The Failure of Common Sense

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“Common sense dictates that in situations where a law enforcement officer has a suspect in their rifle sight, the officer could pull the trigger before any suspect could move a gun toward the officer or another, aim and fire.”1

Pulled from a recent legal filing, the above quote is probably a fair characterization of “common sense.”  It is certainly a belief held by many attorneys and community members whose exposure to deadly force may have been mercifully limited to Hollywood action films. 

So, common sense? Maybe.  But, correct?  Definitely not.

Stimulus / Response

In Force Science News, Training the Humanity Out of Cops (and Other Myths), we observed that police, like all humans, are constrained by the reactionary gap.2 That is, there is always going to be a time lag between a stimulus and a response.  Certainly, fast cops might outshoot slow suspects.  But, even the fastest officers need time to recognize and respond to a perceived threat. 

In the opening quote, the author limits the response time to the time required to “pull the trigger.”  But, in the real world, officers must first detect the stimulus (e.g., object and movement), recognize the context and meaning of that stimulus (i.e., situational understanding), and then decide whether and how to respond.  Once a decision is made, officers still need time to perform the movements required by the response.  In cases involving a rifle, this could include the time needed to aim, manipulate a safety, move their finger to the trigger, and press the trigger.

Together, the mental processing time, movement time, and device manipulation time make up the “response time.”  With practice, officers can decrease response time by speeding up and overlapping these processes, but they can never eliminate the stimulus/response gap.  And, no matter how fast an officer responds to lethal threats, that response will always involve more than simply pulling the trigger.

Turning to VirTra for Realistic Simulations

Convincing readers that even highly-skilled police officers must contend with the stimulus/response gap may be a job best served by realistic simulations.  For a highly-accurate visual demonstration of how the stimulus/response gap can influence officer performance, Force Science turned to VirTra

VirTra specializes in police and military simulator training. Their simulators, interactive weapons, and training scenarios are designed for maximum realism. VirTra’s judgmental use-of-force scenarios have been developed to accurately reflect the reality of perception, decision-making, and timing of human performance.

To visually demonstrate the stimulus/response gap, we asked the experts at VirTra to create a simulation that required a highly-skilled officer to respond to an armed assault.  The goal was to determine whether a law enforcement officer with a rifle could pull the trigger before the suspect could move a gun toward the officer, aim, and fire.  Lon Bartel, VirTra’s Vice President of Training and Curriculum, coordinated the demonstration, and the results were sobering. 

The Simulation Design

To provide the greatest chance to outperform the simulated suspect, Lon Bartel selected Mr. Jeff Knaup to perform as the responding officer.  Jeff is a retired 30-year police officer with nearly 20 years of advanced tactical training and experience.  As a former full-time SWAT operator, Jeff was expected to respond quickly and accurately to the simulated assault.  If an officer with Jeff’s experience could not outshoot the suspect, it would be unreasonable to expect officers with less training to accomplish that feat.

The suspect in the scenario was shown standing while pointing a gun at his own head.  From that position, he suddenly pointed the gun toward the officer, aimed, and fired.  The officer was instructed to maintain a site picture of the suspect but told not to fire until he perceived the suspect moving the gun toward him.

The Results

In the first scenario, the officer was instructed to keep the safety engaged and his finger indexed along the rifle frame until he decided to fire.  In that scenario, the suspect was able to move, aim, and fire the gun at the officer in .40 seconds.  Officer Knaup responded to the suspect’s assault in .86 seconds.  A slow-motion review of the video revealed that the suspect was able to fire two shots at the officer before the officer’s first shot struck him.

Scenario 1

In the second scenario, the officer was instructed to keep the safety off and his finger on the trigger.  The question was whether eliminating the rifle manipulation time would allow the officer to overcome the stimulus/response gap.  In that scenario, the suspect again moved, aimed, and fired the gun at the officer in .40 seconds.  Officer Knaup responded to the suspect’s assault in .60 seconds.  Even after eliminating the time needed to disengage the safety and move to the trigger (and with the officer having already seen the assault one time), slow-motion revealed that the suspect was able to get one shot off before the officer’s first shot struck him. 

