Friday March 23 2018

Our Mysterious Moral Muscle: The Elusive Nature of Self-Control

Remember those New Year’s resolutions you made just over a month ago? Now that we’ve reached the second week of February, if your resolutions are still going strong, you’ve already outlasted 80% of resolution makers, according to U.S. News. [1] Whether it be getting a head start on your beach bod, cutting down on your intake of La Piazza chicken fingers, or simply devoting more quality time to the people you care about, self-control – or rather a lack thereof – seems to be our go-to culprit when we fall short of our goals. Even if you’re someone like me who didn’t start 2018 with any concrete resolutions to speak of, our willpower is put to the test countless times each day when we manage our impulses. Thus, is self-control a virtue? A skill? What exactly is this self-regulatory capacity that our society has enshrined as the key to success?

The concept of self-control as we know it today is largely borne out of the Victorian industrial revolution of the 19th century. [2] The rapidly swelling population and simultaneous decline of religious influence led to concerns over whether the growing lower class would uphold Christian moral values. As a result, the importance of self-control was trumpeted by various publications of the day, including the hugely popular 1859 book Self-Help, which argued that “national progress is the sum of individual industry, energy, and uprightness.” [3] At the turn of the 20th century, Sigmund Freud would explain self-control in terms of the “superego,” the part of the human psyche composed of the values and morals instilled by society, which control our impulses. [4] Fast forward to the 1990s, and groundbreaking research conducted by psychologist Roy Baumeister would bring about the modern paradigm for self-control: human willpower is, in fact, a finite resource that can be depleted. [5] In other words, by successfully overcoming the desire to scroll through your Facebook feed and focusing on your essay, you’ve reduced your ability to resist the big piece of cheesecake afterward. The theory, which he named “ego-depletion,” is supported by several dual-task experiments. In one well-known 1998 example, two groups of hungry university students were each presented with freshly-baked cookies alongside a bowl of plain radishes. One group was instructed to eat only the radishes, while students in the other group were allowed to eat whatever they wanted. The researchers found that the participants who had to exercise self-control and eat radishes performed worse on a subsequent willpower task compared to their unrestrained counterparts, suggesting that they had drained some psychological resource.

Baumeister himself used the metaphor of a “moral muscle” when describing the nature of willpower, and much research conducted in the 17 years following seemed to support the analogy. If self-control is comparable to a muscle, can we train it like we do our physical ones? According to a 2006 study done by Oaten and Cheng, the answer is quite possibly, “Yes.” This study, which compared participants who underwent formal academic or exercise programs with “untrained” controls, concluded that regularly exercising self-control can reduce “ego-depletion” effects, either by expanding the pool of self-control resources or by improving the efficiency of willpower tasks. [6] Similarly, a 2007 study claimed that human self-control is mediated by blood glucose levels, much like our physical muscles. Not only was there a positive correlation between glucose concentration and ego-depletion, glucose supplementation was shown to replenish willpower. [7]

Over the past two decades, the strength model of self-control served as the fodder for countless psychology and self-help books, but recent studies and replication attempts have challenged the legitimacy of the theory. A 2015 meta-analysis published in the Journal of Experimental Psychology, found that there was significant publication bias favoring positive results over null reports when it considered unpublished studies alongside the existing findings. [8] In light of these concerns, the team launched a multinational replication attempt composed of over 2100 participants. The result: no statistically significant indications of “ego-depletion.” [9]

However, this shouldn’t be taken as a total invalidation of the strength model — these recent claims, just like the original studies they question, are subject to scientific debate. They do, however, invite alternative perspectives on self-control to break past the dominant view. To name a notable example, Dr. Fujita, a leading cognitive scientist from Ohio State University, advocates for a “dual-motive conceptualization” of self-control — the view that self-control is the bargaining that occurs between multiple internal decision-making systems, rather than mere impulse suppression. [10]

