Back in the 70's, researchers conducted the now-classic "marshmallow" study to see how children deal with delayed gratification.
Now, they tracked down the original participants and found that their ability (or inability) to defer gratification doesn't change much over the years:
In the earlier study, 4-year-olds were given a choice. They could either have a marshmallow or a cookie now, or, if they waited a little longer, they could have double the treats.
Those who couldn't hold out and took the initial treat qualified as low delayers, while those who could postpone their reward were deemed high delayers. [...]
Because marshmallows aren't as irresistible to adults, the researchers asked participants to react to a series of emotional pictures, primarily happy and sad faces.
"The happy face took the place of the marshmallow," said Dr. B.J. Casey, director of the Sackler Institute at Weill Cornell Medical College and lead author of the study. "The positive social cue interfered with the low delayers' ability to suppress his or her actions."
The findings suggested that those better at delaying gratification as children remained so as adults. Likewise, those who wanted their treats right away were more likely to seek instant gratification as adults.