Scenario 2

Back to Reality

VirTra’s stimulus/response gap demonstration was designed to put the officer in the best possible position to respond to the simulated suspect’s assault. Even the suspect’s assault time (0.40 seconds) was substantially slower than assault times recorded in real life encounters and research studies (avg. 0.25 seconds).3

The highly-skilled officer in this demonstration was purposefully set up to engage in simple decision making (i.e., one stimulus, one response), and yet the suspect was still able to fire at the officer before the officer could effectively respond. 

In the real world, officers are not similarly set up for success.  In, You Don’t Have to Shoot First; But You Better Do Something!, we emphasized this reality:

In the real world, officers do not have the luxury of standing perfectly still and intently focusing on possible weapons.  They are scanning for available cover, improving their position, watching for crossfire, considering backdrops, attempting de-escalation, communicating with responding units, and coordinating with back officers.

This divided attention can significantly increase the time it takes for an officer to accurately perceive and consciously verify that a suspect has pulled a gun.  But multitasking isn’t the only factor that affects perception and threat recognition.

In the real world, an officer’s physical capacity to see can affect perception, identification, and response time.  As can environmental conditions like distance, light, shadows, wind, rain, and other physical obstructions.

We know that divided attention, physical limitations, and the environment can slow perception and response time; the question is, by how much?  The answer is, we don’t know. In complex, real-world use-of-force encounters, response time simply has too many variables to guess.  But whatever that response time proves to be, it will be significantly longer than the …[time]… necessary to respond to a simple [movement].4

The Mission to Evolve Common Sense

When watching simulations, it can be easy to forget the consequences of letting the suspect fire even a single shot before stopping the threat. Those incoming rounds can “extend the officer’s response time…or prevent it altogether.”5

The author of the opening quote found it important to use trigger-pull timing as the most relevant factor in stopping the threat.   What may have been lost is that the trigger pull itself does not stop threats.  Where a firearm is necessary to stop deadly threats, hitting the person early enough, often enough, and in a location that instantly incapacitates or dissuades them may be required.

Of course, it is certainly the case that not everyone armed with a firearm constitutes an imminent threat to officers or others.  Police officers frequently, and often at great risk to themselves, resolve critical incidents without violence, even when those in crisis possess a gun.

It is worth repeating here,

“To admit that action beats reaction is not to endorse a “shoot first” mentality. Reaction studies have done much more than help us understand time-compressed shooting decisions.

Police, more than any other profession, appreciate the immense difficulty of identifying and responding to real-world assaults. To avoid split-second decisions, they have learned to recognize and value threat cues and suspicious patterns of conduct (schemas). Knowing the speed of assaults is why they give orders and prioritize tactics that reduce a suspect’s ability, opportunity, and willingness to assault them.

When circumstances tend toward a possible armed assault, speed studies remind officers to aggressively look to buy time, create space, and negotiate from positions of advantage; before the threat materializes…and so that nobody has to shoot first.”5

Force Science and VirTra will continue to partner to ensure that human performance is accurately reflected in realistic training development—and that honest accountability follows an officer’s use of force.

In the meantime, we thank VirTra for helping us demonstrate that, even with a suspect in their rifle sight, officers cannot reasonably be expected to pull the trigger before a suspect could move a gun, aim, and fire.  An expert lesson we hope will soon evolve to common sense.

