During life or death situations, there are physiological reactions and bodily responses that occur, which can and do impact officer’s tactical training. Since Ferguson, there has been much more negative media attention about an officer’s reactions during deadly situations. Unfortunately, most people do not understand the confounding factors that an officer is faced with during a critical situation such as history with the offender, past experiences, location history, speed of real time, etc. However, one aspect that is most important is the biological aspect of the “fight or flight” stress response that occurs in the human body that is not being addressed to understand officer’s reactions.
Humans, like every other mammal, have a biological and physiological reaction in threatening situations and an officer’s trained responses will be limited due to human biology. Specifically, Siddle & Grossman suggest that when the heart rate reaches above 175 beats per minute (BPM), the most significant symptoms of the sympathetic nervous system occur and vasoconstriction (restricted blood vessels causing reduced blood flow) will be at its highest, as well as auditory exclusion and tunnel vision. Tactical training can and does help an officer anticipate and identify these bodily responses, as well as practice to limit the effect of these innate factors, but the biological response cannot be completed negated.
The “fight or flight” stress response often affects what an officer hears, sees, and can do despite tactical training. These innate body alarm systems will provide lightning fast response to threat which keeps you alive, which is the most important factor in deadly force encounters. Once danger has been sensed, the sympathetic nervous system (SNS) is activated and anything the body deems as non-essential will be limited and suppressed. Therefore, if someone just ate a large meal, the body would not work on digestion and may even void the bladder to concentrate on other lifesaving reactions such as getting blood to the extremities to help the body move quickly and to limit the amount of blood loss to vital organs, if injured. The body’s physiological responses to life and death situations often cause auditory exclusion (temporary loss of hearing), tunnel vision, loss of near, monocular, and night vision, loss of motor control, and vasoconstriction. Solomon & Horn (1986) found that 83% of officers who had been in a police shooting experienced a time distortion, 67% had auditory exclusion, and 56% had a visual disturbance. Arthwhol & Christensen (1997) found 88% of officers had a distortion of sound during a police shooting. Hence, tactical training does help but it does not eliminate or override human biology in life or death situations.

During life or death situations, the body will also assess the situation in a more global way and jump to conclusions based on rough similarities to keep itself alive. For example, if somebody is holding something shiny and metal in the hand and acting aggressive, one may conclude it could be some type of weapon. If one does not, they could likely be stabbed or shot and therefore, the human body will not allow the body to risk their life to assume it is not dangerous. In fact, when the body’s alarm system is activated, adrenaline is released, and the body received a burst of energy, blood pumps faster, muscles tense, eyes widen, breath is faster, hands tremble, etc. As the body’s alarm system is activated, fine motor skills (writing, typing) deteriorate and gross motor skills (running, jumping) improve. According to Siddle & Grossman, the optimal performance for an officer in a life or death situations will be between 115-145 BPM as complex motor skills, visual reaction time, and cognitive reaction time will be at its highest. When an officers heart rate increases above 145, complex motor skills deteriorate.
All research has found that despite police training, biology influences officers psychological reactions during life or death situations. Despite some civilians wanting or expecting officers to be able to overcome human biology, they cannot. Officers are just like every other human. It is important for police departments, police officers, civilians, and the court system to understand that when an officer says he or she cannot recall or has a distortion to their report, this is common because of biology and not due to an officer lying. Officers can practice breath control to decrease the impact of biology taking over during critical incident. Stay Safe!