People are seldom good at assessing their own attributes. Some riddled with anxiety and self-doubt fail to recognize their good qualities. However, on average, the tendency is the other way, with most people (particularly men) thinking they are more talented, attractive, and ethically superior to the average person, which by definition cannot be true. New evidence indicates this occurs because people with an inflated view of themselves are better at convincing others of their talents, allowing them to rise to positions they do not deserve.

Someone who overestimates their own abilities will take on tasks that are beyond them. Embarrassing today, it is easy to imagine this was once frequently fatal, posing a conundrum for evolutionary psychologists.

There’s a price to be paid for underestimating oneself too, of course, but we would expect that on average people would get it right, with most assessments close to reality. Yet study after study has found this not to be the case. Dr Peter Schwardmann of the University of Munich has provided evidence for why excessive self-regard remains so common.

In Nature Human Behavior, Schwardmann describes having 688 people perform an intellectually difficult task. Afterward, a randomly chosen half of the participants were offered money if they could convince some strangers they had done well in a short conversation.

Before meeting the strangers participants were asked to rate their test performance. Those psyching themselves up to convince others of how well they had done rated their performance more highly than the others. To make sure the test was measuring participant’s true beliefs – rather than them just starting the bravado early – Schwardmann also gave financial incentives for those that could accurately predict how they performed relative to other participants. This should have inspired honesty in anyone who doubted their performance.

Schwardmann concludes people believe they’ll have the best chance of fooling others if they have convinced themselves of their own genius, so they do just that.

Apparently, they are right. Participants who claimed in the survey to have done well were more likely to convince others of their strong performance than people with the same scores but a more realistic assessment of their score. To make it harder for participants to convince others of their success, the people they needed to fool were given their own financial incentive, earning money if they could make an accurate assessment of how each person claiming success on the task had really done.

An inflated sense of their talents or performance may work well for the individual, but the social effects are another matter. One doesn't have to look too hard for examples of people who are manifestly unsuited to positions convincing themselves, and then others, they can do the job, with disastrous consequences.