little engine

This essay was written with Anthony Evans.

The Little Engine that Could is a classic story about the virtue of optimism. In this tale, the eponymous locomotive is challenged to carry freight over a steep mountain top. The little engine struggles in climbing the mountain, but ultimately succeeds in his mission. As the engine falters on its journey, it repeats the self-empowering mantra: "I think I can; I think I can." The little engine's message to readers is clear - maintain positive beliefs and you can accomplish great things.

The utility of optimism is supported by research on social cognition. Psychologists Shelley Taylor and Jonathon Brown (1988) theorized that positive biases are beneficial for mental health and well-being. People show a positive bias when they perceive themselves and the world as being better than they actually are. Unrealistic optimism is one example of a positive bias. Most people believe that the present is better than the past, and moreover, that the future will be even better than the present. When asked about the future, most people believe that they are more likely than others to experience good things (and also less likely to experience bad things). Like the little engine, most people believe that they are likely to succeed in future tasks. Taylor and Brown argue that positive biases (such as optimism about the future) make people "happier, more caring, and more productive" (p. 205).

Indeed, optimism is beneficial in many situations. Many behaviors, such as writing a novel or starting a new business, have a low probability of success (and thus require positive illusions). Yet a recent paper by Loran Nordgren and colleagues (2009) shows that optimism can sometimes lead to failure. In particular, people sabotage themselves when they overestimate their capacity for self-control. When people believe they have high self-control, they tend to subject themselves to more temptation than they can handle (and subsequently fail to resist it). When this pattern of behavior occurs, people are exhibiting what Nordgren calls the self-restraint bias.

In one study, Nordgren and colleagues demonstrated the negative effects of optimism on heavy smokers. Participants in the study completed a bogus test and were randomly told that they had a high or low capacity for self-control. After receiving this feedback, they faced a highly tempting situation: They would watch the movie Coffee and Cigarettes while in close proximity to a cigarette. Participants would win money if they could successfully watch the movie without smoking the cigarette. If they capitulated and smoked the cigarette, they received nothing. But there was a catch - participants could choose how much temptation to face (and they received more money if they successfully resisted a greater temptation). For example, subjects would win only two Euros if they could resist smoking the cigarette when it was kept in another room, but they would win eight Euros if they could hold the unlit cigarette in their mouths for the duration of the film.

The smokers faced a dilemma: Should they avoid temptation and play it safe, or should they take a greater risk and try to earn more money? Those who were told that they had greater self-control chose higher levels of temptation, and as a result, they were more likely to fail the test of self-control. In this study (and others), optimism caused participants to take on more temptation than they could handle. For many, the result was failure.

The lesson of the self-restraint bias is that self-talk of the "I-think-I-can" variety is not always the best policy. Because we are naturally optimistic creatures, we have the tendency to subject ourselves to unnecessary temptations. These temptations have the potential to undermine long-term goals of self-control. Trying to avoid temptation in the first place appears to be a more promising strategy for self-control than trusting one's will-power to resist temptation when it comes.

You may wonder how the self-restraint bias squares with the general finding that confidence and optimism are positively related to performance and success. The answer emerges from the design of the self-restraint studies. Optimism tends to predict performance within a given situation (however weakly in some contexts). The point of the self-restraint bias is that the context of performance varies across people and that it is the individuals themselves who choose the context. Optimism may make the little engine more likely to succeed at a given task, but it also makes the engine more likely to choose a task that is insuperable.

When we suggest that successful self-control can be achieved by avoiding temptation, we realize that this is more easily said than done. Choosing to avoid temptation requires an appreciation of the fragility of one's own will in the future. A highly confident individual who accepts the idea that she will not be able to withstand temptation in the future has essentially been transformed into a person with lower (and more realistic) confidence.

Articles cited:

Nordgren, L. F., van Harreveld, F., & van der Pligt, J. (2009). Restraint bias: How the illusion of self-restraint promotes impulsive behavior. Psychological Science, 20, 1523-1528.

Taylor, S. E., & Brown, J. D. (1988). Illusion and well-being: A social psychological perspective on mental health. Psychological Bulletin, 103, 193-210.

Note. Anthony Evans is a PhD student of psychology at Brown University. He can be reached at

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