"For instance, the close buttons don’t close the elevator doors in most elevators built in the United States since the Americans with Disabilities Act. 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 eventually close. But if you do press the buttons, and later 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. Non-functioning mechanisms like this are called placebo buttons, and they’re everywhere." - David McRaney, Placebo Buttons, 10 Feb 2010.