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How ‘dispatch priming’ can drive some disastrous shooting decisions

Officers expecting a gun to be present are much more likely to shoot a suspect who is holding nothing more threatening than a cell phone


Such “mistake-of-fact” confrontations – where police perceive someone as “armed and dangerous” but who turns out post-shooting to have been “neither armed nor immediately dangerous” – are among the most controversial events in the criminal justice system, the new study notes.


Article reprinted from Force Science News #380

“Officers often have to make decisions in situations where information, though provided by apparently trusted sources, may be incomplete and/or inaccurate. Understanding the human factors that drive these tragedies is critical for OIS investigators and use-of-force reviewers. And understanding the risk of being unconsciously influenced by inaccurate dispatches should be a strong reminder to street officers to maintain alertness, and maximize time, distance, and cover whenever possible in their approaches.”

- Dr. William Lewinski, Executive Director, Force Science Institute

A study of a little-explored phenomenon called “dispatch priming” reveals how erroneous information given to officers before they reach a scene can set them up unwittingly for making disastrous shooting decisions once they confront the subject of the call.

Officers expecting a gun to be present, based on pre-arrival communications, are much more likely to shoot a suspect who is holding nothing more threatening than a cell phone, for example.

Such “mistake-of-fact” confrontations – where police perceive someone as “armed and dangerous” but who turns out post-shooting to have been “neither armed nor immediately dangerous” – are among the most controversial events in the criminal justice system, the new study notes.

The study was conducted by Force Science instructor Paul Taylor, an Advanced Force Science Specialist and former municipal officer and sheriff’s deputy who is currently a doctoral candidate at the University at Albany-SUNY.

At this writing, his paper, “Dispatch Priming and the Police Decision to Use Deadly Force,” is pending publication in the journal Criminology.

Here are highlights of his findings, along with their associated psychological underpinnings.


Taylor tested the reactions of roughly 300 active-duty LEOs to decision-making scenarios in an interactive firearms training simulator. Most of these volunteers were male patrol officers, ranging in age from their 20s to their 60s, with an average of 11 years on the job. They represented 18 agencies in two states and were believed to be a typical cross-section of U.S. law enforcement.

Facing a blank simulator screen one at a time with a laser training pistol, all the officers heard the same audio dispatch: a “possible trespass in progress” involving an unfamiliar male who was walking around a house in a residential neighborhood, “peering in the windows.” His race (white), behavior and clothing were described.

That’s all that a control group of 100 officers was told about the call. The other officers were randomly given a supplementary dispatch “update” while they were “en route” to the scene. Half of them were advised that the “subject appears to be holding a gun,” the other half that the “subject appears to be talking on a cell phone.”

All the volunteers were then exposed to a video flashed on the screen of a man matching the description of the suspect, standing facing the officers with his hands in his jacket pocket. Officers were told to regard him as the first person they met at the scene.

For about half the volunteers, the man after a few seconds “rapidly pulled his right hand from his pocket and pointed a cell phone at the officers as if to film them.” For the other half, the man quickly withdrew a handgun and pointed it at them “as if to shoot them.”

The officers had to make a time-pressured decision to shoot or not shoot, with their life potentially at stake.

Shooting at any time during the cell phone scenario was considered an error, Taylor explains, as was not shooting during the gun scenario.

Taylor’s goal going into the tests was to see whether inaccurate pre-arrival information about what a subject was holding in his hand would unconsciously “prime” officers to make improper shooting decisions at the scene – and it did.


“[P]riming officers with incorrect dispatched information about what a subject was holding significantly increased the likelihood” for a shooting error, Taylor writes, while “priming officers with the correct information...significantly decreased the likelihood for error.” Specifically:

  • Officers who were told en route that the subject appeared to be holding a gun shot the person who actually presented a cell phone more than twice as often as officers in the control group did (62 percent v. 28 percent); a significantly high rate of mistake-of-fact decisions.
  • Only 6 percent of officers who had been advised that the subject appeared to be talking on a cell phone ended up inappropriately shooting the suspect who then did present a cell phone in the video – an error rate 10 times less than the inaccurately gun-primed group and nearly five times less than the control group. The 94 percent majority who did not shoot “were able to [accurately] anticipate what the subject was holding and responded appropriately, despite the speed” with which the object in question was presented, Taylor states.
  • Interestingly, all officers who experienced the pointed-gun video accurately responded by shooting, regardless of what prior priming, if any, they may have received. However, Taylor observed anecdotally that officers who had received the cell phone prime “shot much later [when the gun came out] than officers who had received either the gun prime or control dispatch treatments.”


Taylor draws on his Force Science training and other psychological research findings to explain why such outcomes likely occurred.

“When dispatched to a call, an officer’s initial understanding of the incident will be formed almost entirely by the information received from dispatch,” he writes. “[I]n the face of uncertainty, people tend to cling to their initial interpretation of an unfolding event, even when presented [subsequently] with better data.”

Forced to make a difficult decision, people tend to give “greater credence to available information, as opposed to that which is not [yet] known, [and they] will overestimate the accuracy of the information at hand,” Taylor explains. “This is particularly true [in] novel situations,” and for most officers an urgent life-or-death moment is a “relative rarity.”

In situations where only fragmentary information is available and there isn’t time to carefully weigh relevant options, people depend on “heuristics” for quick decision-making, Taylor points out. Heuristics are “cognitive shortcuts,” based on patterns people recognize from their personal experience.

In the context of Taylor’s experiment, the heuristic would be the mental model likely triggered for experienced officers by a suspect suddenly withdrawing a hidden hand and shoving an object forward in an aggressive manner. Under time pressure and the potential of imminent death, plus the psychological influence of gun-oriented dispatch priming, this behavior could readily be interpreted as warranting an immediate deadly force reaction.

Such a shortcut could save an officer’s life. But the downside of heuristics, Taylor explains, is that they “can and regularly do result in error.”

He cites two real-world mistake-of-fact shootings in which the psychology of erroneous dispatch priming likely played a fateful role. In one, officers were sent to deal with a subject “brandishing a knife.” Moments after the first officer arrived, he shot and killed a man who approached him with a pen in his hand. In the other case, officers were dispatched to see about an elderly man “brandishing a revolver.” He was fatally shot when he pulled a wooden crucifix from his pocket.


Other psychological concepts are discussed in Taylor’s analysis of his findings: confirmation bias, goal conflict, “brittle” decision-making, “opaque problem space” and so on.

But the main take-away is a message of awareness – for officers, for investigators, for trainers, for police attorneys, for review-board members and for PIOs, all of whom may be challenged to explain how some mistake-of-fact shootings, which may seem patently irrational in reflection, could reasonably look much different in the moment.

Taylor writes: “[I]t is unlikely and unrealistic to assume dispatchers will not pass information about the presence of a weapon on to responding officers. It is just as unlikely, unrealistic, and perhaps even unreasonable to assume officers won’t use the information dispatch provides them to inform their decision-making in the field.

“[U]nderstanding that officers will rely on dispatched information to make decisions and that that, in turn, will increase the risk of error may encourage officers and agencies to employ tactics that, where possible, allow officers more time in which to evaluate a situation before being forced to make such consequential decisions.”

The FSRC was launched in 2004 by Executive Director Bill Lewinski, PhD. -- a specialist in police psychology -- to conduct unique lethal-force experiments. The non-profit FSRC, based at Minnesota State University-Mankato, uses sophisticated time-and-motion measurements to document-for the first time-critical hidden truths about the physical and mental dynamics of life-threatening events, particularly officer-involved shootings. Its startling findings profoundly impact on officer training and safety and on the public’s naive perceptions.