Small World Experiment

We know it today as “six degrees of separation”, but did you know that number is actually loosely based on the results of an actual experiment?

In the 1960s Stanly Milgram (you know Stanly Milgram he’s the one that tricked subjects in to thinking they were torturing people for science) set out the answer the question of how connected we all really are.

Here’s the general method:

1. Though the experiment went through several variations, Milgram typically chose individuals in the U.S. cities of Omaha, Nebraska and Wichita, Kansas to be the starting points and Boston, Massachusetts to be the end point of a chain of correspondence. These cities were selected because they were thought to represent a great distance in the United States, both socially and geographically.

2. Information packets were initially sent to “randomly” selected individuals in Omaha or Wichita. They included letters, which detailed the study’s purpose, and basic information about a target contact person in Boston. It additionally contained a roster on which they could write their own name, as well as business reply cards that were pre-addressed to Harvard.

3. Upon receiving the invitation to participate, the recipient was asked whether he or she personally knew the contact person described in the letter. If so, the person was to forward the letter directly to that person. For the purposes of this study, knowing someone “personally” was defined as knowing them on a first-name basis.

4. In the more likely case that the person did not personally know the target, then the person was to think of a friend or relative he knew personally who was more likely to know the target. He was then directed to sign his name on the roster and forward the packet to that person. A postcard was also mailed to the researchers at Harvard so that they could track the chain’s progression toward the target.

5. When and if the package eventually reached the contact person in Boston, the researchers could examine the roster to count the number of times it had been forwarded from person to person. Additionally, for packages that never reached the destination, the incoming postcards helped identify the break point in the chain.

When Milgram did this with 300 people trying to contact one man in Boston, the results where that the man received about 100 letters from people he knew. Milgram found that the average number of links was 6.

Milgram never actually used the phrase “6 degrees of separation” and if you are following along you may notice that this experiment has some flaws. However, after a Psychology Today article (go figure) was eventually written about the Small World Experiment, the “6 degrees” was legitimized and now the phrase is sometimes falsely attributed to Milgram.