Stanley Milgram got a lot of press for his experiment in which participants thought they were shocking people to death. We don't give him credit for his other experiment - in which participants forward the ultimate chain letter.
If you thought Stanley Milgram was only responsible for the inner sadness that comes from knowing that most of the people walking along the street with you would under the right circumstances electrocute you to death, think again. He's also responsible for the sneaking insidiousness of the chain letter. One of his most famous experiments (although obviously not his most famous one) involved sending a letter around the United States, asking people to forward it to an ever-growing list of contacts.
The invention of the radio, the telegraph, and other instant-communication devices got people thinking about how connected the people of the world were. Mathematicians and sociologists considered the question of world networks, but Stanley Milgram decided to make an experiment of it. The Small World experiment was inaccurately named. Milgram chose random people from cities within the United States to trace social networks. They weren't even that far apart geographically. In one case, Milgram took random people from Wichita and Boston and tried to trace connections between them - explaining that he wanted social differences, not just geographic distance.
If he had chosen people across the world from each other, he likely wouldn't have gotten any results at all. Funnily enough, the man who made his name getting people to cooperate in horrors had a real problem with people ignoring a useful, and harmless exercise. The experiment involved Milgram sending out a letter to, for example, a person in Wichita. The letter would name a random person in Boston and asked the recipient to forward the message directly to that person, or, if they didn't know the person, to forward the message to a list of contacts that they thought might know the person. People weren't keen on the idea. In one study, out of 296 letters, only about 64 reached their destination. Most of the recipients ignored the request. When people did continue the chain, and the letter reached its destination, Milgram and his staff counted the number of hops it made from initial recipient to its target.
Milgram's study originated the phrase "six degrees of separation," but this was an average, not a rule. Some letters made ten or twelve stops before they found the person named in the initial letter. Others only stopped two times before getting to the target. Today the connections in the world are easier to trace - and are valuable information. It makes you wonder if the data Milgram got was less accurate than it could have been. How many of those people were closely connected, through only about two or three degrees, but didn't know it?
[Via Post-Punk Perception.]