What are the effects of different elements of media on radicalization outcomes? A systematic review

Background Most national counter‐radicalization strategies identify the media, and particularly the Internet as key sources of risk for radicalization. However, the magnitude of the relationships between different types of media usage and radicalization remains unknown. Additionally, whether Internet‐related risk factors do indeed have greater impacts than other forms of media remain another unknown. Overall, despite extensive research of media effects in criminology, the relationship between media and radicalization has not been systematically investigated. Objectives This systematic review and meta‐analysis sought to (1) identify and synthesize the effects of different media‐related risk factors at the individual level, (2) identify the relative magnitudes of the effect sizes for the different risk factors, and (3) compare the effects between outcomes of cognitive and behavioral radicalization. The review also sought to examine sources of heterogeneity between different radicalizing ideologies. Search Methods Electronic searches were carried out in several relevant databases and inclusion decisions were guided by a published review protocol. In addition to these searches, leading researchers were contacted to try and identify unpublished or unidentified research. Hand searches of previously published reviews and research were also used to supplement the database searches. Searches were carried out until August 2020. Selection Criteria The review included quantitative studies that examined at least one media‐related risk factor (such as exposure to, or usage of a particular medium or mediated content) and its relationship to either cognitive or behavioral radicalization at the individual level. Data Collection and Analysis Random‐effects meta‐analysis was used for each risk factor individually and risk factors were arranged in rank‐order. Heterogeneity was explored using a combination of moderator analysis, meta‐regression, and sub‐group analysis. Results The review included 4 experimental and 49 observational studies. Most of the studies were judged to be of low quality and suffer from multiple, potential sources of bias. From the included studies, effect sizes pertaining to 23 media‐related risk factors were identified and analyzed for the outcome of cognitive radicalization, and two risk factors for the outcome of behavioral radicalization. Experimental evidence demonstrated that mere exposure to media theorized to increase cognitive radicalization was