The new research says many people have hundreds of Facebook friends. But people can only really depend on four of them, on average.
Robin Dunbar, a professor of evolutionary psychology at Oxford University, undertook a study to find out the connection between whether people have lots of Facebook friends and real friends.
He found that there was very little correlation between having friends on social networks and actually being able to depend on them or even talking to them regularly.
The average person studied had around 150 Facebook friends. But only about 14 of them would express sympathy in the event of anything going wrong. The average person said that only about 27 per cent of their Facebook friends were genuine.
Those numbers are mostly similar to how friendships work in real life, the research said. But the huge number of supposed friends on a friend list means that people can be tricked into thinking that they might have more close friends.
“There is a cognitive constraint on the size of social networks that even the communication advantages of online media are unable to overcome,” Professor Dunbar wrote. “In practical terms, it may reflect the fact that real (as opposed to casual) relationships require at least occasional face-to-face interaction to maintain them.”