Why Do People Push Placebo Buttons?

Placebo buttons are buttons that actually do nothing except give the user an...  ...computer-controlled traffic signals make the walk buttons at pedestrian crossings on heavily trafficked str...  ...olete. By the late 1980s, most (but not all) walk ...

http://www.neatorama.com/2010/02/09/why-do-people-push-placebo-buttons/