The Marginal Majority Effect: When Social Influence Produces Lock-In

• Authors: Pantelis P. Analytis, Alexandros Gelastopoulos, Gaël Le Mens and Arnout van de Rijt
• Science Advances, Vol. 12, No. 8, February 2026

People are influenced by the choices of others, a phenomenon observed across contexts in the social and behavioral sciences. Social influence can lock in an initial popularity advantage of an option over a higher quality alternative. Yet, several experiments designed to enable social influence have found that social systems self- correct rather than lock in. Here, we identify a behavioral phenomenon that makes inferior lock- in possible, which we call the “marginal majority effect”: a discontinuous increase in the choice probability of an option as its popularity exceeds that of a competing option. We demonstrate the existence of a marginal majority effect in several recent experiments and show that lock- in always occurs when the effect is large enough to offset the quality effect on choice but rarely otherwise. Our results reconcile conflicting past empirical evidence and connect a behavioral phenomenon to the possibility of social lock-in.