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Adolescents show collective intelligence which can be driven by a geometric mean rule of thumb

Research output: Contribution to journalArticle

Original languageEnglish
Article numbere0204462
Number of pages17
JournalPLoS ONE
Issue number9
DateAccepted/In press - 14 Sep 2018
DatePublished (current) - 24 Sep 2018


How effective groups are in making decisions is a long-standing question in studying human and animal behaviour. Despite the limited social and cognitive abilities of younger people, skills which are often required for collective intelligence, studies of group performance have been limited to adults. Using a simple task of estimating the number of sweets in jars, we show in two experiments that adolescents at least as young as 11 years old improve their estimation accuracy after a period of group discussion, demonstrating collective intelligence. Although this effect was robust to the overall distribution of initial estimates, when the task generated positively skewed estimates, the geometric mean of initial estimates gave the best fit to the data compared to other tested aggregation rules. A geometric mean heuristic in consensus decision making is also likely to apply to adults, as it provides a robust and well-performing rule for aggregating different opinions. The geometric mean rule is likely to be based on an intuitive logarithmic-like number representation, and our study suggests that this mental number scaling may be beneficial in collective decisions.

    Research areas

  • Collective intelligence, Group performance, Consensus, Geometric mean, Number representation, Adolescents

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