Force Science News #178:

Important new reaction-time study addresses what’s “reasonable”
in armed-suspect encounters & more

In this edition:


I. Important new reaction-time study addresses what’s “reasonable” in armed-suspect encounters


II. Using sobering scientific truths in training


III. Inbox: Readers write about Force Science exhaustion study



I. Important new reaction-time study addresses what’s “reasonable” in armed-suspect encounters


You are confronting an armed suspect, no cover available. He faces you, with his gun at his side, pointed at the ground. Your gun is aimed at him and you’re ready to shoot. He ignores your commands to drop his weapon.


Are you justified in pulling the trigger before he makes any move to point his gun at you?


According to conclusions reached by researchers in a unique new reaction-time study, your preemptively shooting under such circumstances may well be considered reasonable by the standards of Graham v. Connor.


If the offender suddenly points his gun in your direction, you are highly unlikely to get a shot off to defend yourself before he shoots, the researchers documented. Even under ideal circumstances, you probably can fire no faster than simultaneously with the attacker.


These findings “serve to illustrate the extreme danger that armed suspects present to police officers,” the researchers report. “Even when a police officer has his or her gun aimed at [an armed] suspect and the suspect is not aiming at the officer, the officer is still in extreme danger….


“The reasonableness standard [set forth by Graham] is based on what a well-trained, prudent officer would do in a given situation…. Our results show that even well-trained officers…with their guns aimed at a suspect cannot reasonably be expected” to react faster than a suspect can raise his or her gun and fire.


“This is an important study that advances the understanding of the dynamics of deadly force encounters, which often are quite different from the perceptions held by the general public and the media,” says Dr. Bill Lewinski, executive director of the Force Science Institute. “While the Institute was not involved in this project, the findings are fully compatible with our earlier discoveries regarding officers’ reaction times in life-threatening situations.”


The new study was headed by Dr. J. Pete Blair, an associate CJ professor at Texas State University and a former interviewer/trainer for John E. Reid & Associates. His investigative team included representatives of the Advanced Law Enforcement Rapid Response Training (ALERRT) Center at the university and was supported financially by the CJ Division of the Texas governor’s office.


TESTING SET-UP. “Suspects” in the research were 30 male and female CJ students, averaging about 22 years old and mostly Caucasians. The test subjects were 24 male volunteers recruited from an active-shooter training class at a regional SWAT conference. They averaged nearly 10 years’ policing experience, with nearly 5 years on SWAT, and were considered “elite…particularly [in] the use of deadly force.” They averaged about 34 years old and slightly more than half were Caucasian.


Armed with a Glock training pistol that fired marking cartridges, each officer progressed through a series of 10 rooms in an abandoned school, presumably in response to a “generic ‘person with a gun’ call.” In each room, the officer confronted a suspect armed with a similar pistol at a distance of 10 feet. In some cases, the suspect’s gun was at his/her side, pointed at the floor. In others, the gun was pointed at the suspect’s own head in a suicidal pose.


According to prior instruction, one-fifth of the suspects followed the officer’s order to surrender peaceably. The rest, designated as attackers, were told to try to shoot the officer any time they chose “after an initial command to put down the gun was given.” In all cases, officers had their gun up and on target at the outset of the encounter and were instructed to “attempt to shoot first” as soon as they perceived a move to shoot them.


Later, the research team conducted a meticulous frame-by-frame analysis of video recordings of 159 of the shooting exchanges.


REACTION-TIME RESULTS. Analysis showed that the suspects on average were able to fire in just 0.38 second after initial movement of their gun. Officers fired back in an average of 0.39 second after the suspect’s movement began.


Specifically, suspects moved the gun up from their side and fired in an average of 0.36 second and from their head, on average, in 0.40 second. The average officer responded fractionally faster to movement from the side (0.38) than to movement from the head (0.40).


Statistically, the researchers point out, the hair-splitting differences between these various measurements are inconsequential. The initial gun position “did not appear to significantly affect the firing times of suspects,” the team reports. Nor did it “appear to affect the speed with which the officers fired.” Overall, “officers and suspects appear to have fired at about the same time.”


The miniscule edge did go to the suspects, technically. Examined case by case, they shot faster than officers or precisely simultaneously in more than 60% of the encounters. “Even in situations where the officer was faster, there was less than a 0.2-second difference, suggesting that the suspect would still get a shot off in most of these encounters,” the researchers state.


“The process of perceiving the suspect’s movement, interpreting the action, deciding on a response, and executing the response for the officer generally took longer than it took the suspect to execute the action of shooting, even though the officer already had his gun aimed at the suspect.”


