Parafoveal-on-foveal effects on eye movements in text reading: does an extra space make a difference?

Schiepers proposed that in text reading, the currently fixated word and the next word are processed in parallel but with a time delay of 90 ms per degree of eccentricity. In his model, the benefit of seeing the upcoming word is due to the fact that the parafoveal information from fixation n is combined with the foveal information from fixation n+1 to boost word recognition, at least when the fixation on word n is of an optimal duration (between 210 and 270 ms). We tested this assumption by adding an extra blank space between the foveal and the parafoveal word. According to the model, this should result in a 30 ms longer processing time for the foveal word. However, reading time was shorter for a word followed by a double space than for a word followed by a single space. An effect of parafoveal word length was also observed with a longer word in the parafoveal leading to shorter fixation times on the foveal word. Implications of these low-level parafoveal-on-foveal effects are discussed.