Judith Gierut

Research on phonological disorders in children has conventionally emphasized the speech sound in search of causes, diagnoses, treatments, and prevention of the disorder. This article aims to shift the research focus to the word instead. The motivation comes from advances in psycholinguistics that demonstrate the word is central to the perception, production, and acquisition of phonological information. Three strands of potential study are outlined in evaluation of how words might initiate and boost, but perhaps also, interrupt learning for children with phonological disorders.

To document, validate, and corroborate effect size (ES) for single-subject design in treatment of children with functional phonological disorders; to evaluate potential child-specific contributing variables relative to ES; and to establish benchmarks for interpretation of ES for the population. Data were extracted from the Developmental Phonology Archive for 135 preschool children with phonological disorders who previously participated in single-subject experimental treatment studies. Standard Mean DifferenceAll with Correction for Continuity was computed to gauge the magnitude of generalization gain that accrued longitudinally from treatment for each child, with the data aggregated for purposes of statistical analyses. ES ranged from 0.09 to 27.83 for the study population. ES was positively correlated with conventional measures of phonological learning and visual inspection of learning data based on procedures standard to single-subject design. ES was linked to children's performance on diagnostic assessments of phonology, but not other demographic characteristics or related linguistic skills and nonlinguistic skills. Benchmarks for interpretation of ES were estimated as 1.4, 3.6, and 10.1 for small, medium, and large learning effects, respectively. Findings have utility for single-subject research and translation of research to evidence-based practice for children with phonological disorders.

There is a noted advantage of dense neighborhoods in language acquisition, but the learning mechanism that drives the effect is not well understood. Two hypotheses – long-term auditory word priming and phonological working memory – have been advanced in the literature as viable accounts. These were evaluated in two treatment studies enrolling twelve children with phonological delay. Study 1 exposed children to dense neighbors versus non-neighbors before training sound production in evaluation of the priming hypothesis. Study 2 exposed children to the same stimuli after training sound production as a test of the phonological working memory hypothesis. Results showed that neighbors led to greater phonological generalization than non-neighbors, but only when presented prior to training production. There was little generalization and no differential effect of exposure to neighbors or non-neighbors after training production. Priming was thus supported as a possible mechanism of learning behind the dense neighborhood advantage in phonological acquisition.

Long-term auditory priming of words from dense neighborhoods has been posited as a learning mechanism that affects change in the phonological structure of children's lexical representations. An apparent confound associated with the modality of priming responsible for structural change has been introduced in the literature, which challenges this proposal. Thus, our purpose was to evaluate prime modality in the treatment of children with phonological delay. Nine children were assigned to auditory-visual, auditory, or visual priming of words from dense neighborhoods prior to the treatment of production as the independent variable. The dependent variable was phonological generalization. Results showed that auditory priming (with or without visual input) promoted greater generalization on an order of magnitude of 3:1. Findings support the theoretical significance of auditory priming for phonological learning and demonstrate the applied utility of priming in clinical treatment.

This paper focuses on three seemingly unrelated error patterns in the sound system of a child with a phonological delay, Child 218 (male, age 4 years 6 months) and ascribes those error patterns to a larger conspiracy to eliminate fricatives from the phonetic inventory. Employing Optimality Theory for its advantages in characterizing conspiracies, our analysis offers a unified account of the observed repairs. The contextual restrictions on those repairs are, moreover, attributed to early developmental prominence effects, which are independently manifested in another error pattern involving rhotic consonants. Comparisons are made with a published case study involving a different implementation of the same conspiracy, the intent being to disambiguate the force behind certain error patterns. The clinical implications of the account are also considered.

The purpose was to document the trials to induce first generalization in children with phonological disorders enrolled in treatment. Archival data from 65 preschoolers were examined, with three kinds of generalization documented: treated, within- and across-class gains in production accuracy. Overall, an average of 185 trials was sufficient to induce first generalization, but this varied based on the kind of generalization that occurred. Across-class generalization required the fewest trials and generalization to the treated sound, the most trials. Results bear on applied issues associated with lexical diffusion in clinical treatment and theoretical issues associated with error-driven learning algorithms and abstraction of phonological generalizations from the input.

This paper examines a range of predicted versus attested error patterns involving coronal fricatives (e.g. [s, z, θ, ð]) as targets and repairs in the early sound systems of monolingual English-acquiring children. Typological results are reported from a cross-sectional study of 234 children with phonological delays (ages 3 years; 0 months to 7; 9). Our analyses revealed different instantiations of a putative developmental conspiracy within and across children. Supplemental longitudinal evidence is also presented that replicates the cross-sectional results, offering further insight into the life-cycle of the conspiracy. Several of the observed typological anomalies are argued to follow from a modified version of Optimality Theory with Candidate Chains (McCarthy, 2007).

The effects of the age of acquisition (AoA) of words were examined in the clinical treatment of 10 preschool children with phonological delays. Using a single-subject multiple-baseline experimental design, children were enrolled in one of four conditions that varied the AoA of the treated words (early vs. late acquired) relative to their corresponding word frequency (high vs. low frequency). Phonological generalization to treated and untreated sounds in error served as the dependent variable. Results showed that late acquired words induced greater generalization, with an effect size four times greater than early acquired words, whereas the effects of word frequency were minimized. Results are discussed relative to hypotheses about the role of AoA in language acquisition and the relevance of this variable for phonological learning.

The effect of word-level variables on expressive phonology has not been widely studied, although the properties of words likely bear on the emergence of sound structure (Stoel-Gammon, 2011). Eight preschoolers, diagnosed with phonological delay, were assigned to treatment to experimentally induce gains in expressive phonology. Erred sounds were taught using stimulus words that varied orthogonally in neighborhood density and word frequency as the independent variables. Generalization was the dependent variable, defined as production accuracy of treated and untreated (erred) sounds. Blocked comparisons showed that dense neighborhoods triggered greater generalization, but frequency did not have a clear differential effect. Orthogonal comparisons revealed graded effects, with frequent words from dense neighborhoods being optimal for generalization. The results contrast with prior literature, which has reported a sparse neighborhood advantage for children with phonological delay. There is a suggestion that children with phonological delay require greater than usual cue redundancy and convergence to prompt expressive phonological learning.

The purpose of this article is to motivate the use of effect size (ES) for single-subject research in clinical phonology, with an eye towards meta-analyses of treatment effects for children with phonological disorders. Standard mean difference (SMD) is introduced and illustrated as one ES well suited to the multiple baseline (MBL) design and evaluation of generalization learning, both of which are key to experimental studies in clinical phonology.