Syllable onsets II: three-element clusters in phonological treatment.

This study extends the application of the Sonority Sequencing Principle, as reported in J. A. Gierut (1999), to acquisition of word-initial 3-element clusters by children with functional phonological delays (ages in years;months: 3;4 to 6;3). The representational structure of 3-element clusters is complex and unusual because it consists of an s-adjunct plus a branching onset, which respectively violate and conform to the Sonority Sequencing Principle. Given the representational asymmetry, it is unclear how children might learn these clusters in treatment or whether such treatment may even be effective. Results of a single-subject staggered multiple-baseline experiment demonstrated that children learned the treated 3-element cluster in treatment but showed no further generalization to similar types of (asymmetric) onsets. Treatment of 3-element clusters did, however, result in widespread generalization to untreated singletons, including affricates. Moreover, there was differential generalization to untreated 2-element clusters, with individual differences being traced to the composition of children's singleton inventories. Theoretically, the results suggest a segmental-syllabic interface that holds predictive potential for determining the effectiveness and effects of clinical treatment as based on the notion of linguistic complexity.

Optimality theory in phonological acquisition.

This tutorial presents an introduction to the contemporary linguistic framework known as optimality theory (OT). The basic assumptions of this constraint-based theory as a general model of grammar are first outlined, with formal notation being defined and illustrated. Concepts unique to the theory, including "emergence of the unmarked," are also described. OT is then examined more specifically within the context of phonological acquisition. The theory is applied in descriptions of children's common error patterns, observed inter- and intrachild variation, and productive change over time. The particular error patterns of fronting, stopping, final-consonant deletion, and cluster simplification are considered from an OT perspective. The discussion concludes with potential clinical applications and extensions of the theory to the diagnosis and treatment of children with functional phonological disorders.

Syllable onsets: clusters and adjuncts in acquisition.

The Sonority Sequencing Principle is a presumed universal that governs the permissible sequences of consonants within syllables. In two single-subject experiments, we evaluated this principle as applied to the acquisition of onset clusters and adjuncts by children exhibiting functional phonological delays (age in years;months: 3;2 to 7;8). Experiment 1 tested the hypothesis that children abide by the Sonority Sequencing Principle in development, such that the occurrence and use of marked true clusters implies unmarked clusters, but not vice versa. This claim was validated, in part, by the gradient generalization learning patterns of children who were taught marked clusters. Others who were taught unmarked clusters exhibited limited learning characteristic of within-class generalization, with apparent gaps in sonority sequencing. Experiment 2 examined the role of adjunct sequences /sp, st, sk/, whose markedness status is questionable given their violation of the Sonority Sequencing Principle. Results indicated that children learned adjuncts consistent with patterns of within-class generalization, thereby supporting the view that these sequences are unmarked in structure. Experimental findings are integrated in discussion of the representation of onset clusters and their course of emergence in phonological acquisition relative to the Sonority Sequencing Principle.

Lexical constraints in phonological acquisition.

Lexical diffusion, as characterized by interword variation in production, was examined in phonological acquisition. The lexical variables of word frequency and neighbourhood density were hypothesized to facilitate sound change to varying degrees. Twelve children with functional phonological delays, aged 3;0 to 7;4, participated in an alternating treatments experiment to promote sound change. Independent variables were crossed to yield all logically possible combinations of high/low frequency and high/low density in treatment; the dependent measure was generalization accuracy in production. Results indicated word frequency was most facilitative in sound change, whereas, dense neighbourhood structure was least facilitative. The salience of frequency and avoidance of high density are discussed relative to the type of phonological change being induced in children's grammars, either phonetic or phonemic, and to the nature of children's representations. Results are further interpreted with reference to interactive models of language processing and optimality theoretic accounts of linguistic structure.

Production, conceptualization and change in distinctive featural categories.

This study extends prior investigations of children's abilities to conceptualize distinctive phonological features in development. The purpose was to establish the relationship between a child's productive and conceptual knowledge, and to examine its potential influence on phonological change. Six children evidencing phonological disorders (aged 3;4 to 5;7) participated in evaluations of the productive sound system and the metalinguistic ability to classify phonological information, with particular emphasis on fricatives. Then, children were enrolled in clinical treatment aimed at accurate production of fricatives. Following treatment, production and classification abilities were again tested. Results indicated that if a child's productive knowledge of distinctive featural contrasts changed following treatment, there was also a corresponding change in conceptual knowledge. The specific featural dimensions that were used to classify phonological information were either in parallel to, or in advance of, those features also used in production by the child. Conceptual knowledge was thus equal to or better than productive knowledge for these children.

Treatment efficacy: functional phonological disorders in children.

