The End of Ego-Depletion Theory?

By Neuroskeptic | July 31, 2016 5:39 am

It’s not been a good month for the theory of ego-depletion – the idea that self-control is a limited resource that can be depleted by overuse. Two weeks ago, researchers reported evidence of bias in the published literature examining the question of whether glucose can reverse ego-depletion.

Now, the very existence of the ego-depletion phenomenon has been questioned by an international collaboration of psychologists who conducted a preregistered replication attempt (RRR). The results have just been published in Perspectives on Psychological Science (although they’ve been circulating for a while.)

23 labs participated in the replication effort, with a total final sample size of 2,141 participants. The project was co-ordinated on the Open Science Framework (OSF) and the paper was written by Martin Hagger and Nikos Chatzisarantis.

Methodologically, the replicators did not attempt to reproduce the original version of the ego-depletion task, saying that “the tasks used in the original experiments were deemed too elaborate or complex to be appropriate for a multilab replication.” Instead they focussed on the procedures used by a recent paper, Sripada et al. (2014), which were fully computer-administered, and thus more portable. Importantly, Hagger and Chatzisarantis say that “The decision to use these tasks was based on the recommendation of Roy Baumeister”; Baumeister being the man who introduced the concept of ego-depletion back in 1998… but see below.

When asked to predict the outcome of the experiment, only one lab predicted a null result. The other 22 predicted seeing at least a small effect, perhaps because there have been dozens of published studies reporting positive evidence of ego-depletion.

Contrary to expectations, the replication gave a null result: there was no statistically significant ego-depletion effect, combined across all labs (Cohen’s d = 0.04, 95% CI [−0.07, 0.15]). In two out of the 23 labs, a significant ego depletion effect was seen, but in a third lab, a significant reverse effect occurred. Restricting the analysis to English-speaking participants produced a slightly higher effect size, but it was still non-significant (d = 0.14, 95% CI [−0.02, 0.30]).

ego_depletion_replicationThis looks pretty damning. Hagger and Chatzisarantis comment that these results are much worse than would be expected from the previous literature:

The effects are substantially smaller than the ego-depletion effect size… in Sripada et al.’s (2014) study (d = 0.69) that the present protocol was based on. The present effects are also much smaller than the uncorrected ego-depletion effect sizes reported in Hagger et al.’s (2010a) meta-analysis (d = 0.62)… The results are consistent with a null effect for ego depletion for the current paradigm.

But in a rebuttal piece, ego-depletion pioneers Baumeister and Vohs call the replication project a “Misguided Effort With Elusive Implications“. They say that the task used, borrowed from Sripada et al. (2014), may just not be effective at eliciting ego-depletion. Baumeister admits that he himself recommended that task, but he says that he was never especially keen on it:

In retrospect, the decision to use new, mostly untested procedures for a large replication project was foolish. When planning the Registered Replication Report (RRR) on ego depletion, Hagger asked Baumeister for suggestions. Baumeister nominated several procedures that have been used in successful studies of ego depletion for years. But none of Baumeister’s suggestions were allowable due to the RRR restrictions that it must be done with only computerized tasks that were culturally and linguistically neutral.

Discussions were stalemated, and we felt pressured to come up with something quickly. We learned of a new study by Sripada et al. (2014) that fit the requirements and passed this along to the RRR team. Since there were no viable other options, that method was chosen… Under the circumstances, we understood our approval to mean “Sure, go ahead” and not “Yes, that’s a definitive test of the phenomenon we’ve been studying all these years.”

Baumeister and Vohs go on to promise to conduct their own “preregistered, multisite replication project next year, using well-tested procedures (ones that actually involve self-regulation)”. For now, they conclude that

For two decades, we have conducted studies of ego depletion carefully and honestly, following the field’s best practices, and we find the effect over and over (as have many others in fields as far ranging as finance, health, and sports, both in the lab and large-scale field studies). There is too much evidence to dismiss based on the RRR, which after all is ultimately a single study…

Finally, Sripada and colleagues reply that differences in the experimental procedures might explain why their effect did not replicate

Our study was conducted in an outpatient psychiatry clinic, not a university lab. Second, our participants were drawn from a community sample and were paid $20 for participation, whereas nearly all the RRR studies used undergraduate participant pools and did not pay participants. Third, our paradigm was implemented in the context of a double-blind drug manipulation with Ritalin and a placebo. Participants arrived roughly 90 minutes before the tasks, were presented with an extensive consent detailing effects of Ritalin, ingested an unlabeled capsule, and then waited an hour for the drug (or placebo) effect to take hold. Given the preceding differences, it is likely that our participants were more motivated and invested in study participation than were typical participants in the RRR studies.

In my view, the dispute over the nature of the task is an unfortunate one, and it does complicate the interpretation of these results. Baumeister and Vohs have a point that the Sripada et al. ego-depletion task has not been used as much as other, earlier versions of the paradigm. Then again, it’s always possible to quibble about methodogical issues post hoc. If the results had come out positive, I doubt Baumeister and Vohs would be querying the task’s validity. Either way, it’s great news that Baumeister and Vohs plan to conduct their own RRR. Perhaps that study will provide the definitive test of the theory.

Edit: Hagger and Chatzisarantis have published a rebuttal to Baumeister, Vohs, and Sripada here.

