A lot of people believe that greater confidence will result in greater success. These beliefs come in many forms and can prompt a variety of actions. They include attempts to boost your confidence ahead of a talk, presentation, or job interview. They might prompt you to give yourself a pep talk ahead of an athletic contest. They might lead you to engage in some power posing ahead of an important meeting. All of these strategies are motivated by the notion that being more confident will increase your subsequent performance. Does it?
Those who believe that confidence increases success will often point to evidence showing a strong correlation between the two. The problem with correlations is that they cannot identify causality. That is, it is possible that the correlation between confidence and performance is entirely due to a third variable that causes both. In this case, the most plausible third variable is ability.
Greater ability obviously increases performance and it usually increases confidence. If more confident athletes succeed, that may well be because the most skilled athletes know how good they are and this accounts for both their confidence and their success. If more confident students get better grades it may be because students have a sense of how well they grasp the course material. If more optimistic cancer patients live longer, it might be that patients have a sense of how healthy they are, accounting for their confidence.
If you want to know whether confidence per se is helpful, correlation is not enough. You need an experiment in which you manipulate confidence. I ran such experiments with my colleagues Jenn Logg and Liz Tenney. Try as we might, we could not find evidence that confidence had an effect on performance. When we boosted the confidence of our research volunteers, we could detect no improvement in performance on any of the various tasks we used. Greater confidence did not enhance performance on math tests, trivia quizzes, physical endurance, or athletic performance.
Of course, there probably are circumstances in which greater confidence can give you the courage to take a risk that will succeed. Shy people can sometimes withdraw from social situations that would have enjoyed, if only they had the courage to try. They need more confidence. Talented students from low-income households apply too rarely to selective colleges that would be eager to admit them and provide them with generous financial aid. Plenty of people with good business ideas decline to become entrepreneurs. For those who would have succeeded, their caution is an error. What unifies these examples is that underconfidence leads people to decline beneficial opportunities.
But greater confidence is not always good for you. The students in my classes who are most confident they will ace the exam, and who therefore do not study, are not those who get the best grades. The politicians who are most confident of being elected, and who therefore do not bother to campaign, are not those most likely to win. The rock climbers who are most confident of their invincibility are not those with the longest life expectancies. What unifies these examples is that overconfidence leads people to take too many risks and fail to protect themselves.
Acknowledging that overconfidence and underconfidence are both errors should prompt a search for accuracy. Between the opposing risks of over- and underconfidence lies the thin line of truth and well-calibrated confidence. This is the single simplest, most important, and most useful lesson offered by my book, Perfectly Confident: Believe the Truth.
You should want to boost your confidence if it is too low. But you should want to moderate your confidence if it is too high. The benefits of well-calibrated confidence are legion and easy to identify. Accurate beliefs will guide your decisions about which parties to attend, which colleges to apply to, and which businesses to start. Accurate beliefs will help you figure out which classes you need to study for, when you need to campaign most aggressively, and when you need to protect yourself against failure, accident, or misfortune. The truth is not always easy to identify, especially when it concerns an uncertain future. But it is always worth seeking.
Tenney, E. R., Logg, J. M., & Moore, D. A. (2015). (Too) optimistic about optimism: The belief that optimism improves performance. Journal of Personality and Social Psychology, 108(3), 377–399. https://doi.org/10.1037/pspa0000018