There is no up/down button, just a keypad with numbers on them. People are accustomed to looking for the up button and, upon not finding one, immediately get into a confused state.

If you need lengthy instructions to show someone how to use your UI, you should reconsider your UI.

http://www.jnd.org/dn.mss/are_the_new_elevators_bad_design.h...

At the risk of completely derailing the discussion, sometimes the UI simply just needs to be learned. People who are unfamiliar with elevators would have no idea how to use one.. there's no instructions anywhere, just a panel with numbers. If you aren't familiar with those bathroom faucets that turn on when you put your hands under them, you'll spend a few minutes just staring at it looking for a knob. Eventually, it catches on.

You are right that there's an initial curve, though, and I don't know how to deal with that other than just through the painful experience you described.

Of the top of my head: start off with big up/down buttons. Then show a list of floors. Some people won't notice the second press required, but it's a start. I was confused by those things the first time too.

People see an open elevator door, they get in the elevator. They don't stop to read the instructions because they are not expecting the elevator to come with instructions and also because they know the elevator doors are not going to remain open forever.

These people are already getting on wrong elevators. The example given has banks of elevators for different floors, marked by sign and by buttons for the specific floors covered. If they don't pay attention they'll get a short tour.

If this was a deadly choice, between an elevator and a trash compactor, it might make sense to over-sign it. As is, it's a trivial and obvious mistake, especially if each bank has a sign saying 'Floors 1-x are reached via the other elevator bank' for someone to read on their round-trip.

Part of the reason users are so clueless is because we go too far in padding their environment. People don't slice off fingers because the sharp end of the knife wasn't properly labelled - they exercise caution.