Extremism and Terrorism
The Extremism and Terrorism Hub is dedicated to the study of politically motivated acts of violence that primarily target groups. This form of violence includes lethal political partisanship, hate-motivated crime, online hate and extremism, domestic terrorism, and international terrorism. Grounded in rich theoretical traditions and a variety of research methodology, the hub addresses the underlying causes of these acts of violence, who commits them, who is targeted by them, the individual and societal consequences of them, and potential ways of combating these violent actions.
Online hate and hate crimes project: Ongoing study of online and offline hate crimes. The project has resulted in one research manuscript and one edited book.
Online hate detection and counternarratives. Researching the using of AI and large language models to assist people in constructing effective counter narratives to use when they see online hate.
The political polarization project: A study of political polarization and lethal partisanship in the United States.
Online Hate in a Cross-national Setting: Ongoing study of online hate and extremism in Finland, France, Germany, Hungary, Poland, Spain, The United Kingdom, and The United States. Data has been collected annually in the U.S. since 2013, multiple times in Finland and the United Kingdom, and at least once in France, Germany, Hungary, Poland, Spain.
Books
Hawdon, James, Matthew Costello, and Pekka Räsänen. Forthcoming. Online Hate and Extremism: Patterns of Production, Exposure, and Interventions in a Cross-National Context. Emerald Publishing.
Hawdon, James and Matthew Costello (editors). 2024. Research Handbook on Hate and Hate Crime in Society. Edward Elgar Publishing. Hawdon, James, John Ryan, and Marc Lucht (editors). 2014. The Causes and Consequences of Group Violence: From Bullies to Terrorists. Lexington Press.
Peer Reviewed Books, Journal Articles, and Book Chapters
Costello, Matthew and James Hawdon. 2025. “When is Violence Okay? Moralistic Violence as a Counter-Hegemonic Strategy.” Pp. 245-260 in The Spectacle of Online Life, edited by Danielle Antoinette Hidalgo, Christopher Conner, and Matthew Hannah. Lexington Press.
Costello, Matthew and James Hawdon. 2025. “I Did It for the Lulz: The Fun of Cyberhate.” Pp. 460-478 in Wendy Regoeci and Terance Miethe (eds.), Handbook on Violent Crime and Society. Edward Elgar. https://doi.org/10.4337/9781035317868.00038
Hawdon, James and Mathew Costello. 2025. “Antisemitism and Hate Movements.” Pp. 211-217 in David Snow, Doug McAdam, and Dana Moss (eds.) Contemporary Social Movements. Wiley Blackwell.
Hawdon, James. 2025. “COVID-19 and the Flames of Hate.” Pp. 85 - 104 in James Hawdon, Donna Sedgwick, C. Cozette Comer, and Pekka Räsänen (eds.), Perceptions of a Pandemic: A Cross-Continental Comparison of Citizen Perception, Attitudes, and Behaviors During Covid-19. Emerald Publishing.
Ping, Kaike, James Hawdon, and Eugenia H. Rho. 2025. “Perceiving and countering hate: The role of identity in online responses.” Proceedings of the ACM on Human-Computer Interaction 9(2): 128 https://dl.acm.org/doi/10.1145/3711045
Hawdon, James and Matthew Costello. 2024. “Hate and Hate Crimes in Society.” Pp. 1 - 13 in James Hawdon and Matthew Costello (eds.), Hate and Hate Crimes in Society, Edward Elgar.
Hawdon, James. 2024. “The State’s Role in Hate: Understanding Hate Crime throughout U.S. History.” Pp. 320 – 343 in James Hawdon and Matthew Costello (eds.), Hate and Hate Crimes in Society, Edward Elgar.
