“In the lab, users are primed to watch a short flash of a picture of a random website and know that they have to render an opinion. Apparently, they can do this. So what. That’s not how people use websites.”

Nielsen’s argument, in summary:

1. Web pages load in seconds, not milliseconds. The user cannot judge the whole page in 1/20th of a second if it hasn’t finished loading yet.

2. People scan web pages using slow eye movements (fractions of a second), and it takes several scans to “see” the whole page.

3. Users don’t view random pages, rather they visit sites for a reason and therefore with certain expectations that influence how they visually scan the page.

4. It takes 2 seconds for a user to decide to leave a web page, and even longer to click the Back button.

5. “Empirically, users spend half a minute on average on the first page they visit on a website.”

Nonetheless, Nielsen does seem to agree with the moral of the story — you only have a few seconds to convince a user to stay on your page, so good design is essential.