Why subtitle speed matters: evidence from word skipping and rereading

High subtitle speed undoubtedly impacts viewer experience. However, little is known about how fast subtitles might impact the reading of individual words. This article presents new findings on the effect of subtitle speed on viewers’ reading behaviour using word-based eye-tracking measures with specific attention to word skipping and rereading. In multimodal reading situations such as reading subtitles in video, rereading allows people to correct for oculomotor error or comprehension failure during linguistic processing, or integrate words with elements of the image to build a situation model of the video. However, the opportunity to reread words, to read the majority of the words in the subtitle, and to read subtitles to completion, is likely to be compromised when subtitles are too fast. Participants watched videos with subtitles at 12, 20 and 28 characters per second (cps) while their eye movements were recorded. It was found that comprehension declined as speed increased. Eye movement records also showed that faster subtitles resulted in more incomplete reading of subtitles. Furthermore, increased speed also caused fewer words to be reread following both horizontal eye movements (likely resulting in reduced lexical processing), and vertical eye movements (which would likely reduce higher level comprehension and integration).