Do Subtitles Help You Learn English Vocabulary?

By The Dobi Apps Team · Published 2026-09-11 · Originally published at dobiapps.com

A 332-learner study found high schoolers scored 91% higher with bilingual subtitles than with none, but subtitles did not help young beginners at all.

In short: Subtitles help English vocabulary learning, but the benefit depends heavily on age and subtitle type. A 2024 study of 332 learners found high school students scored 91% higher with bilingual subtitles than with none, while primary school beginners showed no significant benefit from subtitles at all. Matching subtitle type to a learner’s level matters more than simply turning captions on.

Hero image: Story Book - English App, App Store listing.

What Is Captioned Video Learning and How Does It Work for English Vocabulary?

Captioned video means watching a video with on-screen text of the dialogue, either in English (intralingual captions), in a learner’s native language (interlingual subtitles), or a bilingual mix of both. The on-screen text gives a learner a second channel to confirm what they are hearing, the same multimodal principle covered in do comics and graphic novels help you learn English, but built from moving images and captions rather than static panels. Turning a video into active speaking practice, rather than passive viewing, is a separate question covered in shadowing audiobooks for English pronunciation.

The mechanism researchers point to is speech segmentation. Spoken English runs words together with no gaps the way printed text has spaces, so a learner who has not yet automated that skill can hear a stream of sound without reliably telling where one word ends and the next begins. On-screen text shows the word boundaries directly, which is why captions are hypothesized to support listening rather than distract from it, particularly for a learner whose listening skill lags behind their reading skill.

Captioned video is not one single method. The subtitle language, the learner’s age and proficiency, and even whether subtitles are full sentences or highlighted keywords all change how much a learner gets out of watching, which is why the research on this topic reports very different results for different groups rather than one universal effect. New words a video does surface are still worth a review pass afterward, the same follow-up covered in how spaced repetition builds English vocabulary retention.

Do Captions Actually Improve English Vocabulary Learning From Video?

Sijia Chen’s 2024 study, published in The Journal of Specialised Translation, tested exactly this question across 332 English learners in China, split into four school-age groups from second-year primary through high school, comparing no subtitles against intralingual, interlingual, and keyword subtitle conditions.

91% — higher vocabulary test score for high school English learners watching video with interlingual (bilingual) subtitles (M = 0.86) versus no subtitles (M = 0.45), p < .001

Source: Chen, 2024

Middle school students showed a similar pattern at a smaller scale: a score of 0.40 with no subtitles rose to 0.62 with interlingual subtitles and 0.75 with keyword subtitles, both statistically significant improvements. A widely cited 2013 meta-analysis in the journal System, covering ten separate vocabulary studies, reached the same broad conclusion from different data: a large and statistically significant effect of captions on vocabulary learning across proficiency levels, though the size of that effect varies between individual studies.

Younger learners told a different story. Neither of the two primary school groups in Chen’s study showed a statistically significant vocabulary benefit from any subtitle condition over no subtitles at all. Captioned video is not a benefit that appears automatically just because captions are turned on; it depends on a learner already having enough reading fluency to use the on-screen text as a shortcut rather than a second decoding task competing with the video itself.

Should You Choose Bilingual, English-Only, or No Subtitles?

The counterintuitive result in Chen’s data is that English-only (intralingual) captions were not always the strongest performer, even though English-only captions are the more common study advice. Among high school students specifically, intralingual captions scored lowest of all four conditions (M = 0.32), below even the no-subtitle condition (M = 0.45), while interlingual bilingual subtitles scored highest (M = 0.86).

Subtitle condition	Middle school score	High school score
No subtitles	0.40	0.45
Intralingual (English only)	0.56	0.32
Interlingual (bilingual)	0.62	0.86
Keyword subtitles	0.75	0.69

Learner preference lined up more consistently than the test scores did: across every age group in the study, a majority of learners said they preferred bilingual subtitles, from 52% among the youngest group to 84% among middle schoolers. A learner choosing subtitles for a video does not need to guess: bilingual subtitles are both the most preferred option and, for middle and high school learners, one of the strongest performers on an actual vocabulary test.

How Does Captioned Video Compare to Reading While Listening to an Audiobook?

Captioned video and reading while listening to an audiobook both pair audio with on-screen or on-page text, but the visual scene in a video adds context that a printed page does not have, while an audiobook’s full page of text supplies more surrounding language per minute than a subtitle line ever displays.

A dedicated 26-week study of reading while listening, covered in does reading while listening to audiobooks improve English, found the reading-while-listening group gained 566 new words against 123 for a control group taught without it, a format built around full narrative text rather than short subtitle lines. Video captions, by contrast, typically show one short line at a time and disappear within seconds, which limits how much a learner can lean on the on-screen text before it moves on. Neither format is strictly better: a learner gets denser vocabulary exposure per minute from an audiobook’s full text, and gets visual scene context a printed page cannot supply from video.

Does Watching Captioned Video Work for Complete Beginners?

Chen’s data on primary school learners suggests captioned video is not the best starting point for a true beginner. The same logic behind comprehensible input and finding the right English reading level applies here: subtitles only function as a shortcut for a learner who can already decode text quickly enough to read a caption line before it disappears, and a beginner still learning to read loses that shortcut entirely, left instead with fast on-screen text competing for the same attention the video and audio already demand.

A learner still building basic reading speed is better served starting with untimed text, a graded story or a leveled audiobook where the pace is set by the reader rather than by a video’s subtitle timer, and adding captioned video once reading speed can comfortably keep up with a subtitle line.

How Can You Combine Video, Audiobooks, and Reading for Better Vocabulary Results?

A learner does not have to pick one format permanently. Dobi Apps’ Audiobook organizes leveled A1 to C2 audiobooks and ebooks, which gives a learner the untimed, self-paced text-plus-audio format that works before reading speed can keep up with a video’s subtitles, and remains useful afterward for the denser vocabulary exposure a full page of text supplies over a subtitle line.

Storybook, Dobi Apps’ other English-learning app, adds comics and reading games on top of its library of more than 1,000,000 books and audiobooks, which gives a learner a visual, multimodal option closer to what captioned video supplies, pictures alongside text, without requiring a learner’s reading speed to match a subtitle timer. A learner can use Audiobook and Storybook to build the reading fluency captioned video eventually rewards, then add English videos with bilingual subtitles once that fluency is in place.

Frequently Asked Questions

Do bilingual subtitles help more than English-only subtitles?

For older learners, in one large study yes. Middle school and high school students scored highest with bilingual (interlingual) or keyword subtitles, and learners across every age group preferred bilingual subtitles when asked, even when they were not always the group’s best-scoring condition.

Do subtitles help young children learn English vocabulary from video?

Not measurably, according to the same study. Primary school students showed no statistically significant vocabulary gain from any subtitle condition compared to no subtitles at all, which suggests subtitles help learners who can already read fairly fluently more than learners who cannot yet.

Sources

📖 Read the original article on the Dobi Apps blog: Do Subtitles Help You Learn English Vocabulary?

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