Peter Schwardmann and Joel van der Weele
Nature Human Behaviour (2019)
There is ample evidence that the average person thinks he or she is more skillful, more beautiful and kinder than others and that such overconfidence may result in substantial personal and social costs. To explain the prevalence of overconfidence, social scientists usually point to its affective benefits, such as those stemming from a good self-image or reduced anxiety about an uncertain future. An alternative theory, first advanced by evolutionary biologist Robert Trivers, posits that people self-deceive into higher confidence to more effectively persuade or deceive others. Here we conduct two experiments (combined n = 688) to test this strategic self-deception hypothesis. After performing a cognitively challenging task, half of our subjects are informed that they can earn money if, during a short face-to-face interaction, they convince others of their superior performance. We find that the privately elicited beliefs of the group that was informed of the profitable deception opportunity exhibit significantly more overconfidence than the beliefs of the control group. To test whether higher confidence ultimately pays off, we experimentally manipulate the confidence of the subjects by means of a noisy feedback signal. We find that this exogenous shift in confidence makes subjects more persuasive in subsequent face-to-face interactions. Overconfidence emerges from these results as the product of an adaptive cognitive technology with important social benefits, rather than some deficiency or bias.
From the Discussion section
The results of our experiment demonstrate that the strategic environment matters for cognition about the self. We observe that deception opportunities increase average overconfidence relative to others, and that, under the right circumstances, increased confidence can pay off. Our data thus support the the idea that overconfidence is strategically employed for social gain.
Our results do not allow for decisive statements about the exact cognitive channels underlying such self-deception. While we find some indications that an aversion to lying increases overconfidence, the evidence is underwhelming.13 When it comes to the ability to deceive others, we find that even when we control for the message, confidence leads to higher evaluations in some conditions. This is consistent with the idea that self-deception improves the deception technology of contestants, possibly by eliminating non-verbal give-away cues.
The research is here.