Friday, February 10, 2012

Dunbar's Number

We consider Caltech to be a small school, but few of us know everyone on campus. In fact, there seems to be a limitation on the number of people with which we can maintain stable social relationships. This theoretical cognitive limit, also known as Dunbar's number is an old idea (1992) originally based on relative neocortical size. With the recent introduction of social networking sites, like Facebook and Twitter, we might question this limit; does technological innovation allow us to surpass our cognitive limitations, or "might [it] be analagous to a pocket calculator that, while speeding up the way we can do simple math, does not improve our cognitive capabilities." [2,3] Evidence supports the latter. For Twitter, researchers analyzed 380 million tweets and identified 25 million conversations (based on branching consecutive replies), concluding that users could entertain a maximum of 100-200 stable relationships. On Facebook, the average number of friends is about 120, with only seven to ten being 'close friends.'[4] Of course, these articles were written with Dunbar's number in mind and may not be convincing to a skeptic. Not all conversations on Twitter are with people that you have stable social relationships with; and not all of your deep conversations occur on Facebook!

Nonetheless, the theory behind Dunbar's number may play a role in determining the "natural" size of our institutions: our inner circles, friends, acquaintances,  workplaces/dormitories, communities. And understanding these limitations might help us make wiser decisions in the future (like the size of our start-up, or the number of students living in Bechtel House (the new undergraduate dormitory)).

Yet, while we may have cognitive limitations, technology may still provide us a social advantage because, as noted in previous posts, weak ties are incredibly important: they are more often the key to success and opportunities than strong ties. [5]

1 comment:

  1. The average number of friends of a Facebook user has increased to about 235 according to a study done by an independent source (i.e. not Facebook itself, which came up with 120 back in 2009).

    I don't remember the exact number quoted by a Facebook engineer from this summer, but I think it was close to 200. Whether or not people use them, the existence of refined "Close Friends" and "Acquaintances" friend lists are definitely more justified.