MONDAY, Aug. 29, 2011 (HealthDay News) -- Kids who have trouble resisting temptation are more likely than patient preschoolers to grow into adults who lack self-control, a new study suggests.
"What we're seeing is that there are some individuals who consistently presented as high or low delayers," lead study author B.J. Casey, a cognitive neuroscientist at the Sackler Institute for Developmental Psychobiology at Weill Cornell Medical College in New York City, said.
Prior research has shown that people who have trouble delaying gratification have lower SATs scores on average, higher body mass indexes (BMIs), higher divorce rates and a higher risk of substance abuse, Casey said.
Forty years ago, researchers put a group of 4-year-olds through a classic test designed to measure self-control. The kids were left in a room with a cookie or a marshmallow treat (whichever they preferred). An adult told the children if they could wait for him to return, they could have two cookies or two treats instead of just one.
Kids also had the option of ringing a bell on a desk while the adult was away, in which case the experimenter would run back, and the child could eat one treat but not the second.
The kids were then rated as either having low, average or high self-control depending on how long they could wait to eat the treat.
Followed through adolescence and into adulthood, many of the original 500 participants provided assessments of their self-control in their 20s and 30s. In their mid-40s today, 59 of them took another test to measure their self-control and ability to delay gratification.
In the new test, reported in the Aug. 30 issue of Proceedings of the National Academy of Sciences, the adults were shown images of either smiling, fearful or neutral faces, and instructed to press a button based on the facial expression.
The concept is that a smiling face is more enticing than a neutral face. For adults, reaction to faces is a better way of testing self-control than the promise of a cookie or marshmallow.
"As we get older, we're conditioned to respond to positive and negative social cues, so smiling faces are very alluring," said Casey.
The study found that the kids who lacked self-control grew into adults who had a harder time resisting the urge to act when they saw the smiling face than kids who had more self-control as preschoolers.
Researchers also did brain scans of 26 participants and found differences in activation of the ventral striatum, a region involved with reward and implicated in addiction.
Researchers found no difference in the responses when participants were shown only neutral faces, which presumably were less enticing.
Casey said the findings suggest that those who are able to delay gratification may be less susceptible to the pull of "alluring information" -- in this case, the sweet or the smiling face.
"What it tells us is that it's not that they can't control their impulses, like in ADHD. It's probably more associated with their overall sensitivity to how alluring the cue is to them, in terms of the difficulty in not being able to withhold a response," she said.
Sometimes, this trait can be advantageous, Casey said. "Any time you take risks or you're a novelty seeker, sometimes it's going to pay off and sometimes it won't. If you're not a risk taker, you may not take advantage of all opportunities."
Dr. Andrew Adesman, chief of developmental and behavioral pediatrics at the Steven and Alexandra Cohen Children's Medical Center of New York in New Hyde Park, said the study is both unique and significant in that researchers were able to follow up with people over a 40-year span.
Yet he cautioned against drawing firm conclusions about how likely a lack of self control at age 4 is to persist into adulthood. The original research included several hundred kids. In this paper, researchers "cherry picked" those who were on either end of the spectrum at age 4 and continued to have that trait as they reached their 20s and 30s.
While that can help researchers detect differences in brain scans, it leaves out kids who may have had difficulty with delaying gratification and improved over time. Nor does the research get at the role of parenting or education in helping kids learn self-control, he added.
"The findings here are not surprising in that they do show there is stability in some individuals of these traits and there are neurobiological differences underpinning it," he said. "But you have to be careful presuming that the way kids are at 4 is the way they are going to be at 40."
Nemours has more on teaching kids self-control.