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Special Feature: The Marshmallow Test (Slight Return)

I am a big fan of Prof Walter Mischel and his wonderfully simple but hugely influential Marshmallow Tests (you can see some original footage on my video page). Originally conducted in 1972, the children were drawn from Stanford University's creche and included Mischel's three daughters. It involved a series of experiments, children aged 3-5 years were offered one treat that they could eat immediately (for example, a marshmallow, cookie or pretzel) or a larger treat (another marshmallow, cookie or pretzel) if they waited. Researchers then left the room to see how long the children would wait and watched from behind a one-way mirror. At long term follow-up the length of time the child could wait for the treat predicted their long term life outcomes on multiple measures. Impulse control appeared to be a vital cognitive and appeared to have a neurological basis. This sparked huge interest into how human beings delay gratification. In the battle between emotional desires and reason, what really counts?

A number of spin studies were done to explore the area further. One less well known variant of the Marshmallow test was the 'broken promise' version. This experiment tested an important assumption inherent in the Marshmallow Test. The children had to live in a world were they believed that delayed gratification would lead to having two marshmallows. But many children grow in an unpredictable world where the rewards of waiting do not materialize. Interesting, affluent kids perform much better in the Marshmallow Test, because they live in a social world that follows through on rewards (for a review click here). In the broken promise group, where children were made to perform tasks for rewards that failed to materialize, they all subsequently failed to delay gratification in Marshmallow Test experiments (click here for a review).

This research suggests that poor impulse control may not be a liability for some children but an adaptive asset. In an unpredictable world, getting the resources whilst you can may be a valuable life skill in this social context. But it fails to deliver in a more predicable world were long term success relies upon short term sacrifices.

Some recent research has questioned the predictability of the original study. Published in Psychological Science by Dr. Tyler W. Watts, an assistant professor of research and postdoctoral scholar at New York University's Steinhardt School of Culture, Education, and Human Development, and his colleagues, this replication uses a larger and more diverse sample of children to reexamine whether the marshmallow test does in fact predict longer-term cognitive and behavioral outcomes.

Dr. Watts's research finds that although the marshmallow test conceived by psychologist Walter Mischel is related to later achievement, the relationship between a young child's ability to delay gratification and later outcomes is much weaker than previously thought. The new study discovered that while the ability to resist temptation and wait longer to eat the marshmallow (or another treat offered as a reward) did predict adolescent math and reading skills, the association was small and disappeared after the researchers controlled for characteristics of the child's family and early environment. And there was no indication that it predicted later behaviors or measures of personality.

The authors concluded that interventions focused only on teaching young children to delay gratification are likely to be ineffective."Our findings suggest that an intervention that alters a child's ability to delay, but fails to change more general cognitive and behavioral capacities, will probably have very small effects on later outcomes," Dr. Watts explained. "If intervention developers hope to generate the kinds of improvements associated with the original marshmallow study, it is likely to be more fruitful to target the broader cognitive and behavioral abilities related to gratification delay."The data for this study were drawn from the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development, a geographically diverse dataset widely used in the field of developmental psychology.In addition to using a large sample (918 children), Dr. Watts created a subsample based on maternal education and focused much of the analysis on children whose mothers had not completed college by the time the child was born.

This subsample was more representative of the racial and economic makeup of the broader population of children in the U.S. (though Hispanic children were still underrepresented). Participants in the original experiments were limited to children from the Stanford University community."I still remember, as an undergraduate, being fascinated by the findings from the famous marshmallow test when I first encountered them in my Introduction to Psychology course," Dr. Watts said. "Given the attention these findings still receive when decisions are made about the skills early-intervention programs should target, we thought it was important to revisit the older work by replicating the original experiment using a newer sample and updated statistical methods. Of course, 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.(Story Source: New York University.)

However, another study recently published by the American Psychological Association found greater consistency betwen dleay and life outcomes, but, interestngly, children today are better at delaying gratification than previous cohorts. "Although we live in an instant gratification era where everything seems to be available immediately via smartphone or the internet, our study suggests that today's kids can delay gratification longer than children in the 1960s and 1980s," said University of Minnesota psychologist Stephanie M. Carlson, PhD, lead researcher on the study. "This finding stands in stark contrast with the assumption by adults that today's children have less self-control than previous generations."

The ability to delay gratification in early childhood has been associated with a range of positive outcomes in adolescence and beyond. These include greater academic competence and higher SAT scores, healthier weight, effective coping with stress and frustration, social responsibility and positive relations with peers.

Carlson and her colleagues looked at results from the original marshmallow test, as well as replications conducted in the 1980s and early 2000s. In defiance of expectations, kids who participated in their studies in the 2000s waited an average of two minutes longer (during a 10-minute period) than those from the 1960s, and one minute longer than those tested in the 1980s.

Interestingly, today's adults thought that children nowadays would be more impulsive and less able to wait, Carlson found. She and her associates conducted an online survey of 358 U.S. adults who were asked how long they thought children today would wait for a larger treat compared with kids in the 1960s. Approximately 72 percent thought children today would wait less long, and 75 percent believed that children today would have less self-control.

"Our findings serve as an example of how our intuition can be wrong and how it's important to do research," said co-author Yuichi Shoda, PhD, of the University of Washington. "If we hadn't been systematically collecting data on how long children wait in this type of experiment, and if we hadn't analyzed the data, we would not have found these changes. They pose an interesting and important question for future research to understand: Are the changes we found in our sample unique, or do they apply more broadly to children from more diverse backgrounds? What is causing the change, and what are the mechanisms through which these changes occur?"

"That ability to wait did not appear to be due to any change in methodology, setting or geography, or the age, sex or socioeconomic status of the children," Carlson said. "We also took steps to ensure none of the children in the 2000s group were on medication to treat attention deficit hyperactivity disorder at the time of the study."

