The study took place in five classrooms in five schools in three school districts in the Pacific Northwest. Children attended publicly funded preschool programs that provided early intervention for children with special needs.
The study began with 37 children. All children were eligible for early childhood special-education services and had mild to moderate language delays. Based on pretest scores, triads of children with similar receptive vocabulary scores were formed within each district. Within each triad, one member was randomly assigned to a parent dialogic reading group, one member was assigned to a staff dialogic reading group, and one was assigned to a control condition. Thirteen children were assigned to the staff-implemented group, which was not included in this review, and five more children did not complete the study, leaving 19 children remaining in the sample. The mean age of all the children who completed the study was 51.6 months (ranging from 39 to 66 months), and 31.3% of these children were female. The mean age of children in the sample included in
this review was 50.5 months.
The study included two intervention groups: one in which program staff implemented dialogic reading, and another in which parents implemented dialogic reading. The comparison between the staff-implemented group and the no-treatment comparison group did not meet evidence standards because of high differential attrition and lack of baseline equivalence and is excluded from this report. Dialogic reading was implemented over an eight-week period, during which staff or parents engaged in book reading with individual children at least four times per week.
Children in the control group did not participate in dialogic reading. They participated in group story time, which was the standard practice.
The primary outcome domain was children’s communication and language competencies, measured by three nonstandardized measures and two standardized measures. The nonstandardized measures included mean length of utterances, number of utterances, and number of different words used (lexical diversity). Children’s vocabulary knowledge was measured by two standardized tests: the Peabody Picture Vocabulary Test–Revised and the Expressive One-Word Picture Vocabulary Test–Revised. For a more detailed description of these outcome measures, see Appendix A2.
Support for implementation
Parents were trained in the dialogic reading program during two 90-minute instructional sessions held four weeks apart. Videotape training, live demonstration, and role-play were used during the training. Handouts summarizing the training components were provided to parents. The researchers modified the parent training program to address the needs of students with language delays by teaching parents to pause and give their children time to respond.