The Stanford marshmallow experiment was a study on deferred gratification conducted in 1972 by psychologist Walter Mischel of Stanford University.[1] A marshmallow was offered to each child. If the child could resist eating the marshmallow, he was promised two instead of one. The scientists analyzed how long each child resisted the temptation of eating the marshmallow, and whether or not doing so had an effect on their future success.[2] Although the experiment has been repeated many times since, the original study at Stanford has been considered "one of the most successful behavioural experiments".[3]
Contents |
The experiment has its roots in an earlier one performed on Trinidad, where Mischel noticed that the different ethnic groups living on the island had contrasting stereotypes of one another, specifically, on the other's perceived recklessness, self-control, and ability to have fun.[2] He performed an experiment similar to the marshmallow experiment, albeit with a chocolate bar, and discovered that ethnicity did not affect deferred gratification at all, while social and economic backgrounds did.[2]
The purpose of the original study was to understand when the control of deferred gratification, the ability to wait to obtain something that one wants, develops in children.[4] The original experiment took place at the Bing Nursery School located at Stanford University, using children the age of four to six as subjects. The children were led into a room, empty of distractions, where a treat of their choice (Oreo cookie, marshmallow, or pretzel stick) was placed on a table, by a chair.[2] The children could eat the marshmallow, the researchers said, but if they waited for fifteen minutes without giving in to the temptation, they would be rewarded with a second marshmallow.[5] Mischel observed as some would "cover their eyes with their hands or turn around so that they can't see the tray, others start kicking the desk, or tug on their pigtails, or stroke the marshmallow as if it were a tiny stuffed animal", while others would simply eat the marshmallow as soon as the researchers left.[2]
In over 600 children who took part in the experiment, a minority ate the marshmallow immediately. Of those who attempted to delay, one third deferred gratification long enough to get the second marshmallow.[5] Age was a major determinant of deferred gratification.
It was the results of the follow-up study that would take place many years later that surprised Mischel. Since Mischel's daughters knew and grew up with many of the original test subjects, through casual conversation, Mischel discovered there existed an unexpected correlation between the results of the marshmallow test, and the success of the children many years later.[4] The first follow-up study, in 1988, showed that "preschool children who delayed gratification longer in the self-imposed delay paradigm, were described more than 10 years later by their parents as adolescents who were significantly more competent". A second follow-up study, in 1990, showed that the ability to delay gratification also correlated with higher SAT scores.[1]
A 2011 study of the same participants indicates that the characteristic remains with the person for life. Additionally, brain imaging showed key differences between the two groups in two areas: the prefrontal cortex (more active in high delayers) and the ventral striatum (an area linked to addictions).[6][7]
A 2006 paper to which Mischel contributed reports a similar experiment, this time using cookies and a computer-controlled go/no-go test.[8] From the study:
[...] the present findings suggest that an effective attentional control system, as reflected in preschoolers’ ability to direct attention away from tempting aspects of the rewards in a delay-of-gratification task, may share a common mechanism with, or serve as a precursor for, long-term ability to inhibit attentional and behavioral responses, as reflected years later in performance on the go/no-go task. Moreover, because inefficient performance in the go/no-go task has been well documented as being associated with immature development of fronto-striatal and related circuitry, the findings suggest that temptation focus in the delay-of-gratification task at age 4 may already be a marker of the subsequent development of individual differences in this system in adolescence and adulthood.