Experience changes everything. That, at least, is the lesson of a new study of Navy SEALS led by scientists at UCSD. Their experiment was an investigation into the anatomy of emotional perception, or what happens inside the brain when we glimpse angry, fearful or happy faces.

The results were straightforward: Navy SEALS are exceptionally good at detecting angry faces. While the soldiers were slower than control subjects at processing happy or scared expressions, the elite troops excelled at seeing those feelings associated with threats and risk. Furthermore, they showed a slightly more potent response in the insula, a brain area associated with the detection of bodily/interoceptive feelings, such as a racing pulse or clammy hands. Here’s the scientific summary:

These findings support the notion that elite warfighters, when examined cross-sectionally, deploy greater neural processing resources toward potential threat-related facial expressions and reduced processing resources to non-threat-related facial expressions. This finding suggests that rather than expending more effort in general, elite warfighters show more focused neural and performance tuning, such that greater neural processing resources are directed toward threat stimuli and processing resources are conserved when facing a nonthreat stimulus situation.

This is is a novel demonstration of an old idea, which is that the brain tunes itself based on experience. If we’re continually exposed to dangerous situations – and Navy SEALS are an elite fighting force specifically trained for such situations – it shouldn’t be too surprising that the cortex becomes more sensitive to relevant sensory information, which include angry faces. (The assumption, of course, is that angry faces are more likely to fire at you.) An interesting follow-up study could further probe these processing differences. For instance, are Navy SEALS also better at the detection of a single angry face in a large crowd? What about subtle varieties of anger?

On a tangential note, it’s clear that the Defense Department is extremely interested in the neuroscience of warfare. (This Navy SEALS study was actually funded by the Department of Veterans Affairs.) One of my favorite DARPA projects is HORNET, or Human-aided Optical Recognition/Notification of Elusive Threats. (The project is informally referred to as “Luke’s Binoculars”.) The basic concept is to build a visual aid with a built-in EEG monitor, which will continually monitor the brain waves of the subject. The goal of HORNET will be to detect those subconscious fear signals, such as error-related negativity, that are associated with the processing of threats, whether it’s an angry face or a thin wire by the side of the road. Hopefully, by noticing these subliminal symptoms of fear, HORNET can help override our normal inhibitory mechanisms, in which the conscious mind fails to notice a minor threat. In other words, HORNET will help make every soldier think a bit more like a Navy SEAL, exquisitely sensitive to the dangers of the world. Here’s how Northrop Grumman describes the project:

HORNET will utilize a custom helmet equipped with electro-encephalogram electrodes placed on the scalp to record the user’s continuous electrical brain activity. The operator’s neural responses to the presence or absence of potential threats will train the system’s algorithms, which will continue to be refined over time so that the warfighter is always presented with items of relevance to his mission.

Danger Room had a great write up on HORNET last year.