From the report:
It turns out that all that time spent playing make-believe actually helped children develop a critical cognitive skill called executive function. Executive function has a number of different elements, but a central one is the ability to self-regulate. Kids with good self-regulation are able to control their emotions and behavior, resist impulses, and exert self-control and discipline.
We know that children's capacity for self-regulation has diminished. A recent study replicated a study of self-regulation first done in the late 1940s, in which psychological researchers asked kids ages 3, 5 and 7 to do a number of exercises. One of those exercises included standing perfectly still without moving. The 3-year-olds couldn't stand still at all, the 5-year-olds could do it for about three minutes, and the 7-year-olds could stand pretty much as long as the researchers asked. In 2001, researchers repeated this experiment. But, psychologist Elena Bodrova at the National Institute for Early Education Research says, the results were very different.
"Today's 5-year-olds were acting at the level of 3-year-olds 60 years ago, and today's 7-year-olds were barely approaching the level of a 5-year-old 60 years ago," Bodrova explains. "So the results were very sad."
Sad because self-regulation is incredibly important. Poor executive function is associated with high dropout rates, drug use and crime. In fact, good executive function is a better predictor of success in school than a child's IQ. Children who are able to manage their feelings and pay attention are better able to learn. As executive function researcher Laura Berk explains, "Self-regulation predicts effective development in virtually every domain."