At last, a really practical use for technology in the workplace. A Japanese railway company, concerned that its employees may not be looking delighted enough to see passengers, has introduced "smile scanning" software to keep tabs on how enthusiastically they are grinning.

Each morning, according to reports, the 500 or so employees of the Keihin Electric Express Railway Company have to beam stupidly into a camera hooked up to a computer. The machine then analyses things like eye movement, lip curvature and facial wrinkles, and rates the overall quality of their smile on a scale ranging from 0 (suicidal) to 100 (delirious).

Apparently, should the computer deem workers to be too gloomy it flashes up helpful advice like "You still look too serious", or "Lift up your mouth corners". It then prints out a personalised "ideal smile" for employees to carry with them and refer to should they feel their spirits flagging at any point during the day.

If the software ever makes it to the UK I would like to suggest a clinical trial on the Suffolk grocery shop worker who, in the middle of a torrential downpour over the weekend, slammed the door in the face of myself and my one-year-old son with a curt "Sorry, we're closed." (In her case, I'm also wondering if electric shock treatment can be bolted on as an optional extra.)

Then again, the software may already be in use here without our knowledge. Anyone who has experienced the sometimes maniacal over-friendliness of Pret a Manger employees, for example, might well have wondered how it is humanly possible for people to be that cheerful so early in the morning without the threat of some terrible retribution – robots with machine guns, say – hanging over them.

Do we need smile scanning here? And if so, which group of grumpy workers most deserves the once-over?