Human Error in High-Stress Encounters

Image of a person wearing a belt full of essential gear

In my previous article, Psychological Principles of Combat Training, we looked at some basic human behaviors and how to design training and practice regimens that take advantage of those behaviors. I would like to continue in that same direction and look at basic response types and the underlying causes of human error in high-stress encounters. If we understand why we do the things that we do, we can design more effective training.


It can be said that there are two basic response categories. The first type is a physiological response, and the second type is a psychological response.

Physiological responses occur primarily in the body, not the mind (though they may be the product of psychological conditions). The conscious brain is typically not involved. These response types include chemical reactions such as those that occur in the Fight, Flight or Freeze reaction, as well as natural reflexes.

Psychological responses occur entirely in the brain (or mind). For that reason, these are the actions that will be the focus of this article. Psychological responses fall into three main categories: cognitive, instinctive, and conditioned.

Cognitive responses are generated by conscious thought.

Instinctive responses prevail when there is no training or conditioning. It can be argued that instinct is the mind’s “default program.” Fight, Flight or Freeze is an example of an instinctive response. Instincts can be modified or replaced by conditioning.

Though the terms are sometimes used interchangeably, instincts are different than reflexes. Reflexes are stimulus/response actions that typically bypass the brain entirely. For that reason, training has little effect on reflexes, but can potentially alter instincts entirely.

Conditioned responses are what training is really all about. An effective trainer carefully and intentionally designs a proper response to a given situation type and then meticulously develops the mechanisms to hardwire that response into the subconscious, so that in effect, the response becomes instinctive.

When one is well-trained, practiced, and experienced, there is another type of response. That response is a combination of cognitive, instinctive and conditioned and is the best response type of all – the intuitive response. That is a topic for another article.

Once we gain a basic understanding of the various response types, we move on to acquiring a grasp of the different types of human errors.

Instructor demonstrates a common error made at the range


There are two main types of errors: mistakes and slips.

Mistakes result from conscious actions such as wrong or poor decisions or errant conclusions (cognitive).

Form the wrong goal and you make a mistake …

Form an appropriate goal but screw up the execution and it is likely a slip.

We minimize mistakes through policies and procedures, rules and regulations, goals and objectives. These things help people make the right decisions and allow us to point out when a bad decision is made and why … and in the case of legislation, give us parameters for conduct and punishment.

Slips result from automatic or subconscious behaviors (instinctive or conditioned) and typically manifest themselves in the performance of skilled behaviors. Slips should be of paramount concern to trainers because those are the types of things we have to anticipate, and then through training, develop subconscious programs to avoid.

There are six basic categories of slips: capture errors, description errors, data-driven errors, associative activation errors, loss of activation errors, and mode errors.

Of these six categories of slips, here we will look only at capture errors, data-driven errors and mode errors.

Capture Errors

A capture error occurs when a frequently performed activity subconsciously overrides and replaces an intended activity (captures it).

Typically, a capture error happens when two action sequences have the same or similar initial stages. The well-practiced sequence (i.e., the more automatic motor program) will capture and replace the less familiar one.

Duty belt involving capture error

Duty belt configured similar to the one in the shooting incident involving the capture error, with the Electronic Control Weapon in a strong-hand cross-draw position. To effectively reduce the danger of having a capture error in this configuration, the officer would need to practice drawing the ECW hundreds or even thousands of times.

Most people have probably seen or heard a news report where someone accidentally drives their car through the wall of a gas station or restaurant. In many cases, this behavior is a classic capture error. The driver’s brain initiates the action of depressing the brake pedal. The gas pedal is only a few inches away. Whether due to distraction or some other mental interference, the driver hits the gas pedal instead of the brake. The car starts moving. In the driver’s mind, he is stepping on the brake, but the car is moving, so he steps on the brake harder – not realizing that he is pressing the gas. The car goes faster. He steps harder. Then he crashes. As a police officer, I handled several of these calls. Every time, the driver swore he or she was stepping on the brake.

How does this apply to weapons training (or any other type of training)? On New Year’s Day 2009, Oscar Grant was accidentally shot in the back and killed by a police officer who thought he was firing his TASER. When researching this incident, I found seven similar incidents in as many years, and they all had one thing in common: officers drew their TASERs with the same hand they draw their pistol. They also rarely practiced drawing the TASER, but practiced drawing the pistol considerably more often. What happens is that officers initiate the action of drawing their handgun, but under stress and the distraction of attempting to multi-task, the better-rehearsed motor program of drawing the pistol overrides the intended action of drawing the TASER, and tragedy results.

We can fix this in training but only if we accept that the problem is real. The simple answer is when training with a firearm, only the firearm goes in the weapon hand. Sure, we want to train with both hands, but the strongest subconscious motor program is the one created with the preferred hand – and therefore needs the most attention. When training in any psychomotor skill, consistency is paramount.

