Participants making a full smile performed better than the polite-smile group, but the difference wasn't statistically significant and needs to be studied further, she says.

WSJ: Stress-Busting Smiles

Some experts believe only a genuine, full smile, confers health benefits.

WSJ: Stress-Busting Smiles

If you arrive to an already full room, enter slowly, smile and stand tall at the front.

FORBES: Mastering the Cocktail Party in 25 Steps

Damon has a full head of hair, a big smile, and a robust temper, which explodes memorably at one point.

NEWYORKER: Lost Love

Both sisters had a prim, close-lipped smile, genuine but guarded, as if a full-on grin risked conveying complexities best left unmined.

NPR: Elevating the World's Oldest Profession in Chicago

Pinki is now a real pistol, full of energy and confidence, and she has a fantastic smile too -- thanks to the Smile Train charity.

CNN: Pinki brings a smile to the Oscars

"It was full price" is all he'll say, with the trace of a smile.

FORBES: Odd Man In

"She was an incredible woman, always full of energy and hard at work, but never too tired to share her love and a smile with everyone, " the post said.

CNN: Boston Marathon bombing victims: Promising lives lost