Confident Nudges & Strong Opinions

Cass Sunstein and Richard Thaler describe an experiment in their book Nudge where people were placed in a group in a dark room with a small point of light. Due to an illusion with the brain processing visual information, the small point of light appears to move slightly, even though it is stationary. The lead investigator on the study placed a member of his staff in the room who would express strong confidence in the distance that the light supposedly moved, or express doubts about the groups conclusion for how far it moved. What the study showed is that strong confidence or strong doubt from one person can greatly shape the overall beliefs of the entire group.


Individually, people in the study would not arrive at matching or correlating guesses for the distance that the light moved. But when in groups, individuals begin to converge over a common distance (again, the light never moved – study participants only perceived motion due to an optical illusion). When one person in the group was either very sure that the group had the right estimate, or expressed strong doubt that the groups conclusion was accurate, participants tended to agree and move toward their estimate. A high distance guess stated strongly would pull everyone’s estimates up while a low estimate would shrink them. If the group had someone who was very confident in their answer, the participants became more confident, while if someone expressed strong doubts, the remaining participants level of doubt also rose. As Sunstein and Thaler write, “A little nudge, if it was expressed confidently, could have major consequences for the group’s conclusion.”


Most of us probably have to work in groups on a regular basis. This study is important because it shows how much one person can set the expectations and shape the assumptions of everyone in the group. We have all had projects that start out with little coherent information. Everyone has an idea for where the project could go, what shape the final output could take, and what factors will be the most important to include. If one person is has strong opinions in any given area, they can greatly influence the group’s decision-making. The authors continue, “the clear lesson here is that consistent and unwavering people, in the private or public sector, can move groups and practices in their preferred direction.”


These people may be right and may have good insights, but they can also be very wrong. A strong personality expressing confident opinions can push an entire group toward conformity. They can downplay the real threats or weaknesses of a plan, and can be overconfident with the prospects of success. For these reasons it is important to build in mechanisms that check groupthink. It is important to have someone play devil’s advocate, to ask how a plan could fail, to get the group to think about the strengths and weaknesses of a plan in honest terms. Without finding a way to check overconfident or strongly expressed opinions, a group can be derailed from the very start, with everyone conforming to the strong opinions of a single individual.

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