[rz2k]

People can do this with regular elevators, too.

Imagine you’re in a building with 22 floors, and your event with a few hundred people just ended on the 18th floor. The elevator has three bays with cars that only carry about 20 people at a time.

While you’re in the crowd waiting to go down, you hear elevator cars race to the top of the building, then when they come back down, the doors open and you’re met by a car that is already packed with people. A lot of the passengers are avoiding making eye contact, and wait a second, some of them look like people you just saw leaving by the stairs in the fire escape!

Apparently, the elevator algorithm is trying to be efficient by starting at the highest floor with a request. Do you wait where you are, take the fire escape up one floor, two floors, or just walk down 18 floors moderately disgusted with the situation?

[mikeash]

You probably don't even need to take the stairs. Just press the up button and get on the next up elevator while everyone else waits for down. Then wait for it to reverse direction and ride it down.

[rz2k]

You are right, but in practice you have to deal with the repercussions of inspiring leaders among the waiting crowd to police your actions. Going down to the 17th or 16th floor and catching the “up” elevator might not get as many glares.

Where I’ve seen this happen is after speaking events in the university clubs near Grand Central Station in New York. The complete dynamics of the situation probably involve a minor risk to social reputation, and some people playfully trying out game theory to amuse their friends.