在很多年里，纽约市政部门逐步停用了该市控制人行横道信号灯的大部分按钮，但一直没怎么声张。他们认定，计算机操控的计时器更好用。到了2004年，3250个按钮中只剩不到750个还能发挥作用。但是，市政府并没有拆除已经没用的那些按钮，令无数手指白费一番力气。

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.
一开始，按钮被留下来是因为拆除的成本问题。但后来却发现，即使无法控制信号灯的按钮也仍有用处。以色列本·古里安大学的塔勒·奥龙-吉拉德表示，按下按钮的行人不太可能在绿色信号灯亮起前就横穿马路。研究过人们在路口的行为后，她注意到大家更倾向于服从一个声称会听从他们的指令的系统。

Inoperative buttons produce placebo effects of this sort (the word placebo is Latin for “I shall be pleasing”) 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.
密歇根大学安娜堡分校的人机交互专家埃坦·埃达表示，失效的按钮之所以会产生这种安慰剂效应（placebo出自拉丁语，原意是“我会讨人喜欢”），是因为人们喜欢对自己所使用的系统有掌控感。他指出，自己的学生在设计软件时经常会加上一个可点击的“保存”按钮，但其实用户的输入都会自动保存，这个“保存”按钮仅仅是为了让对此不知情的用户放心而已。他说，不妨将这视作对抗机器世界里固有的冷漠的一种善意欺骗。

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.
这是一种观点。但是，安慰剂按钮可能也有不利的一面，至少在过马路的问题上是这样。研究交通系统心理因素的维也纳FACTUM研究所的负责人拉尔夫·里瑟尔认为，行人意识到按钮无效进而感到被骗的怨怒，如今已让这种做法弊大于利。

Something which happened in Lebanon supports that view. Crossing buttons introduced in Beirut between 2005 and 2009 proved a flop. Pedestrians wanted them to summon a “walk” signal immediately, rather than at the next appropriate phase in the traffic-light cycle, as is normal. The authorities therefore disabled them, putting walk signals on a preset schedule instead. Word spread that button-pressing had become pointless. The consequent frustration increased the amount of jaywalking, says Zaher Massaad, formerly a senior traffic engineer for the Lebanese government.
黎巴嫩发生的情况可引为佐证。2005年至2009年间在贝鲁特引入的过街按钮最后被证明是失败的。行人希望按键后能立刻亮起“步行”信号，而不是像通常那样等待交通灯的周期性转换。因此市政部门停用了这些按钮，按预设的时间启动步行信号。曾在黎巴嫩政府担任高级交通工程师的查希尔·马萨德说，过街按钮无用的消息传开，随之而来的懊恼导致更多人乱穿马路。

Beirut’s disabled buttons are, says Mr Massaad, now being removed. They should all be gone within three years. New York has similarly stripped crossings of non-functioning buttons, says Josh Benson, the city’s deputy commissioner for traffic operations, though it does retain about 100 working ones. These are in places where pedestrians are sufficiently rare that stopping the traffic automatically is unjustified. However, internet chatter about placebo buttons has become so common that doubt, albeit misguided, seems to be growing about even these functioning buttons’ functionality. This suspicion, says Mr Benson, has spread beyond New York, to include places such as Los Angeles, where almost all the crossing buttons have always worked, at least during off-peak hours.
马萨德说，贝鲁特正在拆除无效的过街按钮，三年内应该能全部清理完毕。纽约市交通运营处副处长乔什·本森表示，纽约也拆除了无效的过街按钮，但保留了大约100个有效的。这些按钮都设置在行人稀少到已经不适合使用自动交通灯的地方。然而，网上对安慰剂按钮的热议，导致人们对有效的按钮也开始怀疑起来，尽管这是受到了误导。本森表示，这种怀疑已蔓延到了纽约以外的地方，包括几乎所有过街按钮都总是有效（至少在非高峰时段是这样）的洛杉矶。

Truth be told, though, the end may be nigh for all road-crossing buttons, placebo or real. At an increasing number of junctions, those waiting to cross can be detected, and even counted, using cameras or infrared and microwave detectors. Dynniq, a Dutch firm, recently equipped an intersection in Tilburg with a system that recognizes special apps on the smart phones of the elderly or disabled, and provides those people with 5 to 12 extra seconds to cross. That really will be pleasing.
但事实上，无论是安慰剂还是真的过街按钮可能都会很快消亡。越来越多的道路交汇处配备了摄像头或红外和微波探测器，可探测甚至统计等待过马路的行人。荷兰科技公司Dynniq近年在蒂尔堡市的一个十字路口安装了一套系统，能识别老年人或残疾人智能手机上的专门应用，为他们提供额外5到12秒的过马路时间。这的确会很讨人喜欢。