Milgram’s Small World Experiment

Despite being most famous for his obedience study, Milgram also participated in several more benign experiments. Have you ever heard of the term “six degrees of separation”? If so, you can thank Stanley Milgram for that.

In the 1950s, political scientist Ithiel de Sola Pool and mathematician Manfred Kochen posed several questions: What would be the probability of two complete strangers having a mutual friend? What if there were no mutual friend? How long would that chain be for them to reach each other? Approximately a decade later, Stanley Milgram conducted an experiment known as “The Small World Experiment” in an effort to answer these questions.

Milgram gave 300 letters with instructions to people in Omaha, Nebraska, and Wichita, Kansas, and set up one “target” in Boston, Massachusetts. The 300 people were told to mail the letter to a friend that they thought was close to the target (and that they knew on a first-name basis), and this friend would get the same instructions, creating a chain. Milgram received a postcard with each forward and recorded the relationship between the sender and receiver. Milgram discovered that within almost all instances, the chains had approximately five or six links that connected any two people.

Stanley Milgram brought great—and sometimes scary—an insight to humanity in ways that many had never seen before. While his controversial (and now classic) obedience study showed the rather negative side of what an individual could be capable of doing, his small world experiment was able to show the interconnectivity and closeness that people share. To this day, his work continues to be incredibly influential and extremely important, and he is firmly planted as one of the most discussed psychologists in the history of psychology and experimentation.