Road signs aren't the only places benefitting from smiley power. According to the New York Times, electricity companies in 10 major metropolitan areas of the US are now sending their customers bills that compare their energy use to that of their neighbours - with low consumption rewarded with a smiley face.
The Sacramento utility who piloted the scheme found that customers who received these statements reduced energy use by 2 percent more than those who got standard bills.
The lesson of the story is the power of social norms. As Herd animals, each of us is programmed to follow the crowd. This makes telling people what everyone else is doing a convincing way of getting them to adjust their behaviour.
Not all behaviours (e.g. energy consumption) are immediately obvious to people, but as this example shows, the data we capture often allows such norms to be revealed - and shared. It would be interesting for a bank to try something similar to encourage saving, or a mobile phone company to migrate people between contracts.
Since customer complaints also led these energy companies to stop publishing sad faces on their bills, however, it also goes to show that whilst a bit of social nudging is good, obvious pressure from the brands we pay our money to is rarely appreciated.