LAUSR

Groups typically express more confidence than individuals, yet how individual-level confidence combines during collaborative decision tasks is not well understood. We prescreened 686 community members using a novel confidence measure (a true/false trivia test) intentionally designed to be difficult (accuracy rates were not significantly better than chance) and randomly assigned 72 individuals to collaborate on a matched version of the same test in dyads composed of two low-confidence individuals, two high-confidence individuals, or one of each (“mixed”). Consistent with past research, we found that the confidence expressed by dyads was higher than the confidence expressed by individuals; importantly, however, this pattern varied markedly by dyad type, with low-confidence dyads showing the largest increase, mixed dyads showing a moderate increase, and high-confidence dyads showing no increase—despite the fact that all dyads showed similarly low accuracy (about 55%). These results highlight the conditions under which groups express greater confidence than individuals and offer insights for the composition of collaborative decision-making teams. Copyright © 2015 John Wiley & Sons, Ltd.