The study also found the reverse to be true: People who under-rate their own abilities tend to be mistakenly viewed as less able by others.
“We think this supports an evolutionary theory of self-deception,” said study co-author Vivek Nityananda, a neuroscience research associate at Newcastle University in Great Britain, in a released statement. “It can be beneficial to have others believe you are better than you are, and the best way to do this is to deceive yourself — which might be what we have evolved to do.”
Yet, self-deception is not always beneficial. It can also be costly and even dangerous — and not just for the overconfident individual. As Nityananda and his co-author, Shakti Lamba, a behavioral ecologist at Exeter University, note in background information in their study, biased beliefs about people’s abilities have led to “errors with disastrous consequences, including airplane crashes, financial meltdowns and war.”
This is because, as other research has reported, overconfident people are more likely to take risks. So if the rest of us are fooled about such people’s abilities and promote them to positions of responsibilities and power, “we may be creating institutions, including banks, trading floors, emergency services and armies, that are also more vulnerable to risk,” write Nityananda and Lamba.
A real-life setting
The new study involved people in a real-life setting, thus making it the first one to offer direct evidence suggesting that fooling oneself helps fool others, according to Nityananda and Lamba.
The study’s participants were 72 undergraduate students at two British universities who were taking a small, first-year seminar that involved reviewing, debating and discussing course material with a teacher and about seven other students. After the first class, the students were asked to privately predict the grade that they believed they and each of the other students would receive when the course was completed. Seventy-one of them did not know any of the other students.
Six weeks into the course, after the students had gotten to know each other — and the course — better, they were asked to repeat the predictions.
At the end of the semester, the researchers compared both sets of predictions with the students’ actual grades. Thirty-two students (about 45 percent) had underrated how they would do compared to the others, while 29 students (40 percent) had been overconfident and 11 students (15 percent) had assessed their own ability accurately.
The comparison of the predictions also revealed a strong correlation between the students’ ratings of themselves and the ratings of their peers. The students who predicted high marks for themselves received high marks from their peers, no matter how they eventually performed in the course. The same was true for the students who underrated themselves.
Interestingly, the predictions made at the six-week point in the course were the same as those made at the beginning of the course. The overconfident students were still overrated by their peers.
Individual benefits, societal risks
This study, like all studies, has its limitations. It involved a small number of homogenous participants (undergraduate psychology and anthropology students, mostly women, at two large British universities). The findings may not hold up among other groups of people.
Still, say Nityananda and Lamba, the results “support the idea that self-deception facilitates the deception of others.”
“While the benefits of overconfidence are apparent, it is less clear whether underconfidence can also be advantageous,” they add. “There may, however, be situations in everyday life where individuals underplay their abilities to their competitors in order to either avoid immediate conflict or to steal an advantage at the right movement, the ‘underdog’ effect. ‘Dummying up’ or appearing less knowledgeable than you are may also be a way to avoid working as hard as others.”
Yet whether the self-deception involves overconfidence or underconfidence, it likely plays “a profound role in shaping the world we inhabit,” conclude Nityananda and Lamba, “from our smallest interactions to the institutions we build.”
PLOS ONE is an open-access journal, so you can read the entire study at the journal’s website.