Why do people scream?

In non-human primates and other mammalian species, scream-like calls are frequently used as an alarm signal exclusively in negative contexts, such social conflicts, the presence of predators or other environmental threats.

Humans also use screams to signal danger and to scare predators. But new research suggests that humans scream not only when they are fearful and aggressive, but also when they experience other emotions such as despair and elation.

In the past, scientific studies on human screams have focused almost exclusively on vocalizations of anguish—and this oversight nagged at neuroscientist Sascha Frühholz. He and his colleagues set out to characterize the screams we let us for a range of emotions, negative and positive.

By studying screams recorded in a small, padded room, Frühholz and his team identified six acoustically distinct scream categories: pain, anger, fear, joy, passion, and sadness.

Their research was published in PLOS Biology.

The Study

As reported in National Geographic, the researchers recruited 12 volunteers to scream with each emotion. The volunteer was primed with a description of an emotion-evoking scenario for each scream type, such as getting attacked by a stranger in a dark alley.

Each person also recorded a “neutral scream” for comparison, which is just an intense utterance of “ahh.” They then instructed the participant to let loose in the soundproof room.

Frühholz and his team analyzed recordings of each scream by looking at 88 acoustic features, such as measurements characterizing pitch and intensity. They trained a computer algorithm on the various features that differed between screams and found it could correctly categorize screams nearly 80 percent of the time. The most accurate classification was for joy, with 89.7 percent correct classifications.

The team then studied participants listening to the recorded screams, measuring how quickly they could categorize the emotion triggering the scream by clicking an option on a computer screen.

In one set of trials, they tested people’s ability to select the scream type from all six emotions or neutral, and in another, the listeners only had the option of picking one of two scream types. The team also created maps of brain activity for people listening to playbacks of the screams using functional magnetic resonance imaging (fMRI).

They were interested in three particular brain systems in the fMRI scans, Frühholz explains.

1. The first was the auditory system, which is involved in analyzing and classifying each sound.
2. The second was the limbic system, which is involved in emotional responses, particularly during survival situations.
3. Finally, the frontal cortex, which is involved in decision-making and helps put the sound in the broader context of a situation.

The Findings

The researchers found that volunteers more readily recognized—and their brains more efficiently processed—screams that were not considered alerts, including joy, passion, and sadness, compared to the screams of pain, anger, and fear.

They more slowly recognized screams from negative emotions, including pain, fear, and anger. Similar patterns also held for fMRI analysis, which showed non-alert screams sparked greater activity in listener’s brains compared to the alert screams. Exactly why, however, remains uncertain.

For all animal species, screams are considered a vital way to rapidly communicate danger to others nearby; why the joyful screams of this latest study seemed to invoke the strongest response remains unknown.

“The results of our study are surprising in the sense that researchers usually assume the primate and human cognitive system to be specifically tuned to detect signals of danger and threat in the environment as a mechanism of survival. This has long been supposed to be the primary purpose of communicative signaling in screams. While this seems true for scream communication in primates and other animal species, scream communication seemed to have largely diversified in humans, and this represents a major evolutionary step.”

Other Scream Research

Other research has been conducted on screams, including a study out of Emory University that found most people can’t tell the difference between screams of joy and screams of terror when they are heard out of context.

Unlike speech, the study finds screams lack distinctive and consistent acoustic parameters, which make them harder to identify. To see whether people could do so, researchers asked 182 participants to listen to 30 screams from Hollywood movies through headphones. Each scream communicated one of six emotions: anger, frustration, pain, surprise, fear, and happiness.

After hearing each howl, listeners then rated on a scale of one to five how likely the scream was associated with one of these six emotions. The results reveal participants correctly paired screams and emotions in most cases, except when it came to happiness. The group often confused these screams with fear.

“The acoustic features that seem to communicate fear are also present in excited, happy screams. In fact, people pay good money to ride roller coasters, where their screams no doubt reflect a blend of those two emotions.”

Interestingly, similarities between cries of joy and terror could have deep evolutionary roots. The findings may even provide a clue to the age-old question of why young children often scream while playing.

“Nobody has really studied why young children tend to scream frequently, even when they are happily playing, but every parent knows that they do. It’s a fascinating phenomenon.”

The post Screaming Conveys at Least Six Different Emotions first appeared on Humintell.

Any parent of young children know that raising kids can be a bit messy, especially when they’re infants. In addition to plenty of kisses, there’s always drool to be wiped, and slobbery feedings.

Recent research has shown that exposure to family members’ saliva, what is known in the academic world as “saliva sharing”, plays a crucial role in how we make sense of the world around us. It helps shape our discernment of social relationships, starting from our first months of life.

The study entitled “Early concepts of intimacy: young humans use saliva sharing to infer close relationships” was led by Ashley Thomas and recently published in the journal Science.

At MIT, Thomas studies how infants recognize different types of social relationships and how they learn about their specific social worlds, how they place themselves into relationships and into larger social groups.

Saliva Sharing

As reported in MIT News, In human societies, people typically distinguish between “thick” and “thin” relationships.

Thick relationships, usually found between family members, feature strong levels of attachment, obligation, and mutual responsiveness. Anthropologists have also observed that people in thick relationships are more willing to share bodily fluids such as saliva.

“That inspired both the question of whether infants distinguish between those types of relationships, and whether saliva sharing might be a really good cue they could use to recognize them,” Thomas says.

To study those questions, the researchers observed toddlers (16.5 to 18.5 months) and babies (8.5 to 10

months) as they watched interactions between human actors and puppets. In the first set of experiments, a puppet shared an orange with one actor, then tossed a ball back and forth with a different actor.

After the children watched these initial interactions, the researchers observed the children’s reactions when the puppet showed distress while sitting between the two actors. Based on an earlier study of nonhuman primates, the researchers hypothesized that babies would look first at the person whom they expected to help. That study showed that when baby monkeys cry, other members of the troop look to the baby’s parents, as if expecting them to step in.

The MIT team found that the children were more likely to look toward the actor who had shared food with the puppet, not the one who had shared a toy, when the puppet was in distress.

In future work, the researchers hope to perform similar studies with infants in cultures that have different types of family structures. In adult subjects, they plan to use functional magnetic resonance imaging (fMRI) to study what parts of the brain are involved in making saliva-based assessments about social relationships.

Related to Disgust

In a commentary published alongside this new study reported by BT Times, Christine Fawcett of Uppsala University in Sweden notes that the findings not only bring to light what young children understand about the social structures around them, but also raise further questions about how children acquire these expectations and how universal they may be.

She points out that exchanging saliva with a stranger might make individuals feel disgusted, possibly as a method to protect themselves from contamination or disease, but that people will willingly do so with those close to them, even their pets.

According to Fawcett, there may be an evolutionary pressure to suppress disgust with body substances in order to aid in the care of babies, and infants’ experience with this type of caretaking may then lead to a learned expectation that such behavior is connected with closeness.

Various volunteers took part in the series of experiments, but as the study progressed, the researchers recruited a more geographically, ethnically, and economically diverse population. However, all of the participants were from the U.S.

While saliva sharing may be an universal cue, Thomas pointed out that saliva norms and who is considered family vary around the world – and so may what seeing a saliva sharing connection imply.

The post Babies use ‘Saliva Sharing’ to Infer Close Relationships first appeared on Humintell.