At its heart, it is a simple question: can you wait to eat a marshmallow for fifteen minutes in order to get another one?
This question, first asked in Walter Mischel's seminal study with children nearly 40 years ago, has had profound implications over time. The ability to wait – or not wait – has been shown not only to tap into a person's ability to control his or her own desires, but to some extent predict that ability across the lifespan.
The underlying concept that drives behavior in the marshmallow task is delay of gratification: the ability to put off satisfying an immediate desire for a later reward. It is a skill that is hugely important to success in all aspects of life, and one that materializes early on as a child develops.
The initial study, conducted at Stanford in the 1960s, was done with a group of four-year olds. These children were initially given a single marshmallow and presented with a tantalizing option: they could eat it now, or they could wait to eat it until an experimenter returned to the room in fifteen minutes. Waiting would earn them a second marshmallow; if they could not wait, they could ring a bell to call the experimenter back, after which they could eat the one marshmallow. Roughly a third of the initial subject group was able to wait the 15 minutes.
These subjects were subsequently tracked in a longitudinal study that looked for different indicators of personal success as they matured. The children who were able to wait for the second marshmallow were more likely to achieve success in academic, career and personal endeavors.
The study was replicated with another group of toddlers in the 1980s, this time at the Barnard Toddler Center in New York City, a pre-school affiliated with Barnard College and Columbia University. This group of children, much like the Stanford study, was tracked longitudinally. Today this group continues to assist our research by working with us on a series of studies examining brain activity while engaged in a variety of cognitive tasks (none of which, sadly, involve marshmallows). By following the same group across this type of timeframe, the researchers are able to gain profound insights into the cognitive underpinnings of self-control and attachment as it develops over time.