The credibility of acted screams: Implications for emotional communication research.

Researchers have long relied on acted material to study emotional expression and perception in humans. It has been suggested, however, that certain aspects of natural expressions are difficult or impossible to produce voluntarily outside of their associated emotional contexts, and that acted expressions tend to be overly intense caricatures. From an evolutionary perspective, listeners' abilities to distinguish acted from natural expressions likely depend on the type of expression in question, the costs entailed in its production, and elements of receiver psychology.