  1. https://www.documentcloud.org/documents/23889499-klum-amended-petition []
  2. Kliem, L.V. (2023).  Training the Humanity Out of Cops (and Other Myths, Force Science News, 2023. []
  3. See Kantor, Michael & Lewinski, William & Garg, Hina & Tenbrink, Joel & Lau, Jeff & Pettitt, Robert. (2022). Kinematic Analysis of Naive Shooters in Common Law Enforcement Encounters. Journal of Forensic Biomechanics. []
  4. Kliem, L.V. (2020). You Don’t Have to Shoot First; But You Better Do Something!, Force Science News, 2020. []
  5. Id. [] []
16 Responses
    1. As I learned in real life: If it’s training it isn’t real; and if it’s real, it isn’t training. No matter how realistic the practice it can never replicate the speed of a real encounter. This has been recognized in athletics for a long time. Training does give you a better chance than no training or little training. I think your most important point was the fact that real situations present one with so many variables that an officer has to consider that we are at a disadvantage in most situations while the adversary really can focus on doing their worse.

  1. The videos are compelling. The supporting information regarding the differences between a simple stimulus-response decision (essentially predetermined – a ‘race’ even!), amplifies the compelling nature of the videos. Real-world decisions simply do not happen that ‘cleanly’. Real-world situations are complex, confusing, stressful, and, perhaps most importantly, have real-world consequences, that no simulator can replicate. This is another great article on the subject of the ‘reactionary gap – reminding us of the ‘Tueller Drill’, and the original “PPCT Stages of Reaction Time” model: “Perceive”; “Analyze/Evaluate”; “Formulate Plan”; “Initiate Motor Action” – add “Movement Time” to this and you have “Total Response Time”. Yet people still don’t get it – they do not understand ‘brain time’ (threat perception time, figuring-it-out-time, decision-making/planning time). Nor do they understand movement time (time to actually perform the action decided upon – either physically, or by manipulating a system that has its own functionality time). We AIM at the present, FIRE at the past, and HIT the future! Another great article from FSI. Thanks.

    1. Wyatt

      Great point. In these scenarios, the officer already knows what the suspect will do and knows what’s required of him. Even then, the reactionary gap is not overcome. We always fight the uphill battle. We never know what the suspect will do, what external distractions will be in play, and on and on.

  2. Larry E. capps

    As always, another great article from Force Science. Just a thought, but have you ever considered submitting an article like this, and this would be a good one in my view, to some major newspapers as an editorial or opinion piece etc. As a retired officer I believe the more we can help educate the public on sensitive police issues, the better it will be for everyone. As a former police officer I certainly enjoy your articles, as I’m sure most officers do as well–and I suspect a good portion of the reading public would like them too.
    Keep up the good work!

  3. Stan Neufeld

    A tremendous article!
    I experienced this exact situation in 2014. I’ve been retired now for almost 5 years and I still process my “reactionary time.”
    I was told about Force Science at the time and I really enjoy reading it’s articles.
    Yes, it would be great to have those lawyers who are quick to provide their expertise in this, go through a stimulus response scenario and experience it!

    1. Von Kliem

      He was not. We did not want multi-tasking, but your point could have been added as another movement that could have added to response time.

  4. NN

    Worth noting here is the time it takes for a fatal shot to actually take effect. I responded to a person with a gun call as a back-up. Just before I arrived the first officer reported he was there and she did, in fact, have a gun. As I am arriving, I can see her standing in the open door of her car, he in the open door of his. Both cars are facing each other and he has his gun aimed in her direction. I took my eyes off them long enough to relocate the parking lot entrance. As I looked away, I heard a single gunshot. I looked back toward them, thinking he has shot at her. She actually shot herself in the center of the chest. As I watch, she gets into her car and closes the door. I park and get out. He yells to me, “she shot herself. she still has the gun. I can’t see her hands.”. While he covers, I approach from the passenger side. I can see her hands in her lap and the gun in the passenger seat. I can also see blood running from the center of her chest. When I check her she is dead. Yes it only took her a few seconds to die, but she was able to do all that with a fatal heart shot from a .38 caliber revolver. Unlike the Hollywood version with is instantaneous death from a single gunshot.

    1. Von Kliem

      I couldn’t agree more. Wound effects influence timing of response options and realistic expectations on how close is too close.


  5. Hank

    After almost 40 years in Law Enforcement and many years as a firearms instructor, I do not belive there is any such thing as “common sense.” If the was, we wouldn’t have to train anyone.

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