The results indicated that even 40 years later, the same individuals who could not stop themselves from immediately eating the marshmallow and thus kept themselves from getting
two marshmallows also had difficulty suppressing their responses when a positive social cue was present, even when they were instructed not to respond (Fig. 2c). However, they had no problem suppressing habitual responses to neutral cues (Casey et al., 2011). Thus, individuals who, as a group, had more difficulty delaying gratification at 4 years of age continued to show reduced self-control 40 years later. These findings highlight individual differences in self-control that are independent of age and can persist throughout the life span. However, a remaining question is whether the neural correlates underlying individual differences in self-control
are similar to those observed in adolescents in our previously described study.