Smile and the whole world smiles with you, isn't that how the song goes? Well that might not be the case if the results of a small study have any impact on things. The study, conducted by researchers at Western University in Canada and entitled "The effects of smiling on perceived age defy belief," shows that your grin doesn't necessarily help you win – in the age department, that is.

To execute the study, the researchers turned to the Karolinska Directed Emotional Faces database, a collection of images at the Karolinska Institutet in Sweden featuring 70 people, each displaying seven different emotional expressions. From that database, they selected 140 images: 35 men with smiling and neutral faces, and 35 women with smiling and neutral faces.

These images were divided into two mixed sets. If a person was smiling in one set, his or her neutral photo would be placed in the other set. Then 40 students were shown either smiling faces from Set A and neutral faces from Set B, or the reverse. The students were then asked to make a guess as to the age of the faces they saw. Follow-up questions were also asked.

Surprisingly, the majority of students evaluated the smiling faces as being older than the neutral faces by an average of two years. The researchers say this is due to the fact that people can't ignore the wrinkles that appear around the eyes when someone smiles, and that this causes the perceived aging effect.

In a follow-up study, an extra image was added to the mix – one of the photo subject showing surprise. In those cases, the surprised faces were ranked youngest of all.

What's even more interesting is that when asked to recall their rankings after the test was over, most people said they had ranked the smiling faces as the youngest ones.

"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 study co-author Melvyn Goodale, director of the Brain and Mind Institute at Western University. "They were completely blind to the fact they had 'aged' the happy-looking faces. Their perceptions and their beliefs were polar opposites."

The research was published in the Psychonomic Bulletin and Review (PDF).