Abstract: Social conventions govern social behavior in many ways, ranging from left- and right-hand traffic to greetings. We sometimes find that inefficient social conventions, such as bullying in a class, are spontaneously formed, where almost all the people in the group are at a disadvantage. Although such a convention can be disadvantageous for all the people in the group, why are those conventions formed and continue to be maintained? A conformity bias, the behavioral tendency with which people take an action that a majority of the group take, can be one of the key ingredients of this phenomenon. In this study, we investigated the impact of conformity bias and an individual’s trial-and-error learning on the spontaneous formation of social conventions. Analyzing the stationary states of the dynamics and the tipping points at which the dynamics are divided into one converging to the efficient and the other converging to the inefficient convention, we found that by increasing the extent of conformity bias, an inefficient convention tends to be formed. On the other hand, an individual’s trial-and-error learning can suppress conformity bias and promote the formation of efficient conventions.

Keywords: Social convention; Conformity bias; Positive externality; Reinforcement learning model; Tipping points