The pros and cons of placebo buttons

SUPPRESSIO VERI, suggestio falsi. Over the course of many years, without making any great fuss about it, the authorities in New York disabled most of the control buttons that once operated pedestrian-crossing lights in the city. Computerised timers, they had decided, almost always worked better. By 2004, fewer than 750 of 3,250 such buttons remained functional. The city government did not, however, take the disabled buttons away--beckoning countless fingers to futile pressing. Initially, the but...