This report addresses the efficacy of treatment for functional phonological disorders in children. The definition of phonological disorders and their incidence and prevalence are first presented. The impact of this disorder on the lives of children and the role that speech-language pathologists play in treating this disorder are then discussed. Evidence of the positive outcome of phonological treatment is reviewed, with particular emphasis on treatment procedures that have been deemed effective, the specific effects of these treatments on improving intelligibility, and comparisons between treatments in facilitating improved sound production.

Natural domains of cyclicity in phonological acquisition.

This study expands and further validates cyclicity in the course of phonological development by exploring a potential relationship between the acquisition of singletons and clusters. The hypothesis is that children will acquire singletons followed by clusters in an alternating and recursive pattern, in complement to observed subsegmental cyclicity involving larnygeal and supralaryngeal distinctions. Six children with functional phonological disorders participated in one of three experimental conditions administered as a staggered multiple-baseline, multiple-probe design: treatment of singletons only, clusters only, or the singleton-cluster cycle. Results indicated that a singleton-cluster cycle could be induced experimentally, but it was not generally sustained by a child in expansion of the phonological repertoire. In comparison, laryngeal-supralaryngeal cyclicity was consistently maintained by all children, independent of experimental condition. A theoretical implication of these findings is that cyclicity functions as a governing principle of phonological development, but only if it is inherent to the natural domain of language. The clinical application of cyclicity in structuring treatment is considered.

Categorization and feature specification in phonological acquisition.

Distinctive feature specification and representation in phonological acquisition are examined in the context of underspecification theory. Subjects were 30 children aged (3;1 to 5;10) who exhibited systematic differences in their linguistic knowledge of target phonological contrasts. A free classification task was used to tap children's conceptual knowledge of these contrasts, with features of place and manner experimentally manipulated. Three questions were addressed: which features do children use to categorize segmental information, do the defining features of a category shift as the phonological system advances, and which framework of underspecification theory best accounts for the results? All children categorized segments on the basis of marked nonredundant featural properties, and used only one feature value to define category membership consistent with radical underspecification. Linguistic knowledge and linguistic input both influenced children's category judgements, but to different degrees. The emergence of phonological categories involved increasing feature differentiation as the child's productive phonology advanced.

An experimental test of phonemic cyclicity.

Laryngeal-supralaryngeal cyclicity has been put forth as an acquisition principle that describes expansion of the phonemic inventory as a bivalent cycle with alternations between the elaboration of laryngeal and supralaryngeal properties of the system (Gierut, 1994). This study evaluated experimentally the claims of the principle by manipulating the domain of the cycle and the phase relationship of the cycle as independent variables, and by monitoring longitudinally the order of emergent phonemic distinctions in the sound systems of seven children with phonological delays (aged 3;4 to 5;8) as the dependent variable. Three general findings emerged: (1) the course of acquisition for all children was consistent with cyclicity; (2) there were no differences in phonemic acquisition between children taught a laryngeal as opposed to a supralaryngeal distinction; and (3) children taught out-of-phase with the cycle evidenced greater phonemic expansion than those taught in-phase with the cycle.

Triggering a principle of phonemic acquisition.

This experimental clinical study evaluated different treatment manipulations of the principle of Laryngeal-Supralaryngeal Cyclicity as a follow-up to Gierut (1994b). Laryngeal-Supralaryngeal Cyclicity states that the acquisition of phonemic distinctions will occur as a bivalent cycle with laryngeal and supralaryngeal distinctions emerging in turn. In this study, children with seemingly static phonemic systems participated in a treatment programme that introduced sequentially new distinctions to the inventory. One child was presented with alternating laryngeal and supralaryngeal properties consistent with the principle, whereas the other child was exposed only to consecutive supralaryngeal distinctions. Results indicated that the latter treatment condition triggered greater phonemic expansion, as based on the longitudinal course of emergent phonemic distinctions for each child. These findings were comparable to those of the earlier investigation, and have implications for treatment efficacy and theories of language acquisition.

Phonemic structures of delayed phonological systems.

The phonemic inventories of 30 children (aged 3;4-5;7) with phonological delays were examined in terms of featural distinctions in order to address universal vs. individual accounts of acquisition. Phonetic inventories of these same children were also identified for comparison purposes. Across children, four hierarchical and implicationally related types of phonemic inventory were identified. The typology uniquely captured common distinctions maintained by all children, and at the same time, allowed for individual differences in the specific phonemic composition of each system. These cross-sectional results have theoretical implications for the longitudinal course of phonemic acquisition. In particular, children appear to have a number of linguistic choices that relate to the course, the specifics, and the mechanism of change in acquisition.

The conditions and course of clinically induced phonological change.

