When Will We Meet Again? Regularities of Social Connectivity and Their Reflections in Memory and Decision Making

In 1967, the social psychologist Stanley Milgram reported a fascinating observation. For a study on social connectivity, he randomly picked several individuals in Wichita, Kansas, and asked them to get a message delivered to a particular target person in Cambridge, Massachusetts—a distance of more than 1,300 miles. There were two catches. First, Milgram provided no address but only the name and some basic information about the target person, such as the area where he lived and his profession (the target person was the same for everybody). Second, people could only forward the message to someone they knew on a firstname basis. That is, the task for each person in the chain was to pass on the message to someone she thought would be most likely to know the target person or know someone else who might know him. The astonishing result was not only that many of the messages reached the target, but also that the number of intermediaries needed turned out to be rather small, ranging between two and ten (with a median of five).