Human screams are signs of more than just fear, a new study has revealed. It also underlines that human screams are more acoustically diverse than they were previously thought to be. Not only does a human scream to raise the alarm about an imminent threat to his/her life or the pain caused by an injury but also to express joy, excitement and even aggression.
The study published in the open-access journal, PLOS Biology, says that non-alarming screams, the ones without negative contexts, are perceived and processed by the brain more efficiently. In the studies done previously, the focus of researchers was largely on alarming fear screams, and therefore the broader significance of various scream types couldn’t be clear. According to a report on Eurekalert, the new study focuses on addressing this knowledge gap using four different psychoacoustic, perceptual decision-making, and neuroimaging experiments in humans.
The study carried out by a team at the University of Zurich, Department of Psychology, led by Sascha Fruhholz, tried to find the meaning behind the full spectrum of human scream calls. The results show that humans scream to communicate six different emotions -pain, anger, fear, pleasure, sadness and joy. Fruhholz said that her team was surprised that listeners responded more quickly and accurately, and with higher neural sensitivity, to non-alarming and positive scream calls than to alarming screams.
The Fruhholz-led team carried out four experiments for their study and as a part of which twelve participants were asked to vocalise positive and negative screams that might occur in various situations. Another group of individuals analysed the emotional nature of screams and classified them. Their brain underwent functional magnetic resonance imaging (fMRI) while listening to the screams.
“The frontal, auditory and limbic brain regions showed much more activity and neural connectivity when hearing non-alarm screams than when processing alarm scream calls,” said Fruhholz.
More complex social environments have reshuffled neurocognitive priorities:
It was previously thought that human and primate brains were specialists at recognising threat and danger signals communicated in the form of screams. But contrary to this, human scream calls have developed a diverse range, exhibiting different emotions, throughout human evolution.
“It’s highly possible that only humans scream to signal positive emotions like great joy or pleasure. And unlike with alarm calls, positive screams have become increasingly important over time,” he said.
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