Sascha Frühholz, alone in a small, stuffed room, takes a deep breath and leaves a cleaving ear. He was there in part because of The Beatles.
Frühholz, a cognitive neuroscientist at the University of Oslo in Norway, could not get videos of the group’s concerts from the 1960s out of his mind. When the music starts to pop up, the audience responds viscerally with joy, screams and screams. There was even a name for this: Beatlemania. “These people have no other way to express this overwhelming joy,” he says.
Although the observation may be obvious, scientific studies on human screams have focused almost exclusively on voices of anxiety – and this oversight has hurt Frühholz. He and his colleagues characterized the screams we uttered for negative and positive emotions. By studying the screams in the small, stuffed room, the team identified six acoustically different screaming categories: pain, anger, fear, joy, passion and sadness. The study was published in PLOS Biology.
Unexpectedly, the researchers also found that volunteers more easily recognized screams – and processed their brains more efficiently – screams that were not considered warnings, including joy, passion and sadness, compared to the screams of pain, anger and fear. For all animal species, screams are considered an important way to quickly communicate danger to others in the environment; why the joyful screams of this latest study seem to evoke the strongest response remains unknown.
The study of non-verbal vocalization in humans is relatively new, says Katarzyna Pisanski, a voice researcher at the University of Lyon who was not part of the study team. Most of the early work on humans focused on speech and language as it is unique in the animal world. “That’s what makes us human,” she says.
But increasing numbers of studies are looking at non-verbal vocalizations such as screams and laughter, similar to the sounds made by other beings. Humans pronounce these sounds with striking diversity, and the function of the different acoustic forms can hold the key to helping us understand the evolution of human communication.
“We need to study what makes us the same to understand how we differ,” Pisanski says.
Create a scream
Frühholz and his colleagues initially recorded their own screams as they tried to identify the typical range of emotions that make these intense utterances flare up. They came up with different scenarios, like thinking about how you would shout if your favorite football team won the championship, and then trying to recreate it.
Eventually, they decided on six different screams they wanted to evaluate: pain, anger, fear, joy, passion, and sadness. They recruited 12 volunteers to scream with every emotion. The volunteer has a description of an emotional situation for each type of scream, such as being attacked by a stranger in a dark alley. Each person also records a ‘neutral scream’ for comparison, which is just an intense expression of ‘ahh’. They then instructed the participant to break free in the soundproof room.
“It’s not really difficult,” Frühholz says of creating screams for different emotions. But a lot of screaming can be exhausting. “It’s the most intense vocalization we can actually produce,” he says.
One challenge with all these studies is that it has to be done in a laboratory environment. It is unethical to cause pain or fear in students, says Pisanski. The options for studying screams are therefore limited: they can be performed or taken from previous recordings such as on YouTube.
The screams performed tend to be a bit more uniform than natural screams, but previous work suggests they are fairly accurate, Pisanski says. “In general, it’s the best we can do, given the limitations of finding true voices,” she says. “And people are pretty good at it.”
The team analyzed the recordings of each scream by looking at 88 acoustic characteristics, such as measurements that characterize pitch and intensity. They trained a computer algorithm on the various functions that differ between screams and found that it could categorize screams correctly almost 80 percent of the time. The most accurate rating was for joy, with 89.7 percent correct ratings.
The team studies participants who listen to the recorded screams and measures how quickly they can categorize the emotion that causes the scream by clicking on an option on a computer screen. In one set of trials, they tested people’s ability to choose the scream type from all six emotions or neutral, and in the other, the listeners only had the choice to choose one of two types of scream. The team also made maps of brain activity for people listening to the screaming replay using functional magnetic resonance imaging (fMRI).
They are interested in three specific brain systems in the fMRI scans, Frühholz explains. The first was the auditory system, which is involved in the analysis and classification of each sound. The second was the limbic system, which is involved in emotional reactions, especially during survival situations. Finally, the frontal cortex, which is involved in decision making and helps to place the sound in the broader context of a situation.
A hard surprise
The researchers unexpectedly found that listeners were able to quickly recognize the non-awake screams, and especially joy. They recognize slower screams of negative emotions, including pain, fear and anger. Similar patterns also occurred for fMRI analysis, which showed that non-warning screams caused greater activity in the listener’s brain compared to the warning screams. Exactly why, however, it remains uncertain.
The finding contradicts the believed evolutionary function of a scream as a way to convey danger dangerously to anyone with a hearing impairment. “It’s amazing,” Pisanski said, adding that she was not sure what the result might be.
In the last two decades, says Frühholz, the view of the brain as a “threat detector” has become increasingly common among scientists. But the new study suggests that this idea may not be the case for screams.
“It will make us think about screaming in a more nuanced way,” says Adeen Flinker, assistant professor of neurology at New York University, who was not part of the new study. In a 2015 study, Flinker and his colleagues identified a loud, strong sound variation, known as roughness, as a key to a listener’s ability to quickly detect sounds that he intends to notice. promotes, not only screams, but also artificial warnings like whistles. .
The new study identified the trait in both negative and positive screams, although the roughness is weaker in positive screams, Flinker says. But even with this rudeness, the participants did not so easily acknowledge and process negativity compared to positive screams. While this new finding does not necessarily eliminate the importance of rudeness in eliciting response to alarm sounds, “he complicates things,” he says.
Flinker says it is possible that the listener’s environment may have an effect on the perception of each scream. When listeners imagine standing in a dark alley before hearing a scream, it can affect how a scream is interpreted, regardless of the emotion of the scream.
In a perhaps less surprising result, the new study also found that positive screams are those that are mostly misidentified as awake screams. It seems that such a misidentification of the emotion behind a scream will be beneficial to people over time. As Pisanski puts it, “better safe than sorry.”
More research will help scientists further degrade the human response to different types of screams. Although a scream may seem far removed from everyday words, it is important to study such nuances in vocalizations and what these non-verbal sounds communicate to others, to redirect the language to its roots, Pisanski says.
“To understand the evolution of human vocal communication and ultimately how we came to speak, we really need to understand all of these differences.”