Found this article whilst looking for more details, the same results seem to have been reported for several years, including following the subjects into middle

Found this article whilst looking for more details, the same results seem to have been reported for several years, including following the subjects into middle age: https://anderson-review.ucla.edu/new-study-disavows-marshmallow-tests-predictive-powers/ https://anderson-review.ucla.edu/new-study-disavows-marshmal... > As the researchers predicted, the study finds only a tiny correlation between marshmallow test times and midlife capital formation. A graduate’s score on the self-regulation index was, however, modestly predictive of their middle-age capital formation, the study finds.