Longitudinal follow-ups of Walter Mischel's marshmallow test found that longer delay times in children correlated with higher academic achievement, higher income, better health, and lower rates of incarceration and behavioral problems.
"The longer children could wait before eating the single marshmallow, the more likely they were to do well in school, more likely make more money, have more friends, have better physical and mental health, and also have lower incarceration and problematic social behavior reports." (said at 0:05:20)
The speaker overstates and conflates the findings of Walter Mischel's original marshmallow test follow-ups with broader longitudinal self-control research (such as the Dunedin study by Moffitt et al., which specifically examined adult income and criminal convictions). Mischel's longitudinal follow-ups of the Bing Nursery School cohort (a small, affluent Stanford preschool sample) reported correlations with adolescent SAT scores, social-cognitive competence, and adult BMI, but not incarceration. Furthermore, subsequent large-scale conceptual replications (e.g., Watts et al., 2018; Bates et al., 2024) demonstrate that delay time in the marshmallow test does not reliably predict long-term adult functioning once family background, socioeconomic status, and early cognitive ability are controlled.
- context: 'Willpower' over the life span: decomposing self-regulation. (Social cognitive and affective neuroscience 2011)
"In the 1960s, Mischel and colleagues developed a simple 'marshmallow test' to measure preschoolers' ability to delay gratification. In numerous follow-up studies over 40 years, this 'test' proved to have surprisingly significant predictive validity for consequential social, cognitive and mental health outcomes over the life course." (abstract, results)
pubmedfull study (doi) - partial: Preschoolers' delay of gratification predicts their body mass 30 years later. (The Journal of pediatrics 2013)
"Performance on the delay of gratification task accounted for a significant portion of variance in BMI (4%; P < .01), over and above the variance accounted for by sex alone (13%). Each additional minute that a preschooler delayed gratification predicted a 0.2-point reduction in BMI in adulthood. Longer delay of gratification at age 4 years was associated with a lower BMI 3 decades later." (abstract, results)
pubmedfull study (doi) - contradicts: Revisiting the Marshmallow Test: A Conceptual Replication Investigating Links Between Earl… (Psychological science 2018)
"We replicated and extended Shoda, Mischel, and Peake's (1990) famous marshmallow study, which showed strong bivariate correlations between a child's ability to delay gratification just before entering school and both adolescent achievement and socioemotional behaviors... But this bivariate correlation was only half the size of those reported in the original studies and was reduced by two thirds in the presence of controls for family background, early cognitive ability, and the home environment... Associations between delay time and measures of behavioral outcomes at age 15 were much smaller and rarely statistically significant." (abstract, results, passage verified)
pubmedfull study (doi) - contradicts: Delay of gratification and adult outcomes: The Marshmallow Test does not reliably predict … (Child development 2024)
"Using a preregistered analysis, Marshmallow Test performance was not strongly predictive of adult achievement, health, or behavior. Although modest bivariate associations were detected with educational attainment (r = .17) and body mass index (r = -.17), almost all regression-adjusted coefficients were nonsignificant... Results indicate that Marshmallow Test performance does not reliably predict adult outcomes." (abstract, results, passage verified)
pubmedfull study (doi)