Using dichoptic moving-window presentation techniques to investigate binocular advantages during reading

摘要

Previous research indicates that binocular visual presentation results in superior reading performance. However, it is not entirely clear whether this is due to facilitated encoding of foveal or parafoveal information, or what amount of binocular visual input is necessary in order for binocular advantages during reading to occur. In a set of two experiments, we used a novel, dichoptic binocular gaze-contingent moving window technique to selectively manipulate the amount of binocular information available on a fixation-by-fixation basis during reading. In Experiment 1, sentences were presented with monocular input either exclusively in the fovea or in the parafovea. In Experiment 2, we further varied the amount of binocular visual information available in the parafovea to the right of fixation in order to quantify the amount of parafoveal binocular text necessary for uninterrupted reading. Results from Experiment 1 showed that monocular presentation of parafoveal text to the right of fixation was as disruptive to reading as monocular presentation of the entire sentence, even when foveal text was binocular. Experiment 2 demonstrated that this disruption could be reliably counteracted if at least one word in the parafovea to the right of fixation was also binocular. Interestingly, even though parafoveal monocular viewing conditions impaired reading performance in both experiments, binocular coordination processes (i.e. vergence movements) were efficient in all dichoptic presentation conditions. Furthermore, if only foveal input was monocular, fixation disparity was indistinguishable from the binocular reading condition. This implies a degree of dissociation between binocular coordination and reading performance in conditions of reduced binocular visual quality. Implications of the findings for binocular saccadic targeting will be discussed. The experiments demonstrate the importance of a unified, binocular input for the pre-processing of text to the right of fixation and underline the complex interplay between visual and cognitive processes during reading.