When I was a student in the School of Journalism and Mass Communication (in a time before the world-wide web) I learned that readers tend to scan printed materials in either a Z-shaped or spiral pattern. For many years I have been advising people to place important web content such as navigation and headlines in relation to those shapes.
As it turns out, people probably scan print and web content differently. According to new research by Jakob Nielson and the Nielsen Normon Group, people tend to view web content in an F-shaped pattern. 232 study participants viewed thousands of web pages. Heat maps were generated to show which parts of the web pages their eyes focused on the longest.
The heatmaps showed that, in general, study participants started reading near the upper-left corner of a page and read from left to right. Next, readers dropped down and read another line (probably a heading or headline). Then they looked down the left side of the page and scanned from top to bottom. This created an F-shaped pattern on the heat maps.
What does this mean for your web pages?
For a quick and excellent summary of the study, which includes several heat map images, see F-Shaped Pattern For Reading Web Content by Jakob Nielsen at http://www.useit.com/alertbox/reading_pattern.html