How we change what others think, feel, believe and do
Willpower as Muscle
Willpower and muscle are surprisingly similar, both as analogy and in physical practice.
The exercise of will requires cognitive effort, with the brain using more glucose from the blood. And as the blood glucose is a limited supply, it can run low, leading to a sense of exhaustion. The human brain takes a lot of energy to run, consuming 20% of the body’s calories even though it constitutes only 2% of the body’s mass.
Muscles can be made stronger with exercise. Willpower is similar, although this is perhaps more of an analogy than physical similarity. When you learn, exercise and practice using willpower, you get better at it and will become exhausted less easily.
The principle of exhaustion means people can be worn down, which can be a deliberate strategy in the exercise of will. If I believe I have a stronger, fitter will than you, then all I need to do is to keep using it until you are forced to give up.
Exhaustion in exercising will can be both physical and mental. When you start thinking that you may not succeed, this results in an exhaustion based on what you are thinking, perhaps anticipating exhaustion rather than physical depletion.
Physical and willpower exhaustion are different. You feel and know when you are physically tired but may well not realize that your will is weakening. This can lead to unexpected problems. Exhaustion as weakening of the will is also known as ego depletion.
Paradoxically, when the will tires, people may become more energetic as emotions are loosened and intensified. Ego depletion has hence been said to 'turn up the volume on life'. This give a way to know when your will is sagging: when you become more aroused.
The correlation between glucose and willpower helps explain why dieting is so difficult: When you are depleted and need more glucose, you have to eat to get it and lack willpower to eat less while doing so. This creates a double bind: if you choose to eat you put on weight, if you do not, you lack the willpower not to eat and so still eat and put on weight.
Willpower and muscle are so closely related, just clenching your muscles when you need more willpower can apparently help self-control. This is perhaps why people who are trying hard to control their urges often seem tense.
Baumeister et al (1998) found that subjects who had to resist the temptation to eat freshly baked cookies gave up on on a subsequent task that required persistent effort sooner than participants who did not have to resist eating the cookies. Other studies found similar energy depletion in tasks including:
This is not without challenge and Hui et al (2012) found that exerting self-control did not increase carbohydrate metabolization, and that just rinsing one’s mouth with, but not ingesting, carbohydrate solutions had a positive effect on self-control.
An effect to consider in changing minds is that when people are tired their willpower will be less than normal. Hence they may be more persuadable in the evening, after exercise or when they are tired from any other activity.
When persuading, do ensure your blood glucose is up to good levels before acting in any way that requires willpower, for example by having a meal or energy drink a while before the persuasive activity.
Baumeister, R.F., Bratslavsky, E., Muraven, M. and Tice, D M. (1998). Self-control depletion: Is the active self a limited resource? Journal of Personality and Social Psychology, 74, 1252–1265.
Gailliot, M.T,. Baumeister, R.F., DeWall, C.N., Maner, J.K., Plant, E.A., Tice, D.M., Brewer, L.E. and Schmeichel, B.J. (2007). Self-control relies on glucose as a limited energy source: Willpower is more than a metaphor. Journal of Personality and Social Psychology, 92, 2, 325-336
D. C., Hui, C. M., Scholer, A. A., Meier, B. P., Noreen, E. E., D’Agostino, P. R., & Martin, V. (2012). Motivational versus metabolic effects of carbohydrates on self-control. Psychological Science, (in press)
Risher, B. (2011). Muscle Your Way to More Willpower. Prevention, 63, 3 (March)
Ackerman, J.M., Goldstein, N.J., Shapiro, J.R. and Bargh, J.A. (2009). You Wear Me Out: The Vicarious Depletion of Self-Control. Psychological Science, 20, 3, 326
And the big