In Japan, workers are being subjected to a new sort of control – computer scanning to see if their smiles are wide enough. Every day, staff at 15 railway stations in Tokyo are having to bare their teeth at a computer that rates the curvaceousness of their smile on a scale of one to 100. For those who can't muster a broad enough grin, the computer issues directions on how to improve performance. Lift up the corners of your mouth more, it orders. Staff are then given a print-out of their best smile to refer to as needed.

Oddly, the very same day that I read about the smile police in the east I received an e-mail from the west about a less coercive but no less enthusiastic attempt to get us to beam at each other. Smile and Move is a movement based in Richmond, Virginia, that is peddling its message on Facebook, Twitter, mugs, books, posters and videos. On YouTube, there is a three-minute video trying to brainwash us into smiling. “Love it! Keep it up!” say the comments posted on the site. Later on that same day, I cycled to the dentist and in the waiting room picked up a copy of The Times. The main feature showed a life coach photographed with a pencil clamped between his jaws demonstrating how to improve our smiles.

What is going on? I wondered. Should we all be smiling more?