Irving Lester Janis (May 26, 1918 – November 15, 1990) was an American 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.
[1][2] A Review of General Psychology survey, published in 2002, ranked Janis as the 79th most cited psychologist of the 20th century.
[4] In 1947, Janis became a faculty member of the Yale University Psychology Department, where he remained for nearly forty years.
This work described how people respond to threats, as well as what conditions give rise to irrational complacency, apathy, hopelessness, rigidity, and panic.
He did extensive work in the area of "groupthink," which describes the tendency of groups to try to minimize conflict and reach consensus without sufficiently testing, analyzing, and evaluating their ideas.