Voter Learning, Unidimensional Ideology, and Polarization

52 Pages Posted: 20 Dec 2023 Last revised: 26 Mar 2024

Date Written: November 21, 2023


We model a spatial, two-party election where voters can flexibly acquire costly information about their ideal points before voting. In equilibrium, learning about ideal points creates unidimensional and polarized ideology even if the true distribution of ideal points is multidimensional and unimodal. A lower cost of information can lead to more ideological and platform polarization, reducing voter welfare. Under aggregate uncertainty about voter preferences, elections fail to aggregate preferences in more than one dimension and party platforms necessarily lie in a two-dimensional subspace. We also consider an extension to an industrial organization setup, where a lower cost of information translates not only to more product differentiation but also to higher prices, reducing consumer surplus.

Keywords: rational inattention, electoral competition, polarization, product differentiation

JEL Classification: D43, D72, D83, L13, L15

Suggested Citation

Vaeth, Martin, Voter Learning, Unidimensional Ideology, and Polarization (November 21, 2023). Available at SSRN: or

Martin Vaeth (Contact Author)

Princeton University ( email )

United States

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