The Meta-Analysis That First Cast Doubt on Ego Depletion

By the mid-2010s, hundreds of studies had tested some version of ego depletion, and a straightforward average of their published effects looked reasonably solid. This meta-analysis dug deeper, applying statistical techniques designed to detect and correct for publication bias, the tendency for studies finding a significant effect to be published while null results quietly go in a drawer. Once that correction was applied, the true underlying effect shrank dramatically, becoming statistically indistinguishable from zero. The authors also found clear evidence of small-study effects, where smaller studies reported systematically larger effects than bigger, more reliable ones, a classic signature of an inflated literature.

As a meta-analysis of existing published studies rather than new data collection, its conclusions depend on the accuracy of the bias-correction methods used, which remain debated among statisticians. What made it consequential was timing and method: it was among the first rigorous signals, using accepted techniques rather than simply failed replications, that the published ego-depletion literature as a whole might not reflect a real, reliable effect, setting the stage for the large-scale replication efforts that followed.