Aggressive Human Voices Can Hijack Your Brain

Threatening voices monopolize the brain’s attention longer than happy voices.

Posted Dec 10, 2018

Hearing someone holler or being yelled at sets off alarm bells in the brain and makes it practically impossible to think of anything else other than the sound of the angry human voice that is monopolizing your surrounding environment. On the prosocial side, even the most soft-spoken parent will use the primal power of an angry voice to alert a child — who is about to put his or her well-being in danger by doing something like crossing the street without looking both ways — to "Stop, right there!" and take a few extra milliseconds to assess potential threats in the environment.

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On the maladaptive side, using an aggressive voice is a signature trait of every rage-aholic. Mean bosses don’t tend to speak using joyful tones; as part of their power trip, they know a happy voice doesn’t have the same disorienting impact as blowing one's lid and sounding angry.

We all know these real-world examples of how a threatening voice seems to hijack your brain, but what is the neuroscience behind the ability of an aggressive voice to cause your attention to focus on nothing else? For the first time, new research from the University of Geneva (UNIGE) has identified specific brain mechanisms that alert us to potential danger by refocusing attention towards an angry voice for almost twice as long as the sound of a voice expressing joy. These findings were recently published in the journal Social Cognitive and Affective Neuroscience.

For this study, the researchers monitored auditory attentional processing in the brain using electroencephalography (EEG) while study participants processed 22 brief human voice sounds (600 milliseconds) that expressed either anger or joy. When participants heard an aggressive voice, the brain deployed significant spatial attention resources to identify precisely where the vocalization was coming from in an attempt to pinpoint the location of a potential threat.

More specifically, when participants heard vocal aggression, the brain went on high alert and dedicated two different types of attentional resources to create a 360-degree map of the surrounding space and locate where the angry voice was situated in the room. Because we don’t have eyes in the back of our heads, the ability to identify the proximity of potential threats (that we can’t see) using our ears is key to evolutionary survival.

"That's why we are interested in how fast our attention responds to the different intonations of the voices around us and how our brain deals with potentially threatening situations," first author, Nicolas Burra of UNIGE, said in a statement. "When the brain perceives an emotional target sound, N2ac [a cerebral marker of auditory attention] activity is triggered after 200 milliseconds. However, when it perceives anger, the N2ac is amplified and lasts longer, which is not the case for joy."

Interestingly, after 400 milliseconds, the N2ac attention towards aggressive vocalization appears to disengage, and another cerebral marker of auditory attention called “LPCpc” swings into action. This auditory spatial attention marker is used to hone in on the location of a sound by balancing the intake of stimulation from left and right auditory space. LPCpc activity was also more robust for angry voices than for happy voices.

The authors sum up their findings, “Measurements of the N2ac and LPCpc components suggest different attentional selectivity for threatening and happy voices. Our results extend conclusions from the visual modality and reveal that the rapid orienting/engagement toward threatening stimuli as well as the rapid reorienting/disengagement from threatening stimuli are fundamental neural mechanisms occurring both in the visual and auditory modality. In sum, our results reveal a general, dynamic principle for the organization of the relationship between spatial attention and threat detection in the human central nervous system.”

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Nicolas Burra, Dirk Kerzel, David Munoz, Didier Grandjean, Leonardo Ceravolo. "Early Spatial Attention Deployment Toward and Away from Aggressive Voices." Social Cognitive and Affective Neuroscience (First published: November 9, 2018)  DOI: 10.1093/scan/nsy100

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