Laboratory evidence shows that when people have to argue for a given position, they persuade themselves about the position’s factual and moral superiority. Such self-persuasion limits the potential of communication to resolve conflict and reduce polarization. We test for this phenomenon in a field setting, at international debating competitions that randomly assign experienced and motivated debaters to argue one side of a topical motion. We find self-persuasion in factual beliefs and confidence in one’s position. Effect sizes are smaller than in the laboratory, but robust to a one-hour exchange of arguments and a tenfold increase in incentives for accuracy. (JEL C93, D12, D72, D83, D91, I23)

Across five experiments (N = 1,714), we test whether people engage in wishful thinking to alleviate anxiety about adverse future outcomes. Participants perform pattern recognition tasks in which some patterns may result in an electric shock or a monetary loss. Diagnostic of wishful thinking, participants are less likely to correctly identify patterns that are associated with a shock or loss. Wishful thinking is more pronounced under more ambiguous signals and only reduced by higher accuracy incentives when participants’ cognitive effort reduces ambiguity. Wishful thinking disappears in the domain of monetary gains, indicating that negative emotions are important drivers of the phenomenon. (JEL C91, D12, D83, D91)