I just had the wacky idea that I could force users in an experimental situation to engage in movements that help track their reading behavior in a web browser. This method would employ Javascript and CSS–in short, the script would obscure text outside of the foveal vision area–the readable foveal vision area would be centered near the cursor, requiring the user to move the cursor with her fixations. Combine this with coordinate-based Javascript mouse tracking and user input that reports to a server via AJAX a la UsaProxy, and you’ve got an interesting, albeit limited, method of tracking eye movements.
A quick search on Google shows that David Walsh has already worked out a very elegant script that approximates this. My own idea would be to not use a “flashlight” effect, but a “frosted window” effect using moveable, translucent PNG layers (rather than a background) that retains basic shapes, features, and colors, but obscures microfeatures–i.e. the graphemes–of text. Here’s one mock-up to illustrate the idea:
Now there are a number of obvious problems with this idea in research practice–the obfuscation may significantly alter the layout and (potentially distracting) elements of the page; it may negatively affect users ability to gauge document length and position; it wouldn’t necessary reflect normal reading behavior; and, of course, it could be terribly annoying to the reader, etc. That’s just off the top of my head; if you have more ideas, please share.
