Humans can judge a person's strength from their aggressive roars
Animals such as dogs, grizzly bears and tigers listen to other animals' roars to size them up before they attack when competing for food, territory or mates. Now scientists have discovered humans do the same, and we're pretty good at it, too.
Jordan Raine, a researcher at the vocal communication lab at the University of Sussex in England, conducted the recent study.
"Historical accounts indicate that soldiers have roared in battles throughout history from the Roman army all the way to the Red Army," says Raine. "We can see it in various sports, and even the U.S. National Park service recommends roaring as a defence strategy against bears."
Humans are great at sizing up other humans
To set up the experiment, Raine collected sounds from 61 drama students from the Royal Central School of Speech and Drama and the University of Sussex.
He then had the actors, one at a time, roar at him at the top of their lungs in a small room followed by aggressive speech. "It was quite a traumatic experience," recalls Raine. (The actors were told to imagine themselves in a war scenario where they were charging at the enemies.)
After collecting the sounds, he measured the actors' height and upper body strength by taking an amalgamated measure of their hand grip strength and bicep circumference.
He then played the recordings to about 100 listeners and asked them to judge whether the actor in the recording was stronger or weaker than them or taller or shorter than them.
"Under these conditions, we found that listeners are actually really good at judging strength and height from the voice," says Raine. "Listeners incorrectly judged vocalizer who are stronger than themselves as weaker only 18 per cent of the time, and when they were judging much stronger vocalizers, that figure dropped all the way down to six per cent."
Sex differences in results
Further analysis revealed sex differences in the results.
Raine noticed that when male participates roared, they were much more likely to be rated as stronger than when they produced aggressive speech.
"So although the roar provides honest information about a person's formidability and their fighting ability, male vocalizers, in particular, seemed to be able to use their roar to exaggerate their strength and intimidate opponents."
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Another finding showed men tended to underestimate women's strength while women tended to overestimate men's strength. This was observed when female listeners were rating male vocalizers that were similarly strong to themselves: they were more likely to rate them as stronger even in cases where males were weaker than them.
"This happened about 25 per cent of the time," says Raine, "so it's quiet a big gap between reality and perceptions."
While women might be frustrated upon learning this, a good could come from it. In a self-defence situation, research shows that fighting back in some cases is actually the best strategy, he adds.
"While it is true that most men are physically stronger than the average women, where the difference in strength doesn't look to be big, our research suggests that women may be better equipped to deal with physical threat than they think."