Extrinsic rewards undermine altruistic tendencies in 20-month-olds
Warneken and Tomasello report that 20-month-old infants who received a material reward during a treatment phase helped less in a later test phase than infants who received social praise or no reward. The authors call this an overjustification effect and conclude that early helping appears intrinsically motivated and that socialisation practices using extrinsic rewards may undermine it. No sample size or procedure detail beyond the abstract is used.
Warneken and Tomasello report that 20-month-old infants who received a material reward during a treatment phase helped less in a later test phase than infants who received social praise or no reward. The authors call this an overjustification effect and conclude that early helping appears intrinsically motivated and that socialisation practices using extrinsic rewards may undermine it. No sample size or procedure detail beyond the abstract is used.
Written from the abstract, university publication record and Crossref, 2026-11-02.
What our sources record
Recorded when this source was checked, figures included, with page references and quotation marks removed.
Warneken, F., & Tomasello, M. (2008). Extrinsic rewards undermine altruistic tendencies in 20-month-olds. Developmental Psychology, 44(6), 1785-1788. doi:10.1037/a0013860 https://doi.org/10.1037/a0013860