Who used the term groupthink to refer to a kind of collective tunnel vision?

The term "groupthink" was coined by psychologist Irving Janis in the early 1970s. He used it to describe a phenomenon where the desire for harmony and conformity within a group leads to irrational decision-making and a lack of critical thinking. This collective tunnel vision often results in poor decisions as group members suppress dissenting viewpoints and fail to consider alternative solutions.