ResearchBlogging.orgHagger, M., & Chatzisarantis, N. (2016). A Multilab Preregistered Replication of the Ego-Depletion Effect Perspectives on Psychological Science, 11 (4), 546-573 DOI: 10.1177/1745691616652873

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  • Chandra Sripada

    Great summary, Neuroskeptic. I do have a quibble though.

    I think it is better to separate the following two things: 1) the depletion effect, which says self-control performance decreases with prolonged use; and 2) the glucose hypothesis, which says the best explanation for the depletion effect is decrease in blood glucose. A lot of people believe (or at least did believe) the depletion effect was real but they did not subscribe to the glucose hypothesis. So best to keep these ideas separate.

    Focusing specifically on the depletion effect, I think it would premature to say this effect is not real. As we say in our Reply, there are effects that are “close cousins” of the depletion effect (such as the vigilance decrement effect) that are well supported in entirely independent lines of research that span decades of work. Going forward, I think the variable to keep an eye on is time-on-task. I predict we are going to see reliable and replicable results when tasks are extended (e.g., >30 minutes). I suspect the shorter tasks (e.g., 5 minutes) widely used now are more susceptible to motivational moderators and other noise factors.

    But then again, this prediction might turn out to be wrong! After all, we were taken by complete surprise by the RRR results. The bottom line is that there is more work to do, and it really is premature to talk about the “end of ego-depletion.”

    • http://blogs.discovermagazine.com/neuroskeptic/ Neuroskeptic

      Many thanks for the comment!

  • http://www.mazepath.com/uncleal/qz4.htm Uncle Al

    If the scholarly conclusion is real world faerie dust, whose fault is it – the expert researcher or the unqualified lab animal?

  • Martin Hagger

    @Neuro_Skeptic We rebutted Baumeister & Vohs’ complaints about tasks & responded to Sripada et al. in our commentary http://journal.frontiersin.org/article/10.3389/fpsyg.2016.00621/full

    • http://blogs.discovermagazine.com/neuroskeptic/ Neuroskeptic

      Thanks! I will update the post.

  • 7eggert

    The description of flawed methods is buried in the middle of the text, counting on ego depletion to prevent the casual readers from finding it.

  • Obsbi

    I wonder what would change the end (or not) of ego depletion on concrete topics

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  • M Peirce

    What seems to be missing in this thread is a conceptually oriented discussion that sufficiently clarifies Baumeister’s objections.

    Consistent with his remarks in other disputes targeting whether his experiments can be replicated, Baumeister emphasizes that his own experiments and other responsible experiments in the field that confirm his findings, and that have been targets for replication, crucially involve first setting up a strong specific habit. Ego depletion then occurs (is defined) as the result of effort to overcome/override habits where doing so is very difficult. As thus conceptualized, this is very different from merely having a task that requires effort and concentration to accomplish (cognitive fatigue). His objection to the Hagger study was that it did not sufficiently establish, for the cross-out-e task, that (a) there was indeed a habit in place that subjects had to overcome (a habituated action impulse to override, not just a task that required effort) and (b) (implied) if there was a habit, it was strong enough that a depletion effect would be reasonably expected, and discernible above the noise. (Analogously, leg-strength depletion isn’t likely to show up unless subjects are made to do a full out sprint for a long enough distance, or enough sets of lifting sufficiently heavy weights.)

    From what I could tell from reading Hagger’s rebuttal, Baumeister’s objections were not sufficiently addressed. Hagger emphasizes that it really does take effort to do the e-crossing task, but that doesn’t address B’s objection that a habit needed to be in place to overcome – not merely tendencies to be distracted, or to do other things instead of the assigned action, but a tendency to do some specific habituated response. Hagger’s rebuttal also doesn’t adequately address the strength of effort issue – that whatever habits subjects might be working to override (e.g., to be distracted by hunger or to attend to other environmental inputs) require enough impulse-overriding effort to yield a depletion effect.

    Count me in Baumeister’s camp regarding this replication attempt: One has to establish that one is manipulating the variables as those variables are hypothesized by the theory, and so, must guard against testing less precise conceptions of the relevant variables and mechanisms. And one must guard against claims of non-replication when the effects that aren’t showing up (depletion from light jogging) are outside of the window for which the target experiments show effects, and that are hypothesized by the theory (depletion from sprinting). This study, along with most others that purportedly fail to replicate ego depletion experiments, doesn’t quite fulfill these requirements. It does, however, narrow the range of mentally effortful actions for which ego depletion has been demonstrated and can be assumed to occur.

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  • david nicholls

    One thing that confuses me about glucose as the basis of willpower and ego depletion is that taking a short break (without eating) or doing something else for a while often seems to replenish my ability to carry out a task I’m completely unable to continue. Wonder what’s going on there? Some of the studies like of judges doing a better job after lunch (explained as getting glucose) might be explained just by their taking a break. Still I think from my own experience & observation willpower is quite limited & can be used up, no clue if it’s based on glucose or not.

  • s klein

    The problem with “The end of ego-depletion theory” is that there ever was a “Beginning to ego-depletion theory”.

    It is not a theory in any serious sense: Just cobbled together “ideas” conjoined with ill-defined terms in the service of a demonstration (not in the service of exploring the implications of a week-defined, logically coherent set of empirically substantiated propositions that have been fashioned into a rigorous, parametrically testable theory).

    But such is the (all too common) state of psychological “science”.

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Neuroskeptic is a British neuroscientist who takes a skeptical look at his own field, and beyond. His blog offers a look at the latest developments in neuroscience, psychiatry and psychology through a critical lens.

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