This two-part study continued the evaluation of minimal pair treatment in phonological change (Gierut, 1989, 1990, 1991a; Gierut & Neumann, 1992). Three linguistic variables relevant to change were experimentally manipulated within an alternating treatments design to determine specifically the interplay of a maximal number of feature distinctions, feature class, and relationship of treated phonemes to a child's grammar in inducing sound change. The conditions of treatment that were shown to facilitate optimal phonological change in previous research were again experimentally replicated. Specifically, minimal pairs comparing two phonemes previously unknown to a child that also differed by maximal and major class features were found to be the preferred context motivating change. Important individual differences emerged and underscored the role of a child's pretreatment grammar in phonological change. These differences contributed to descriptions of possible courses of change followed by children with phonological disorders and bear upon the predictability of change and the effectiveness of treatments that may condition change.

Teaching and learning /θ/: A non-confound.

The purpose of this study was to replicate and extend the findings on the effectiveness of homonymous versus non-homonymous treatment approaches for children with phonological disorders, following Gierut (1991b). The present study was motivated by a potential confound noted in the previous report; namely, the specific sounds /θ, θ/ treated in the presumably less effective homonymous condition may have inhibited degree of phonological change. It was thus necessary to teach these more difficult, late-acquired interdental fricatives in the more effective non-homonymous treatment condition using identical methods and procedures. Results indicated that a non-homonymous teaching approach again motivated greater phonological change than a homonymous approach, regardless of sounds that were taught. These findings have implications for the independence of linguistic structures of treatment in inducing sound change, and bear upon assumptions about ease of sound learning based on normative developmental sequences.

Homonymy in phonological change.

This study examines the role of homonymy as a motivator of phonological change in treatment. The relative effectiveness of two treatment structures in improving the production of treated and untreated error sounds was evaluated. One treatment structure emphasized homonymous forms by comparing 1:1 a desired ambient target with its corresponding replacement error from the child's grammar, consistent with conventional minimal pair treatment (Weiner, 1981). The other treatment did not focus on homonymy, nor did it make explicit reference to a child's grammar. In line with treatment of the empty or unknown set (Gierut, 1989), two errored sounds were simply compared with each other. Differential learning was observed among the treatments such that the non-homonymous structure resulted in greater accuracies of treated sounds and in more new untreated sounds being added to the phonological system. The findings have potential implications for the status of homonymy in phonological change and in the structure of phonological treatment.

Differential learning of phonological oppositions.

This study evaluated whether variations in the structure of minimal versus maximal opposition treatments would result in empirical differences in phonological learning. Subjects were 3 children who excluded at least six sounds from their pretreatment phonetic and phonemic inventories. An alternating treatments design in combination with a staggered multiple baseline across subjects was used to evaluate differences in learning the two types of oppositions. Results indicated that treatment of maximal oppositions led to greater improvement in the children's production of treated sounds, more additions of untreated sounds to the posttreatment inventory, and fewer changes in known sounds than treatment of minimal oppositions. Moreover, individual differences suggested that phonological learning was enhanced not only by the number but also by the type of distinctions being taught. A potential sequence of relative clinical effectiveness was proposed such that teaching multiple and major class distinctions greater than teaching multiple distinctions greater than teaching few distinctions among sounds.

Maximal opposition approach to phonological treatment.

The purpose of this paper was to evaluate a phonological treatment program of maximal rather than minimal feature contrasts by charting the course of learning in a child displaying a systematic error pattern involving the nonoccurrence of word-initial consonants. Generalization data indicated that the child learned 16 word-initial consonants following treatment of only three sets of maximal opposition contrasts. Overgeneralization data indicated that the child restructured his phonological system based on a larger concept of "word initialness." Basic components of and differences between various forms of contrast treatment are discussed.

A functional analysis of phonological knowledge and generalization learning in misarticulating children.

It has been suggested that a child's productive phonological knowledge may be one factor that potentially accounts for individual differences in generalization learning observed among phonologically disordered children (Dinnsen & Elbert, 1984; Elbert, Dinnsen, & Powell, 1984). This paper evaluates the hypothesis that productive phonological knowledge influences generalization. Three related studies involving 6 functionally misarticulating children were conducted. In the first study, a description of each child's phonological system was developed using procedures of standard generative analysis. Based upon these descriptions, each child's productive phonological knowledge of his or her own sound system was determined and then ranked on a continuum ranging from "most" to "least" knowledge relative to the adult target. The second study implemented an experimental treatment program based upon each child's productive phonological knowledge, with treatment sounds selected directly from each child's continuum of knowledge. The third study reassessed each child's productive phonological knowledge following treatment. The results of these three studies indicated that a child's productive phonological knowledge of the sound system influenced the overall amount of generalization learning. However, the extent of generalization learning was associated with the point on the knowledge continuum at which treatment was initiated. These findings are discussed with reference to individual differences in generalization learning.