Human screams communicate at least six emotions

Human screams indicate more than fear and are more acoustically diverse than previously thought, according to a study published in the open-access journal on April 13, 2021. PLOS Biology by Sascha Frühholz of the University of Zurich, and colleagues. Strikingly, non-frightening screams are more efficiently perceived and processed by the brain than frightening screams.

In non-human primates and other mammalian species, scream-like calls are often used as an alarm signal exclusively in negative contexts, such as social conflicts or the presence of predators or other environmental threats. It is also accepted that people use screams to indicate danger and to scare off predators. But people scream not only when they are scared and aggressive, but also when they experience other emotions, such as despair and excitement. Previous studies on this topic have largely focused on frightening screams of anxiety, and the broader meaning of different types of screams is therefore not clear. In the new study, the researchers addressed this knowledge gap using four different psychoacoustic, perceptual decision-making and neuroimaging experiments in humans.

Twelve participants were asked to express positive and negative screams that could be caused by different situations. Another group of individuals assessed the emotional nature of the screams, divided the screams into different categories and underwent functional magnetic resonance imaging (fMRI) while listening to the screams.

The results revealed six psychoacoustically different types of screaming calls, indicating pain, anger, fear, pleasure, sadness and joy. Perhaps it is surprising that listeners respond faster and more accurately and with a higher neural sensitivity to non-alarm and positive scream calls than to anxious screams. Specifically, less frightening screams elicited more activity in many auditory and frontal brain regions. According to the authors, these findings show that screaming calls are more diverse in their signal and communicative nature in humans than are often accepted.

Dr Frühholz notes: “The results of our study are surprising in a sense that researchers usually assume that the primate and human cognitive system are specifically designed to detect signals of danger and threat to the environment as a mechanism of survival. It has long been assumed to be the primary purpose of communicative signal in screams.While true for screaming communication in primates and other animal species, screaming communication seems to be largely diversified in humans, and is an important evolutionary step Humans share it with other species, the potential to indicate danger when they scream, but it seems that only humans scream to indicate positive emotions such as extreme joy and pleasure. The signal and perception of these positive emotions in “Screams seem to have taken precedence over humans in alarm signals, probably because of the demands of developed and complex human contexts.”