Experiments among shoals of golden shiner fish have shown that a single emphatic individual can alter the trajectory of an entire school of fish regardless of whether it is in the best interest of the group. Likewise, it has been found that among humans, the most confident, talkative member of a group often becomes the group’s leader, more or less regardless of the quality of his or her input (a phenomenon called the “babble effect.”)

In 1906, Galton collected data from a group of people at a country fair who were trying to guess the weight of a fat ox. Of the roughly eight hundred people who wagered a guess, most were wide of the mark. However, the average of all their guesses was nearly perfect. This experiment would later be repeated many times. Oddly, researchers learned that the key to the experiment was that each person needed to judge the weight of the ox independently, without sharing their guesses with one another. In similar experiments where people were given access to one another’s answers, the collective intelligence of the group worsened. Often, the early guesses provoked a false consensus to form, a vicious circle that caused the later guesses to hurtle toward ever-greater error. “The more influence a group’s members exert on each other,” wrote Surowiecki, “the less likely it is that the group’s decisions will be wise ones.”

–Robert Moore