We really know only a percentage of the complexity of the human brain. It is the center of conscious thought, language processing, imagination, calculation, memory, abstract conceptual thought and an almost infinite number of tasks. The brain is constantly attempting to make sense of stimulus — always processing and categorizing information. The human mind generalizes for it to make sense of otherwise unrelated phenomena. For example, the brain enables us to distinguish a threat in camouflage from a similar background.
The brain's ability to recognize anomalies increases survivability. Distinguishing a threat amongst non-threats is an example of pattern recognition. This skill is especially beneficial to protective detail members. An emotionally distraught face distinguished from a crowd of a smiling faces might be a clue for agents to anticipate imminent danger.
Regular exposure to training conditions can massage the subconscious into quickly spotting anomalies. After a few years of service, most officers are capable human lie detectors with remarkable accuracy. Even without formal training, their subconscious recognizes when a person's mannerisms are incongruent with what is coming out of his or her mouth. Recent studies show that about one out of a thousand acquire this talent naturally. The most logical explanation is that they trained themselves, through exposure, to automate their responses.
Most people can detect overt expressions. What distinguishes human lie detectors is their ability to read micro expressions that flash unnoticeably (sometimes as quickly as 1/25 of a second) to the uninitiated. These are subconscious non verbal communications that reveal another layer of a person. It is theorized that people with uncanny lie detector abilities generally read micro expressions quicker.
The fact is a person's subconscious, precipitated by training, is infinitely faster than a person's conscious efforts. For example, how does a wide receiver manage to catch a high pass and set two toes in-bounds in a fraction of a second? Training and automation. Why are some people naturally better at this task than others? Automation.
Training creates an automated response. This is the "muscle memory" misnomer that shooting instructors use. Obviously, muscle does not have memory. If it did, we would all convince our muscles to remember when we were in our 20s.
Training is the brain's ability to form pathways for a task; the task is "learned" when the brain finds efficient neural pathways. The pathways create a network to the various cortices. Thus, there is a series of connections to the visual cortex for an officer to recognize and orient on a B-27 or a Tactical TED.
The more robust the network of connections, the better the muscle memory. The connections strengthen each other and create other associations. The more durable the association from practice, the smoother the person's response. The product of these new associations is called behavior.
Observe, orient, decide, act
The response to a threat is smoother because training causes the brain to observe and orient faster. These are the first two components of OODA (Observe, Orient, Decide and Act), also known as the OODA Loop. This system theory is the brainchild of the late Col. John Boyd, who theorized that a person undergoes a constant interaction with the changing environment. Scholars of the OODA Loop know that the quicker a person can observe and orient, the better his or her response to a threat. Boyd proved this true time and again by prevailing as a fighter pilot and as an outspoken military trainer.
Despite his reputed abrasive behavior, Boyd could be considered the architect of winning modern day tactics. His résumé included 50 years of experience and a short call out of retirement to consult on the winning maneuver in Desert Storm.