While early studies suggested that the marshmallow test reliably predicts later life success, recent preregistered replications and longitudinal analyses indicate that its predictive validity is weak once demographic and background factors are controlled.
The claim that the marshmallow test predicts later life success is contested in contemporary developmental psychology. While older literature and popular culture championed the test as a powerful indicator of future outcomes, direct replication attempts and rigorous longitudinal studies (such as paper [8]) have challenged these findings, showing that performance does not reliably predict adult functioning after adjusting for socioeconomic status and other covariates. Therefore, the verdict is CONTESTED.