The effect of subtitle speed and individual differences on subtitle processing in L1 and L2: an eye-tracking study on intralingual English subtitles

The growing popularity of intralingual English subtitles in audiovisual content is transforming how both native and non-native English speakers engage with media. This trend has been accompanied by rising subtitle speeds, driven by global streaming platforms and social media, where a greater reliance on automation for subtitle creation often results in verbatim, excessively fast subtitles. This study investigates the impact of subtitle speed on L1-English and L2-English (L1-Polish) viewers, focusing on individual characteristics that impact subtitle processing. We tested 83 participants (33 L1 and 50 L2 speakers) while they watched English-language videos with intralingual subtitles. Eye movements were monitored to measure early and late stages of the reading process, word skipping, and proportional time spent in the subtitle area. Results indicate that L2 speakers were more affected by faster subtitles than L1 speakers: they spent more time in the subtitle area, skipped fewer words, and had lower recall accuracy. Additionally, factors such as age, working memory, previous exposure to audiovisual materials, and familiarity with subtitling were found to influence the viewing process. This paper presents the findings and assesses their implications for future subtitling research and practices.