Reshared post from Bruno Gonçalves

Recent empirical evidence has shown that enabling collective intelligence by introducing social influence, can be detrimental to the aggregate performance of a population (Lorenz et al. 2011). By social influence, we understand the pervasive tendency of individuals to conform to the behavior and expectations of others (Kahan 1997). In separate experiments, Lorenz et al. asked participants to re-evaluate their opinions on quantitative subjects over several rounds and under three information spreading scenarios — no information about others' estimations (control group), the average of all opinions in each round and full information on other subjects' judgements. They found evidence that under the latter two regimes, the diversity in the population decreased, while the collective deviation from the truth increased. This result justi ed the disheartening conclusion that allowing people to learn about others' behaviours and adapt their own as a response does not always lead to the group acting "wiser". Rather, as the authors posited, not only is the population jointly convinced of a wrong result, but even the simple aggregation technique of the wisdom of crowds is deteriorated. From a policy-maker's perspective, such groups are, thus, not wise.

Current research has not yet investigated thoroughly the theoretical link between social influence and its eff ect on the wisdom of crowds. In this paper, we build upon the empirical study in (Lorenz et al. 2011) by developing a formal model of social influence. Our goal is to unveil whether the e ffects of social in influence are unconditionally positive or negative, or whether its ultimate role is mediated through some mechanism, so that the e ffect on the group wisdom is only indirect. We adopt a minimalistic agent-based model, which successfully reproduces the fin dings of the said study and gives enough insight to draw more general conclusions. In particular, we confirm that small amounts of social influence lead to faster convergence, however, it is the starting con figuration of the population (in terms of its initial diversity and deviation from the truth) that ultimately attribute the net e ffect of social in influence on the wisdom of crowds.

Bruno Gonçalves originally shared this post:

Effects of Social Influence on the Wisdom of Crowds. (arXiv:1204.3463v1 [cs.SI])

Wisdom of crowds refers to the phenomenon that the aggregate prediction or
forecast of a group of individuals can be surprisingly more accurate than most
individuals in the group, and sometimes – than any of the individuals
comprising it. This article models the impact of social influence on the wisdom
of crowds. We build a minimalistic representation of individuals as Brownian
particles coupled by means of social influence. We demonstrate that the model
can reproduce results of a previous em…

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