Snap Decisions on the Web
http://www.uie.com/brainsparks/2006/01/18/snap-decisions-on-the-web/

Perfetti, Christine
User Interface Engineering
2006

Abstract:

We’ve seen in testing that users make important judgments very quickly when they arrive at a web page. That’s one of the reasons we use 5-second tests as our primary technique for evaluating users’ first impressions.