University of California Psychologist Dacher Keltner has been studying smiles.
Yearbook smiles to be specific.
Mills college class of 1960. We focused on the strength of muscle contrast around the eyes and the strength of the muscle that pulls the lip corners up. Involuntary smiles involve muscles around the eyes that can't be controlled. They feel less negative on a daily basis, more nurturing, and confident in their lives. It turns out they know a lot about the class of 1960 at Mills College.