Eye Movement Control During Reading: The Effect of Word Units

In recent years psychologists have shown a renewed interest in eye movement in reading (see reviews by Levy-Schoen & O’Regan, 1979; McConkie, 1983; Rayner, 1978a). This work has been motivated by more than a simple curiosity about the nature of eye movement control. Rather, eye movement data are regarded as having the potential for testing theories about the ongoing perceptual and language processing taking place during reading. As people read, a great deal of variability is exhibited in how far they move their eyes and in how long their eyes remain centered on different locations in the text. There is general faith in, and some evidence for, the notion that this variability reflects differences in the nature of the perceptual and cognitive processes occurring at different locations in the text. It is assumed that if we could discover the ways in which mental processes influence eye movement behavior, then we would be able to use eye movement records to infer the nature of the processing occurring at different places in the text. In effect, the eye movement pattern would then become a language by which the brain communicates some of its activities to the psychologist. The hope that this can be achieved is a strong motivator for research on eye movement control in reading (Just & Carpenter, 1980; McConkie, Hogaboam, Wolverton, Zola, & Lucas, 1979).