Ok this will be a tangent, but I also take this one step farther and also talk about "documentation". Just for the record, I don't think documentation is all good or all bad, but it definitely can be used incorrectly and in excess. And Norman Doors and a great way to get this point across.
When someone creates or installs a Norman Door by accident or out of ignorance and then realizes there is a problem, they often think "I know, I will document it!" and they add little placards to the door that says "Push/Pull" or some such. They see that this helps with a small subset of users and thinks "there, I fixed the problem, people just need to read the documentation and now it is their problem if they don't". But if you watch users of the door, a large portion will still use the door incorrectly because... people don't read documentation. If they don't read documentation, is it the users fault the door was designed incorrectly or was it the designers problem?
I use this as an example for my developers on thinking before documenting troublesome code or a confusing interface to first ask "can I design this so it is less confusing?" and if so, that would usually be preferable to adding documentation "to solve the problem". Well designed code (or doors) with no documentation always beats poor designs with documentation.
