How can you make out a FAKE SMILE?

The following self help and motivational insight has been adopted from Daniel Pink’s book A Whole New Mind

A genuine smile involves two facial muscles: (1) the zygomatic major muscle, which stretches from the cheekbone and lifts the corners of the mouth; and (2) the outer part of the obicularis oculi muscle, which orbits the eye, and is involved in “pulling down the eyebrows and the skin below the eyebrows, pulling up the skin below the eye, and raising the cheeks.” Artificial smiles involve only the zygomatic major.