How to choose phonology goals?

I find out via Twitter (don’t you love twitter!) that “teach complex sounds first” is making the rounds again (still!) and I am prompted to respond. Besides the fact that I have disproven the theoretical underpinnings of this idea, it bothers me that so many of the assumptions wrapped up in the assertion are unhelpful to a successful intervention. Specifically, we should not be treating “sounds”, there is no agreed upon and universal ordering of targets from simple to complex, and there is no reason to teach the potential targets one at a time in some particular order anyway. So what should we do? I will describe a useful procedure here with an example.

There is this curious rumour that I promote a “traditional developmental” approach to target selection that I must lay to rest. In fact, I have made it clear that I promote a dynamic systems approach. An important concept is the notion of nonlinearity: if you induce gradual linear changes in several potential targets at once, a complex interaction will result causing a nonlinear change across the system known as a phase shift. How do you choose the targets to work on at once? Francoise and I show how to use a “quick multilinear analysis” to identify potential targets  at all levels of the phonological hierarchy, in other words phrases, trochaic or iambic feet, syllables, onsets, rimes or codas, clusters, features or individual phonemes. Many case studies and demonstrations are laid out in our book that will shortly appear in a beautiful second edition. Then we show how to select three targets for simultaneous treatment using Grunwell’s scheme designed to facilitate progressive change in the child’s phonological system. I will demonstrate both parts of this process here, using a very brief sample from a case study that is described in our book. The child’s speech is delayed for her age of two years which can be established by comparing the word shape and phonetic repertoire to expectations established by Carol Stoel-Gammon.

case-study-6-3-sample-for-blog

Potential treatment targets can be identified by considering strengths and weaknesses at the prosodic and segmental tiers of the phonological hierarchy (full instructions for this quick multilinear analysis are contained in our book). The table below describes units that are present and absent. Note that since her language system is early developing, her phonology is probably word-based rather than phoneme based; therefore ‘distinction’ refers to the presence of a phonetic distinction rather than a phonemic contrast.

case-study-6-3-quick-multilinear-analysis

Now that we have a sense of potential targets from across the whole system, how do we select targets using Grunwell’s scheme? We want to ensure that we address word shape and segmental goals. We also want to choose one goal to stabilize a variable structure in the system, another to extend something that is established to a new context, and a third to expand the system to including something new. Here are my choices (others are possible):

case-study-6-3-grunwell-goals

There is a good chance that fricatives and codas will emerge spontaneously with this plan because we will have laid down the foundation for these structures. If they don’t it should not be hard to achieve them during the next therapy block. The idea that you can only induce large change in the system by teaching the most complex targets first is clearly not true as I have explained previously – in fact, complex sounds emerge more easily when the foundation is in place. Furthermore, Schwartz and Leonard (1982) also recommended in their study on selection effects in early phonological development that it was best to teach IN words to children with small vocabulary sizes – in other words expand the vocabulary size gradually by using word shapes and phonemes that are in the inventory, but combined in new ways.

It would be possible to use the stabilize-extend-expand scheme and choose different, more complex goals. For example, we could consider the nonreduplicated CVCV structure (cubby, bunny, bootie) to be the stabilize goal. Then we could introduce word final labial stops as the extend goal, generalizing these phones from the onset where they are well established to a new word position (up, tub, nap). Finally, we could introduce a word initial fricative as the expand goal (see, sock, soup). This plan with more complex targets might work but you are risking slower progress, given the empirical findings reported in Rvachew & Nowak (2001) and in Schwartz & Leonard (1982). Furthermore, you would be failing to recognize a major constraint on the structure of her syllables (the limitation to only 2 segments, VV or CV with CVV and CVC currently proscribed). If you focus only on introducing “complex sounds” without attending to this major issue at the prosodic levels of her phonological system, you will be in for a rough ride.

I attach here another example, this one a demonstration from the second edition of our book, chapter-8-demonstration-8-2, to appear in December 2016. Francoise and I have taken a great effort to show students how to implement an evidence based approach to therapy. I invite readers to take a peak!

