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We tend to think that everyone deserves an equal say in a debate. This seemingly innocuous assumption can be damaging when we make decisions together as part of a group. To make optimal decisions, group members should weight their differing opinions according to how competent they are relative to one another; whenever they differ in competence, an equal weighting is suboptimal. Here, we asked how people deal with individual differences in competence in the context of a collective perceptual decision-making task. We developed a metric for estimating how participants weight their partner's opinion relative to their own and compared this weighting to an optimal benchmark. Replicated across three countries (Denmark, Iran, and China), we show that participants assigned nearly equal weights to each other's opinions regardless of true differences in their competence-even when informed by explicit feedback about their competence gap or under monetary incentives to maximize collective accuracy. This equality bias, whereby people behave as if they are as good or as bad as their partner, is particularly costly for a group when a competence gap separates its members.

Original publication

DOI

10.1073/pnas.1421692112

Type

Journal article

Journal

Proc Natl Acad Sci U S A

Publication Date

24/03/2015

Volume

112

Pages

3835 - 3840

Keywords

bias, equality, joint decision-making, social cognition, Adult, China, Cognition, Communication, Computer Simulation, Cooperative Behavior, Cultural Characteristics, Decision Making, Denmark, Humans, Interpersonal Relations, Iran, Male, Prejudice, Reproducibility of Results, Social Behavior