I was of the belief that the idea of limited willpower (i.e. ego depletion) was false. It seems that the truth is that it's more in contention than anything else.
It does seem contested. The 2015 meta-meta-analysis takes an approach that I haven't seen before, which is to quantify the lack of nonsignificant results in the 2010 meta-analysis, showing that if it was a meta-analysis with little publication bias, there would have been far more nonsignificant results. They basically suggest to re-do the reproduction of the original 1998 study: I wouldn't be surprised if it does exist but only/mostly under some narrow set of circumstances, e.g. low glucose availability impacting decision making.We hope that the findings we present here will motivate researchers to re-examine the replicability and the magnitude of the depletion effect. Because our findings suggest that very large experiments will produce estimates of the depletion effect that are approximately zero, a useful next step would be a coordinated series of large, pre-registered direct replications of the original experiments (e.g., Baumeister et al., 1998).