Blind infants tend to show the same facial expressions as do sighted infants, but as blind infants grow older, their expressions become less animated. this indicates that facial expressions

The Facial Expressions may be innate but are maintained by operant shaping. Various studies have shown that basic facial expressions, such as joy or anger, are the same in different cultures, the fact that blind people also present them corroborates the fact that expressions are innate. However, when blind people grow up these expressions tend to be less marked because their use has not been reinforced by means of operant condition, such as imitation or reinforcement.