Whom Should a Platform Amplify? Truth, Engagement, and Networked Polarization

Abstract

Social-media platforms allocate reach, deciding whose content becomes widely visible. We study this as feed/reference design in a networked coordination game where users track an unknown state, coordinate with others, and hold biased ideal actions. Amplification changes both who receives information and who becomes a salient coordination reference. Making a private signal commonly observed adds a second common signal and removes the usual non-monotonicity of truth-tracking accuracy in public-signal precision; under a broadcast budget, accuracy depends only on total amplified precision. For any finite network and biases, a network intervention's effect on accuracy splits exactly into an information gain and a quadratic bias cost governed by a Katz--Bonacich influence-overlap matrix, yielding an exact source-ranking rule and a closed-form amplification threshold. A reduced-form engagement objective instead favors validating, same-type links, producing more segregated networks and lower accuracy. Amplification's value depends jointly on information, bias propagation, and the platform's objective.