Can you dramatically change people’s behavior with a smiley face?

In South Lanarkshire there are 226 Vehicle Activated Signs that don’t just tell drivers their speed, but show them a smiley or sad face, depending on whether they’re under or over the limit… Thanks to these little faces, the number of people exceeding the speed limit in the Lanarckshire area fell by 53%.  And when you realise that these things operate at about 2% of the cost of a speed camera, there’s even more reason to be cheerful.

Source is Matt Sadler.

Hat tip goes to an inspiring TED talk by Rory Sutherland which explains why details matter, big picture strategy can be overrated, and why we should sweat the small stuff: