Effects of audio support on multimedia learning processes and outcomes in students with dyslexia

Adding audio to written text may cause redundancy effects, but could be beneficial for students with dyslexia for whom it supports their reading. Studying both learning process and learning outcomes in students with and without dyslexia can shed light on this issue and helps to find out whether there are constraints to the redundancy effect as proposed in the Cognitive Theory of Multimedia Learning. We examined to what extent adding -redundant- audio affects multimedia learning in 42 university students with dyslexia and 44 typically developing students. Participants studied two user-paced multimedia lessons (text-picture, text-audio-picture) with retention and transfer post-tests. An SMI RED-500 eye-tracker captured eye-movements during learning. Regarding process measures, students had longer study times, with more focus on pictures, and more transitions between text and pictures in the text-audio-picture condition. Regarding learning outcomes, negative redundancy effects on transfer knowledge (deep learning), but not on (factual) retention knowledge were found across both groups. When relating learning processes to learning outcomes, longer study time predicted higher transfer knowledge in both groups in the text-audio-picture condition, whereas in the text-picture condition, more study time predicted lower transfer knowledge in typically developing students only. To conclude, adding audio seems to have a negative effect on the quality of knowledge and leads to less efficient learning across the two groups. Reading ability does not impact the universality of the redundancy effect, but students with dyslexia should only use audio support when aiming to learn factual knowledge and should be aware that it increases study time.