All About Website Usability Blog – Holly Phillips

The huge difference between .1 and 1 second, part 1
November 14, 2009, 4:09 am
Filed under: confidence, visual design

Jakob Nielsen’s Oct 5 Alertbox describes the difference in user expectations about timeframes on the web.  While he discusses instances where users are willing to wait 1 hour, 1 day, 1 week, and even longer for specific types of results, the really interesting thing is his finding about the perception of response times of 0.1 second vs 1 second.

On the surface, it would seem that there shouldn’t be much difference in user satisfaction to have to wait 0.1 second vs 1 second for a page to respond.  It’s not like that extra 9/10ths of a second will significantly contribute to the time available to read a page.  But the interesting finding is not that one seems appreciably faster than the other.  Instead, it’s the subjective impression given by the time:  Nielsen found that a page that responds in less than 0.1 seconds feels as if you made something happen, whereas a page that takes 1 second to respond feels as if the computer is doing something to create the response.

Why is this so interesting?  We’ve watched users interact with webpages that have very similar designs at different sites.  In one case, both pages had a tabbed-structure on the lower half of the page, where clicking on one of the tabs kept the upper-half of the page constant but changed the lower-half of the page.  On the first site, the new tab was brought up immediately (less than 0.1 seconds), and on the second it was brought up in about 1 second (we of course alternated which sites the users saw first).  Users didn’t comment on the speed, but instead commented about how they preferred the first site because “you don’t have to go to a whole new page for each tab, like on the second site”.  In reality, neither design was taking the user to a new page.  But in the perceptions of the user, the second site was slower specifically because it had to bring up a new page.  Ie, the slower page implied that the computer was doing something, whereas the faster page implied the user was controlling the action.

This perception of having to bring up a new page then led to comments about the second site “being harder to navigate, since you have to go to all these different pages”.  The first site was deemed easier to navigate since “all the information is right there on the same page so I never had to navigate around” — even though they actually did navigate to the different tabs.

To me, this finding is incredibly insightful and helps explain how seeminly tiny time differences can have profoundly different cognitive impacts on website visitors.


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