This Tidbits is a Scream!

Screaming plays an important role in animal behavior. The first non-human animal screams were probably in response to an attack by a predator.  A sudden loud, high-pitched screech might momentarily startle the aggressor and allow an escape. An additional function for non-human primate screams is a call for help when threatened. 

Humans are more sophisticated in our use of screaming. In a recent study, researchers established that differences in tone and frequency allow our screams to convey anger, frustration, pain, surprise, fear and happiness.

In the study, 30 recordings were selected from 26 different vocalizers based on their sound quality (no interfering sounds) and their ability to convey emotion. The researchers recruited 182 participants who listened to the recordings and tried to identify the emotion behind each of the screams. They were then asked to rate from 1 to 5 how strongly they agreed with a statement identifying an emotion expressed by the scream.

For the most part, participants were good at judging the original context of a scream simply by listening to it through headphones without any visual cues. But there was one significant exception. When they listened to screams of excited happiness, they tended to judge the emotion as fear. This was a surprising finding. Such an interpretive mistake may have something to do with the original reason for screaming in our ancestors; namely, self-preservation. It may be an example of ancestral carryover bias: if it’s a close call, you will err on the side of fear.

On the other hand, there are certain human activities in which happiness and fear are expressed together. For example, a ride on a roller coaster elicits screams that undoubtedly reflect a blend of both emotions (a hybrid scream?).

Have you ever noticed how much screaming ensues when young children are at play? Every parent knows this (Even grandparents I might add). It almost seems like a reflex, as if they have no control over it. Just visit a playground frequented by young children and you will readily witness this. It has never really been studied, but one scientist suggested that screams of excitement when small children are at play serves the evolutionary role of familiarizing a parent to the unique sound of their screams. “The more you hear your child scream in a safe, happy context, the better able you are to identify a scream as belonging to your child under more threatening conditions, so you will know to respond when you hear it.”