Ideological Alignment, Cognitive Biases, and Media Exposure in Political Outgroups and Polarization: A Systematic Review

Abstract

Political communication research increasingly theorizes ideological alignment, cognitive biases, and media exposure as a sequential causal chain shaping attitudes toward political outgroups and polarization, yet whether the field empirically tests this three-variable model or only invokes it rhetorically has not been systematically examined. This mixed-methods systematic review synthesizes empirical evidence published between January 2000 and 2026 across four databases (Scopus, Web of Science, PsycINFO, PubMed) using an Antecedent–Mechanism–Outcome (AMO) framework and PRISMA 2020 reporting standards, integrating quantitative gap-mapping with qualitative thematic synthesis of how each construct in the chain is conceptualized. A Full-Chain AMO Inclusion Rule retained 158 studies for primary synthesis from 784 records identified; 412 partial-pathway studies were retained as a contextual pool for gap-mapping. Of 158 included studies, 65 (41.1%) satisfied the rule through cognitive-bias mechanisms alone without measuring media exposure; 50 (31.6%) measured media exposure only by self-report; 36 (22.8%) manipulated it experimentally; and 8 (5.1%) used behavioral or trace-data measurement. Only 22.8% formally tested mediation, and 68.4% sampled exclusively from the United States, raising questions about cross-national generalizability. Thematic synthesis revealed that apparent convergence on shared construct labels masks substantive disagreement about what each construct is and where it sits in the information-processing stream. The field’s integrated theoretical model is not the empirical model it predominantly tests. Closing this gap — through behavioral media-exposure measurement, formal mediation estimation, longitudinal designs, and cross-national replication including in hybrid-media contexts such as the Philippines — is the field’s most actionable priority.