Reading List

Rvachew, S., & Brosseau-Lapré, F. (2018). Developmental Phonological Disorders: Foundations of Clinical Practice (Second Edition). San Diego, CA: Plural Publishing. (Ready for order in December 2016)

Grunwell, P. (1992). Processes of phonological change in developmental speech disorders. Clinical Linguistics & Phonetics, 6, 101-122.

Stoel-Gammon, C. (1987). Phonological skills of 2-year-olds. Language, Speech & Hearing Services in Schools, 18, 323-329.

Rvachew, S., & Bernhardt, B. (2010). Clinical implications of the dynamic systems approach to phonological development. American Journal of Speech-Language Pathology, 19, 34-50.

Rvachew, S. & Nowak, M. (2001). The effect of target selection strategy on sound production learning. Journal of Speech, Language, and Hearing Research, 44, 610-623.

Schwartz, R., & Leonard, L. (1982). Do children pick and choose? An examination of selection and avoidance in early lexical acquisition. Journal of Child Language, 9, 319-336.

 

 

 

Cross-linguistic perspective on “atypical” error patterns

As a clinical phonology instructor working in a linguistically and culturally diverse environment I am conscious of the need to prepare my students for clinical practice with children who may speak languages that are not English. I am forced to narrow my focus in the classroom to English normative data because there is only so much time and because most of the available clinical data pertains to English. At the same time I know that those students who plan to practice in English-dominant environments will have some bilingual children on their caseloads. That part of my class that plans to stay in Montreal will be working in a bilingual environment, switching hourly between English dominant and French dominant patients who often know a second or third language. Finally a good proportion of the class are international students who plan to return to their home countries to practice in a language that is neither English nor French. Therefore the question of how best to ensure that they have analytical tools and background knowledge that will allow them to apply what they have learned in an English context to other languages is paramount. Sharynne McLeod’s work and the Multilingual Children’s Speech website  is enormously important in this regard.

I really enjoyed the systematic review by Hambly, Wren, McLeod and Roulstone on “the influence of bilingualism on speech production”. I especially liked the introductory summary of Stackhouse and Wells’ psycholinguistic model whereby phonological development is “simplified into three phases: input → storage → output”. This model figures prominently in our book and was one influence on the organization of our discussion of treatment procedures in Part III. In their review, Hambly et al. describe many papers that recount instances of apparently atypical error patterns in bilingual children with typical or atypical speech development. Many of these patterns reflect transfer from one language to another such as unexpected voicing patterns, trills or spirants crossing over from first language Punjabi, Russian or Spanish to second-language English. The papers reviewed also described patterns that were rare across languages however: for example, the rare occurrence of backing in a variety of first and second language contexts lead some authors to the conclusion that backing is universally rare and therefore always atypical. Francoise and I are aware of a context in which an error pattern that might be mistaken for backing is not rare however. Our papers describing typical and atypical French phonology take a multilinear and multirepresentational approach and highlight the disconnect between the persistence of a phonological pattern approach to the description of children’s speech despite the important insights offered by the psycholinguistic approach to phonological development.

Although the theoretical underpinnings of phonological processes are not necessarily implied when clinicians and researchers speak of phonological patterns I think that it is helpful to recall the theoretical roots of this approach. The original idea was that the child’s underlying representations were adultlike even though the child’s motor abilities were not up to the task of producing speech that matched adult expectations. Therefore one assumed that the child’s underlying representation for a word such as “cone” would be /kon/ but an innate simplification process would front the /k/, leading to [ton]* in the output. The error pattern in “cone” → [ton]*, “key” → [ti]*, “cake” → [tet]* is called velar fronting, implying that an underlying present velar is fronted during the transition to the output form. The opposite pattern, in which a front sound, e.g., /t, d, s, z/ is produced as a back sound, e.g., /k,ɡ,ʃ,ʒ /, is referred to as backing but is atypical by virtue of infrequence. I am not going to recount all of the evidence against this position here but suffice it to say if it doesn’t work for phonological development in the case of a child learning one language according to a typical trajectory it is even less tenable as an explanation for mismatches in bilingual children’s speech and it is clearly not tenable as an explanation for mismatches in the speech of children with a phonological disorder.

