At the highest floor of the Eiffel Tower, there are two elevators facing each other.

If human beings were fully rational beings, two equally long queues should have formed, each unfolding in its own direction.

But again and again, only one queue appears.

A long line of visitors patiently waits for one elevator...

...while the other elevator stays empty and available.

People tend to infer their own action not from the total situation, but from the behavior of the people already in front of them.

Enter.

Turn around.

Face the door.

Avoid prolonged eye contact.

Become strangely silent.

Who taught us this?

Many everyday conventions are acquired without an explicit teacher.