Mask-related costs in measuring preview benefit: Evidence from a distributional analysis based on target word reading times.

Skilled reading involves processing the upcoming word in parafoveal vision before it is fixated, leading to shorter fixations on that word. This phenomenon, parafoveal preview benefit, is a key component of theoretical models of reading; it is measured using the invisible boundary paradigm, in which reading times on a target word are compared for instances when preview is accurate and when the target word is masked while in the parafovea. However, parafoveal masks have been shown to induce unintentional processing costs, thereby inflating measures of preview benefit. The degraded mask has been explored as a potential solution to this problem, leading to mixed results. While previous work has analyzed the preview effect by comparing mean reading times on the target word, the present study provides a more comprehensive analysis by examining the distribution of the preview effect across target word fixation times for unrelated and degraded masks. Participants read sentences containing target words whose preview was either identical, unrelated, or degraded, and their eye movements were recorded. Analyses revealed that although there were no mean differences between reading times for the unrelated and degraded conditions, the pattern of the effects varied as a function of target word fixation times. Unrelated masks resulted in positively sloped generally linear delta plots, while degraded masks resulted in relatively flat delta plots for fixations longer than 200 ms. These differences suggest that different cognitive mechanisms are involved in the processing of the two mask types. Implications for understanding and measuring preview benefit are discussed.

Stable preview difficulty effects in reading with an improved variant of the boundary paradigm.

Using gaze-contingent display changes in the boundary paradigm during sentence reading, it has recently been shown that parafoveal word-processing difficulties affect fixations on words to the right of the boundary. Current interpretations of this post-boundary preview difficulty effect range from delayed parafoveal-on-foveal effects in parallel word-processing models to forced fixations in serial word-processing models. However, these findings are based on an experimental design that, while allowing to isolate preview difficulty effects, might have established a bias with respect to asymmetries in parafoveal preview benefit for high-frequent and low-frequent target words. Here, we present a revision of this paradigm varying the preview's lexical frequency and keeping the target word constant. We found substantial effects of the preview difficulty in fixation durations after the boundary confirming that preview processing affects the oculomotor decisions not only via trans-saccadic integration of preview and target word information. An additional time-course analysis showed that the preview difficulty effect was significant across the full fixation duration distribution on the target word without any evidence on the pretarget word before the boundary. We discuss implications of the accumulating evidence of post-boundary preview difficulty effects for models of eye movement control during reading.

Parafoveal preview effects depend on both preview plausibility and target predictability.

Recent studies using the boundary paradigm have shown that readers benefit from a parafoveal preview of a plausible continuation of the sentence. This plausibility preview effect occurs irrespective of the semantic or orthographic relatedness of the preview and target word, suggesting that it depends on the degree to which a preview word fits the preceding context. The present study tested this hypothesis by examining the impact of contextual constraint on processing a plausible word in the parafovea. Participants' eye movements were recorded as they read sentences in which a target word was either highly predictable or unpredictable. The boundary paradigm was used to compare predictable, unpredictable, and implausible previews. The results showed that target predictability significantly modulated the effects of identical and plausible previews. Identical previews yielded significantly more benefit than plausible previews for highly predictable targets, but for unpredictable targets a plausible preview was as beneficial as an identical preview. The results shed light on the role of contextual predictability in early lexical processing. Furthermore, these data support the view that readers activate a set of appropriate words from the preceding sentence context, prior to the presentation of the target word.