Determining why some individuals, but not others, succumb to drugs, alcohol, or obesity has been an area of investigation for some time.
The issue was originally reviewed by a study in the late 1960s and early 1970s that used marshmallows and cookies to assess the ability of preschool children to delay gratification.
If they held off on the temptation to eat a treat, they were rewarded with more treats later. Some of the children resisted, others didn’t.
Now, 40 years later, researchers revisited some of the same children and learn that the differences remain: Those better at delaying gratification as children remained so as adults; likewise, those who wanted their cookie right away as children were more likely to seek instant gratification as adults.
This discovery was supported by brain imaging that showed key differences between the two groups in two areas: the prefrontal cortex and the ventral striatum.
“This is the first time we have located the specific brain areas related to delayed gratification. This could have major implications in the treatment of obesity and addictions,” said lead author B.J. Casey, Ph.D.
In the current study, Casey and her co-investigators recruited 59 adults who participated as young children in the original study and represented either extreme of the delayed-gratification spectrum — high delayers and low delayers.
Because marshmallows and cookies can be less rewarding to adults, the researchers substituted two tests.
In the first, participants looked at a screen displaying a series of faces and were asked to signal only when a face of one gender was shown. This “cool” test revealed no significant differences between the two groups. A second, “hot” test used emotional cues such as a happy or frightened face.
In this test, results were varied and consistent with the childhood grouping of individuals responding to immediate verse delayed gratification.
“In this test, a happy face took the place of the marshmallow. The positive social cue interfered with the low delayer’s ability to suppress his or her actions,” said Casey.
The second test was then repeated while the participant’s brain was scanned using functional magnetic resonance imaging (fMRI).
The results showed that the brain’s prefrontal cortex was more active for high delayers and the ventral striatum — an area linked to addictions — was more active in low delayers.
The findings are published in the Proceedings of the National Academy of Sciences.
Source: Cornell University