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Paper   IPM / Cognitive / 13836
School of Cognitive Sciences
  Title:   Equality bias impairs collective decision-making across cultures
  Author(s): 
1.  A. Mahmoudi
2.  D. Bang
3.  K. Olsen
4.  Y. Aimee Zhao
5.  Z. Shi
6.  K. Broberg
7.  S. Safavi
8.  S. Han
9.  M. Niliahmadabadi
10.  C. Frith
11.  A. Roepstorff
12.  G. Rees
13.  B. Bahrami
  Status:   Published
  Journal: Proceedings of the National Academy of Sciences
  Vol.:  112
  Year:  2015
  Pages:   3835-3840
  Supported by:  IPM
  Abstract:
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.

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