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Kids & Marshmallows Revisited

Kids & Marshmallows Revisited Photo Credit: Dvortygirl [GFDL, CC-BY-SA-3.0 or CC-BY-SA-2.5-2.0-1.0], via Wikimedia Commons

An update on a landmark experiment probes the neurological roots of delayed gratification.


Transcript

A new look at self-control. I’m Bob Hirshon and this is Science Update.

In a landmark psychological study, preschoolers were given a choice: they could eat one treat now, or two treats later. Kids who could wait longer had fewer behavioral problems and higher SAT scores years later. Recently, Stanford psychologist Ian Gotlib and his colleagues studied some of the same people, now in their forties. The subjects’ relative willpower was still consistent with their four-year-old selves, and that related to differences in brain activity.

Gotlib:
The differences in activation seem to be in areas of the brain that are responsible for the regulation of emotions that are responsible for cognitive-executive control.

The most impulsive subjects not only had lower activity in the control centers, but stronger responses in the emotional centers. The results also suggest that people with addictions or self-control issues may feel pleasure more intensely than others. I’m Bob Hirshon for AAAS, the Science Society.


Making Sense of the Research

The original experiment that this study followed up on is now commonly known as the “Stanford Marshmallow Experiment,” and was conducted by Stanford psychologist Walter Mischel in the early 1970s. The basic experiment was incredibly simple: a child (age 4-6) was seated at a table with a marshmallow (or a cookie or pretzel stick, if the child preferred), and the researcher said he would leave the room for a few minutes. The child was promised two marshmallows if he or she could resist eating the first while the researcher was gone. Researchers then observed the child through a one-way mirror, and measured how long they were able to wait.

At the time, the researchers found that about a third of the children were able to earn the second marshmallow, but only a small number ate the marshmallow immediately. The older the child, the better they were able to delay gratification—in other words, wait for a reward. Mischel's team noted the various techniques that children used to resist eating the marshmallow, from turning their backs to it to “strok[ing] the marshmallow as if it were a tiny stuffed animal.” 

But things really got interesting many years later, when Mischel began following up on the now-grown children who participated in the original study. First, he found that preschoolers who could better delay gratification were rated as more competent by their parents in their teenage years. A few years later, he found that the best marshmallow-resisters also went on to score higher on the SAT than those who couldn't help themselves. 

Gotlib's study looked again at the same people. This time, he brought them back into the lab, to do similar delayed-gratification studies as well as brain-imaging studies that wouldn't have been possible when they were preschoolers. He found that the present-day subjects' ability to delay gratification was remarkably similar to what they showed in the preschool experiment. He also found that the brain activity of the subjects reflected their performance on the marshmallow test. When facing temptation, the most impulsive people had low activity in the parts of their brain responsible for self-control, while they had stronger activity in the brain's emotional centers. 

This has interesting implications for addictions, including gambling, overeating, and drug abuse. The results suggest that many people with these impulse-control problems may not only have trouble resisting temptation, but also may get more delight out of giving in. In other words, for example, food may taste better, or generate happier feelings, to people who have trouble dieting than to people who are better at passing up cookies. Or marshmallows. If so, then addiction treatments may be more effective if they address both kinds of vulnerability.

Now try and answer these questions:

  1. What was the Stanford marshmallow experiment?
  2. What were the original findings?
  3. What were some of the follow-up findings, including the most recent?
  4. What does this say about the psychology of self-control?
  5. Why is it useful to follow a group like this over many years?

You may want to check out these related podcasts:

The Science Update Drug Cravings looks at rats to shed light on why so many drug users relapse after getting sober.

The Science Update Emotion Perception looks at another lifetime trend: that children who are physically abused tend to have social problems as adults.


Going Further


For Educators

The Science Update lesson Drug Cravings looks at rats to shed light on why so many drug users relapse after getting sober.

The Science Update lesson Emotion Perception looks at another lifetime trend: that children who are physically abused tend to have social problems as adults.


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