Most often, a human scream signals fear of imminent danger. But screaming can also express joy or excitement. For the first time, researchers University of Zurich have demonstrated that non-alarming screams are more efficiently perceived and processed by the brain than their alarming counterparts.
The researchers investigated the meaning behind the full spectrum of human scream calls. The results revealed six emotionally distinct types of scream calls indicating pain, anger, fear, pleasure, sadness and joy. They found humans respond to positive screams more quickly and accurately and with higher neural sensitivity than to alarming screams.
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In the trials, 12 participants were asked to vocalise positive and negative screams that might be elicited by various situations. A different group of individuals rated the emotional nature of the screams, classifying them into categories. The brain activity of participants listening to the screams was monitored using functional magnetic resonance imaging (fMRI) to know how they perceived, recognised, processed and categorised the sounds. They found different brain regions showed much more activity and neural connectivity when hearing non-alarm screams than when processing alarm scream calls. “It's highly possible that only humans scream to signal positive emotions like great joy or pleasure. Unlike with alarm calls, positive screams have become increasingly important over time,” Sascha Frühholz says in a press release. Researchers suggest that this may be due to the communicative demands brought about by humans’ increasingly complex social environments.