On combat was published in 2004 by Lt. Col. Dave Grossman. He talks about how the body reacts to stressful situations. The human body performs at its most optimum level between 115bpm and 145bpm. Once your body reaches 115bpm, your fine motor skills begin to deteriorate. He talks about stress acclimation, which is being able to accomplish tasks while your bpm is above 145. Lt. Col. Grossman explains how auditory exclusion works. It is when your body doesn’t register a sound that has just taken place during a high stress situation. The reason your brain doesn’t process the sound is because the brain isn’t processing inputs that seem unnecessary for survival. Many people that have been in explosions do not even have ringing in their ears due to auditory exclusion taking place. He then touches on Maslow’s Four Levels of Mastery. In order, these consist of unconscious incompetence, conscious incompetence, conscious competence, and unconscious competence. Lt. Col. Grossman talks about officer involved shooting and how their memory of the situation is affected. Within the first 24 hours after a shooting officers recall 30 percent of the situation. After 48 hours, officers recall 50 percent. After 72 to 100 hours officers recall 75 to 95 percent. This is a good read and valuable even to citizens. He covers a lot of information that would be valuable for citizens and law enforcement. Most of the book talks about the body response to high stress situations, but he does spend some time covering a lot of other useful information.