Constant time delay to teach reading to students with intellectual disability and autism: a review

The ability to read promotes academic success and serves as an essential prerequisite skill for many postsecondary opportunities. However, developing proficient reading skills is particularly difficult for many individuals with intellectual disability (ID) and autism spectrum disorder (ASD). Reading is an important life skill for all individuals, and it is essential for reading instruction to be grounded in research to achieve optimal learning outcomes. We conducted a review of the literature covering a 15-year period (2005-2020) to examine research measuring the effects of an evidence-based practice, constant time delay (CTD), when used as a reading intervention to teach participants with ID and/or ASD. Studies evaluated the acquisition of functional or academic reading skills across two instructional delivery methods: teacher-delivered and technology-based CTD. All reviewed research used a single case research design to experimentally validate the effects of CTD as a reading intervention, and findings across studies revealed a functional relationship between variables. That is, when applied as a reading intervention, CTD led to acquisition of academic or functional reading skills in participants with ID and/or ASD regardless of delivery method. Recommendations for research and practical application of CTD when teaching reading are provided.