In a famous experiment from the 1950s, social psychologist Solomon Asch demonstrated the influence a group exerts on our opinions and judgments.
In this experiment, subjects would agree with the answer of the group despite the evidence of their own eyes that the majority’s answer was the wrong one. It showed how readily people will deny what they see and submit to the majority view, and how hard it is for one person to stand strong against the convictions of the many. This holds implications for business meetings, political processes, jury deliberation, or even negotiation.
For two videos that chillingly depict the force of group opinion — one a contemporary replication of Asch’s experiment — see “Individual Conformity to (Incorrect) Group Consensus” at Sociological Images.