Improving the Accuracy of Firearm Identification in a Dynamic Use of Force Scenario

AuthorM. Hunter Martaindale
Published date01 March 2021
Date01 March 2021
Subject MatterArticles
untitled Article
Police Quarterly
Improving the
2021, Vol. 24(1) 104–130
! The Author(s) 2020
Accuracy of Firearm
Article reuse guidelines:
DOI: 10.1177/1098611120944387
Identification in a
Dynamic Use of
Force Scenario
M. Hunter Martaindale1
Law enforcement officers are sometimes required to make split-second use of force
decisions. One factor that can impact their decision-making process is the presence
of a weapon. This experiment sought to improve the speed and accuracy of weapon
identification in a dynamic use of force scenario through the principles of deliberate
practice. This research utilized randomized control trial with random assignment to
either a control or test condition. Eighty-seven participants completed the pretest,
intervention, and posttest. Participants’ vision was recorded via a mobile vision-
tracker. With only 20 minutes of training, the test group made 1/3 the amount of
decision errors as the control group (Cohen’s d ¼ 0.95). The test group was about
16% faster than the control group at visually finding the object in the suspect’s hand
and determining if it was a gun or not (Cohen’s d ¼ 0.91).
decision-making, police training, training, use of force, vision-training
1Texas State University, ALERRT Center
Corresponding Author:
M. Hunter Martaindale, 1251 Sadler Drive, Suite 1200, San Marcos, TX 78666, United States.

In recent years, there have been instances where police officers have erroneously
applied deadly force (i.e., the deadly force was applied when it should not have
been). In these cases, the civilian was either unarmed or had an object other than
a gun in his hand (e.g., a wallet). For example, on September 4, 2014, South
Carolina State Trooper Sean Groubert initiated a traffic stop for a seat belt
violation. The dash-mounted camera within his patrol car captured the whole
scene. The driver, Levar Jones, pulled into a gas station parking lot. Once his
vehicle came to a stop, Jones stepped out of the vehicle. Groubert asked Jones to
produce his driver’s license. Mr. Jones abruptly turned toward his vehicle to
retrieve his wallet. While Jones was reaching into the vehicle, Groubert repeat-
edly yelled at him to “get out of the car.” As Jones backed out of the vehicle and
turned back around with his wallet in hand, Groubert fired four shots.
Fortunately, Jones survived being struck in the hip by one bullet (BBC News,
No weapon was found in Jones’ vehicle. Groubert stated that he saw Jones
lunge into the vehicle and then make a quick movement back toward the troop-
er. It appeared Groubert applied a heuristic response (i.e., a mental shortcut to
speed up decision-making) to Jones’ movement rather than positively identify-
ing the item in his hand. As a result, Groubert was arrested. In March 2016,
Groubert plead guilty to one felony count of assault and battery of a high and
aggravated nature. He was sentenced to 12 years in prison (McLeod, 2017).
Because of this, and other tragic incidents, I wondered if a simple training
method could be developed to both (1) improve the speed in which officers
are able to visually find, and verbalize, an object in a dynamic (i.e., quickly
evolving) use-of-force situation, and (2) improve officers’ ability to accurately
identify an object as a gun. Therefore, the principal research question was:
Can a vision-training program based on the concepts of deliberate practice
improve an individual’s ability to correctly identify a gun in a dynamic
use-of-force scenario?
Literature Review
The case of former trooper Groubert illustrates the life or death decisions that
officers must make—sometimes in a matter of seconds—and what can happen
when an officer makes an erroneous decision to shoot. Recent use-of-force cases
(e.g., George Floyd in Minneapolis, Minnesota; Breonna Taylor in Louisville,
Kentucky; Levar Jones in Columbia, South Carolina; Tamir Rice in Cleveland,
Ohio; and Charles Kinsey in North Miami, Florida) have highlighted the issues
surrounding police training and decision-making. While such cases receive much
attention in the media, it is well known that prevalence of police use of force in
the general population is exceedingly rare. According to the Police-Public
Contact Survey conducted by the Bureau of Justice Statistics, data collected
from 2002 to 2011 reveal an estimated annual average of 44 million people