Thus, the precise nature of human self-control still remains elusive. After all, questions involving human nature aren’t exactly known for producing clear, unequivocal answers. However, while we can’t conclude with certainty whether self-control is best described as a “moral muscle” or a competition between internal motives, we can confidently say that the best way to stick to our long-term goals is to reduce our dependence on “fallible” self-control in the first place when it comes to pivotal moments. Instead of banking on our willpower to plow through an all-nighter without zoning out, perhaps instead space out the essay-writing across multiple days. To prevent the chicken fingers at La Piazza from beckoning you in the first place, perhaps walk into Centro@Commons instead. Whether you consider it resting your moral muscles or assisting your long-term motivations in the battle of internal decision-making, your future self will be grateful.


  1. Peacock K. BUPA – New Year’s Resolutions. London: ComRes; 2015 [Accessed 19th February 2018].
  2. Baumeister RF, Tierney J. Willpower: rediscovering the greatest human strength. New York, NY: Penguin Books; 2012 [Accessed 19th February 2018].
  3. Smiles S. Self-Help; With Illustrations of Character and Conduct [Internet]. Online Library of Liberty. Boston , MA: Ticknor and Fields; 1859. Available from: http://oll.libertyfund.org/titles/smiles-self-help-with-illustrations-of-character-and-conduct  [Accessed 19th February 2018]
  4. Lapsley DK, Stey P. Id, Ego, and Superego. In: Encyclopedia of Human Behavior . 2nd . Elsevier; 2011 [Accessed 19th February 2018].
  5. Baumeister RF, Bratslavsky E, Muraven M, Tice DM. Ego depletion: Is the active self a limited resource? Journal of Personality and Social Psychology [Internet]. 1998 ;74(5):1252–65. Available from: https://www.ncbi.nlm.nih.gov/pubmed/9599441 [Accessed 19th February 2018]
  6. Oaten M, Cheng K. Improved Self-Control: The Benefits of a Regular Program of Academic Study. Basic and Applied Social Psychology [Internet]. 2006;28(1):1–16. Available from: http://www.tandfonline.com/doi/abs/10.1207/s15324834basp2801_1 [Accessed 19th February 2018]
  7. Gailliot MT, Baumeister RF, Dewall CN, Maner JK, Plant EA, Tice DM, et al. Self-control relies on glucose as a limited energy source: Willpower is more than a metaphor. Journal of Personality and Social Psychology [Internet]. 2007;92(2):325–36. Available from: https://www.uky.edu/~njdewa2/gailliotetal07JPSP.pdf [Accessed 19th February 2018]
  8. Carter EC, Kofler LM, Forster DE. Supplemental Material for A Series of Meta-Analytic Tests of the Depletion Effect: Self-Control Does Not Seem to Rely on a Limited Resource. Journal of Experimental Psychology: General [Internet]. 2015; Available from: https://www.ncbi.nlm.nih.gov/pubmed/26076043 [Accessed 19th February 2018]
  9. Hagger MS, Chatzisarantis NLD. A Multilab Preregistered Replication of the Ego-Depletion Effect. Perspectives on Psychological Science [Internet]. 2016Jul1;11 (4):546–73. Available from: http://journals.sagepub.com/doi/abs/10.1177/1745691616652873?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%3dpubmed [Accessed 19th February 2018]
  10. Fujita K. On Conceptualizing Self-Control as More Than the Effortful Inhibition of Impulses. Personality and Social Psychology Review [Internet]. 2011;15(4):352–66. Available from: https://www.ncbi.nlm.nih.gov/pubmed/21685152 [Accessed 19th February 2018]

Written by Edward Cui, Honours Health Sciences (Class of 2021)

Edited by Angela Dong, Honours Health Sciences (Class of 2020) 


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The Meducator is McMaster University’s undergraduate Health Sciences Journal. It publishes pieces that critically address current issues with a high degree of scientific rigor, but in a way that is accessible to a broad audience.


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