This is your brain on a slow website: Lab experiments quantify “web stress”

A hat tip to Stephen Thair, who heads up the London Web Performance Meetup Group, for his recent Web Performance 101 presentation, which pointed me toward this study that measures the neurological impact of poor web performance.

Last year, CA Technologies commissioned Foviance to conduct a series of lab experiments at Glasgow Caledonian University. The participants wore an EEG (electroencephalography) cap to monitor their brain wave activity while they performed two commonplace online transactions: finding and buying a laptop on a leading e-commerce site, and finding and buying travel insurance on an insurance website. The experiment also used EOG (electrooculograph) technology to track eye movements and facial muscle movements.

Participants completed tasks using either a 5Mb web connection, or a connection that had been artificially throttled to 2Mb. Slowing down the connection allowed Foviance to simulate the real-world user experience of an unresponsive website.

What they found

Brain wave analysis from the experiment revealed that participants had to concentrate up to 50% more when using badly performing websites.

EOG technology and behavioural analysis of the subjects also revealed greater agitation and stress in these periods.

This data was backed up by feedback from participants after the study. When asked what they liked most and least about the websites they were asked to use for the study, participants frequently cited their speed as a top concern.

“The website was very slow, so it took a really long time to load the book preview.”
“What I liked least about the site is its speed.”

The study also found that people are most likely to experience the greatest levels of stress during two points in the sales cycle:

  • Search – Finding and selecting products
  • Checkout – Entering personal information and concluding the sale


If people are already stressed during search and checkout, it seems logical that having these points in the transaction perform slowly would compound this stress. A lot of companies focus their performance optimization efforts on key landing pages and product pages, but clearly search and checkout need attention, too.

According to CA Technologies’ 2009 Web Stress Index, more than three quarters (77%) of European consumers blame either the website owner or the website host when an online application fails. Even if the problem is due to external factors, such as connectivity, slow site speed becomes a defining characteristic of the website in the minds of many people. As the report states:

“People think of a website through their experience of it, without much regard to any externalities that might be causing those problems.”

As I’ve harped here many times in the past, there’s a serious disconnect between how fast a website actually is and how fast a company believes its site to be. Foviance’s study confirms this:

“Most businesses have no insight into the actual speed with which customers experience their web applications because they test their website at server level. It is essential that companies have a clear understanding of how their website applications perform from the customer’s perspective, and that these are optimised to eliminate web stress. If companies fail to reduce the ‘web stress’ associated with their web channel, they risk losing customers and sales.

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