Noise: A Flaw in Human Judgment

by Daniel Kahneman

This study offers a clue about how groups shift and why they are noisy (again in the sense that similar groups can make very different judgments, and single groups can make judgments that are merely one in a cloud of possibilities). Members are often in a position to offer the functional equivalent of an early up vote (or down vote) by indicating agreement, neutrality, or dissent. If a group member has given immediate approval, other members have reason to do so as well. There is no question that when groups move in the direction of some products, people, movements, and ideas, it may not be because of their intrinsic merits but instead because of the functional equivalent of early up votes. Of course Muchnik’s own study involved very large groups. But the same thing can happen in small ones, in fact even more dramatically, because an initial up vote—in favor of some plan, product, or verdict—often has a large effect on others.