Research psychologist and a professor
Irving Lester Janis (May 26, 1918 – November 15, 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 making collective decisions. A Review of General Psychology survey, published in 2002, ranked Janis as the 79th most cited psychologist of the 20th century.
The advantages of having decisions made by groups are often lost because of powerful psychological pressures that arise when the members work closely together, share the same set of values and, above all, face a crisis situation that puts everyone under intense stress