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Masked Emotion: Police Officer Perception of Threatening or Nonthreatening Expressions in the era of COVID-19
Last registered on January 05, 2021


Trial Information
General Information
Masked Emotion: Police Officer Perception of Threatening or Nonthreatening Expressions in the era of COVID-19
Initial registration date
January 04, 2021
Last updated
January 05, 2021 6:58 AM EST
Primary Investigator
University of California-Irvine
Other Primary Investigator(s)
PI Affiliation
University of California-Irvine
Additional Trial Information
In development
Start date
End date
Secondary IDs
This project estimates the ability of 500 officers in the Los Angeles Police Department to assess non-verbal expressed emotion in the era of covid-19. One of the central strategies currently used to control the spread of COVID-19 is encouraging, or requiring, the public to cover their face. The impact of these coverings on policing is currently unknown. In the proposed pilot study, we will test the impact of a simple, non-medical coronavirus mask on a police officer’s ability to detect emotion, and their assessment of that emotion as threatening or nonthreatening. Eligible officers will be asked to assess expressed emotions in a series of photographs. Officers assigned to the control group will be given a set of unmasked emotive pictures to assign, and the treatment group will be given a set of otherwise identical masked emotive pictures.

This pilot will serve as a preliminary test of the non-verbal communication skills and de-escalation tactics of police officers, and how public health directives have impacted how police and the community interact. This is critical for understanding how the COVID pandemic has impacted policing, which as an institution plays a central role in the persistence of structural inequality in the US.
External Link(s)
Registration Citation
Coles , Carolyn and Emily Owens . 2021. "Masked Emotion: Police Officer Perception of Threatening or Nonthreatening Expressions in the era of COVID-19." AEA RCT Registry. January 05. https://doi.org/10.1257/rct.6987-1.0.
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Experimental Details
Intervention Start Date
Intervention End Date
Primary Outcomes
Primary Outcomes (end points)
Speed and accuracy are the outcome measures. Speed at which an officer designates a face as threatening or nonthreatening. Accuracy of the officers assignment of emotion to the pictured expression.
Primary Outcomes (explanation)
Secondary Outcomes
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
All eligible officers will be randomly assigned to a control or treatment group where they will be given a survey link to engage in the study. Each detective and patrol officer will have the opportunity to take the survey once, to prevent them from “learning” the study. The control group will view unmasked photos and the treatment group will view masked photos only. Both groups will be presented with several photos of the neutral faced pictures to assign threat or non-threat and after completion of that round, they will be viewing the sequence of photos to assess facial expression. On the back end of the survey we will keep track of the time it takes to make decisions on each of the questions and their accuracy of identifying the facial expressions.
Experimental Design Details
Not available
Randomization Method
randomization done by Qualtrics conditioning algorithm
Randomization Unit
We will conduct a stratified random sample. The sample population will come from the Los Angeles Police Department officers. Within their ranks only patrol officers and detectives will be eligible to participate. Across the 22 districts, eligible officers will be randomly assigned to control or treatment by the online platform algorithm.
Was the treatment clustered?
Experiment Characteristics
Sample size: planned number of clusters
Sample size: planned number of observations
500 police officers
Sample size (or number of clusters) by treatment arms
21 police districts, 2 job assignments (patrol and detective), 500 officers
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Supporting Documents and Materials
Document Name
Masked Emotion_ Pic Examples
Document Type
Document Description
Original pictures used from the Chicago Face Database. Edits to include face mask done by research staff.
Masked Emotion_ Pic Examples

MD5: 0cc3d39de00f229d916c624e779dd8e0

SHA1: e1aef1346cfabc9eaca6d426e7c880ff0ab036ef

Uploaded At: January 04, 2021

IRB Name
IRB Approval Date
IRB Approval Number