We can have a fun conversation with max four people

After celebrating a birthday in Leppävaara, we had taken the 520 to get back home. The four of us were sitting around the middle of the bus, chatting, laughing. The four of us, and Savya, who was mostly getting fussy, chatting and laughing.

We were a bit loud. Nitin remarked at one point that we had turned this into our drawing room. No body says anything in Finland, they stare daggers at you. I did not notice anyone, others had though.

At Suurpelto, a fifth friend joined us on the bus. He sat a little bit at the back, and I could sense the conversation shift as he joined. It wasn't that we did not like him. We did.

He would chip in from time-to-time. But it did not feel as natural as while the four of us were talking earlier.

Turns out, there is a good reason for this.

Professor Robin Dunbar has a theory for the maximum number of people who can join in a conversation for it to remain fun. That number is four.

He said: “You very rarely get more than four people in a conversation. In the normal run of things, when a fifth person joins a group, it’ll become two conversations within about 20 seconds.” Alternatively, a “lecture” situation develops in which one person holds court and the others act as an audience.

In larger groups, “you have to decide whether the person who is speaking is really so important you’d rather be standing there saying nothing”, he said. If the speaker is not very interesting, the audience tends to splinter into groups of four or fewer. Dunbar believes that the underlying reason is that we can only track what a certain number of people are likely to be thinking at one time.

He also has a theory for the maximum number of connections we are able to sustain: 150.

I have seen this in action many times earlier. Of course I did not know the magic number then. But on long tables during lunches or dinners, conversations tend to split off. Or one person becomes the centre of attraction: talking everybody's head off.

Neither of these scenarios are permanent though. Smaller groups eventually splinter off with their own conversations.

We got off from the bus at Matinkylä and continued to our homes. All I was thinking about then was to not slip on the icy pavements!