Equality Bias Impairs Collective Decision-Making across Cultures. Mahmoodi, A.; Bang, D.; Olsen, K.; Zhao, Y. A.; Shi, Z.; Broberg, K.; Safavi, S.; Han, S.; Ahmadabadi, M. N.; Frith, C. D.; Roepstorff, A.; Rees, G.; and Bahrami, B. Proceedings of the National Academy of Sciences, 112(12):3835–3840, March, 2015.
doi  abstract   bibtex   
[Significance] When making decisions together, we tend to give everyone an equal chance to voice their opinion. To make the best decisions, however, each opinion must be scaled according to its reliability. Using behavioral experiments and computational modelling, we tested (in Denmark, Iran, and China) the extent to which people follow this latter, normative strategy. We found that people show a strong equality bias: they weight each other's opinion equally regardless of differences in their reliability, even when this strategy was at odds with explicit feedback or monetary incentives. [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.
@article{mahmoodiEqualityBiasImpairs2015,
  title = {Equality Bias Impairs Collective Decision-Making across Cultures},
  author = {Mahmoodi, Ali and Bang, Dan and Olsen, Karsten and Zhao, Yuanyuan A. and Shi, Zhenhao and Broberg, Kristina and Safavi, Shervin and Han, Shihui and Ahmadabadi, Majid N. and Frith, Chris D. and Roepstorff, Andreas and Rees, Geraint and Bahrami, Bahador},
  year = {2015},
  month = mar,
  volume = {112},
  pages = {3835--3840},
  issn = {1091-6490},
  doi = {10.1073/pnas.1421692112},
  abstract = {[Significance]

When making decisions together, we tend to give everyone an equal chance to voice their opinion. To make the best decisions, however, each opinion must be scaled according to its reliability. Using behavioral experiments and computational modelling, we tested (in Denmark, Iran, and China) the extent to which people follow this latter, normative strategy. We found that people show a strong equality bias: they weight each other's opinion equally regardless of differences in their reliability, even when this strategy was at odds with explicit feedback or monetary incentives.

[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.},
  journal = {Proceedings of the National Academy of Sciences},
  keywords = {*imported-from-citeulike-INRMM,~INRMM-MiD:c-13545322,~to-add-doi-URL,cognitive-biases,decision-making,decision-making-procedure,democracy,feedback,knowledge-integration,science-based-decision-making,science-policy-interface,weighting},
  lccn = {INRMM-MiD:c-13545322},
  number = {12}
}
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