A little optimism can be a good thing. If we believe we are going to be successful, we are more likely to take on difficult tasks, such as sitting exams or losing weight. But if we overestimate our chances of success, there is a danger that we may not try hard enough. For instance, those who are most worried about passing exams often get the best results. They are motivated by terror of failure.
Recent work by University of Illinois psychologists Justin Kruger and Jeremy Burrus has found that too much optimism can be bad for us motivationally. They point out that unfounded optimism is a widespread and deeply ingrained part of our psyche.
In the late 1970s, psychologist Neil Weinstein asked 258 students to compare their chances of experiencing several events - some desirable (live past 80, own home) and some undesirable (heart attack before age 40, lung cancer) - with those of the average person. The students should have rated themselves as just as likely to experience the events as anyone else. But they estimated they were more likely to experience the desirable events and less likely to experience the undesirable events. Weinstein's results made two important points about human judgment: that people are unrealistically optimistic about their own futures, and that they have a remarkable capacity to believe what they want to believe.
Kruger and Burrus suggest some of this could be because of egocentrism, the notion that the self figures more prominently in our judgments. Most people focus on their own likelihood of experiencing the event; they don't assess the average person's chances.
Blind optimism can be our enemy. If we believe it's inevitable that we'll lose weight at some time, we won't try hard enough to cut down on food now.
What does that cream bun with our morning tea matter if we'll be slim soon anyway? So if we want to lose weight or pass exams, we have to appreciate the future consequences of our present behaviour and ask ourselves how successful the average person is likely to be. We must acknowledge the uncomfortable reality that if they're not likely to lose weight on a daily diet of cream buns, then neither are we.
If we can guard against unrealistic optimism and accept that it is only with hard work that we will achieve our goals, then a better (and perhaps thinner) future is inevitably ours.
Dr Raj Persaud is Gresham professor for public understanding of psychiatry, and director of the Centre for Public Engagement, King's College London.
His latest book is The Motivated Mind (Bantam Press). Email: email@example.com