In a world where speed cameras and traffic calming devices are getting on drivers' nerves everywhere, an experiment in Scotland has shown that they needn't be such a pain.
South Lanarkshire has 226 Vehicle Activated Speed (VAS) signs that reward drivers who drive under the speed limit with a smiley face.
Those who drive above the speed limit are met with a sad face.
It's a simple concept and one that appears to be paying off. Since implementing the personalized smiley feedback to drivers, speeding in the area has decreased by 53 per cent.
It looks like no one wants to make the sign sad.
"It's a basic rule of human behaviour that we enjoy making people happy and prefer to avoid making them sad...but it may still surprise you how effective a reward a smile can be," creative planner Matt Sadler writes.
The smiley SID (Speed Indication Displays) "provides a non-confrontational warning to drivers, warning them of their speed via an LED display and putting social pressure on them to decrease speed when required."
The VAS signs cost about 98 per cent less to operate than speed cameras, making the safety smile as cost-efficient as it is effective.