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 buttons survived because of the cost of removing them. But it turned out that even inoperative buttons serve a purpose. Pedestrians who press a button are less likely to cross before the green man appears, says Tal Oron-Gilad of Ben-Gurion University of the Negev, in Israel. Having studied behaviour at crossings, she notes that people more readily obey a system which purports to heed their input.
Inoperative buttons produce placebo effects of this sort because people like an impression of control over systems they are using, says Eytan Adar, an expert on human-computer interaction at the University of Michigan, Ann Arbor. Dr Adar notes that his students commonly design software with a clickable “save” button that has no role other than to reassure those users who are unaware that their keystrokes are saved automatically anyway. Think of it, he says, as a touch of benevolent deception to counter the inherent coldness of the machine world.
That is one view. But, at road crossings at least, placebo buttons may also have a darker side. Ralf Risser, head of FACTUM, a Viennese institute that studies psychological factors in traffic systems, reckons that pedestrians’ awareness of their existence, and consequent resentment at the deception, now outweighs the benefits.
多年来，纽约当局在没有惊动公众的情况下，停用了市区内大部分人行横道的交通灯控制按钮。取代这些按钮的是电脑控制式计时器，它们的使用效果几乎总是更胜一筹。截至 2004 年，在 3250 个交通灯控制按钮中，能够正常使用的只有不到 750 个。然而，市政府并没有拆掉已经停用的按钮 - 不计其数的手指仍旧按来按去，徒劳而无功。