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. Here, we investigated these issues as they relate to human screams. We also examined whether listeners' abilities to distinguish acted from natural screams might vary as a function of individual differences in emotional processing and empathy. Using a forced-choice categorization task, we found that listeners could not distinguish acted from natural exemplars, suggesting that actors can produce dramatisations of screams resembling natural vocalisations. Intensity ratings did not differ between acted and natural screams, nor did individual differences in emotional processing significantly predict performance. Scream duration predicted both the probability that an exemplar was categorised as acted and the probability that participants classified that scream accurately. These findings are discussed with respect to potential evolutionary implications and their practical relevance to future research using acted screams.