Chances are you've heard of the marshmallow test, one of the most well-known experiments in psychology. A preschooler sits down, alone, at a table and is presented with a treat (usually a marshmallow) by a researcher. The child is told that the researcher needs to leave the room for a few minutes before being given a simple choice. If they can hold out until the adult returns (around 15 minutes) they can have two marshmallows. If they can't, they only get the one.
As it turns out, the iconic experiments on delayed gratification, first conducted by psychologist Walter Mischel, didn't just reveal that those who waited received a bigger reward. Over the years, as the original cohort of preschoolers from Standford University's Bing Nursery grew up, researchers tracked their progress in a number of follow-up studies as teens and adults. They found that children who waited for that second treat had more academic competence, lower BMI 30 years later, lower levels of substance abuse and were more able to deal with stress and frustration, than those who simply couldn't resist.
But a new study, published this month in Psychological Science, has called into question just how important a child's ability to delay gratification at age four is to their future success. Dr Tyler Watts of New York University and his colleagues analysed data, which replicated the original test, using a much bigger and more diverse sample - 918 children drawn from the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development. (In an interview with The Atlantic, Mischel himself admitted that the original Standford nursery population was "an unbelievably elitist subset of the human race")
Interestingly, they also failed to find any evidence of a link between holding out for that second marshmallow and later behaviours or personality measures. "We were surprised to see virtually no relation between gratification delay and later behavioral outcomes," Dr Watts said, explaining that they looked at a range of different behaviours including mothers' reports of their teens' adolescent anti-social behaviours and depressive characteristics, as well as teens' self-repors of "risky behaviours" including alcohol use and sexual risk-taking.
Dr Watts, who admits to being fascinated by the famous Marshmallow study when he first encountered it back in his Introduction to Psychology course, is careful to note that these new findings don't suggest that gratification delay is "completely unimportant". Rather, focusing only on teaching young children to delay gratification is "unlikely to make much of a difference".
"At least in the case of gratification delay, a narrowly focused program that tunes up gratification delay is unlikely to have large long term effects," he said.
And his advice to mums and dads is clear: "If I was a parent, and my child was not able to pass the marshmallow test at age four, I wouldn't be too concerned."