The secret's out! Keeping a poker face can make you look younger

Smiling can make you appear two years older than if you wear a poker face, according to a new study which contradicts the popular belief that putting up smile can make you look younger.

"We associate smiling with positive values and youth. Think of all the skin-care and toothpaste companies that sell the same idea every day," said Melvyn Goodale, from the University of Western Ontario in Canada.

Researchers flashed images of people with smiling, neutral and surprised expressions to the participants. They found that participants perceived the surprised faces as the youngest and smiling faces the oldest.

"The striking thing was that when we asked participants afterwards about their perceptions, they erroneously recalled that they had identified smiling faces as the youngest ones," said Goodale.

"They were completely blind to the fact they had 'aged' the happy-looking faces. Their perceptions and their beliefs were polar opposites," Goodale said. The ageing effect of a smile stems from people's inability to ignore the wrinkles that form around the eyes during smiling. A look of surprise, on the other hand, smoothens any wrinkles, researchers said.

"It may seem counter-intuitive, but the study shows that people can sincerely believe one thing and then behave in a completely different way," Goodale said.