A child's success in his or her 30s in measures of health, wealth and more can be predicted by how well they can control their impulses as early as age three, says a new study, published today in Proceedings of the National Academy of Sciences.
Children with lower self-control scores, the researchers found, were more likely to have a number of physical health problems including sexually transmitted infections, weight issues, and high blood pressure. They were also more likely to be dependent on drugs; to have worse financial planning and money management skills; to be raising a child in a single-parent household; and to have a criminal record.
The study led by Avshalom Caspi of Duke University and colleagues followed 1,000 children from birth to age 32 in Dunedin, New Zealand.
Self-control was assessed by several measures including lack of control, impulsive aggression, hyperactivity, lack of persistence, inattention and impulsivity. The children were evaluated every two years from ages three to 11 to create a combined overall self-control measurement.
Researchers gathered data on the participants' health, wealth, family and criminal status when the participants reached age 32, then looked for correlations between the self-control score and these outcomes, correcting, for I.Q. and socioeconomic status.
"Children with low self-control tended to make mistakes while they were adolescents, including starting to smoke tobacco, becoming a teen parent of an unplanned baby and leaving secondary school with no qualification," the researchers added in a summary of their work.
But even those who avoided such outcomes had poorer scores on other factors as adults, they noted.
The researchers also looked at 500 non-identical twins and found that the sibling with a lower self-control score had a greater likelihood of poor school performance, beginning smoking or exhibiting antisocial behaviors.
"We did our best to pit self-control against alternative causes, and it survived all the tests we threw at it," Caspi and Duke colleague Terri Moffitt wrote in an email to Discovery News.
This was a surprise. "I thought intelligence would be the most important predictor of success," Moffitt added, "and did this work on self-control rather reluctantly."
In what the researchers think is the most novel finding, the results held for children across the spectrum of self-control. In other words, even at the upper echelons of the self-control spectrum, kids with more self-control performed better.
"It means all of us could benefit from improving our self-control," Caspi and Moffitt said, which could make widespread programs to improve self-control more appealing. "Universal interventions that benefit everyone avoid singling out and stigmatizing anyone."
Children whose self-control improved over time had better performance as adults than those whose did not, suggesting that interventions to improve self-control can make a difference down the line.
Improvements can come at an individual level, as well. "We do believe good parenting can improve self-control and improve life success," the authors said.
Developmental child psychologist Janice Zeman of the College of William and Mary agrees that parents can have a role in improving their children's self control. "If you teach them self-control, developmentally appropriately in the preschool years, then your middle childhood years are much easier," Zeman said.
"When you have a routine and expectations, children understand they can wait. If you have to wait for your snack for 15 minutes, that's not harsh and unusual punishment," she said. "Those are the beginning, rudimentary kinds of teaching of self-control."
Not using ineffective threats or "telling them to do things 10 times and at the 11th time, giving in," she said, all move toward better self-control.
On the flip side, some parents can expect too much for their children's age, Zeman said. And parental self-control helps, too, Zeman added, especially when it comes to being consistent.
Indeed, the findings call to mind the recent media buzz over the " Tiger Mom," Amy Chua who made headlines for her strict parenting style, forbidding sleepovers and demanding long musical practices from her children.
"That's one way to teach self-control, with extreme discipline," said Ernst Fehr at the University of Zurich. "There may be other ways. There was also a ' Dolphin Mom ' that was coined, one that induced the child in a more playful way. There's a kernel of truth in this 'Tiger Mom' approach, but it doesn't need to go this far."
These findings imply that social programs that target better self-control could improve a range of outcomes. For grown-ups, too, there may still be hope.
"Our particular article in PNAS points to both adolescence and early childhood as propitious windows for intervention. But we can't rule out adulthood," Caspi and Moffitt wrote.
Earlier work by the researchers showed that study participants who got highly responsible jobs in their 20s showed significant increase in their self-control skills thereafter. Perhaps there's still time to meet those New Year's resolutions, after all.