You can't put a price on a smile, so goes the popular saying. But a team of British academics claim to have done just that. After developing computer software to test people's responses when someone's face cracks into a smile, researchers at Bangor University have calculated the economic value of a grin. Sadly, their findings suggest that flashing gleaming gnashers isn't going to make you a millionaire: each smile is, they report, worth precisely one third of a penny.

With three smiles earning just a penny, not even the Cheshire cat would be able to give up his day job, but, according to the academics, working out the value of a grin could have a significant impact on our human interactions. Danielle Shore, who led the research with her colleague at Bangor's school of psychology, Erin Heerey, says smiles act as a form of "social currency – a valuable reward that people will pay to receive". She says her research suggests they have the power to do anything from luring shoppers to spending more than they intended to creating lucrative working relationships.

But just before you start flashing fake smiles at everyone in a get-rich-quick kind of way, take pause. Shore found that positive responses to smiles only worked when they were genuine. Her research involved recruiting students to play a game against computerised opponents. The computer avatars either smiled genuinely – defined as having the presence of "laugh lines", tiny wrinkles in the corners of the eyes – or politely. Through playing the game, participants learned to associate a probability of winning money with each of the computer figures, with some programmed to have a better chance of winning than others. The avatars indicated participants' wins by displaying either genuine or polite smiles. Later in the game, participants were asked to choose which opponents they wanted to play on each round.

"We were able to determine the value of a smile based on their choices," Shore explains. "The really surprising finding was that participants preferred genuinely smiling opponents to politely smiling ones, even when the politely smiling ones offered them a greater chance of winning. We expected our participants – all university students, whom you might expect to be highly motivated to earn money – to prefer genuinely smiling opponents only when the odds of winning were equal. The fact that they chose opponents who were less likely to pay out was a big surprise."

It was after totting up all the results from those experiments and working out how much extra candidates would pay for a smile that the academics found the value of a genuine smile.

"It's a bit funny to think about smiles in monetary terms – and the actual economic value of a smile does depend on the person with whom you are interacting and the context of the interaction," says Shore. "But in our study, students gave up the equivalent of just over a third of a penny to see a smile. A genuine smile seems to add value to a person or conversation, and therefore has the power to influence how we view people and the decisions we make during conversations.

"Smiles might be helpful in closing deals on the high street, while if a waiter seems genuinely happy to serve, you might tip more for your meal and recommend the restaurant to your friends. This sort of thing could help boost the economy." Would-be Lord Sugars and Richard Bransons should, Shore suggests, consider throwing more smiles around.

"When meeting people for the first time, your impression of them may depend on how they smile," says Shore. "Our lab has found that when people don't return smiles, this can lead to breakdowns in the conversation. Smiles encourage collaboration and productivity in work – if more genuine smiles are seen in a meeting, that meeting is likely to achieve its aims more quickly and with fewer difficulties."

But as for whether more smiling bankers and politicians would put Britain back into the top flight of economic recovery, Shore isn't so confident. "There are limitations to these findings, and one of them relates to the social context within which smiles occur," she admits.

"We are currently working on examining how the context of the smile shapes behaviour." The Bangor academics' latest software has computerised faces smiling genuinely when candidates win and lose games. So far, the data suggests participants "really dislike the faces that appear to take pleasure at their losses". Adds Shore: "We all know that the current financial crisis was precipitated, at least in part, by banks. For people who have seen tax rises, taken pay cuts or lost their jobs because of the crisis, I can well imagine that seeing genuinely smiling bankers with multimillion-pound bonuses or happy politicians who have just passed tax increases would not make people inclined to feel positively."

The academics are also investigating how humans' brains work while conversing with others. "People are social experts. No two social interactions are the same and when you start a conversation with someone, it is difficult to tell where it is going to lead," says Shore. "Yet, we still manage to produce interactions that show a high degree of co-ordination and that almost seem as if they were rehearsed.

I am interested in how people are able to adjust their behaviour to adapt to changing social situations and how the brain manages the neural computations involved." Shore – who says she is a "smiley person" – has bold hopes about the potential impact of her research, suggesting its findings could be used to boost everyone's quality of life.

"If people perceive that others are friendly, they will enjoy their interactions more and build stronger relationships," she says. "We know that people's social networks are an important determinant of longevity and health. If you smile more, it may help you to build stronger social networks that can provide support throughout life." And that's one kind of social networking that isn't possible to carry out on Facebook or Twitter.