Examining semantic parafoveal-on-foveal effects using a Stroop boundary paradigm

The issue of whether lexical processing occurs serially or in parallel has been a central and contentious issue in respect of models of eye movement control in reading for well over a decade. A critical question in this regard concerns whether lexical parafoveal-on-foveal effects exist in reading. Because Chinese is an unspaced and densely packed language, readers may process parafoveal words to a greater extent than they do in spaced alphabetic languages. In two experiments using a novel Stroop boundary paradigm (Rayner, 1975), participants read sentences containing a single-character color-word whose preview was manipulated (identity or pseudocharacter, printed in black [no-color], or in a color congruent or incongruent with the character meaning). Two boundaries were used, one positioned two characters before the target and one immediately to the left of the target. The previews changed from black to color and then back to black as the eyes crossed the first and then the second boundary respectively. In Experiment 1 four color-words (red, green, yellow and blue) were used and in Experiment 2 only red and green color-words were used as targets. Both experiments showed very similar patterns such that reading times were increased for colored compared to no-color previews indicating a parafoveal visual interference effect. Most importantly, however, there were no robust interactive effects. Preview effects were comparable for congruent and incongruent color previews at the pretarget region when the data were combined from both experiments. These results favour serial processing accounts and indicate that even under very favourable experimental conditions, lexical semantic parafoveal-on-foveal effects are minimal.