It's an expression with incredible nuance. A simple smile can convey anything from joy to despair, through amusement and embarrassment. Exactly how people decode these multiple meanings has long puzzled scientists. A happy smile was thought to involve the muscles around the eyes – those responsible for ‘crow's feet’ wrinkles. If these contracted, it was a good sign. New research however suggests that it’s a lot more complicated. Subjects watched videos of virtual reality faces smiling in a variety of ways (shown as snapshots) and judged the emotion behind the expression. Crow’s-feet muscles themselves were not enough to produce ‘happy’ smiles but had to work in tandem with another muscle to reliably give off good vibes. The size of the smile and whether lips and mouth are open also appear to make a difference. Giving smiles may be free... but trying to decipher them is very costly indeed.
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