No evidence that same-language subtitles improve children's reading fluency

High-profile campaigns globally have argued that same-language television subtitles may help children improve their reading. In this intervention study, we tested the causal hypothesis that exposure to subtitles improves children's reading fluency. We tested 127 British children in Years 2 and 3 before and after a 6-week home-based intervention, in which children were randomly assigned to an experimental group that watched television with English subtitles or a control group that watched television without subtitles. Children's reading fluency was assessed via two standard tests of reading fluency and their engagement with subtitles while watching videos, measured with eye-tracking. Results showed that both groups improved their reading fluency over 6 weeks. Crucially, there was no evidence that subtitle exposure (of around 66 hr on average) drove an improvement in reading fluency, or that greater subtitle exposure provided any additional benefit. We conclude that same-language subtitles are unlikely to improve children's reading fluency. However, the primary school reading curriculum has a positive impact on reading fluency that can be observed over a relatively short time-scale.