And this was in near-ideal conditions from the officers’ perspective. The volunteers were “highly experienced” and “knew they would be encountering suspects with guns.” The confrontations took place in “well-lit rooms,” with only a single offender, “with both parties remaining stationary,” with no distractions, with no attempts by the suspects to deceive the officers by feigning compliance before shooting, with officers not nearly as stressed as they would be “during an actual life-or-death situation,” and with none reporting “confusing sensory and perceptual distortions.”


Moreover, “the suspects extended their arms to bring the gun in line with their eyes before shooting in almost every exchange,” rather than “simply rotating the gun and firing.” Thus their assault was slower than a spontaneous street encounter might be.


The researchers concede that “many of the elements that occur in real-life shootings” would doubtless add significant time to the average officer’s reaction time.


The good news in this study concerns accuracy. Suspect role-players, largely untrained in gun-handling, scored hits only about half the time. With their already on target, officers were able to successfully shoot suspects nearly 90% of the time. This is contrasts with actual OISs, where the reported police accuracy rate is “generally less than 50%,” the study team notes.


CONCLUSIONS. “Police officers have a legal right to use force, including lethal force, when it is reasonable to do so,” the researchers state. “An officer may shoot when there is an imminent risk of harm to self or others, or to stop someone who poses a danger to others if allowed to escape….


“There is a perception amongst some community members that officers are too quick to shoot those who only appear to pose a threat…. There are people who seem to believe that the ‘reasonable’ officer should wait until a suspect with a gun begins to use the gun against the officer before the officer utilizes lethal force. [But] would waiting be reasonable in situations where the suspect has his weapon in hand but not aimed?”


That’s the critical question Blair’s study addresses. “As our findings show, most officers can’t fire faster than a suspect with a weapon in hand, even if it is not aimed at the officer,” his team writes. Consequently, “we think that an officer who decided to shoot [in the kinds of situations tested] meets the legal definition of reasonableness,” given the “close range of the encounter, the lack of available cover, the failure of the suspect to comply with multiple warnings, and the data” collected.


The researchers stress, however, that they “do not believe that the findings support” automatically shooting “everyone with a gun” or “everyone with a gun who does not comply.” Armed encounters vary in their details, and “the individual officer must consider the totality of circumstances” in choosing a fitting response, including whether issuing commands is feasible or desirable before firing.


The researchers believe that certain training implications are clear from their findings. First, they support having officers participate in scenarios similar to those they used to convey “a better understanding of the dynamics involved” in armed confrontations and to “help correct inaccurate beliefs about shooting ability.” Also they believe training should “teach officers how to mitigate the dangers posed by armed suspects” through such means as distance and cover.


They hope that their findings “will help officers, and those who judge the actions of officers, to make more informed decisions about the reasonableness of officers’ actions” in deadly encounters.


A full report on the study has been accepted for publication later this year in the peer-reviewed journal Police Quarterly. Publication can be tracked at:


Meanwhile, Blair has 2 research projects on the board that Force Science News will be following up on in the future. He is underway with a study of room-entry tactics, designed to identify which technique is fastest for revealing subjects hidden in corners, best suited for accurate fire from officers, and least conducive to hits from offenders.


He plans also to comprehensively catalog and analyze active-shooter incidents. Results from the building-entry study, at least, are expected by this fall.



II. Using sobering scientific truths in training


At the recent ILEETA annual conference, long-time instructor Larry Hahn explained in detail how he incorporates Force Science findings into officer-survival training and deplored firearms programs and DT instruction that haven’t yet adapted to scientific truths about action and reaction to better protect LEOs on the street.


A certified Force Science Analyst and former patrol sergeant with the Waterloo (IA) PD, Hahn currently administers Iowa’s regional Law Enforcement Academy at Hawkeye Community College. In his presentation, “Applying Force Science Research to Training,” he emphatically underscored that understanding the lightning speed with which an armed offender can attack and the lag an officer necessarily experiences in responding is critical to developing solid tactics for prevailing in dangerous encounters.


“If officers don’t understand how vulnerable they can be when someone wants to kill them, how can they realistically assess a potential threat and know what’s a reasonable response?” Hahn asks. “How can they be motivated to follow good tactics that turn the action/reaction phenomenon to their advantage?”


SHOCK TREATMENT. In his training, the initial reality immersion is 3-pronged:


• Cold facts. Drawing on reports readily accessible at and in the Force Science News archives, Hahn lays out the sobering facts of threat velocity. He layers on statistical documentation from one study after another showing how suspects in a fraction of a second can produce and fire a gun while even an officer primed for trouble may still be processing what is happening through his behind-the-curve OODA loop.


