AED Comparative Study
Usability Testing| Data Analysis
Team:
1 researcher from Philips, 1 school instructor, 4 HCDE master students
Duration:
Sep 2024 — Mar 2025
Background:
School project collaborated with Phillips
Methods:
Quantitive and qualitative research methods
Automated External Defibrillator
AED is a portable medical device designed to assist individuals experiencing sudden cardiac arrest or a heart attack.
Commonly found in public spaces, it enables bystanders to respond quickly in life-threatening situations, potentially saving lives.
Background
Existing studies have only tested the devices in a simulated environment (e.g., no noise, no onlookers, etc.)
Existing studies have not explicitly explored the design specifications of the devices
Comparative usability study of 4 on-market AEDs
How do laypeople respond to public-access AEDs in an in-situ environment?
How does that inform the design of AEDs? (e.g., interface design, pad design, verbal, written, and graphical instructions, etc.)
Setting and task
We presented participants with a scenario in which they had to use an AED to save an unconscious person within 5 minutes. To simulate a realistic environment, we used a gym setting complete with background noise, music, and people.
Participants
We conducted testings with 86 participants, aged 18 to 70, with limited AED experience. The participants came from diverse backgrounds and had different education levels.
Data Collection
We recorded videos of participants during the testing process and captured photos of the pads placement. After the simulation, we asked participants questions about their experience:
General impressions
Device design
Pad placement process
Clarity of instructions
CPR instruction design
Qualitative Data Analysis
We analyzed participants' experiences and observations to identify recurring patterns and develop thematic codes.
Videos for observations
Interview Scripts for quotes
Affinity diagram to find patterns
Quantitive Data Analysis
We measured the time participants spent on each task and collected their experience ratings on a 1-5 scale for analysis.
Time Annotation
Experience on a scale of 1 to 5
Findings
We categorized the insights into different aspects, highlighting critical UX issues.
Initial confusion/hesitation
Uncertainty about how to activate the device.
Difficulty finding clear instructions at first glance.
The power button requires a long press to activate, which is not intuitive.
Device design
Difficulty pressing the button or opening the case.
Distracting elements that draw attention away from essential functions.
Unclear visual cues, such as colors or design, making it hard for users to determine how to remove the line from pads.
Some pads may not be suitable for individuals of different body sizes.
Support material design (graphic guidance)
Cross-referencing visual instructions in multiple places caused delays and cognitive load.
Inconsistent visual instructions led to confusion.
Unclear or poorly ordered steps made the process harder to follow.
Users struggled to filter out non-critical information and focus on essential actions.
Difficulty understanding pad orientation and placement.
Voice prompt design (Instruction clarity)
Regarding clothing removal: missing the phrase "bare chest," which led participants to leave some clothing on.
Confusion between the terms “remove pads” and “peel pads” caused misunderstandings.
Participant was instructed to "press the flashing light," but they were unsure whether the flashing element was actually a button or just a visual cue
Voice prompt design (Others)
Long pauses without status updates from the machine caused confusion.
Misalignment between audio instructions and user behavior led to confusion and anxiety.
Users getting stuck on a specific step and receiving redundant information from the beginning created further confusion.
CPR
Didn’t realize the metronome was for CPR frequency.
Unclear or missing instructions on how to perform CPR.
Lack of feedback made it unclear if CPR was performed correctly.
Require more precise information/instruction.
Delays in CPR instructions caused uncertainty.
What I learned for future user experience design
Understand and accommodate diverse user needs. I’ve learned that people process information differently. I need to consider users' cognitive abilities and habits and ensure the design supports everyone.
Minimize cognitive load. Since people can only focus on so much at a time, I’ll prioritize simplicity. Keeping interfaces clean and focused will help avoid overwhelming users with unnecessary elements or distractions.
Clear information. It is important to provide clear information to users so they understand the steps, and to ensure that all information is consistent and aligned.
Provide feedback and confirmation. I’ve realized how important reassurance is for users. By providing clear feedback—using color, sound, or text—Design can confirm their actions and give them the confidence to keep going.
