Cultural diversity and wisdom of crowds are mutually beneficial and evolutionarily stable

Benoît De Courson,Léo Fitouchi,Michael Benzaquen,Jean-Philippe Bouchaud

doi:10.1038/s41598-021-95914-7

Abstract

The ability to learn from others (social learning) is often deemed a cause of human species success. But if social learning is indeed more efficient (whether less costly or more accurate) than individual learning, it raises the question of why would anyone engage in individual information seeking, which is a necessary condition for social learning’s efficacy. We propose an evolutionary model solving this paradox, provided agents (i) aim not only at information quality but also vie for audience and prestige, and (ii) do not only value accuracy but also reward originality—allowing them to alleviate herding effects. We find that under some conditions (large enough success rate of informed agents and intermediate taste for popularity), both social learning’s higher accuracy and the taste for original opinions are evolutionarily-stable, within a mutually beneficial division of labour-like equilibrium. When such conditions are not met, the system most often converges towards mutually detrimental equilibria.

Highlights

The ability to learn from others is often deemed a cause of human species success
The very fact that the aggregate prediction is better than individual ones creates a tension: why would anyone make up his/her mind independently when he/she would be better off sampling around and endorsing the majority opinion? A very close analogy can be found in the Grossman-Stiglitz paradox in financial economics[3]: if, as often assumed, the price of an asset aggregates all available information, there is no reason to gather information, which makes it absurd that the price reflects anything to begin with
This parallels the question of the evolution of social and individual learning strategies

Summary

Methods and results

It makes sense to include a fourth strategy: anti-conformism, consisting in sampling around, and endorsing the minority opinion If such a behaviour spreads in the population, it challenges the very credibility of our scenario, as an original agent is no longer necessarily a source of reliable information. In terms of opinion diversity (not shown), the phase where anti-conformists are present produces heterogeneity, and polarisation: the average size of the minority group is close to 50%, i.e. the population is evenly split, as would be expected for an anti-conformist bias (see Fig. 1): if the probability to follow the minority is greater than the size of such minority, the only stable fixed point corresponds to 50% of the population holding one opinion, and 50% holding the other

Discussion

Findings

Limitations