Comparison of constant time delay and the system of least prompts in teaching preschoolers with developmental delays

This investigation compared the effectiveness and efficiency (sessions, errors, percent of errors, and minutes of instructional time through criterion) of constant time delay and the system of least prompts in teaching sight words to developmentally delayed preschoolers. Maintenance of sight words and generalization across instructors and materials were assessed. Also, students' acquisition of relationships between the target behavior and previously learned information were assessed. Two sessions were conducted each day in their classroom, one with each procedure. Two of the children were taught 16 words and one child learned 12 words. The parallel treatments design was used to assess the effectiveness of the two instructional strategies. The results indicated that (a) both strategies produced criterion level responding in the instructional setting, (b) constant time delay resulted in fewer total trials, errors, percent of errors, and minutes of direct instructional time through criterion than the system of least prompts, (c) both strategies produced criterion-level responding that maintained in 1-, 3- and 5-week follow-up probes, (d) both strategies resulted in generalization across instructors and materials, and (e) both strategies resulted in cross-modal generalization from expressive to receptive, receptive and expressive identification of the words' function or action, and matching the written word to a photograph of its referent.