UCSB researchers have discovered that the human mind is capable of estimating another person’s physical prowess solely by hearing the sound of that person’s voice.

Along with a team of academics, Aaron Sell — a postdoctoral fellow at UCSB’s Center for Evolutionary Psychology — recently released the results of an experiment on human mechanisms that assess an opponent’s fighting power. The experiment, which was part of a broader study on the neurocognitive architecture of the brain, revealed that humans possess an instinctive mechanism that uses vocal cues to determine a potential enemy’s physical power.

Of course, Sell said, simply looking at an opponent has historically been the most relied-upon way of sizing up an enemy.

“The easiest way to estimate fighting ability is to look at the body,” Sell, the lead author of the experiment on auditory assessment mechanisms, said. “The size of the body and the shape and muscularity of the upper body can indicate a lot about how physically strong someone is.”

Nevertheless, Sell said, due to the difficulty in judging the fighting ability of a heavily clothed opponent or when situated in a dark setting, the ability to process non-visual cues became a necessary evolutionary step.

“Our studies actually showed that if you can see a guy’s body, you can get a really good indicator of his strength,” Sell said. “But if you can hear his voice, then your assessment gets even more accurate. So, there is something in the voice that you are not getting from the body.”

According to Greg Bryant, an assistant communications professor at UCLA who analyzed the auditory samples from the case study, past research indicates that humans in fights have often had to resort on auditory cues when they weren’t able to easily see who they were fighting.

“We know the voice reflects health and genetic quality in a variety of ways,” Bryant said in an e-mail. “We also believe that deriving information from non-visual cues might have been important evolutionarily — for example, assessing formidability in the dark or at a distance.”

Additionally, Leda Cosmides, UCSB psychology professor and co-director of the Center for Evolutionary Psychology, said the study adds support for theories on the existence of universal vocal cues.

“[From the results] it does not matter what language the person is speaking, the ability to judge a strange voice is not language-specific,” Cosmides said. “The voices are from different languages and different cultural groups, yet the cues must be the same because people are doing just as well in assessing them.”

Interestingly, Sell said, in the study both women and men were able to judge a man’s fighting ability through vocal cues, yet neither gender proved effective at assessing a woman’s strength by hearing her speak.

“None of the assessment mechanisms seem to work as well on women,” Sell said.