Effects of subtitle speed on proportional reading time: Re-analysing subtitle reading data with mixed effects models

How much time do viewers spend reading subtitles and does it depend on the subtitle speed? By posing these questions, in this paper we re-analyse previous data to address this issue while promoting two methodological advancements in eye-tracking audiovisual research: (1) the use of proportional reading time (PRT) as a metric of time spent on subtitle reading and (2) the analysis of data via linear mixed models (LMMs). We tested 19 Polish L1 viewers with advanced English proficiency watching two clips with English soundtrack with Polish subtitles. First, we compared PRT at two different subtitle speeds: 12 characters per second (cps) and 20 cps. Then, we used actual subtitle speed rates to better understand the speed-PRT relationship. The results showed a significantly higher PRT for 20 cps compared to 12 cps, with the models predicting a PRT of 45.24% at 20 cps. We have also found strong evidence of the advantage of LMMs over more commonly used statistical techniques.