Is a small world getting even smaller?

In 1967 Stanley Milgram, an American social psychologist, conducted a series of experiments to study the nature of “small world” – a phenomenon produced by the overlap of personal social networks. For instance, he tried to find out the average path length for social networks of people in the US. He sent out 160 packages to randomly selected individuals in Kansas and asked them to deliver the package to a person living in Boston, Massachusetts. Since the senders didn’t know the package recipient personally, they were allowed to forward the package to somebody they knew on a first-name basis and who were likely to know the final recipient. The first package reached the recipient in Boston via only two people. However, on average the delivery chain consisted of 5 people. That’s how the theory of “6 degrees of separation” appeared. It suggests that anyone is 6 or fewer steps away from any other person in the world.

One possible path of a message in the “Small World” experiment by Stanley Milgram in 1967. Image credits: Ageev Andrew

There were numerous attempts to replicate Milgram’s experiment. For example, in 2003 Columbia University repeated it using e-mail instead of regular mail. The e-mail chain length was 6 on average as well, which confirmed Milgram’s findings. At the same time, the participation rate was low: more than 60.000 people sent initial emails, but only 384 (less than 1%) messages reached final recipients (in Milgram’s experiment – 29%). This fact highlights the importance of motivation for cooperation in social networks, as well as provides us with some insights on changes in society. For example, this decrease in number of delivered messages can be explained by social capital decay (see Putnam for more information on this topic), as well as by changes in social networks triggered by technological development.

As the technologies advanced, some suggested that the distance between people in networks should decrease, because different social circles started to intersect and the number of individuals with bridging capacity increased in population. The 2011 Facebook and University of Milan research study confirms it. This study shows that the number of degrees of separation in Facebook decreased from 5,28 in 2008 to 4,74 in 2011, despite the fact that the number of Facebook users has grown.

Map showing communication network within Europe and North America following an unbiased random walk (upper) and under 30% targeting (lower). The area of red circles are proportional to centrality. Source:

Map showing communication network within Europe and North America following an unbiased random walk (upper) and under 30% targeting (lower). The area of red circles are proportional to centrality. Source:

But how long would it take to deliver the message across the social network? This element of Milgram’s experiment is less studied, although it can be useful both for social networks researchers and communication practitioners. In the original experiment, the first package arrived in 4 days, but the others took longer to reach the recipient. However, recent work by Rutherford, Cebrian, Rahwan, Dsouza, McInerney, Naroditskiy, Venanzi, Jennings, deLara, Wahlstedt and Miller reveals that today individuals are just 12 hours of separation from each other. They explain this by the “ability of social networks to mobilize in a targeted manner, using geographical information in recruiting participants” (Rutherford et al., 2013). Rutherford et al. also say that it may be possible to decrease this time using appropriate incentives.

All in all, there are still a lot of things we should learn about the impact of new technologies on society and social networks. One thing is certain: our small world is getting smaller and changes are coming. Are we ready for them?


Posted on February 23, 2014, in COMM506, MACT and tagged , , , , , , . Bookmark the permalink. 2 Comments.

  1. Great post Tanya. I find it fascinating that in the 2003 experiment less than 1% of the messages made it through. The communication costs are so much lower to send an email than write a letter, yet so few continued the chain. I wonder why the lack of motivation?

  1. Pingback: 10 Master Ideas of Social Networks: brought to you by MACT 2013 Cohort! | Tanya's blog about everything

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