Parafoveal preview effects in reading unspaced text

In English reading, eye guidance relies heavily on the spaces between words for demarcating word boundaries. In an eye tracking experiment, we examined the impact of removing spaces on parafoveal processing. Using the gaze-contingent boundary paradigm (Rayner, 1975), a high or low frequency pre-boundary word was followed by a post-boundary preview presented either normally (i.e. identical to the post- boundary word), or with letters replaced creating an orthographically illegal preview. The spaces between words were either retained or removed. Results replicate previous findings of increased reading times during unspaced reading (Rayner, Fischer & Pollatsek, 1998) and indicate rather limited evidence for more distributed processing: Observations of processing of the previous word (spill-over effects) or processing of the next word (parafoveal-on-foveal effects) influencing fixation durations on the currently fixated word were limited. Spill-over effects were only observed in the unspaced layout when the post-boundary preview was correct, presumably because the orthographically illegal, incorrect preview was visually salient enough to allow for relatively easy word segmentation and therefore more focused processing of the pre- boundary word. As such, results points towards a system that prefers narrowly focused processing of a single word, at least when means for easy word segmentation are available