Usability testing

The Firefox extensions installation process


I ran a usability test on the Mozilla Firefox browser. My research question was “How can we improve the process of installing and managing Mozilla Firefox’s extensions?” and I examined the popular AdBlocker extension in particular. With recent redesigns, I'd had trouble using this browser feature and I wanted to see if I was alone. The browser was tested during the month of April, 2016. 

My approach.

I recruited 3 participants, given 3-5 users is standard for this kind of test. I narrowed participants based on these screener questions.
  • Have you heard of or used browser extensions?
  • Have you installed/uninstalled features such as phone apps?
  • Have you used Firefox within the last 5 years?
If "yes" were answered to the above, I then conducted a usability test and an exit interview.


M.S., Academic Project

Finding #1: Installation confirmation is poor

After installation, the extension website shows up. The AdBlocker website was ambiguous about the installation status, with a large “Install for Firefox” button just below "installation success" text. All users were confused by this and proceeded to confirm task success in other ways. 

Finding #2: Firefox's search function needs work

All participants were distracted by the amount of information on the extensions search page. One user described the results on this page as “overwhelming,” and another had the urge to “window shop” to verify she had found the correct extension.

Finding #3: Time-on-task

The following graph measures how long it took for each participant to install the extension AdBlocker. Users were allowed to use whatever method they wished to complete the task. Participant 1 chose to use a Yahoo search, while the others chose to access the extension through the Firefox menu. Admittedly, this difference in process somewhat muddies the mean, which was 42.6 seconds.
20 seconds (Yahoo)
48 seconds
60 seconds


Based on the findings, I made 3 recommendations.
  • Have a standardized installation confirmation, no matter what the extension.
  • Add “Extensions” into the default Firefox menu, so it could be found faster.
  • Use consistent iconography. 

What I learned.

Having had a year of grad school between me and this project, I'm not sure why I recommended consistent iconography instead of an improved extension search function. I think this shows my own bias, since the puzzle piece redundancy (seen below, used for "extensions" and "add-ons") always bothered me, as if Firefox was trying to take shotcuts in its menu. But, this did not bear out in my data as more of a stumbling block than the search function. Lesson learned: Don't take biases into your recommendations, even if they prompted the research in the first place. The fact that using a Yahoo search accomplishes a task 2x-3x faster than Firefox's own UI is fascinating enough.