This month, UR researchers Celeste Kidd, Holly Palmeri and Richard Aslin revisited the decades-old “marshmallow test,” which examines the influence of environmental factors on young children’s abilities to delay gratification. The original experiment, performed by Stanford University Psychology Professor Walter Mischel in the late 1960s, studied the cognitive mechanisms and genetic influence that determined whether the participating children would exercise self-control and resist the treat. UR researchers now propose that the participants’ environment plays an equally important role in their decision.
The original “marshmallow test” studied 600 children and their ability to delay eating a treat. At the beginning of the experiment, the children were presented with a marshmallow, but were told if they waited for 15 minutes, they would receive two marshmallows instead. A small portion of the children ate the treat immediately, one-third of the participants waited the full time to receive the second marshmallow and the remainder attempted to wait for a period of time by distracting themselves, but ultimately ate the marshmallow before the experimenter returned. Using these results, Mischel concluded that genetics must influence the children’s predisposition to resist the treat.
Mischel and other researchers continued to study the importance of self-control and delayed gratification, tracking the participants into their thirties. They discovered that the subjects who did not resist temptation were “less competent.” After performing genetics tests, Mischel concluded that the ability to resist the treat did indeed stem from genetics.
“In general, trying to separate nature and nurture makes about as much sense as trying to separate personality and situation,” he wrote in an article published in The New York Times. “The two influences are completely interrelated.”
But UR researchers offer a new perspective — that environment plays an equally important role in the ability to delay gratification. After observing youth in a California shelter, Kidd saw that the children regularly had objects taken from them, but this did not provoke a reaction. With this in mind, Kidd wanted to reexamine the marshmallow test, this time taking into consideration participants’ beliefs in reliability.
The participants were divided into two groups and subjected to a preliminary experiment before the marshmallow test. Children in both groups were promised a container of crayons and stickers. However, only one of these groups received the goods as promised, thus creating a reliable and unreliable group. Those placed in the reliable groups waited, on average, four times longer than those who were not. Since those in the unreliable group did not expect the experimenter to keep their promise this time, after they had failed two times prior, the children ate the marshmallow sooner.
Unlike Mischel, Kidd concludes that the environment, not genetics, has more to do with one’s self-control.
“If you are used to getting things taken away from you, not waiting is the rational choice,” she said. “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.”
Graziano is a member of the class of 2016.