Stanford marshmallow experiment facts for kids

The Stanford marshmallow experiment was a famous study about how well children could wait for something they wanted. It was led by psychologist Walter Mischel at Stanford University in 1972.

In this study, a child was given a choice: they could have one small treat right away, or they could wait a short time (about 15 minutes) and get two treats. The researcher would leave the room during this waiting time. The treats were usually a marshmallow or a pretzel stick, depending on what the child liked most.

Later studies looked at these same children years later. They found that kids who were able to wait longer for the bigger reward often had better results in life. This included things like higher SAT scores, more education, and a healthier body mass index (BMI).

However, a more recent study with many more children found that the original results might not be as strong as first thought. This new study suggested that a child's family background and how much money they had might explain some of the differences, not just their willpower. Another study in 2020 also questioned how well the marshmallow test could predict future success.

The First Experiment

The very first experiment about waiting for a reward was done by Walter Mischel and Ebbe B. Ebbesen at Stanford University in 1970. They wanted to understand when children learn to control themselves and wait for something they want.

The researchers thought that if the treat was right in front of the children, it would remind them why they were waiting. They believed this would help the children wait longer for the bigger reward.

Children were taken into a simple room with no distractions. A treat they chose (like two animal cookies or five pretzel sticks) was placed on a table. The researchers told the children they could eat the treat. But, if they waited 15 minutes without eating it, they would get a second treat.

Mischel and Ebbesen watched what the children did. Some kids covered their eyes or rested their heads on their arms to avoid looking at the treat. Many tried to keep themselves busy. They talked to themselves, sang, played games with their hands and feet, or even tried to fall asleep while waiting. One child actually did fall asleep!

Who Took Part?

This first experiment included 32 children. There were 16 boys and 16 girls. They all went to the Bing Nursery School at Stanford University. The children were between three and a half and five years and eight months old. Most of them were around four and a half years old. Three children couldn't understand the rules, so they were not included in the study.

How the Experiment Worked

Two researchers ran the experiment. In the room, there was a table with a cake tin on it. Inside the tin were five pretzels and two animal cookies. There were two chairs in front of the table.

The experimenter showed the child some toys and said they could play with them later. Then, the toys were put away in a box so the child couldn't see them. The experimenter told the child they had to leave the room. If the child ate the pretzel, the experimenter would come back. This was repeated a few times to make sure the child understood.

Then, the experimenter came back and opened the cake tin. They showed the child the pretzels and animal crackers. The child was asked which one they liked more. Once the child chose, the experimenter explained the choice again. The child could either wait for the more preferred treat until the experimenter returned on their own, or they could call the experimenter back right away. If they called the experimenter back, they would only get the less preferred treat.

The experimenter would then leave the room. They would return either when the child called them or after 15 minutes had passed.

What They Found

The results were the opposite of what the researchers expected! They thought seeing the treats would help children wait. Instead, having the treats right there made the children more frustrated. This made it harder for them to wait.

It seemed that not thinking about the treat helped children wait longer, rather than focusing on it.

The Stanford Marshmallow Experiment

The next study, done by Mischel, Ebbesen, and Zeiss in 1972, is the one most people call the Stanford marshmallow experiment. This is because it used marshmallows as the main treat.

Why They Did It

Building on their earlier work, the researchers thought that anything that distracted a child from the treat they were waiting for would help them wait longer. They believed that playing, thinking about other things, or even daydreaming would help children distract themselves. They hoped this distraction would make the waiting less frustrating.

To test this, they set up three different situations:

• Children could do an activity (like playing with a toy).
• Children could think about other things (like a game).
• Children had no activity or distraction.

They thought that children would wait longer when they had something to do or think about. They expected children with no distractions to wait less time.

Experiment 1 Participants

This experiment included 50 children (25 boys and 25 girls) from the Bing Nursery School at Stanford University. They were between three and a half and five and a half years old. The average age was four and a half. Six children were not included because they didn't understand the instructions.

Experiment 1 Procedures

Two researchers, one male and one female, conducted the tests. The small room had a table with a barrier. Behind the barrier was a slinky toy and a cake tin with a small marshmallow and a pretzel stick. There was also another table with toys the child could see.

