  We study how personalized news aggregation for rationally inattentive voters
(NARI) affects policy polarization and public opinion. In a two-candidate
electoral competition model, an attention-maximizing infomediary aggregates
source data about candidates' valence into easy-to-digest news. Voters decide
whether to consume news, trading off the expected gain from improved expressive
voting against the attention cost. NARI generates policy polarization even if
candidates are office-motivated. Personalized news aggregation makes extreme
voters the disciplining entity of policy polarization, and the skewness of
their signals is crucial for sustaining a high degree of policy polarization in
equilibrium. Analysis of disciplining voters yields insights into the
equilibrium and welfare consequences of regulating infomediaries.
