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Usability Testing | Axon

Overview

Client
Axon is the largest producer of body worn cameras and other products used by law enforcement agencies
 
Purpose

  • To better understand the experiences of police officers working in the field

  • To evaluate the design and usability of a future generation Axon hardware product

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Objectives

  • Conduct background research to learn about the impact of cognitive load and stress on officers' experiences in the field

  • Learn about participants' day-to-day realities to support or deny background research findings 

  • Ask officers to "walk us through" their experience with the prototype and explain how they see it impacting their work

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Process

1. Conducted background research on cognitive load for police officers in the field and how it affects information processing

2. Drafted recruitment screener

3. Received prototype from Axon and tested its functions

4. Wrote moderator's guide based on examination of the prototype

5. Conducted 1:1 90-minute Usability Testing, with 30 minutes in-between sessions (onsite with remote notetakers)

  • All sessions were recorded via Zoom 

6. Identified findings and ranked them by severity (low, medium and high severity) 

8. Compiled findings and recommendations​ and presented to client

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Tools

  • Zoom 

  • Likert Scales (administered after each task)

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Participants

  • 8 participants​

    • All field officers

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Project Duration

4 months

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Group Members

Elizabeth Rosenzweig, Rivka Barrett, Megan Campos, Afrand Shahroudi

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My Role

  • Conducted background research on cognitive load 

  • Drafted and edited moderator's guide

  • Examined and tested the functions on the prototype before usability testing sessions

  • Took notes during usability testing sessions

  • Helped identify findings from usability testing sessions 

  • Produced quantitative data to support findings

  • Helped compile findings and recommendations into a final report for the client

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Keywords: Usability testing, data analysis, statistical analysis, hardware, prototype

Findings

I cannot discuss findings regarding the prototype we tested. However, I can share my background research and general findings concerning police officers' experiences in the field.

 

Stressful Work Environments

  • Officers often deal with unpredictable, high-risk situations when working in the field

  • They may have to put themselves in danger

  • Due to the public's often negative views of law enforcement, officers may also face hostility and physical aggression 

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Hearing and Sound

  • Hearing loss is a common occupational hazard associated with working in the police force (Win, 2015)

  • A person with normal hearing can detect sounds between 0-140 dB. However, sounds that are 90 dB or louder are often uncomfortable for listeners (Center for Disease Control, 2014)

  • In a typical working environment for a police officer, many factors can increase the risk for hearing loss and cognitive load

    • Even traffic and vehicle horns can significantly contribute to noise levels (Win, 2015)

    • For police motorcyclists in particular, the sound intensity of their environment can range between 63-105 dB (Win, 2015)

  • Officers may wear earplugs or muffs but these only reduce sound intensity by 15-30 dB (American Hearing Research Foundation, 2012; Win, 2015)

  • The high risk of hearing loss, as well as cognitive load associated with occupational noise, further highlights the importance of providing multimodal cues to officers in the field

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Attitude Towards Surveillance

  • Being under surveillance changes the behavior of both police and the general public

  • Officers reported considering surveillance a form of protection, both in terms of physical safety and protecting their reputations

  • They generally consider it a benefit to their work in the field

Cognitive Load​​

  • "Cognitive load" describes the mental effort needed to attend to and hold information within working memory (Sweller, 1994)

  • Working memory is limited in capacity and can only retain information for short periods of time (Sweller, 1994)

  • Officers often experience high cognitive load when in the field. Cognitive load and unpredictable, high-risk situations force police officers to make important decisions with limited information or time

  • Providing multiple modes of information (such as both audio and visual cues) may improve a person's capacity for retaining important information (Mousavi et al., 1995)​​

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In the field, police officers often need to wear and manage several pieces of equipment. In addition, they need to be on alert and aware of their surroundings, which can also affect attentional capacity.

What I Learned

  • Learning to work with new hardware can be challenging, and sometimes unexpected things happen. An important part of planning and moderating usability testing sessions means being prepared for any situations that arise and adapting quickly

  • When evaluating the design and usability of a hardware prototype, it is important to consider factors in users' typical environments that may impact their experience using the device, such as occupational noise or cognitive load

  • Researchers should also consider how technologies may affect people's behavior and improve or hinder social interactions

References

“About Sound.” Center for Disease Control. (2014, July 24). Retrieved April 11, 2018, from https://www.cdc.gov/ncbddd/hearingloss/sound.html.

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Mousavi, S.Y., Low, R., and Sweller, J. (1995). Reducing Cognitive Load by Mixing Auditory and Visual Presentation Modes. Journal of Educational Psychology, 87(2)

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“Noise Induced Hearing Loss.” American Hearing Research Foundation. (2012, October). Retrieved April 11, 2018, from https://www.american-hearing.org/disorders/noise-induced-hearing-loss/.

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Sweller, J. (1994). Cognitive Load Theory , Learning Difficulty , and Instructional Design. Learning and Instruction, 4, 295–312. https://doi.org/10.1016/0959-4752(94)90003-5

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Win, K. N., Balalla, N. B., Lwin, M. Z., & Lai, A. (2015). Noise-induced hearing loss in the police force. Safety and health at work, 6(2), 134-138.

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