identify who the close contacts are of people who have them. The two questions that have been used time and time again, are “Who do you spend your free time with?” and “Who do you discuss important matters with?” We just let them keep going and they sort of keep going until they’re tired of naming people, and the average person in this Gallup survey, which is nationally representative of the United States, names four to five contacts.
There are a lot of people out there who don’t name anybody. I can’t remember what the number is, but it’s on the order of 10 or 20 percent. There are a lot of really lonely people out there and there are a lot of people with a single connection, or with two. You have a lot of people who are only marginally connected to the network as a whole.
X: I thought the number was more like 100 to 150.
JF: On Facebook, the average right now, coincidentally, is exactly 150. We talk about this a bit in the book, this idea of what is a natural human group size. We have found this regularity in a wide variety of our studies that interpersonal effects can spread up to three degrees of separation. So if I start jogging, and I feel great, than you’ll be more likely to do it if you’re my friend. And your friend will also be more likely to do it, and their friend also will be more likely to do it. So it spreads up to three degrees of separation, and we can’t see it spreading any further than that.
X: Which is why Kevin Bacon won’t return my phone calls.
JF: That’s right! You’re too far removed from Kevin. The crucial thing is that it’s more than one degree of separation, I think we have strong evidence at this point that these personal effects spread from person to person to person. And the other crucial thing is that it’s not six. So you’re not getting to Kevin Bacon. You’re not getting to every one on the planet. You’re not going to, on average, be able to influence many people.
X: So why is it three?
JF: If you think about the fact that we have on average about five friends. That means we have about 25 friends of friends, and about 125 friends of friends of friends. Somewhere in that ballpark. We think about early human groups that anthropologists say are