for that second marshmallow are not necessarily doomed to a life of failure. A more nuanced picture was offered in a 2018 study that replicated the marshmallow test with preschoolers. It found the same correlation between later achievement and the ability to resist temptation in preschool, but that correlation was much less significant after the researchers factored in such aspects as family background, home environment, and so forth. Attentiveness might be yet another contributing factor, according to a 2019 paper.

There have also been several studies examining the effects of social interdependence and similar social contexts on children's ability to delay gratification, using variations of the marshmallow test paradigm. For instance, in 2020, a team of German researchers adapted the classic experimental setup using Oreos and vanilla cookies with German and Kenyan schoolchildren, respectively. If both children waited to eat their treat, they received a second cookie as a reward; if one did not wait, neither child received a second cookie. They found that the kids were more likely to delay gratification when they depended on each other, compared to the standard marshmallow test.

An online paradigm

Rebecca Koomen, a psychologist now at the University of Manchester, co-authored the 2020 study as well as this latest one, which sought to build on those findings. Koomen et al. structured their experiments similarly, this time recruiting 66 UK children, ages 5 to 6, as subjects. They focused on how promising a partner not to eat a favorite treat could inspire sufficient trust to delay gratification, compared to the social risk of one or both partners breaking that promise. Any parent could tell you that children of this age are really big on the importance of promises, and science largely concurs; a promise has been shown to enhance interdependent cooperation in this age group.

Koomen and her Manchester colleagues added an extra twist: They conducted their version of the marshmallow test online to test the effectiveness compared to lab-based versions of the experiment. (Prior results from similar online studies have been mixed.) "Given face-to-face testing restrictions during the COVID pandemic, this, to our knowledge, represents the first cooperative marshmallow study to be conducted online, thereby adding to the growing body of literature concerning the validity of remote testing methods," they wrote.

The type of treat was chosen by each child's parents, ensuring it was a favorite: chocolate, candy, biscuits, and marshmallows, mostly, although three kids loved potato chips, fruit, and nuts, respectively. Parents were asked to set up the experiment in a quiet room with minimal potential distractions, outfitted with a webcam to monitor the experiment. Each child was shown a video of a "confederate child" who either clearly promised not to eat the treat or more ambiguously suggested they might succumb and eat their treat. (The confederate child refrained from eating the treat in both conditions, although the participant child did not know that.)

Then the scientist running the experiment would leave the Zoom meeting for an undisclosed period of time, after telling the child that if both of them resisted eating the treat (including licking or nibbling at it), they would each receive a second one; if one of them failed, neither would be rewarded. Children could not see or communicate with their paired confederates for the duration of the experiment. The scientist returned after 10 minutes to see if the child had managed to delay gratification. Once the experiment had ended, the team actually did reward the participant child regardless of the outcome, "to end the study on a positive note."

The results were controlled for unavoidable accidental distractions, so the paper includes the results from both the full dataset of all 68 participants and a subset of 48 children, excluding those who experienced some type of disruption during the 10-minute experiment. In both cases, children whose confederate clearly promised not to eat their treat waited longer to eat their treat compared to the more ambiguous "social risk" condition. And younger children were slightly more likely to successfully delay gratification than older children, although this result was not statistically significant. The authors suggest this small difference may be due to the fact that older children are more likely to have experienced broken promises, thereby learning "that commitments are not always fulfilled."

Of course, there are always caveats. For instance, while specific demographic data was not collected, all the children had predominantly white middle-class backgrounds, so the results reflect how typical children in northern England behave in such situations. The authors would like to see their online experiment repeated cross-culturally in the future. And the limitation of one-way communication "likely prevented partners from establishing common ground, namely their mutual commitment to fulfilling their respective roles, which is thought to be a key principle of interdependence," the authors wrote.

DOI: Royal Society Open Science, 2025. 10.1098/rsos.250392  (About DOIs).

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Jennifer Ouellette Senior Writer
Jennifer is a senior writer at Ars Technica with a particular focus on where science meets culture, covering everything from physics and related interdisciplinary topics to her favorite films and TV series. Jennifer lives in Baltimore with her spouse, physicist Sean M. Carroll, and their two cats, Ariel and Caliban.
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