In Experiment 1, children were tested in different ways:

• Waiting for the treat with an outside distraction (a toy).
• Waiting for the treat with an inside distraction (thinking about something else).
• Waiting for the treat with no distraction.
• Having a distraction (toy) without having to wait for a reward.
• Having an internal distraction (thinking) without having to wait for a reward.

Experiment 2 Participants

This experiment had 32 children from the Bing Nursery School. They were between three years nine months and five years three months old. The average age was four years nine months. Six children were removed from the study because they didn't understand the rules or ate the treat while waiting.

Experiment 2 Procedures

Experiment 2 looked at how what children thought about affected how long they waited. The setup was similar to Experiment 1. However, after asking the children if they understood, the experimenter suggested ideas for them to think about while they waited. These were called "think food rewards" instructions. They were meant to make the children think about different things during the waiting time.

Experiment 3 Participants

This experiment had 16 children (11 boys and 5 girls). They were between three years five months and five years six months old. The average age was four years six months.

Experiment 3 Procedures

In Experiment 3, everything was the same as in Experiments 1 and 2, but the treats were not visible to the children while they waited. In the earlier experiments, the treats were right in front of them. To change this, the children were told the food needed to stay fresh. The marshmallow and pretzel stick were then placed under the cake tin and put under the table, out of sight. In this experiment, the children were also given the "think food rewards" suggestions, just like in Experiment 2.

Overall Results

These three experiments showed some important things. How well children could wait for a treat depended a lot on whether they could avoid thinking about the treats or push the thoughts away. Also, when children thought about the treats that weren't there, it was just as hard to wait as when the treats were right in front of them.

But, when the children waited for the treat and it was not visible, they were able to wait longer and get the bigger reward. The Stanford marshmallow experiment is important because it showed that waiting successfully isn't just about thinking about something else. It's about using ways to reduce how frustrating the waiting feels.

The researchers described how frustrated the children got while waiting. "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, verbalized 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."

Later Studies

In studies done years later, Mischel found surprising connections between the marshmallow experiment results and how well the children did in life.

The first follow-up study in 1988 showed that children who waited longer for the treat were described by their parents ten years later as being much more capable teenagers.

A second follow-up study in 1990 found that being able to wait for the treat also connected to getting higher SAT scores.

A 2011 brain study looked at some of the original Stanford participants when they were adults. It showed important differences in their brains. People who waited longer as kids had more activity in their prefrontal cortex (the part of the brain that helps with planning and control). Those who waited less had more activity in their ventral striatum (a part of the brain linked to rewards) when they tried to control their urges.

A 2012 study at the University of Rochester changed the experiment a bit. They split children into two groups. One group was given a broken promise before the marshmallow test. For example, they were told they'd get a sticker, but didn't. The second group had a promise that was kept. The group whose promises were kept waited up to four times longer (12 minutes) for the second marshmallow! This study suggested that trust might be a big part of why children wait, not just self-control. If children don't trust that they'll get the promised reward, they might not wait.

In the original Stanford studies, children first played a game where they called the experimenter back by ringing a bell. This helped build trust. The actual waiting part didn't start until the children clearly understood that the experimenter would keep their promise. The children in the original studies seemed to believe they would get the reward if they waited. However, Mischel's earlier work showed that in other situations, children might not be sure they'll get the delayed reward. In those cases, waiting might not be the best choice for them.

A 2018 study tried to repeat the marshmallow experiment. It found that the connection between waiting longer and later success was much smaller than in the original study. These connections became even smaller when they considered things like a child's early thinking skills, family background, and home life.

A 2020 study at the University of California also showed that a person's reputation (whether they are seen as trustworthy) plays a big role in the experiment.

In 2021, researchers at the Marine Biological Laboratory found that cuttlefish (a type of sea animal) could also pass a version of the marshmallow test! These nine-month-old cuttlefish could wait between 50 and 130 seconds for a better treat. This is similar to how long chimpanzees and crows can wait. The cuttlefish that were better at waiting also showed better learning skills.

See also

In Spanish: Prueba del malvavisco para niños