Showing off your pearly whites with a broad smile can help you make friends and influence people.

Volunteers from the 56 ethnic groups in China celebrate the launch of the "Smile bracelet" to symbolize their friendly relations on October 29, 2006. [China Daily]

But would that smile have such an impact if you were only allowed to show four upper and four lower front teeth?

This may sound strange, but it is apparently something Beijing police are instructing new officers on before they are posted at airport checkpoints in the run-up to next summer's Beijing Games.

According to local media, the 100 new recruits, who will report to duty from this month, have been taking pains to practice their new smiles with the aid of handheld mirrors. Showing only eight teeth is supposed to make them appear friendly without looking "goofy."

While people may find this amusing, I did not know whether to laugh or cry when I visited a local vocational school the other day and was met by a gaggle of grinning teenage girls.

The girls, all of them are aspiring air stewardesses who may help host the Olympic victory ceremonies next summer, have been receiving daily training on how to smile from ear to ear by biting down on horizontally-placed chopsticks.

The practice sessions can literally be face-numbing.

"We have found this to be the most effective training technique," one teacher told me. "So we let them practice this every now and then throughout the day."

In my previous column on Beijing's new campaign to promote smiling, "Smiling shouldn't be a chore", I argued that, unlike in the West, where people are encouraged to smile to convey that they are friendly, kind and trustworthy, the Chinese have traditionally been encouraged to adopt a more serious pose in front of strangers.

To rectify this, local universities have found it necessary to train their student volunteers for the 2008 Games in how to flash smiles from three meters away. When at work, the volunteers are supposed to check on each other from time to time to make sure there are no frowns or scowls as the day wears on.

One of the aspiring flight attendants at the school told me that part of the training "teaches us to think positively so we are in the mood to smile."

However, the training seems to have become increasingly stressful. The repertoire of techniques has grown to include carefully measured smiles, although smiling without showing your teeth is considered to be beautiful in traditional Chinese culture.

Readers who responded to my previous commentary suggested that the organizers should get to the root of the issue and give the volunteers a genuine reason to smile, or hire friendly people, for whom smiling comes naturally.

One reader regrets that smiling "has to be an expression that is taught just to express a united appearance to the rest of the world."

I agree. At the end of the day, what is the point of going all out to impress visitors if your sincerity is called into question?

Some participants of Beijing's charm offensive have learned first-hand the importance of being natural.

One student volunteer recalled: "If you don't treat smiling as a work assignment, but as something normal, you may find it very easy to smile all the time."

This might be a better way for people to develop the habit of smiling often - and getting a smile in return.