Continuing with the example of backing I am going to show that this is a poor description of apparent backing errors in English or French speaking children with a phonological disorder. In English speaking children, backing alveolar consonants is indeed rare and thus termed “atypical”. The atypical nature of the error is further enhanced by the phonological problem that it represents: when analyzed from a multilinear perspective, fronting means that the child is using the default Coronal feature or is delinking the marked Dorsal feature, resulting in a simplification; on the other hand, backing is in most contexts phonologically impossible since it involves adding a marked feature unless the child has a very unusual phonological system in which Dorsal is the default place feature. How then does the error arise? Answering this question requires that one examine the articulatory roots of the child’s problem as was done by Fiona Gibbon in her description of “Undifferentiated Lingual Gestures in Children with Articulatory/Phonological Disorders.” Electropalatography shows that this error pattern is rooted in an abnormal lingual gesture during speech that is pervasive, affecting all the lingual phonemes and often resulting in other atypical errors such as lateral distortions of sibilants. One thing that is important and interesting about the child’s error pattern is that it is revealed to be not backing of front sounds at all since all the lingual phones are produced with a similarly undifferentiated gesture (neither front nor back but whole tongue dorsum in contact with the palate); the listener’s percept of a front or back sound is determined by the timing of the release phase of the gesture. In this case, in English, the error is a highly atypical error reflecting a motor speech problem that is not accurately described as backing.

Now, turning to French, we have published raw data from francophone children with a phonological disorder in the Canadian Journal of Speech-Language Pathology and Audiology: we have observed that in both typical and atypical development it is very common for French speaking children to substitute a back sound for a front sound in a very particular context, specifically the /ʁ/-clusters. We show first of all that the output form [kʁ] is easiest for the children to acquire and thus the place features of the two consonants appear to facilitate production of each other, e.g., as in ‘crayon’ /kʁɛjɔ̃/ → [kʁɛjɔ̃]. Second, in the case of /tʁ/-clusters, spreading of place from the /ʁ/ to the unspecified place node on the /t/ is very common resulting in an apparent backing error, e.g., as in ‘train’ /tʁɛ̃/ → [kʁɛ̃]*. Interestingly, we see the spreading of the Dorsal feature from the second segment in the cluster back to the first segment of the cluster even when the /ʁ/ target is produced as [w] and in the case of /w/ clusters (recall that this phone has both labial and dorsal place features), e.g., “doigt” /dwa/ → [ɡwa]*. Finally, we observe even more unusual productions such as, ‘framboise’ /fʁɑ̃bwaz/ → [kwɑ̃bjaz]*, suggesting that the features of /f/ are difficult for the child to capture perceptually in these words, perhaps resulting in substitution of a preferred form in the complex onset. We have seen similar error patterns in the speech of francophone children with typically developing speech. The conclusion to be drawn in the case of French is that this error is not a backing error at all; it is a spreading error that makes perfect sense in its typical context. In this case it is not atypical, neither from the perspective of its frequency nor from the perspective of its phonological origins.

I have shown that an error pattern that may look similar on the surface can have a very different origin in two languages and thus be atypical in one and typical in the other. My overall conclusion from this discussion only partly echoes that made by Hambly et al: it is true that SLPs need more information about how phonology develops in children who are learning different languages and multiple languages. However it is even more important for SLPs to have the analytical tools to describe children’s phonology at multiple levels of representation (perceptual, articulatory, phonological) and to identify the origin of children’s error patterns after taking all these domains of phonological learning into account.

Further Reading

If you are not familiar with multilinear phonology, here is a source  intended for a clinical audience:
Bernhardt, B., & Stoel-Gammon, C. (1994). Nonlinear phonology: Introduction and clinical application. Journal of Speech and Hearing Research, 37, 123-143.

For another example of “backing” that is typical in another language, see:
Li, F., Edwards, J., & Beckman, M. E. (2009). Contrast and covert contrast: The phonetic development of voiceless sibilant fricatives in English and Japanese toddlers. Journal of Phonetics, 37(1), 111-124.

For our complete multirepresentational explanation of francophone children’s cluster productions, ask us for a copy of this manuscript:
Rvachew, S. & Brosseau-Lapre, F. (accepted with minor revisions). Pre- and post-treatment production of syllable initial /ʁ/-clusters by French-speaking children. In M. Yavas (Ed.), Unusual productions in phonology: universals and language-specific considerations. Psychology Press/Taylor Francis.