There are three basic types of human smile: “reward”, “affiliative” and “dominance” smiles. That’s according to a new paper by psychologists Magdalena Rychlowska and colleagues.
Here’s the authors’ illustration of the types, as posed by actors:
Reward smiles, the authors say, are used to signal enjoyment:
Reward smiles are displayed to reward the self or other people and to communicate positive experiences or intentions… the reward smile may have evolved from the play face of primat