Irving Janis was born on May 26, 1918 in Buffalo, New York. He received a bachelor of science degree from the University of Chicago in 1939, then received a doctorate from Columbia University.

During the Second World War, Janis was drafted into the U.S. Army, where he carried out studies of military morale. In 1947, Janis became a faculty member of the Yale University Psychology Department, where he remained for the next forty years.

During his career, Janis studied decisionmaking in areas such as dieting and smoking. This work described how people respond to threats, as well as what conditions give rise to irrational complacency, apathy, hopelessness, rigidity, and panic.

Janis also made important contributions to the study of group dynamics. He did extensive work in the area of “groupthink,” which describes the tendency of some groups to try to minimize conflict and reach consensus without sufficiently testing, analyzing, and evaluating their ideas. His work showed how pressures for conformity restrict the thinking of the group, bias its analysis, promote simplistic and stereotyped thinking, and stifle individual creative and independent thought.

Janis wrote or co-wrote more than a dozen books, the best-known of which are Groupthink: Psychological Studies of Policy Decisions and Fiascoes, Decision Making: a Psychological Analysis of Conflict, Choice, and Commitment, and Crucial Decisions: Leadership in Policymaking and Crisis Management.

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

In 1967, Janis was awarded the Socio-Psychological Prize by the American Association for the Advancement of Science (b). In 1981, he received the Distinguished Scientific Contribution Award of the American Psychological Association. In 1991, he won the Distinguished Scientist Award from the Society of Experimental Social Psychology.

He retired from Yale University in 1985, and in 1986 was appointed Adjunct Professor of Psychology Emeritus at the University of California, Berkeley.

Janis was married to Marjorie Janis, with whom he had two daughters. He died of lung cancer on November 15, 1990 in Santa Rosa, California.