Police Quarterly 24(1)
aged 16 or older who had one or more face-to-face contacts with police. Of those
who experienced police contact, only 1.6% reported the threat or use of non-
lethal force (Hyland et al., 2015). For example, a law enforcement officer could
threaten to use OC Spray as an application of force, or the officer could actually
use OC Spray should the situation call for it. Other forms of nonlethal force
include, hand controls, baton, CED (Taser), bean bag, rubber bullets, etc.
The frequency of the erroneous application of force is difficult to determine.
In 2016, the Washington Post recorded 963 police shootings nationwide that
resulted in the loss of a civilian’s life. Of these, 48 events resulted in an unarmed
civilian being shot.1 Five of these 48 events occurred because the police officer
misidentified an item as a gun. Five deaths out of 963 is not a trivial loss of life.
The loss of an innocent life is not merely an emotional loss for the civilian’s
loved ones. Each of these incidents can also result in multimillion-dollar mon-
etary settlements by the law enforcement agency or city. Additionally, although
rare, an officer may lose his or her job, or even go to prison. The effects of an
erroneous shooting are far reaching. Furthermore, these data do not capture
events where the civilian did not die from injuries, wasn’t struck by the officer’s
shot, or in which the officer applied more force than was legally justified due to
misidentifying the threat level posed by the suspect. Because of these facets, the
actual number of cases where erroneous force was applied is unknown.
Visual Acuity
The core of the research seeks to train officers to more effectively distinguish
between firearms and innocuous objects (e.g., wallets). It is important to have a
basic understanding of how the human visual system works. In simple terms,
light that is reflected from surfaces in the environment is focused through the
eye’s lens. The refracted light then comes in contact with the retina. The retina is
composed of sensory cells known as rods and cones. Rods and cones are respon-
sible for converting the light to electrical impulses to be processed by the visual
cortex (Ahmad et al., 2003). The concentration of rods and cones are densest in
an area at the back of the retina known as the fovea. Because of this dense
concentration, it is the fovea that is responsible for the most accurate vision.
Visual acuity drops rapidly as imagery moves away from the optimal angular
distance from the fovea—1 to 2 degrees of arc (Ruch, 1965). Foveal vision is the
area where an individual’s primary visual focus is concentrated.
To put foveal vision into perspective, 2 degrees of arc is equivalent to the
width of the thumb when the arm is fully extended in front of an individual.
If the individual concentrates on the thumb, she is utilizing her foveal vision.
However, if she were to try and see items outside of her foveal vision, without
shifting her eyes, her visual acuity would drop precipitously (she would be
using peripheral vision in this instance; see Figure 1 below; Billinghurst &
Thomas, 2016). Ruch (1965) found that acuity falls to 50% at 2.5 degrees,

Figure 1. Peripheral Vision Diagram.
25% at 7.5 degrees, and 4% in the furthest periphery. In other words, only
50% of the available visual data is gathered when foveal vision is merely 0.5
degrees away from an item. However, it is not apparent that visual data are
missing because the visual system will fill in the missing information based
upon what is present, previous experiences, and what one expects to see (Otten
et al., 2017). In short, when information is missing, the brain will guess at the
missing details and fill them in to complete the visual world. The images the
brain uses to fill in missing information may be dependent on a variety of
factors including heuristics developed through direct experiences or implicit
biases (see the Visual performance and law enforcement section for additional
discussion). Consider the following example: A law enforcement officer
approaches a group of people. An individual standing to the right of the officer
pulls out a black object (the individual is in the officer’s peripheral vision).
The vision literature would suggest when it comes to identifying items during
a dynamic situation such as this, it is critical that officers place their foveal
vision on the item to positively identify any potential weapon. If they do not,
the brain will fill in the details which may result in the officer “seeing” a firearm
when the suspect is holding a wallet, for example.
Vision Training and Performance
Scholars have long sought to understand how vision training may impact sports
performance. Much of the scholarly efforts focused on differences between
expert and novice athletes’ ability to visually fixate (i.e., utilize foveal vision)
on important cues in their respective sports (Bard & Fleury, 1981; Petrakis,

Police Quarterly 24(1)
1986, 1987; Salmela & Fiorito, 1979; Tyldesley et al., 1982; Vickers, 1992).
Tyldesley et al....

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