Studying Treatment Intensity: Lessons from Two Preliminary Studies

Abstract

Determining how best to meet the needs of learners with Down syndrome requires an approach to intervention delivered at some level of intensity. How treatment intensity affects learner acquisition, maintenance, and generalization of skills can help optimize the efficiency and cost-effectiveness of interventions. There is a growing body of research on the effects of treatment intensity but almost no systematic study of it with children with Down syndrome, providing little guidance about how to approach the study of intensity. In two preliminary studies, we manipulated different aspects of the dose of treatment intensity and measured effects on skill acquisition using single-subject experimental designs. Intensity varied in terms of number of opportunities per session, session duration, and spacing of opportunities (interstimulus interval). Matched responses within a skill area were randomly assigned to a level of intensity and acquisition was compared. Results reveal lessons about what aspects of intensity to manipulate and how, selecting experimental designs, measuring multiple outcomes, and the influence of learner characteristics. These lessons highlight directions for future approaches to tease apart the relative contributions of different aspects of intensity on skill acquisition and determine the most effective intensity of early intervention for children with Down syndrome.

How to Study the Influence of Intensity of Treatment on Generalized Skill and Knowledge Acquisition in Students with Disabilities

“…For example, Ennis and colleagues (in press) studied dose frequency in the sense that they descriptively compare the effect sizes of change for academic engagement and writing skill in their single group of secondary students who received Self-Regulated Strategy Development for fewer sessions per week than is typical to those effect sizes that have been observed in the literature for the same treatment delivered more frequently. Neil and Jones (in press) studied the effects of the number of response opportunities per session, the length of the intervention session, and the distribution of response opportunities across the session on the acquisition of various skills in young children with Down syndrome. We would consider these manipulations to be related to treatment dose.…”

“…Three studies in this special issue used a multi-element/adapted alternating treatments design (Haegele & Burns, in press; Neil & Jones, in press; Ross & Begeny, in press). These designs are well-suited to asking questions about effects of treatment intensity on non-reversible dependent variables, but they are accompanied by two related requirements.…”

“…For example, Neil and Jones (in press) randomly assigned five responses to five conditions (one response per condition). Sampling theory tells us that randomly assigning only one unit to each condition is much less likely to produce equivalent target sets across conditions than randomly assigning a much larger number of units per condition (Glennerster & Kudzai, 2013).…”

“…For example, Neil and Jones (in press) used within-treatment session data as their dependent variable, and their results were used to make statements about intensity effects on learning. These investigators did observe large shifts in level immediately following treatment onset.…”

Effects of intervention intensity on skill acquisition and task persistence in children with Down syndrome

“…Neil and Jones () began to isolate the effects of the spacing of opportunities from the number of opportunities by designing a series of conditions in which the value of one parameter was held constant, while the others varied. In an investigation of the effects of dose in discrete trial intervention for children with Down syndrome, Neil and Jones () manipulated three parameters of dose (opportunities per session, session duration and spacing of session opportunities) and measured acquisition of receptive communication targets. For one child, number of opportunities and spacing of those opportunities varied, but session duration was held constant.…”