In what way can the behavioral expression of emotions be deceiving?

Behavioral expression of emotions can be deceiving when people simulate a expression in behalf of the situation they are. For example, simulating a smile (happy facial expression) when one’s disappointed about a gift they received, for the sake of being polite to the person who gifted them. They can be deceiving because the behavioral expression not always is linked to people’s true emotions.

answer; i believe the correct answer is prefrontal cortex;