Perceptions of Movement Patterns and Concealment Detection in Naive Observers and Law Enforcement Officers: A Lens Model Analysis

AuthorDawn M. Sweet,Adele Quigley-Mcbride,Christian A. Meissner,Katharine Ringstad
Published date01 March 2023
Date01 March 2023
Subject MatterArticles
CRIMINAL JUSTICE AND BEHAVIOR, 2023, Vol. 50, No. 3, March 2023, 351 –373.
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© 2022 International Association for Correctional and Forensic Psychology
A Lens Model Analysis
Department of Psychology & Communication, University of Idaho
Wilson Center for Science and Justice, Duke University School of Law
Department of Psychology, Iowa State University
Drake University
This research investigates whether police officers can reliably use behavioral cues to determine whether a person is conceal-
ing an object. Using a Lens Model framework, we performed a mega-analysis of three experiments. In each study, officers
and laypersons judged whether people were concealing an object and reported “articulable behaviors” they used to perform
this task. Although participants were able to articulate behaviors that they believed were helpful, results showed that these
behaviors were not related to whether the person was actually concealing. Officers and laypersons were equally poor at judg-
ing whether someone was concealing or not. Current officer training on the use of nonverbal behaviors to determine who is
concealing a dangerous object may be ineffective, and a reconsideration of training is warranted. In light of the findings,
requiring officers to provide “articulable behaviors” in Fourth Amendment cases may not provide a sufficient safeguard
against unreasonable searches of civilians.
Keywords: Fourth Amendment; Lens Model; nonverbal behavior; judgment; police training; decision-making
Without visual confirmation of a weapon, law enforcement officers often use behavior-
based cues to determine whether an individual is concealing a dangerous or illegal
object. An officer’s ability to accurately detect who is concealing a firearm and to articulate
AUTHORS’ NOTE: This research was funded by a grant from the Motorola Solutions Foundation.
Correspondence concerning this article should be addressed to Dawn M. Sweet, Department of Psychology &
Communication, University of Idaho, 875 Perimeter Dr., MS 3043, Moscow, ID 83844-3043; e-mail: sweet@
1140360CJBXXX10.1177/00938548221140360Criminal Justice and BehaviorSweet et al./Detecting Concealed Objects in Legal Contexts
why they believe that to be the case can have consequences under the Fourth Amendment
of the U.S. Constitution, which asserts a citizen’s right to be free from “unreasonable search
and seizure.” In Terry v. Ohio (1968), the court determined that, before performing a search,
officers must have a reasonable suspicion that a person has committed, is committing, or is
about to commit a crime, as well as a reasonable belief that the person may be “armed and
dangerous.” The exact meaning of “reasonable suspicion” is unclear, but officers are
expected to reference behaviors, movements, observations, and other “articulable behav-
iors” or “articulable suspicions” to justify their decision to perform a search. In other words,
for a search to be considered reasonable under the Fourth Amendment, officers must be able
to explain their decision to search someone for a dangerous object, such as a firearm, and
their explanation must include specific, articulable behavioral evidence before their justifi-
cation can be considered valid.
Officers have a particularly challenging task when patrolling communities. They must
remain alert so that they can watch for suspicious behavior and signs of criminal activity
while serving their primary goal, namely protecting the public. Unlike other public safety
services such as aviation security, officers do not generally have access to supportive tech-
nologies that are very effective and accurate with respect to identifying concealed prohib-
ited objects. In other words, those working in aviation security are not required to rely
solely on their experience and observation skills to identify dangerous concealed object
because they can use metal detectors, full body scanners, and X-ray machines to facilitate
the identification of concealed prohibited items. Although extremely useful, these kinds of
technological aides cannot be integrated into an officer’s normal routine in a practical way
(e.g., Chen et al., 2005; Sheen et al., 2001).
Instead, when officers decide to stop and search someone on the street without a warrant,
they must rely on the observable and articulable behaviors, movements, and other informa-
tion about a suspicious person that can be determined from afar. It is these subjective behav-
ioral judgments that form the basis of the “reasonable suspicion” rule and result in reasonable
or unreasonable contact with a citizen. To perform this task well, officers rely upon their
perception and interpretation of behavioral cues derived from their experience and any
training they may have received. Thus, research addressing the ability of officers to detect
concealment in contexts that trigger Fourth Amendment issues could help establish whether
police officers can reliably discriminate the movement patterns of those who are concealing
a prohibited object from those who are not, and which behaviors are most diagnostic of
As is the case with many laws, the legal requirements associated with Terry stops,
instances in which officers stop someone and perform a warrant-less search based on
something they observed about the person, are not based on scientific evidence. Officers
report drawing on their training and experience with concealment cases in situations
that invoke the Terry rule. For instance, in United States v. Briggs (2013), the defendant
“repeatedly looked over his shoulder at the officers. . .grabbed at the waistlines of his
pants” and, as the officer moved closer, sped up. Based on their training and experience,
the officer felt this was the type of behavior exhibited by someone concealing a weapon
at their waistline. The court agreed that the stop was justified, but this decision was based
on a “common sense,” “totality of the circumstances” legal approach, not empirical evi-
dence demonstrating that such behaviors are, in fact, reliably and consistently associated
with weapon concealment. Furthermore, the supreme court expressly rec ognized the lack

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