Self-control at four: what it predicts, and what it doesn't
The short version: Self-control in childhood really does matter for later life — but a single waiting test at age four tells you much less than its fame suggests. The skill is built across years, and it can be practiced.
The studies
Moffitt, T. E., Arseneault, L., Belsky, D., et al. (2011). A gradient of childhood self-control predicts health, wealth, and public safety. Proceedings of the National Academy of Sciences, 108(7), 2693–2698. doi:10.1073/pnas.1010076108 · free full text
Who was studied: About 1,000 children in Dunedin, New Zealand, followed from birth to age 32, with self-control rated repeatedly between ages 3 and 11; plus about 500 pairs of British siblings.
Design: Long-term cohort (observational)
What they found: Children with more self-control grew into adults with better physical health, less substance dependence, better finances and fewer criminal convictions. It wasn't only the least self-controlled children who did worse — every step up in self-control went with better outcomes. The link held after taking account of intelligence and family social class, and within sibling pairs the sibling with less self-control did worse despite sharing a family.
Watts, T. W., Duncan, G. J., & Quan, H. (2018). Revisiting the marshmallow test: A conceptual replication investigating links between early delay of gratification and later outcomes. Psychological Science, 29(7), 1159–1177. doi:10.1177/0956797618761661 · free full text
Who was studied: Children from a large US study who did a waiting task at age four and were followed to age 15; the main analyses focused on children whose mothers had not finished college.
Design: Longitudinal replication (observational)
What they found: Waiting longer at four did predict better achievement at fifteen — but the link was about half as strong as in the original 1990 marshmallow studies, and it shrank by about two thirds once family background, early cognitive ability and the home environment were taken into account. Most of the difference came from whether a child could wait at least 20 seconds. Links with behavior at fifteen were small.
How strong is the evidence?
Strong for the general claim that self-control matters (Dunedin is one of the best cohorts in the world, and the sibling comparison helps). Weak for the popular claim that one marshmallow test at four predicts a child's future. Both studies are observational: they show links, not that training self-control causes the outcomes.
What these studies don't show
- They don't show that a child who can't wait at four is set on a worse path. Most of the difference came from being able to wait about 20 seconds, and family circumstances explain much of the rest.
- They don't test any program. Whether practicing self-control changes adult outcomes is a separate question — reviews of preschool programs suggest self-control can be trained, with the biggest gains for children who start lowest.
What it means for parents
- Treat waiting as a skill, not a trait. Children wait better when they have a trick — turning their back, singing, keeping their hands busy — not when they're told to try harder.
- Make waits visible and short: a sand timer or "when the song ends" is easier than an open-ended "later".
- Don't read too much into one bad day or one test. The Dunedin finding is about years of everyday self-control, not a single moment.
Boss of My Want (lesson 13) practices waiting with a sand timer and a set of tricks; the Pause Button (lesson 4) practices stopping in the moment.