Facial recognition study sheds new light on threat response and the ‘spidey sense’

 

 Normal, everyday function in the brain demands a bit of filtering. This is what’s happening when we learn to tune out the noises our own house makes at night, but lay awake when staying with relatives for the holidays, because all the little noises their house makes keep us from falling asleep.

Neuronal circuits in the brain called the default mode network maintain a sort of cognitive cruise control, analyzing the input streams to the brain in real time and deciding what should make its way into our conscious attention. Thoughts or sensations that don’t make it through the default mode network never get assigned to memory; instead, they’re discarded as irrelevant when decision-making interneurons fail to pass on rejected firing pattern. That way we don’t have to remember every single thing we’ve ever experienced, which is evidently exhausting.

But how do we make sure we don’t miss the important things? Humans are social creatures, and social threats have the potential to do real harm. How do we make sure that we don’t ignore a rustling in the bushes, only to find out too late that it was a tiger? It turns out that anxiety presents an advantage, in the form of a “sixth sense” for danger (read: spidey sense!).

Reports that study participants radiated black lines while under observation remain unconfirmed.

Researchers from the Université Pierre et Marie Curie in France have just released a study that used computational modeling and EEGs to reveal the ways that the human brain manages its own threat responses. Their EEG findings suggest that threat level tunes cognitive and subconscious processing, whether or not the subject is aware of the threat — and that emotions that signaled a threat to the observer are better represented in motor cortical regions within a fraction of a second after the facial expression was shown to the volunteer.

Fearful or angry faces represented social threats in this study

Participants in the French study were presented with images of human faces expressing fear or anger to varying degree. As the perceived threat level increased, face-selective regions in all of the participants’ brains lit up faster. But for those subjects with higher anxiety levels, the signal was also rapidly passed to motor-specific brain regions — possibly representing a hardware pathway for the fight-or-flight response. And these effects were independent of whether or not the subject was paying attention at the time.

In other words, more anxious people react faster to the same amount of perceived threat. And they don’t even have to be paying attention to get that decreased latency. Their motor circuits are already warmed up and ready to fire.

There’s an obvious evolutionary advantage to this kind of subconscious processing. In a fight-or-flight situation, fractions of a second can make the difference between escaping or evading an attack and being caught off-guard. This new research illustrates that while we may think of social scenarios as playing out within our conscious mind, an enormous amount of background processing goes on below that threshold.

Who knew anxiety might actually be a superpower?