Willpower

March 2026

• Mar 6, 2026ConceptsDecision Journaling for Better Judgment Over TimeLevav and colleagues tracked 1,067 car purchases at German dealerships and found buyers deliberated carefully over early options then increasingly accepted defaults by the end of the sequence. Linder and colleagues found inappropriate antibiotic prescribing rose 26 percent in afternoon appointments across roughly 21,900 visits. This page is careful about the contested science: the famous parole board finding is reported as an association, not a measured depletion state.26 MIN34.5k

December 2024

• Dec 26, 2024ConceptsEgo Depletion: Is Willpower a Limited Resource?Why willpower-as-fuel became psychology's central replication case. Hagger's 2010 meta-analysis of 83 studies reported a medium-to-large effect, and in 2016 Hagger himself led a preregistered replication across 23 laboratories and 2,141 participants that found no effect. The glucose version fared worse: the reported blood sugar drops of 1 to 2 milligrams per deciliter are far too small to affect a brain regulated between roughly 70 and 100.19 MIN9.4k

January 2024

• Jan 9, 2024ConceptsHow Willpower Works: The Science of Self-ControlMartin Hagger's 2016 pre-registered multi-lab study tested ego depletion across 23 labs in 36 countries using the same paradigm, and the effect was not found. Tyler Watts' 2018 replication of Mischel's marshmallow test, with a larger and more socioeconomically diverse sample, found the link between early delay of gratification and later outcomes substantially reduced once socioeconomic status, family stability and cognitive ability were controlled.14 MIN7.6k

November 2023

• Nov 14, 2023ConceptsInsights on the Effectiveness of WillpowerHagger's pre-registered multi-site replication produced results consistent with chance variation around zero, and the marshmallow test did not survive either: with roughly 900 children and controls for socioeconomic background, the link to later outcomes largely disappeared. What does hold up is Galla and Duckworth's finding that disciplined people encounter fewer temptations rather than resisting more.13 MIN13.1k

August 2022

• Aug 10, 2022ConceptsWhat Science Reveals About WillpowerWhat the willpower research actually supports after the replication crisis. Baumeister's 1998 ego depletion model was replicated dozens of times, but Hagger and colleagues ran a pre-registered multisite study in 2016 with 2,141 participants across 23 laboratories using the same protocol and found no significant effect. The current best estimate is a modest phenomenon whose magnitude was substantially inflated by publication bias in the early literature.15 MIN8.5k