Diversity Promotes Collective Intelligence in Large Groups but Harms Small Ones

Pescetelli, Niccolo, Alexis Rutherford, and Iyad Rahwan. 2020. “Diversity Promotes Collective Intelligence in Large Groups but Harms Small Ones.” PsyArXiv. January 2. doi:10.31234/osf.io/b8q2c

Abstract: Diverse groups are often said to be less susceptible to decision errors resulting from herding and polarization. Thus, the fact that many modern interactions happen in a digital world, where filter bubbles and homophily bring people together, is an alarming yet poorly understood phenomenon. But online interactions are also characterized by unprecedented scale, where thousands of individuals can exchange ideas simultaneously. Evidence in collective intelligence however suggests that small (rather than large) groups tend to do better in complex information environments. Here, we adopt the well-established framework of social learning theory (from the fields of ecology and cultural evolution) to explore the causal link between diversity and performance as a function of group size. In this pre-registered study, we experimentally manipulate both group diversity and group size, and measure individual and group performance in realistic geo-political judgements. We find that diversity hinders the performance of individuals in small groups, but improves it in large groups. Furthermore, aggregating opinions of modular crowds composed of small independent but homogeneous groups achieves better results than using non-modular diverse ones. The results are explained by greater conflict of opinion in diverse groups, which negatively impacts small (but not large) groups. The present work sheds light on the causal mechanisms underlying the success (or lack thereof) of diverse groups in digital environments, and suggests that diversity research can benefit from adopting a wider social learning perspective.


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