The reactionary gap is a fundamental concept in personal safety and law enforcement. It refers to the distance you must maintain between yourself and a potential threat, allowing you sufficient time to react if the situation escalates.

Reactionary gap can be summed up as the relationship between time and space. More space equates to more time, which in turn provides more opportunities to solve a tactical problem. Conversely, less space means less time, resulting in fewer opportunities to address the issue.

The reactionary gap allows you to maintain a safe distance from potential threats, giving you time to assess the situation and decide on the best course of action. This could be anything from escaping the situation or calling for help to preparing to defend yourself.

Action vs. Reaction

Ballistic motions require a complex sequential interplay between perception, cognition and muscular-skeletal movement. We learn to accomplish predictable ballistic motions by training to forego the feedback process. This is commonly and erroneously referred to as “muscle memory.” The motion is performed smoothly as long as we don’t let other stimuli interfere with the instructional sequence. Speed and accuracy can be enhanced by the repetitive process but within the limits set by neuro-physiological and biomechanical processes.

Master muscle memory in Defensive Shooting Fundamentals

Action is always faster than reaction. Reaction time is the interval time between the presentation of a stimulus and the initiation of the muscular response to that stimulus. The number of stimuli that are presented, each requiring their own response, is a primary factor affecting response. If there’s only one possible response (simple reaction time) it will take less time to react. If there are multiple possible responses (choice reaction time) it will take longer to react.

Reaction time will increase proportionally to the number of possible responses until a point in which it maintains constant despite the increases in possible responses. This is known as Hick’s Law, named after William E. Hick who discovered it in 1952.

Fitts’ Law, named after Paul Fitts who proposed it in a 1954 scientific paper, is a predictive model that applies to human psychomotor behavior. It’s a formal relationship that models speed/accuracy trade-offs in rapid, aimed movement. Fitts also proposed an index of human performance that combines a task’s index of difficulty with the movement time (in seconds) in selecting the target. Fitts’ Law has been shown to generalize a variety of physical activity and ergonomic situations where speed and accuracy play important roles.

The 21-Foot Rule

The “21-Foot Rule” is a principle that originated from a SWAT magazine article by Salt Lake City Police Officer Dennis Tueller titled “How Close is too Close” published in 1983 with a video of the same name. Tueller conducted experiments to determine how quickly an average healthy adult male could cover a distance of seven yards (or 21 feet) — the time was approximately 1.5 seconds. This time frame was significant because it was also the estimated time a trained individual would need to draw a handgun and fire two centered hits on a life-size silhouette at 7 yards.

The 21-Foot Rule was thus born from these findings, suggesting that if an individual armed with a knife or a club was within 21 feet of you, you were within their danger zone. However, it’s important to note that both the distance of 21 feet and the time factor were approximations based on training experience.

Over time, the term 21-Foot Rule started being used in law enforcement training circles, leading to some misconceptions. Some people began to believe that they were automatically justified in shooting a suspect armed with a knife simply because they were 21 feet away. Conversely, others thought they wouldn’t be justified in using deadly force against an attacker further than 21 feet away.

Both Dennis Tueller and Caliber Press, which popularized Tueller’s work, have denounced the notion of such a rule. The truth is the proper use of force and justification of deadly force depends on objective reasonableness and the totality of circumstances.

The Discovery Channel television program MythBusters covered the Tueller drill in a 2012 episode titled “Dual Dilemmas.” The team found that with attacks initiated from 20 feet, it was possible to shoot a knife-wielding attacker when armed with a holstered handgun, but only just as the attacker reached the shooter. At shorter distances, the attacker was always able to stab the defender prior to being shot. It’s important to keep in mind that in the Mythbusters scenario, the subjects were aware in advance of the knife attack and the response (simple reaction time). The reactionary gap would be significantly greater in most real-world scenarios.

While the Tueller drill laid the foundation for the reactionary gap, there is no definitive answer as to how far a reactionary gap should be. Factors like terrain, physical conditioning, situational awareness, skill level and the nature of the attack can affect the required distance. The reactionary gap also varies depending on whether you can see the subject’s hands. This is because hidden hands could potentially conceal a weapon, necessitating a larger gap for safety.

Proactive Self-Defense Measures

Being aware of the reactionary gap allows for proactive measures and tactical advantage. For instance, when in public, position yourself near readily accessible cover or exit points that can provide a quick escape route if needed. Being on the move can make you harder to hit and using effective cover can further enhance your safety. In crowded public areas, which are often targets for attacks, these measures can be particularly useful.

The same principles apply when dealing with non-ballistic weapons like edged or impact weapons. The closer you are to a threat armed with a non-ballistic weapon, the less time you have to react, increasing your risk of injury. On the other hand, maintaining a larger distance gives you more time to respond, thereby reducing your likelihood of getting hurt.

Although the employment of appropriate tactics, techniques and procedures cannot eliminate the reactionary gap, it can lessen it. Understanding and effectively managing the reactionary gap is a vital skill for personal safety. By maintaining an appropriate distance from potential threats and staying alert to changes in the situation, you can significantly enhance your ability to respond effectively to sudden threats.