Based on excerpts from this article. Involuntary facial expressionsI propose that all facial expressions of emotion are involuntary; they are neither voluntarily nor deliberately made.
Note, I say all facial expressions of emotion, not all facial movements. Facial expressions of emotion are a subset of facial movements.When an emotion occurs, impulses are always sent to the facial muscles.
There is no choice about that. We can choose to try to interfere with the appearance of that expression, we may be able to interrupt the action of the facial muscles or dampen them so that nothing is visible, but we cannot choose to prevent the impulses from being sent to the facial nerve.
Read more on paulekman.com