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

Abstract

Social-media platforms allocate attention by deciding whose content receives reach. We study this problem in a network coordination model in which users learn from observed signals but also care about coordinating with others. Amplifying a source, therefore, spreads information while potentially making that source a more influential coordination reference. For any finite directed network, we show that the effect of an intervention on truth-tracking accuracy decomposes into an information gain and a change in network-amplified bias risk. The latter depends on how sources' influence profiles interact with the network's entire bias composition, so the most informative source need not be the best source to amplify. Broadcasting can improve the use of common information, while amplification of directionally biased sources can reduce accuracy. Integrated communities can outperform segregated ones; users may reject informative cross-cutting links, and engagement-oriented platforms may favor connections that reduce collective accuracy.

This manuscript substantially revises and supersedes an earlier working paper circulated since 2020 under the title "Can a social planner manipulate network dynamics and solve coordination problems?'' (SSRN No.~3587024)