The effect of substitution patterns on phonological treatment outcomes

Abstract

It has been suggested that phonological learning in children with articulation disorders is influenced by the variability or consistency of substitutes used for sounds that are excluded from the inventory. This proposal was based on a post-hoc analysis of children's pre-treatment inventories and substitution patterns, as well as their generalization patterns at the termination of phonological intervention. In the present investigation, an experimental treatment study was conducted as a direct test of a hypothesized relationship between substitution variation and treatment outcomes. Ten children with multiple articulation errors were divided into two groups on the basis of the variability or consistency of their substitutes for sounds that were omitted from their phonetic inventories. The first group (consistent substitute; CS) of children used the same substitute for the omitted sound in all word-positions, whereas children in the second group (variable substitute; VS) varied the substitute within and across word positions. The two groups of children were matched, as closely as possible, on variables for age, phonological knowledge, receptive vocabulary, the sound that was chosen for treatment, and its word-position (i.e. either word-initial or word-final position). Traditional treatment techniques were employed so that only the target sound was presented during therapy sessions. Results confirmed the hypothesis in that all children in the CS group learned the treated sound and generalized it to other contexts; by contrast, no child in the VS group evidenced knowledge of the treated sound by the conclusion of the experiment. These results provide further evidence of the importance of category representation for phonological learning and generalization.