US defence secretary Pete Hegseth’s plan to livestream the execution of Nidal Malik Hasan has incurred condemnation from human rights groups and politicians on all sides. But according to Coltan Scrivner, an author and psychologist at Arizona State University and expert on morbid curiosity, people are still likely to watch in large numbers. He explains why we are drawn to dark and disturbing content, and Madeleine Finlay tells Ian Sample how consuming this kind of material can harm observers’ mental health. Help support our independent journalism at <a href="https://www.theguardian.com/sciencepod">theguardian.com/sciencepod</a>