Effect of caption rate on the comprehension of educational television programmes by deaf school students

Television captioning has great potential to provide deaf children with access to the audio track of programmes. However, use of captions may be limited by the lower English literacy skills of the deaf population compared to the general population. Here, we investigate how the rate of caption delivery affects the comprehension of educational programmes by better- and poorer-reading deaf school children. Participants watched three short documentaries, with captions presented at 90, 120, or 180 words per minute (wpm). Across both reading levels, comprehension was uniformly higher at 90 and 120 wpm than at 180 wpm. Independent of caption rate, better readers scored higher overall than poorer readers. These results suggest that the rate of captions in children's television programmes can safely use 120 wpm as a slowest speed. Future research should seek to pinpoint the optimal rate, which appears to lie between 120 and 180 wpm.