Author: Jillian Seaton

Who remembers the famous Marshmallow Study of the late 60s? Maybe it sounds vaguely familiar, but for those of you who recount the 60s with a distinct haze, weren’t born yet, or don’t actively study psychology, I’ll give you a refresher.

The experiment went like this: a group of preschool age children were monitored separately, each being placed directly in front of a fluffy, tasty marshmallow with the promise that if they could wait and not eat the marshmallow now, they would receive two marshmallows later. Over the course of the past four decades, this study has been regarded as a classic experimental measure of children’s self control (or lack thereof).  As time progressed, researchers found that individual differences in the ability to delay gratification with the marshmallow correlated strongly with success in later life, including higher SAT scores, less substance abuse, and better social skills.

Celeste Kidd, a doctoral candidate in brain and cognitive sciences at the University of Rochester, has revisited this study and taken it a step further, finding that the ability to delay gratification is influenced just as much by the environment as by innate ability – meaning that nature as well as nurture are playing equal hands.

Kidd and her research team set up two contrasting environments to split between 28 preschoolers: a reliable environment, and an unreliable environment. In both settings, the children were told twice to wait for something better; first for art supplies, and second for stickers. The difference was the promises were delivered in the reliable environment, while the unreliable environment came up empty-handed both times.  The third promise followed the same steps as the original marshmallow study: wait 15 minutes without eating the marshmallow, and then receive two marshmallows instead.

Perhaps unsurprisingly, children who experienced reliable interactions immediately before the marshmallow task were able to hold out longer – by a lot. The children in the reliable environment were able to wait an average of four times longer than the children in the unreliable environment.  Additionally, only one of the 14 children in the unreliable group waited the full 15 minutes, compared to nine children in the reliable condition.

Previous studies that explored the effect of teaching children waiting strategies showed much smaller effects. This large result provides evidence that wait times do reflect rational decision-making about the probability of a reward.  According to Kidd,

“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. Delaying gratification is only the rational choice if the child believes a second marshmallow is likely to be delivered after a reasonably short delay. If you are used to getting things taken away from you, not waiting is the rational choice.”

However, don’t worry if you try this trick at home with your own kids and they gobble up the marshmallow immediately. This doesn’t mean you’ve failed at being reliable. It just means things are different when you’re the person they’re with day in and day out. And besides – maybe it’s just snack time.