• Grim reality. Using dash-cam videos of actual shooting encounters, he transforms these sterile statistics into real-time, real-life experiences that often show officers desperately fighting to recover from the speed of the attacks, trying—often unsuccessfully—to save their lives.


• Surprising drills. With simulator exercises and force-on-force drills that employ Airsoft guns, Hahn drives home the vital point that the trainees themselves are not immune to the consequences of harsh science. “Even veteran officers often don’t realize how fast a gunfight can go down,” he says. “They come in thinking they can outdraw and outshoot any threat. This training opens their eyes—and their minds.”


TACTICAL IMPACT. Tactics are then evaluated in light of action/reaction realities. Officers are forced to reconsider such practical field problems as how to approach a downed suspect whose hands are hidden under his body, what positioning to take on a vehicle stop, how to deal with a visible weapon in the suspect’s waistband, whether to attempt a shot at a hostage-taker with a closely clutched captive, and so on.


“The value of movement and the use of cover for delaying or disrupting a suspect’s ability to attack are stressed very strongly,” Hahn explains. For instance, trainees are shown that moving laterally out of the suspect’s line of fire while drawing and shooting is virtually as fast as standing still to shoot—and much more unexpected to the adversary.


“This is making excellent use of Force Science findings,” says Dr. Bill Lewinski, executive director of the Force Science Institute. “As Larry Hahn impresses on his trainees, an officer is so far behind the reactionary curve in some situations that there’s little he or she can do to defend themselves but to attempt to shoot, often after a suspect has already shot at them.


“It is much more desirable to avoid being in that position, if possible, so emphasizing what an officer can do to off-set the action/reaction handicap is a highly constructive element of good training.”


CHALLENGES. Even backed by scientific findings, trainers can face daunting challenges in instilling good reactive behavior, Hahn and Lewinski acknowledge. Hahn mentions, for example, the “training scar” borne by officers who have learned to shoot only while standing stationary. “This response is so deeply ingrained that we have to constantly remind them to move, draw, and fire in crisis scenarios,” Hahn says, “even though they’ve been shown that moving will definitely make them less vulnerable and have practiced moving in repeated drills.”


One of many unknowns in training is how many repetitions of new methods are required to break through bad training from the past. “I’ll bet it is at least quadruple the repetitions needed to learn a new skill for which you have no wrong-way history,” Hahn speculates. “And the problem is compounded by firearms qualification protocols that simply reinforce the old, unscientific ways.”


And then there are trainers who mask reality for their students in truly mind-boggling ways. For example, Hahn says he has witnessed instructors in deadly force exercises tell role-playing suspects to slow down their actions in drawing and firing at an officer so that the officer is guaranteed to fire back before the suspect can get a round off, thus giving the officer the psychological satisfaction of “winning.”


“Officers need to learn to win, that’s true,” Hahn says. “But to distort the unpleasant reality of action versus reaction so that a trainee gains an unwarranted confidence is a profound disservice that could prove fatal. It’s not realistic and it’s not scientific. It’s fraud.”


For more information on practical and successful applications of Force Science findings to training, Hahn can be reached at:



III. Inbox: Readers write about Force Science exhaustion study


In Transmission #176 [4/25/11], we reported final findings of Force Science’s recent research into the limits of officer endurance in physical confrontations and the impact of exhaustion on memory. Your responses included:


Aerobic vs. anaerobic fitness


The short duration of the activity and the massive increases in blood lactate suggest that the primary metabolic pathway utilized by the experimental group was NOT aerobic, but rather, anaerobic. So if the fitness level of a given officer was rated as high employing an aerobic measure, then the fact that an officer fatigued in roughly the same time as a less fit officer means only that the “more fit officer” had indeed no more training in utilizing the anaerobic pathway than did the less fit officer. You cannot train only aerobically and expect that you can derive anaerobic fitness. Training for high intensity, anaerobic engagements should make use of brief, high intensity efforts.


H. Anthony Semone, PhD

Member, Police Policy Studies Council

Specialist in clinical, health, and exercise psychology

Wyndmoor, PA



Answers about memory after desperate fights


I have been an officer for 40 years, and have finally found the science that I could not verbalize regarding what happens during the time you are fighting for your life. Why you remember most of the action as if it was in slow motion, but other parts are impossible to remember! Your article helps me to have a better insight about memories and lapses. Thank you.


Ofcr. Stewart Barquist

University of Las Vegas (NV) PD


Have thoughts or comments you want to share with Force Science News? You can always e-mail us at: We welcome notes from readers!



Written by Force Science Institute

May 15th, 2011 at 1:52 pm

© 2017 Force Science Institute Ltd.