Right. I thought about including a description of pursuit movement, but omitted it because I didn't think it came up frequently when viewing web pages. Humans actually have a whole bunch of special-case eye movement patterns, like the "catch-something heuristic" (http://en.wikipedia.org/wiki/Gaze_heuristic), which we share with dogs! (http://www.mansfield.osu.edu/faculty/dshaffer/Shaffer%20Publ...)