# Ideological Transmission as Complex Contagion **Entity class:** Radicalization-modeling framework ## Definition **Ideological transmission as complex contagion** models violent-extremist ideology as informational content whose adoption can depend on repeated or reinforcing social exposures. It is not a claim that ideology is literally a pathogen or that exposure determines violence. The framework supplies mathematical language for susceptibility, exposure, reinforcement, clustered events, network topology, state transitions, intervention, disengagement, and uncertainty while preserving agency, heterogeneous response, competing influences, and the distinction between cognitive radicalization and mobilization to violence. ## Evidence Mason Youngblood's 2020 study analyzed 416 far-right extremists in the United States whose activity or plot was exposed from 2005 through 2017. Its spatio-temporal results were consistent with complex contagion and reinforcement; its scope and dataset do not establish a universal law of radicalization. NIJ's 2023–2024 syntheses find that peers, family, online subcultures, and other social relationships can facilitate or inhibit radicalization and disengagement, including among lone actors, while warning that findings are not generalizable across all contexts. ## Relationships - **method:** [[wiki/Complex Contagion|Complex Contagion]], [[wiki/Social Network Analysis|Social Network Analysis]], and [[wiki/Epidemic Modeling|Epidemic Modeling]]. - **counterterrorism use:** [[wiki/Counterterrorism Predictive Graph|Counterterrorism Predictive Graph]], [[wiki/Contact Tracing|Contact Tracing]], and [[wiki/Countering Violent Extremism|Countering Violent Extremism]]. - **homology:** [[wiki/From Radiation Field to Social Field|From Radiation Field to Social Field]]. - **boundary:** ideology, association, and exposure do not establish violent intent or criminal conduct. ## Sources / Provenance - [Youngblood — Extremist ideology as a complex contagion, 2020](https://www.nature.com/articles/s41599-020-00546-3) - [NIJ — Five Things About Social Networks in Domestic Radicalization, December 2023](https://nij.ojp.gov/library/publications/five-things-about-role-social-networks-domestic-radicalization) - [NIJ — Role of Social Networks, April 2024](https://nij.ojp.gov/library/publications/role-social-networks-facilitating-and-preventing-domestic-radicalization-what)