People match confidence levels to make decisions in groups

When trying to make a decision with another person, people tend to match their confidence levels, which can backfire if one person has more expertise than the other, finds a new study led by UCL and University of Oxford researchers. The study, published in Nature Human Behaviour , shows that the degree of stated confidence in one's opinion is infectious when working in a team, which can blur the boundary between well-informed and poorly-informed opinion, sometimes to the detriment of group decision making. 'Making a decision collectively is most effective if the person with the most expertise expresses their opinion with the most confidence. If my opinion is more reliable than yours, then I should also be more confident. But it's difficult to express that effectively if you don't know whether the person you're working with is habitually overconfident or too modest,' said Dr Dan Bang (UCL Wellcome Centre for Neuroimaging), who led the study while based at both UCL and the University of Oxford. 'We found that even when an expert is paired with someone who lacks expertise, both participants will align their confidence levels so that their opinions will carry more equal weight,' he said. In six experiments involving 202 participants in Iran and the UK, the researchers asked people to perform a visual perceptual task.