Only humans scream for pleasure, joy or sadness

The infamous scream has traditionally been linked to an alarm signal among animals and also to an expression of violence or despair among humans.

However, it is a form of communication that is not always negative.

A study by Sascha Frühholz, a researcher in Cognitive Psychology and Affective Neuroscience at the University of Zurich (Switzerland), has identified six fundamental types of screaming associated with as many emotional states: fear, anger, pain, sadness, joy and pleasure.

The last three, according to the work, published in

Plos Biology

, are exclusively human and make a huge difference.

“They are more efficient than alarm bells, they help to establish social bonds and they represent a great evolutionary advantage”, according to Frühholz.

To reach these conclusions, the Swiss researcher's team has reproduced 420 squeaks in four experiments that are easily differentiated from other “non-verbal affective vocalizations”.

A dozen volunteers, supervised by specialists, have made it possible to group the screams into an alert category (fear, pain and anger) and another that does not imply alarm (sadness, joy and pleasure), as well as to monitor the neurological response, through functional magnetic resonance imaging (FMRI) while the trial participants listened to the screams.

The work determines that listeners respond more quickly and accurately, and with greater neural sensitivity, to non-alarming and positive screams than to those that are expressions of alertness and negative emotional states.

The shouts of pleasure or joy generate, according to the research, "more activity in more auditory and frontal brain regions."

"These findings show that screams, as signals and forms of expression, are more diverse among humans, whose brain processes them more efficiently," concludes the research.

What we know so far is that many species use squeaks to communicate, but only humans scream when they are sad and especially when they experience joy and pleasure.

Sascha Frühholz, researcher in Cognitive Psychology and Affective Neuroscience

In this way, although screams are not exclusive to humans, they are more diverse and efficient in our species.

This is how Frühholz explains it: "What we know so far is that many species use screaming to communicate, but only humans scream when they are sad and especially when they experience joy and pleasure."

“The reason”, according to the Swiss researcher, “is that humans thrive in social environments and most of them are safe, without environmental threats such as predatory wild animals.

In these human environments, emotions and positive screams are a priority because they are less relevant as alarm signals ”.

Scream effects

In addition to the environmental and social reason, the researcher adds another biological reason to add twice as many high-sounding expressions to the human catalog as that of animals, which often resort to shouting to express alerts: “The human vocal repertoire is more flexible and diverse, which gives it an evolutionary advantage.

Expressing different emotions is relevant for those who perceive them because that is how they know how to react ”.

And he explains: “If he does it out of grief, the receiver will approach to help relieve him.

If a person yells in anger or aggressively, the receiver will try to walk away because he may be harmed.

And if someone screams for joy or pleasure, the establishment of social ties benefits because the tendency is to connect with the person and share the joy.

You can shout with joy with other people, like the followers of a group do at concerts ”.

Noting and perceiving positive emotions with yelling is a higher priority among human beings than alarm communication

The study opens a way to investigate the communicative virtues of screaming.

In this sense, the Swiss researcher states: “The results are surprising because researchers tend to assume that primates and the human cognitive system are specially tuned to detect danger and threat signals in the environment, as a survival mechanism.

This has long been assumed to be the primary purpose of communicative yelling signaling.

But while this appears to be true in primates and other animal species, screaming communication has greatly diversified among humans and this represents an important evolutionary step.

Humans share with other species the potential to signal danger by screaming, but it seems that only people scream to also signal positive emotions such as extreme joy and pleasure.

Noting and perceiving these positive emotions in screams is a higher priority among human beings than alarm communication ”.

Soccer fans shout during a match Mark Humphrey / AP

This change in priority has also resulted in a greater efficiency of screaming associated with non-alarming emotional states.

According to the measurements of perception and sensitivity in the decision-making process carried out during the experiments, “the warning cries [with some exceptions] were in general”, according to the research, “worse discriminated, generated slower responses and showed less perceptual sensitivity than non-alarm screams ”.

In this way, the screams linked to alert signals (pain, anger, fear) provoke less activity in the regions of the auditory cortex and the amygdala, where the central neural network that supports the social, acoustic and affective evaluation of the sounds.

The non-alarm screams (pleasure, sadness, joy) showed greater neuronal activations, especially in the right hemisphere in the auditory cortex.

"These findings in people are surprising and largely diverge from studies in non-human primates," the study notes.

Another study from Emory University (Atlanta, USA) on the discrimination of the different types of screams supports the ability of people to discern the emotions they express, although the work clarifies that those linked to happiness can be confused with associated with fear if not heard in context.

In this regard, Harold Gouzoules, Professor of Psychology and lead author of the study, explains in Emory's research: “To a large extent, the study participants [182] were quite good at judging the original context of a scream, simply listening to it through headphone without any visual cue.

But when the participants heard cries of happiness they tended to judge the emotion as fear. "

According to the researchers, "the bias towards interpreting the scream as fear probably has deep and evolutionary roots."

“The first animal cries were probably in response to an attack by a predator.

It is an essential and central answer.

So mistaking a happy cry for one of fear could be an ancient bias ”.

He also disagrees on the interpretation of the sound associated with happiness.

While Frühholz links it to the establishment of social networks, for Gouzoules, although he admits that it is "a speculation", it could be that, when children scream with excitement while playing, for example, they do it to "familiarize a parent with the sound the only one of his screams ”.

In this sense, he explains: "The more you listen to your child screaming in a safe and happy context, the more capable you will be of identifying a scream as belonging to your child, so that you know how to respond when you hear it."

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