The researchers offered several possible explanations for why children in the 2000s waited longer than those in prior decades. They noted a statistically significant increase in IQ scores in the last several decades, which has been linked to rapidly changing technologies, increased globalization and corresponding changes in the economy. At a more psychological level, increases in abstract thought, which are associated with digital technology, may contribute to executive function skills such as delay of gratification, they said.

Another explanation may be society's increased focus on the importance of early education, according to Carlson. In 1968, only 15.7 percent of all 3- and 4-year-olds in the United States attended preschool. That number increased to more than 50 percent by the year 2000. The primary objective of preschool also changed from largely custodial care to school readiness in the 1980s, including an emphasis on self-control as a foundation for educational success. Parenting also has changed in ways that help promote the development of executive function, such as being more supportive of children's autonomy and less controlling, the researchers noted.

"We believe that increases in abstract thought, along with rising preschool enrollment, changes in parenting and, paradoxically, cognitive skills associated with screen technologies, may be contributing to generational improvements in the ability to delay gratification," Carlson said. "But our work is far from over. Inequality persists in developmental outcomes for children in poverty."

Walter Mischel, of Columbia University, who also co-authored this paper, noted that "while the results indicate that the sampled children's ability to delay is not diminished on the marshmallow test, the findings do not speak to their willingness to delay gratification when faced with the proliferation of temptations now available in everyday life."

Gender has also been found to be a influencing factor. Self-regulation is something all children must develop, and poorer self-control in childhood is associated with worse adult health, economic and social outcomes. However, a new study from The Ohio State University found that more self-regulation may not necessarily reduce the risk of obesity, especially in girls.Girls who scored at either the low or the high end on measures of self-regulation when they were 2 years old were more likely than girls with average self-regulation to be obese at age 5, while boys with high self-regulation were less likely to be obese than their peers with low or average self-regulation, found the study, which appears in the journal JAMA Pediatrics.

The difference raises important new questions about the role of gender in the development of childhood obesity, said lead author Sarah Anderson, an associate professor in Ohio State's College of Public Health."Although we tend to assume that more self-regulation is always a positive, it may not be," she said.Those seeking answers about how to prevent childhood obesity should be mindful of the possibility that interventions to improve self-regulation might not play out the same way for boys and girls, she said."People are trying ways to prevent obesity in young children, and some of those approaches involve improving self-regulation. Our study suggests that could have an unintended impact for some girls," Anderson said."This study leads one to think about how young children are potentially responding differently to messages and expectations based on whether they are boys or girls. We should be cautious about assuming that increases in self-regulation are optimal for everyone."

The study analyzed data from a nationally representative sample of 6,400 U.S. children born in 2001 to see whether a child's ability to self-regulate when they were 2 years old was associated with their risk of obesity in kindergarten -- and to look for any differences between genders. The data came from the National Center for Education Statistics.Self-regulation was measured using a four-part in-home assessment that looked at a child's adaptability, persistence, attention and frustration tolerance. Each child received from one point to five points on each measure, for a possible score of 20 -- a very high level of self-regulation."

Observers were looking at things like how readily a child gave up a block when an adult said it was time to play with something else, how difficult it was to hold their attention and how easily frustrated they became when things weren't going their way," Anderson said."Going in, we thought what many people think -- that we would see lower rates of obesity as self-regulation increased."But when they looked at their data, in which they separated children into quartiles ranging from "least regulated" to "most regulated," the researchers found that girls in the least and most self-regulated groups were more likely to be obese at kindergarten age than their female peers in the middle categories.

There was little difference in boys' risk of obesity except for among the most-regulated, who were least likely to be obese. Obesity was determined by measuring height and weight and defined as a body mass index greater than or equal to the 95th percentile."We should not assume that interventions to increase self-regulation will necessarily lead to benefits for both genders -- it may be different for boys and girls," Anderson said.

The researchers said there are many ongoing efforts to promote self-regulation in children for a variety of desired outcomes, including obesity prevention and improved school readiness.In neither gender did the researchers see a clear step-wise pattern where increased self-regulation meant decreased rates of obesity.Researchers believe that a variety of factors may contribute to links between self-regulation and obesity, including physiological differences and behavioral responses to demands in a child's environment that could affect appetite, food intake, sleep and activity level."Obesity prevention is a complex and humbling task.

Gender is another social influence that may affect the success of obesity prevention efforts," said Anderson's co-author, Robert Whitaker of Temple University.This study adds to other obesity research that has found important differences between genders, Anderson said."All we can do based on this research is speculate, but it's possible that girls and boys are reacting differently to social expectations and that could play a role in childhood obesity," Anderson said."If you're a boy and if the people around you are more OK with you getting easily frustrated and not paying attention, the social stress from your environment may be less than it is for a girl."It's also possible that girls are rewarded more than boys for "good" behavior, propelling them to put themselves under added stress in the interest of appeasing adults, the researchers wrote."These stresses might result in differences in energy balance and metabolism between girls and boys, especially in the group observed to have high self-regulation."

Materials provided by Ohio State University. Original written by Misti Crane.

Journal Reference:Vincent Rigalleau, Sophie Cambos, Laurence Blanco. Early Weight Gain in Pregnancy and Infant Birth Weight. JAMA Pediatrics, 2018; 172 (6): 598 DOI: 10.1001/jamapediatrics.2018.0413

Story Source: Materials provided by American Psychological Association. Note: Content may be edited for style and length.

Journal Reference:

Stephanie M. Carlson et al. Cohort Effects in Children’s Delay of Gratification. Developmental Psychology, 2018 DOI: 10.1037/dev0000533

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