Using Time Delay to Teach Literacy to Students with Severe Developmental Disabilities

A review of the literature was conducted for articles published between 1975 and 2007 on the application of time delay as an instructional procedure to teach word and picture recognition to students with severe developmental disabilities in an effort to evaluate time delay as an evidence-based practice. A total of 30 experiments were analyzed using quality indicators for single-subject design research. In general, we found that time delay was an evidence-based practice for teaching picture and sight word recognition supported by standards for evidence-based practice proposed by Horner et al. (2005). We discuss lessons learned in summarizing a body of literature to define an evidence-based practice and suggestions for better defining the practice.