Towards a More Inclusive Learning Environment: The Importance of Providing Captions That Are Suited to Learners' Language Proficiency in the UDL Classroom

Captions have been found to benefit diverse learners, supporting comprehension, memory for content, vocabulary acquisition, and literacy. Captions may, thus, be one feature of universally designed learning (UDL) environments [1, 4]. The primary aim of this study was to examine whether captions are always useful, or whether their utility depends on individual differences, specifically proficiency in the language of the audio. To study this, we presented non-native speakers of English with an audio-visual recording of an unscripted seminar-style lesson in English retrieved from a University website. We assessed English language proficiency with an objective test. To test comprehension, we administered a ten-item comprehension test on the content of the lecture. Our secondary aim was to compare the effects of different types of captions on viewer comprehension. We, therefore, created three viewing conditions: video with no captions (NC), video with premade captions (downloaded from the university website) (UC) and video with automatically generated captions (AC). Our results showed an overall strong effect of proficiency on lecture comprehension, as expected. Interestingly, we also found that whether captions helped or not depended on proficiency and caption type. The captions provided by the University website benefited our learners only if their English language proficiency was high enough. When their proficiency was lower, however, the captions provided by the university were detrimental and performance was worse than having no captions. For the lower proficiency levels, automatic captions (AC) provided the best advantage. We attribute this finding to pre-existing characteristics of the captions provided by the university website. Taken together, these findings caution institutions with a commitment to UDL against thinking that one type of caption suits all. The study highlights the need for testing captioning systems with diverse learners, under different conditions, to better understand what factors are beneficial for whom and when.