Researchers from the University of Rochester reported on a new type of experiment in the journal Cognition. They say their study showed that the ability to delay gratification is influenced by two things: an innate ability to wait, and the person's environment.
They found that young kids who had been exposed to reliable environments would wait 12 minutes for the two promised marshmallows, compared to children in unreliable environments who waited just three minutes.
Lead author, Celeste Kidd, said:
"Our results definitely temper the popular perception that marshmallow-like tasks are very powerful diagnostics for self-control capacity.
Being able to delay gratification - in this case to wait 15 difficult minutes to earn a second marshmallow - not only reflects a child's capacity for self-control, it also reflects their belief about the practicality of waiting," says Kidd. "Delaying gratification is only the rational choice if the child believes a second marshmallow is likely to be delivered after a reasonably short delay."
Coauthor Richard Aslin said that their findings remind us about how complex human behavior is. "This study is an example of both nature and nurture playing a role," he says. "We know that to some extent, temperament is clearly inherited, because infants differ in their behaviors from birth. But this experiment provides robust evidence that young children's actions are also based on rational decisions about their environment."
Marshmallow studies started off at Stanford University in the 1960s. This research builds on those studies and subsequent ones. In the original ones, Walter Mischel et al demonstrated that young children who were able to delay gratification tended to be more successful later in life. Preschoolers who waited longer tended to subsequently have higher SAT scores, were less likely to be involved in substance abuse, and had better social skills (according to parental reports).
The marshmallow studies have often been quoted as evidence that rather than intelligence (IQ), self-control or emotional intelligence matter more when navigating towards a successful life.
In this experiment, Celeste Kidd and team wanted to determine more closely why some preschoolers can resist the tempting marshmallow while others succumb to nibbling, licking and evening gobbling up the tasty treat.
The researchers randomly selected 28 children aged 3 to 5 years into two environments, a reliable and unreliable one.
They had expected to then work with a larger group of kids. However, the results were so compellingly clear that it was not necessary. They did not need a larger group to rule out factors which could have affected the results, such as hunger.
What happened in the Rochester experiment?All the children were given a create-your-own-cup kit. They had to decorate a blank sheet of paper that would then go into the cup.
The unreliable condition group - the children received a container of old, used and partly broken crayons. The researcher said that if they waited a bit, they would soon be provided with a bigger and much nicer set of new art supplies.
Two-and-a-half minutes later, the researcher came back and said "I'm sorry, but I made a mistake. We don't have any other art supplies after all. But why don't you use these instead?"
Then the researcher placed a quarter-inch sticker on the table in front of each child. They were told that the researcher would soon come back with lots of better stickers they could use. They waited the same length of time; the researchers came back empy-handed.
The reliable condition group - the same set up was presented to the children as in the unreliable condition group. However, the researcher came back after a while with five to seven large, die-cut stickers.
The marshmallow taskWith the two groups, the reliable condition group and the unreliable condition group, the researchers tried out the marshmallow task. The researcher said "one marshmallow right now. Or - if you can wait for me to get more marshmallows from the other room - you can have two marshmallows to eat instead."
All the art supplies were removed and a single marshmallow was placed in front of each child in a small desert dish four inches from the edge of the table. The researchers and the kids' parents could see them through a video system until the first child ate a marshmallow or 15 minutes had passed, whichever came first. All the kids were then given three extra marshmallows.
Co-author, Holly Palmeri, described observing the children as they attempted to wait as long as they could, as "quite entertaining". Many of them took a little bite from the underside of the marshmallow and carefully placed it back in the desert cup so that nobody would notice. A smaller number nibbled bits off the top as well, forgetting it would be impossible to hide the evidence because both ends had been nibbled at.
"We had one little boy who grabbed the marshmallow immediately and we thought he was going to eat it. Instead he sat on it. Instead of covering his eyes, he covered the marshmallow."
The unreliable situation group - the children waited for an average of three minutes and two seconds before eating the sweet. Only one of them waited 15 minutes.
The reliable situation group - they waited an average of 12 minutes and two seconds. Nine kids waited a full 15 minutes.
Aslin said "I was astounded that the effect was so large. I thought that we might get a difference of maybe a minute or so. . . . You don't see effects like this very often."
In previous research, where kids were not exposed to reliable or unreliable situations, they waited an average of 5.71 to 6.08 minutes. By manipulating the environment, children's waiting times could be doubled or halved. In those studies they found that if the treat was hidden, their waiting times increased by 3.75 minutes, while reminding the kids about the larger reward extended their waiting times by 2.53 minutes.
This study demonstrates that children's waiting times reflect rational decision-making regarding the likelihood of reward.
Other studies have shown that kids are sensitive to the certainty or uncertainty in future rewards. Apparently, according to one study, children with no father in the house prefer more immediate rewards rather than larger ones they have to wait for.
These findings are reassuring, says Kidd. She said that the predictive power of earlier experiments all those years ago were "depressing" for her. Then, she was working as a volunteer at a homeless shelter for families in Santa Ana, California. "There were lots of kids staying there with their families. Everyone shared one big area, so keeping personal possessions safe was difficult. When one child got a toy or treat, there was a real risk of a bigger, faster kid taking it away. I read about these studies and I thought, 'All of these kids would eat the marshmallow right away.' " Kidd added:
"If you are used to getting things taken away from you, not waiting is the rational choice. Then it occurred to me that the marshmallow task might be correlated with something else that the child already knows - like having a stable environment."
Does this mean that if your toddler gobbles up dessert without waiting for the others to start that he will not respond to proper reliable role models? Not necessarily, the authors say. "Children do monitor the behavior of parents and adults, but it is unlikely that they are keeping detailed records of every single action. It's the overall sense of a parent's reliability or unreliability that's going to get through, not every single action."
Kidd urges parents not to try out the marshmallow test at home and then draw conclusions about their child. Being a parent in the experiment is already a factor which makes any of the findings unreliable - the child has many expectations about what a loved one is likely to do.
In August 2011, an article in Proceedings of the National Academy of Sciences followed up some of those marshmallow experiment kids forty years later. They found that those who were able to delay gratification remained so, while those who wanted their treat straight away had not changed much either.