“Being able to delay gratification — in this case to wait 15 difficult minutes to earn a second marshmallow — not only reflects a child’s capacity for self-control, it also reflects their belief about the practicality of waiting,” says Celeste Kidd, a doctoral candidate in brain and cognitive sciences at the University of Rochester and lead author on the study.” Delaying gratification is only the rational choice if the child believes a second marshmallow is likely to be delivered after a reasonably short delay.”You can imagine the social policy the researchers would like to support. The ability to delay gratification is tied to future economic success (according to the old study), and if the capacity for delaying gratification is purely a matter of character, it seems to justify different economic results. One can feel good about being a big old conservative, who favors equal opportunity and scoffs at equalizing the results. You want differential outcomes, because they are deserved and they are incentives.
But if we find out that a child raised around unreliable adults will adapt by taking the rewards that are available in the present and that this child has shown good aptitude in refraining from delaying gratification, our conservatism won't feel so comfortable anymore and we're amenable to arguments about equalizing outcomes.