David McRaney educates us:
The close buttons in most elevators don’t close the elevator doors. The button is there for workers and emergency personnel to use, and it only works with a key.
Whether or not you press the buttons, the doors will close. But if you do press the buttons, and eventually the doors close, a little spurt of happiness will cascade through your brain. Your behavior was just reinforced. You will keep pressing the button in the future.
Mechanisms like this are called placebo buttons, and they’re everywhere.