... an average man—one with 120 friends—generally responds to the postings of only seven of those friends by leaving comments on the posting individual’s photos, status messages or “wall”. An average woman is slightly more sociable, responding to ten. When it comes to two-way communication such as e-mails or chats, the average man interacts with only four people and the average woman with six. Among those Facebook users with 500 friends, these numbers are somewhat higher, but not hugely so. Men leave comments for 17 friends, women for 26. Men communicate with ten, women with 16.
What mainly goes up, therefore, is not the core network but the number of casual contacts that people track more passively. This corroborates Dr Marsden’s ideas about core networks, since even those Facebook users with the most friends communicate only with a relatively small number of them.
Put differently, people who are members of online social networks are not so much “networking” as they are “broadcasting their lives to an outer tier of acquaintances who aren’t necessarily inside the Dunbar circle,” says Lee Rainie, the director of the Pew Internet & American Life Project, a polling organisation. Humans may be advertising themselves more efficiently. But they still have the same small circles of intimacy as ever.
From the Economist.