Stephan Lewandowsky (born 3 June 1958) is an Australian psychologist. He has worked in both the United States and Australia, and is currently based at the University of Bristol, UK, where he is the chair of cognitive psychology at the School of Psychological Science. His research, which originally pertained to computer simulations of people's decision-making processes, recently has focused on the public's understanding of science and why people often embrace beliefs that are sharply at odds with scientific evidence.