Saccade generation during reading: Are words necessary?

Most current theories of eye movement control during reading are word based in multiple ways: They assume that saccade onset times result from word-based processes, and that words are involved in selecting a saccade target. In the current study the role of words was examined by occasionally replacing the text with one of five alternate stimulus patterns for a single fixation during reading, and observing the effects on the time, direction, and length of the saccade that ends that fixation. The onset times of many saccades are unaffected by replacing spaces with random letters, thus removing visible word-units; also, the effects of this removal on saccade length is not different than that of having space-delimited nonwords. It does not appear that words play a critical role in generating saccades. The results are compatible with the Competition/Interaction theory of eye movement control during reading (Yang & McConkie, 2001).