Irving Janis

Irving L. Janis (26 May 1918 - 15 November 1990) was a research psychologist at Yale University and a professor emeritus at the University of California, Berkeley most famous for his theory of "groupthink" which described the systematic errors made by groups when taking collective decisions. He retired in 1986.

He also collaborated with Carl Hovland on his studies of attitude change, including the sleeper effect.