A Multiple Single-Case Experimental Design: DTTC Treatment in young children

Overview

Dynamic Temporal Tactile Cueing (DTTC) is a treatment approach designed for children with severe childhood apraxia of speech, yet the use of DTTC with children younger than three-years of age has not been examined. We used a multiple single-case experimental design to examine the use of DTTC in children with childhood apraxia of speech over six weeks of intervention. A linear mixed effect model was used to estimate the change in word accuracy for treated and untreated words across all children from Baseline to Post- treatment and to Maintenance. A Quasi-Poisson regression model was used to estimate mean change and calculate the effect size per individual child and at the word level.

Method

A multiple single-case design was used to examine the use of DTTC in children with childhood apraxia of speech (aged 2.5-5 years) over the course of six weeks of intervention. Changes in word accuracy were measured in treated words from Baseline to Post- treatment and from Baseline to Maintenance (six weeks post treatment). Generalization of word accuracy changes to matched untreated words was also examined. A linear mixed effect model was used to estimate the change in word accuracy for treated and untreated words across all children from Baseline to Post- treatment and to Maintenance. A Quasi-Poisson regression model was used to estimate mean change and calculate the effect size per individual child and at the word level.

Results

Group level analyses revealed significant changes in word accuracy for treated and untreated words at Post-treatment and Maintenance. At the child level, six of seven children displayed medium to large effect sizes where word accuracy increased in an average of 3.4/5 words across all children. Each child displayed some degree of generalization to untreated targets, specifically for words with the same syllable shape as the treated words.