For the past few decades, something strange has been happening in clinical trials. Painkillers aren't getting worse, but the placebos they're tested against appear to be getting better. In one landmark study, the advantage of pain medication over placebo shrank from 27.3% in 1996 to just 8.9% in 2013. Even stranger? This trend was found almost entirely in American trials. In this episode of The Rest Is Science, Professor Hannah Fry and Michael Stevens (Vsauce) investigate the extraordinary science of the placebo effect; how our expectations influence pain, why belief can change the way our bodies respond, and what this means for the future of medicine. Why does the way a treatment is presented matter so much? And how can simply expecting something to hurt actually make it hurt? But the placebo effect doesn't stop at medicine. From pedestrian crossing buttons that do nothing to the surprising psychology of road safety, Hannah and Michael explore just how easily our expectations can shape our experience of the world. ------------------- For more information about Cancer Research UK, their research, breakthroughs and how you can support them, visit https://www.cancerresearchuk.org/our-research/rest-is-science Cancer Research UK is a registered charity in England and Wales (1089464), Scotland (SC041666), the Isle of Man (1103) and Jersey (247). A company limited by guarantee. Registered company in England and Wales (4325234) and the Isle of Man (5713F). Registered address: 2 Redman Place, London, E20 1JQ." ------------------- Video Editor: Oli Oakley Animator: Sam Benson Video & Social: Bex Tyrrell Assistant Producer: Lucy Lipscombe Producer: Simona Rata Senior Producer: Lauren Armstrong-Carter Chief Digital Officer: Samuel Oakley Exec Producer: Neil Fearn