Download the full report here: http://www.radware.com/social/neurostrata-fall2014/
Everyone has strong opinions about progressive images, but there’s little to no hard evidence that proves whether progressive image rendering helps or hurts the user experience. It’s time to end the data-free analysis so we can all get on with our lives.
Some factions believe that by loading images progressively, we improve perceived performance by showing the user something while they look at the screen. Others believe that watching an image load progressively increases user frustration. We took these assumptions to the lab to see if we could definitively answer the question: do progressive images deliver a better or worse user experience?
Using a proven neuroscientific approach that we pioneered in a previous study, we served test participants with multiple versions of a set of pages for an ecommerce workflow. Each set of pages rendered images differently:
-Baseline images, normal speed
-Baseline images, throttled speed
-Progressive images, normal speed
-Progressive images, throttled speed
Using automated facial coding technology that measures moment-by-moment emotional responses in facial micro-expressions, we extracted data about users’ perception of these experiences. Using Implicit Priming Testing, we also extracted measures of frustration and emotional engagement from the experiences.
Using this data, we were able to answer questions such as:
--Is there a correlation between image type/quality and the perceived user experience?
--Does image quality matter more on some pages than on others (e.g. home page vs product page)?
--What is the bottom-line threshold for user tolerance of slow images?
--At what point does superior image quality cease to offer additional benefit to the user experience?
--Using anecdotal feedback from participants’ exit interviews, are people conscious of differences in image speed/rendering?
The results of this study have huge ramifications:
---Ending the highly subjective data-free debate over whether progressive images help or hurt the user experience.
---Potentially saving tons of developer time in manually optimizing images.
---Feature development in automated front-end optimization tools — like ours! (Disclosure: Progressive image rendering is a feature we offer in our own solutions, so this research was a nail biter for us. In the past, we’ve drunk the progressive JPEG Kool-aid, but we’re ready to abandon or modify this feature if it means delivering the best possible user experience to our customers’ users.)
---Ultimately serving the best — and fastest — experience to users.