Duty belt with ECW in standard draw position

Duty belt with ECW in standard draw position for reaction hand. This would greatly reduce the risk of this type of capture error without prolonged practice -- though practice is still recommended.

Psychologists will argue that to resolve the TASER issue, practicing more with both weapons may eliminate the problem by making both motor programs equally familiar in the subconscious. When someone’s life may be on the line, my personal preference is to be as certain as possible. The best way I can think of to eliminate the risk is to use my reaction hand for non-lethal weapons. Following the same theory, be consistent with where you place your weapon and what type of holster you use. Accuracy is a function of consistency.

Data-Driven Errors

Many human behaviors are automatic responses triggered by the arrival of sensory data. Examples include swatting at an insect you hear buzzing around your head, or ducking when you hear a gunshot.

Sometimes these data-driven activities can intrude into an ongoing action sequence, causing a data-driven error. I have been on the range plenty of times when a piece of ejected brass went down someone’s shirt and they began jumping up and down and waving their gun around the range. I have seen people swat flies with their weapon in their hand, sweeping their own heads with the muzzle.

Another instance where data-driven errors can occur is in what we call command language.

Command language essentially is what you yell at the bad guy either before you shoot him or while you decide if you are justified to shoot him. “Don’t move” and “Drop the weapon” are the only ones I practice. Some people laugh at the fact that I actually practice what to say to a bad guy. The reality is that when you are under extreme stress, if you don’t practice simple, common-sense command language, you may be surprised at what comes out of your mouth.

An officer in Florida on a high-stress traffic stop began to tell a suspect to “Get on the ground.” At that same moment, the suspect put his hand in his coat. That movement essentially initiated a data-driven response by the officer that under no stress would have been, “Get your hands up!” But combine the two in an overloaded brain, and the command that came out was, “Get up!” When the suspect did what he was told, he was shot, because what the officer was thinking was not what he actually said. By practicing a simple command like “Don’t move” or “Drop the weapon,” we program it into our subconscious. In a life-threatening situation, we don’t have to think of what to say.

Mode Errors

Image of a handheld light

My primary light, a 500-lumen light held ice-pick style. It has a simple on/off switch that with light pressure provides momentary on and off capability.

A mode error applies to devices that have different operational modes. Different actions have different outcomes depending on the mode the device is in. Tools that you plan to use under stress need to be simple. This is why we don’t put TASERs on shotguns. Under stress, we forget which trigger to pull or we pull both at the same time. This is also why I don’t carry one of those flashlights that requires you to press the button a different number of times to get the flashlight to work in different modes – like dim, bright, and strobe. Under stress, you will spend conscious brain power trying to get the flashlight to turn on in the correct mode when you should be concentrating on the threat. Again, bad things can happen.

In conclusion, we have looked at some very simple ways to train to avoid subconscious errors. My next article will cover more basic issues that will help you train and practice better so you can win!

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14 Responses to “Human Error in High-Stress Encounters”

  1. David Salamone


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  6. richnable

    Thanks Gary - that is exactly right. While we don't really know how each of us will react until we are in an actual high-stress encounter, we can with some degree of accuracy, predict response types with some degree of probability. That is how we have to gear our training. Past behavior is a good indicator of future behavior and our only crystal ball to predict the future is the study of those general behavior patterns. We can use a general knowledge of human behavior to predict probable outcomes but becasue we are all individuals - nothing is an absolute certainty.

  7. Gary

    Nice article but if I may comment. One cannot know what their reactions may be when a situation does occur. Unless there are simulated training with unpredicted situations most of the time the human body and brain may very well just react. Been there done that

  8. richnable

    You are exactly right. Competition raises the stress levels and causes some interesting errors to manifest themselves. The only caution I have for competition shooters is to realize the differences between competition habbits and habbits that we need for life threatening encounters. Though sometimes they can be similar, often they may not be: which can lead to dangerous conditioning. I actually plan to address this in an upcoming article!

  9. Mark

    The article highlights why I try to shoot competitively when possible. I've done and seen others do some dumb things under pressure even when we knew better and had other intentions. Doing it the right way repeatedly minimizes having to think about it in an emergency when one's attention can't be diverted from the threat to correctly operating the equipment itself.

  10. richnable

    Thanks Paul - One of my main motivations for researching and writing these articles comes from trying to understand why people behave the way that they do under stress so that I could optimize my training classes. You can't have an effective training program unless the training mirrors the real world. We all make great decisions and perform to our best when we are sitting in our easy chairs. When confronted with the stresses of life threatening encounters no one knows how they will act unless they have been there before. Good training makes you go there.