Doubts have been raised about the 'six degrees of separation' theory, which claims each of us is no more than five points of contact away from anyone else on the planet. Pádraig Collins reports
In Ireland we tend to think we're not that far removed from the great and good, at least at election time. Yet the 35-year-old theory that there are just "six degrees of separation" between any two human beings on the planet is being questioned.
In 1967, Stanley Milgram, a Harvard University social psychologist, asked people in Kansas and Nebraska to post a letter to a stranger in an unspecified address in a major city such as Boston.
The "starters" had to get the letter to someone they knew on a first-name basis who would be more likely to reach the target. That person was to forward it to someone closer again, and so on.
The astonishing finding of Milgram's research was that an average of five jumps and six people could link any two randomly chosen people in the US. The "six degrees of separation" theory was born.
The past decade saw the idea take hold in popular culture. Fred Schepisi's 1993 film of the same name had a wealthy New York couple (Donald Sutherland and Stockard Channing) duped by a young man (Will Smith) pretending to be a friend of their children.
Then computer science students at the University of Virginia began an Internet game (www.cs.virginia.edu/oracle/) which linked any actor with Kevin Bacon in five moves or less. Clark Gable to Bacon takes only two. Gable was in Mogambo (1953) with Donald Sinden. Sinden was in Balto with Bacon in 1995.
However, all is not as it seems. A professor of psychology at the University of Alaska, Judith Kleinfeld, recently tracked down the details of Milgram's original research.
What she found was disconcerting. In Milgram's first, unpublished, study, only three out of 60 letters made it from starter to stranger. A later study yielded 44 connections out of 160.
Milgram did not include uncompleted chains in his analysis, with the explanation that perhaps people just didn't bother sending the letters on. This seems unlikely though, as the letters were officious-looking documents with a gold-embossed "Harvard" logo.
"If the subjects knew how to reach the targets, they probably would have," said Kleinfeld in a Psychology Today article.
She also found that people who took part in the study were not random at all, but were recruited through ads in newspapers likely to attract travelled, well-connected people.
So why did people so readily accept the theory? Kleinfeld suggests the belief that we live in a small world gives people a sense of security and that small-world experiences we encounter naturally reinforce people's religious faith as evidence of "design".