Onset-to-Onset Temporal Eye-Voice Span as an Indicator of Cognitive Investment in Reading Aloud and Sight Translation: An Empirical Study Drawing on Eye-tracking and Audio-recording Data

Eye-Voice Span (EVS) is “a measure of the amount of material or time by which the voice lags behind the eyes in oral reading” (Morton 1964: 347). Both spatial EVS and temporal EVS happen naturally and inevitably during reading-speaking processes (Gibson and Levin 1975). A considerable body of psycholinguistic evidence has suggested that both spatial EVS and temporal EVS are very common during Reading Aloud (RA) (e.g., Buswell 1920；Laubrock and Kliegl 2015). Recently, researchers have also found that temporal EVS occurs ubiquitously during Sight Translation (STR) (e.g., Dragsted, Hansen and Sørensen 2009; Zheng and Zhou 2018). The aim of this study is to measure the dynamic temporal distance between human subjects’ reading input and speaking output, to gain a better understanding of the nature of temporal EVS during STR and RA, and then to use it as an indicator of cognitive effort. Three groups of subjects from Durham University were recruited to perform RA and STR tasks in an eye-tracking laboratory. The RA and STR processes were recorded using a Tobii eye-tracker and an audio recorder. The findings show the following results. Firstly, the subjects’ temporal EVS has a strong correlation coefficient with some major eye-tracking measurements, including total fixation duration, fixation count, and the sum of fixation and saccade durations. The present study, therefore, suggests that temporal EVS and these eye-tracking measurements are all representative of sub-categories of the cognitive effort devoted to completing a RA/STR task. Secondly, temporal EVS at sentence initials is found to be longer than temporal EVS at sentence terminals, as is spatial EVS. This finding indicates that the temporal EVS is not a random measurement, but one that varies predictably and potentially changes due to influences from cognitive processing. Thirdly, the duration of temporal EVS has a positive correlation with the cognitive effort devoted to the tasks, meaning that temporal EVS can serve as a dynamic indicator to measure the cost of cognitive effort in reading-speaking processes. Finally, temporal EVS is used to compare different STR processes, which provide potential applications for temporal EVS in future process-oriented translation studies