Hawdon, J., Reichelmann, A., Costello, M., Llorent, V., Räsänen, P., Zych, I, Oksanen, A. & Blaya, C. (2024). Measuring hate: Does a definition affect self-reported levels of perpetration and exposure to hate in surveys? Social Science Computer Review. 42(3): 812-831. https://doi.org/10.1177/08944393231211270
Costello, Matthew, James Hawdon, Ashley Reichelmann, Atte Oksanen, Catherine Blaya, Vicente Llorent, Pekka Räsänen, Izabela Zych. 2023. “Defending Others Online: The Influence of Observing Formal and Informal Social Control on One’s Willingness to Defend Cyberhate Victims.” International Journal of Environmental Research & Public Health, 20(15): 6506 https://doi.org/10.3390/ijerph20156506
Hawdon, James. Ashley Reichelmann, and Matthew Costello. 2022. “Riding the Cyberwaves: The Ebbs and Flows of Internet Cyberhate.” Pp. 1-15 in R Baikady, S Sajid, V. Nadesan, J. Przeperski, M.R. Islam, and J Gao (eds) The Palgrave Handbook of Global Social Change. Palgrave Macmillan, Cham. https://doi.org/10.1007/978-3-030-87624-1_296-1
Hawdon, James and Matthew Costello. 2022. “Confronting Online Extremism: Strategies, Promises, and Pitfalls.” Pp. 469-489 in Barbara Perry, Jeff Gruenwald, and Ryan Scrivens (Eds.) Far-right extremism in Canada and the United States. Palgrave.
Costello, Matthew, Ashley Reichelmann, and James Hawdon. 2022. “Utilizing Criminological Theories to Predict Involvement in Cyberviolence among the iGeneration” Sociological Spectrum 42(4-6): 260-277. DOI: 10.1080/02732173.2022.2105767
Celuch, Magdalena, Atte Oksanen, Pekka Räsänen, Matthew Costello, Catherine Blaya, Isabella Zych, I., Vincente Llorent, Ashley Reichelmann, and James Hawdon. 2022. “Factors Associated with Online Hate Acceptance: A Cross-National Six-Country Study among Young Adults.” International Journal of Environmental Research & Public Health, 19(1), 534. https://doi.org/10.3390/ijerph19010534
Bernatzky, Colin, Matthew Costello, and James Hawdon. 2022. “Who Produces Online Hate?: An Examination of the Effects of Self-Control, Social Structure, and Social Learning.” American Journal of Criminal Justice. 47(3): 421-440. https://doi.org/10.1007/s12103-020-09597-3
Costello, Matthew, Salvatore J. Restifo, and James Hawdon. 2021. Viewing Anti-Immigrant Hate Online: An Application of Routine Activity and Social Structure Social Learning Theory. Computers in Human Behavior, 124, https://doi.org/10.1016/j.chb.2021.106927.
Reichelmann, Ashley, James Hawdon, Matthew Costello, John Ryan, Catherine Blaya, Vicente Llorent, Atte Oksanen, Pekka Räsänen, and Izabela Zych. 2021. “Hate Knows No Boundaries: Online Hate in Six Nations.” Deviant Behavior, 42:9, 1100-1111. https://doi.org/10.1080/01639625.2020.1722337
Hawdon, James and Matthew Costello. 2021. “Learning to Hate: Explaining Participation in Online Extremism.” Pp. 167-182 in Derek Silva and Mathieu Deflem (eds.) Radicalization and Counter-Radicalization. (Sociology of Crime, Law, and Deviance, vol. 25). Emerald Publishing Limited. https://doi.org/10.1108/S1521-613620200000025010
Phadke, Shruti, Jessie Seiler, Tanushree Mitra, Kiran Garimella, Matthew Costello, and James Hawdon. 2021. “Addressing Challenges and Opportunities in Online Extremism Research: An Interdisciplinary Perspective.” Companion Publication of the 2021 Conference on Computer Supported Cooperative Work and Social Computing, pp. 356-359.
Institute of Criminology and Legal Policy at the University of Helsinki
University of Turku, Finland: https://www.utu.fi/en
Costello, Matthew, James Hawdon, and David Snow. (2023). Radicalization on the Internet: Virtual Extremism in the United States, 2015-2017. The Inter-university Consortium for Political and Social Research (ICPSR) https://www.icpsr.umich.edu/web/ICPSR/studies/37679 4,036. Also available at Clemson Open. https://open.clemson.edu/all_data/46/
Hawdon, James, John Ryan, Catherine Blaya, Mathew Costello, Vicente Llorent, Atte Oksanen, Ashley Reichelmann, Pekka Räsänen, and Izabela Zych. (2018). Online Hate in Six Nations: Exposure to and the Production of Online Hate among 18–26-year-olds in Finland, France, Poland, Spain, the United Kingdom and the United States. Institute for Society, Culture and Environment. Virginia Tech.