Social Psychology Textbook audiT: Ego Depletion

Since 2011, social psychology is in a crisis of confidence. Many published results were obtained with questionable research practices and failed to replicate. The Open Science Collaboration found that only 25% of social psychological results could be successfully replicated (OSC, 2015).

One of the biggest scandals in social psychology is the ego-depletion literature. The main assumption of ego-depletion theory is that working on a cognitively demanding task lowers individuals’ ability to do well on a second demanding task.

A meta-analysis in 2010 seemed to show that ego-depletion effects in laboratory studies are robust and have a moderate effect size (d = .5). However, this meta-analysis did not control for the influence of questionable research practices. A subsequent meta-analysis did take QRPs into account and found no evidence for the effect.

This meta-analysis triggered a crisis of confidence in the ego-depletion effect and an initiative to investigate ego-depletion in a massive replication attempt. The outcome of this major replication study confirmed the finding of the second meta-analysis. There was no evidence for an ego-depletion effect, despite the massive statistical power to detect even a small effect (d = .2) (Hagger et al., 2016).

There have been different responses to the replication failure. The inventor of ego-depletion theory, Roy F. Baumeister, blames the design of the replication study for the replication failure (cf. Drummond & Philipp, 2017). However, others, including myself (Schimmack, 2016), pointed out that Baumeister and colleagues used QRPs in their original studies and therefore do not provide credible evidence for the effect. Some ego-depletion researchers, like Michael Inzlicht (pdf), openly expressed concern that ego-depletion may not be real.

“We did run multiple studies, some of which did not work, and some of which worked better than others. You may think that not reporting the less successful studies is wrong, but that is how the field works.” (Roy Baumeister, personal email communication)  [Schimmack, 2014]

Social psychology textbooks responded differently to these developments in ego-depletion research.

Gilovich et al., (2019, 5ed) simply removed ego-depletion from their textbook, while the 3ed (2013) covered ego depletion, including the even more controversial claim that links ego-depletion to blood glucose levels, which was also obtained with QRPs (Schimmack, 2012).

In contrast, Myers and Twenge (2018, 13ed) continue to cover ego-depletion without mentioning any replication failures or concerns about the robustness of the evidence.

Neither treatment of the doubts about ego-depletion is acceptable. Simply removing ego-depletion misses the opportunity to teach students to think critically about social psychological research; which probably is the point. However, presenting ego-depletion is even worse. Examples like this show that social psychologists are unwilling to be open about the recent developments in their field and that students cannot trust social psychology textbooks to provide a balanced and scientific introduction to the field.

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