Professor Killen specializes in the history of modern Europe, especially Germany, and in the history of science and medicine in Europe and the United States. The recipient of fellowships at the UCLA Humanities Consortium in Los Angeles, the Max-Planck Institute for the History of Science in Berlin, and the Remarque Institute at New York University, he has written about psychiatry, the human sciences, and brain science. He is currently working on a book about the history of cybernetics.

• Modern Europe
• Europe since 1945
• The Third Reich
• Psychiatry, Madness, and Modern Society
• The Modern European City
• Science, Technology, and Modernity

 Books and Edited Volumes

• Berlin Electropolis: Shock, Nerves, and German Modernity (University of California Press 2006).
• 1973 Nervous Breakdown: Watergate, Warhol, and the Birth of Post-Sixties America (Bloomsbury 2006).
• Co-editor with G. Eghigian and C. Leuenberger, “The Self as Scientific and Political Project,” Osiris, Vol. 22 (2007).
• Co-editor with Stefan Andriopoulos, "Brainwashing and Mind Control from the Cold War to the War on Terror," Grey Room, v. 45 (2011)
• Homo Cinematicus: Science, Motion Pictures, and the Making of Modern Germany (University of Pennsylvania Press, 2017).
• Nervous Systems: Brain Science in the Early Cold War (HarperCollins 2023)
• Co-editor with Danielle Carr, "Neurophysiology and Intellectual History," Journal of the History of Ideas (forthcoming in Fall 2026).

Recent and Forthcoming Articles

• “Der Münsterberg-Effekt. Deutsche Filmpropaganda am Ende des Ersten Weltkrieges,” in Montage AV 27, 1 (2018): 93-108
• “Mental Hygiene in Interwar Germany: Public Health Films Between Science and Superstition,” in Social History of Medicine Vol XX, No XX (Nov. 2022): 1-15
• “August Sander’s Portfolio ‘The Doctor and the Pharmacist’: German Patients between Professional and Lay Medicine,” Seminar Vol 59, 1 (2023): 118-134
• “Ludwig Mayer’s Hypnosis Films,” forthcoming in Useful Films: Film in European Neuropsychiatry 1900-1950 (University of Manchester Press forthcoming).
• “Hallucination in the Age of the ‘Explorable Brain’,” forthcoming in Reconsidering John Lilly: Between Brain Science, Cold War, and Counterculture (MIT Press forthcoming).
• "Brain Warfare," in Cognitive Warfare: A Handbook (forthcoming)