DO NOT PRESS THIS BUTTON
Why telling someone not to press a button can turn it into a personal challenge.
There is an extremely effective way to make someone want to do something:
tell them not to do it.
A normal button is just a button.
A button labelled DO NOT PRESS is now a personal challenge.
There is even a name for part of what is happening: psychological reactance. When people feel their freedom to choose is being restricted, a tiny rebellion can appear.
Which may explain why nobody particularly cares about a lift button until somebody puts a sign over it saying:
OUT OF ORDER. DO NOT PRESS.
At which point pressing it becomes essential.
For research purposes.
Obviously.