Target Selection Sound Learning vs System Shifting

Traditional vs Phonological Approaches to Target Selection Traditional Based on phonetic (subordinate) factorsBased on phonetic (subordinate) factors –developmental norms –stimulability –consistency of error AssumptionsAssumptions –motoric basis of sound learning –ease of acquisition –sequential order of acquisition Phonological Based on phonemic (superordinate) factorsBased on phonemic (superordinate) factors –phonological complexity –distance metric AssumptionsAssumptions –learnability is enhanced with the greatest amount of change occurring in the least amount of time

Influence of Phonological Complexity on Clinical Management Shift in traditional methods of target selection easier –Traditionally, select sounds that were assumed to be easier to produce and followed a developmental sequence –Early, stimulable, and known (inconsistent) sounds phonological complexityCurrently, new methods of target selection examine the role phonological complexity has on learnability (later, non-stimulable, and unknown sounds) –Specifically, select sounds that are more complex (later, non-stimulable, and unknown sounds) –Shift from “sound learning” to “system shifting”

Set-Subset Relationships Traditional Select simpler targets that are consistent with child’s current performance and/or developmental norms Expose child to “more- of-the same” Phonological Complexity X Select complex targets that are outside the child’s subset grammar To acquire more, a child must be exposed to more X

A Third Option for Target Selection The distance metric represents a different perspective to target selection that doesn’t rely on the dichotomous characterization of targets as early ~ late; stimulable ~ non-stimulable; known ~ unknown, etc. RATHER, it is based on the function a particular sound has within a given child’s system –Using phoneme collapses that represent compensatory strategies developed to accommodate a limited phonetic inventory, we can use a distance metric to select those targets that will result in the greatest amount of change in the least amount of time

Distance Metric (Williams, 2003) one rule setSelect up to 4 different target sounds from one rule set based on two parameters: –Maximal Distinction: select targets that are maximally different from child’s error in terms of PVM –Maximal Classification: select targets from each of the following: (a) different manner classes (b) different places of production (c) different voicing (d) different linguistic units

Target Selection Using Distance Metric d k ʧ f s ʃ st sk tr kr kl 1:11 phoneme collapse Maximal Distinction clusters fricatives affricate stops M a x i m a l C l a s s i f i c a t i o n t

Targets Selected for Adam Targets Selected for Adam g bstops d ð f v sfricatives z gʃgʃ ʧaffricates ʤ gl dr fr grclusters tr kw st 1:18 phoneme collapse

Distance Metric Systemic/functional characteristics of target sounds are specific to each child’s own unique system Assumes that the importance of target sounds is broader than the characteristics of the sound itself. The function of a sound is dependent on the role it plays in a particular child’s unique sound system and therefore it will vary from child to child.

With the distance metric, targets are the salient “corner puzzle pieces” that help the child put together the big picture of the adult sound system Target Selection: The BIG Picture

Comparison of Target Selection Approaches

Problems Using Developmental Norms for Target Selection Range of differences across developmental norm studies (Prather et al., 1975; Templin, 1957; Sander, 1972; Smit et al, 1990; GFTA, 2000) Interpretation of norm charts (developmental progression vs customary production vs mastery) Small methodological differences result in large discrepancies in developmental norms More recently, look at developmental sequence (Shriberg, 1993)

A Sequence of Development Early 8m b j n w d p h Middle 8t k g  f v ʧ  Late 8    s z l r 

Early 8

Middle 8

Late 8

So … do we know when speech sounds develop based on normative studies? Probably not! 2 potential problems with selecting children for therapy based solely on norms (according to Lof): –Which set of norms can you believe? –Holding children with SSD to a HIGHER standard i.e., why are we enrolling children in therapy only when at least 90% of their peers are producing the sound correctly? In essence, we’re not enrolling children until all of the other children have MASTERED the sound It seems we’re withholding tx for kids with SSD because they are being held to a higher standard

Practice Selecting Treatment Targets w glide w glide l liquid l liquid f h s fricatives ʃ sw clusters sw clusters sl sl

Practice Selecting Treatment Targets b d stops d stops g Ø ð v fricatives v fricatives z ʤ affricate ʤ affricate

Estimates of changes in “Big 10” errors PhonemePercentage of children at age 6 with sound in error % of children at age of typical acquisition still in error How much change? /s/17%10%Less than half /z/18%10%Less than half /  / esh11%7%Less than half / ʧ/ 10%8%Very little /  / dja10%6%About half /v/Age of acquisition <6 /r/22%8%Two-thirds Vocalic /r/18%4%Three-fourths /  / thada23%5%Three-fourths /  / ev19%5%Three-fourths

History of Residual Errors From percentage of changes after age 6, it’s clear that improvement only occurs for some phonemes (/r, ɝ, ,  / More than half of the children still in error at age 6 are not going to improve on /s, z, ʃ, ʧ, dja/ –In fact, they will get to practice their error for another year or two if use developmental norms In particular, self-correction of /s/ is unlikely; especially if it is a lateralized distortion

Residual Errors Need to predict which children with one or more residual errors will correct them without intervention and which ones will not Research suggests that children 5-6 years old who are not stimulable for an accurate production will need intervention; those who are stimulable may self-correct. Therefore, may want to do short-term intervention with first graders who are not stimulable in order to make them stimulable and then monitor for change –“jump-start” the process and prevent later intervention

Choosing Challenging Targets for Intervention How can we get kids to jump to the norms? How can we achieve 2-3 year gains in 1 year? Are we applying our resources in the best possible way? Nelson, Camarata, & colleagues suggest we need to consider the level of challenge of task

High and Low Challenge Targets Low Challenge Targets Could run risks: hold child below optimal learning rates child less interested child’s ability is greater than their assessment performance High Challenge Targets Could frustration discourage the child? YET with rich supports and supportive contexts, child can get RAPID change child is positively engaged Series of studies by Nelson & colleagues reported that higher challenges were picked up quicker

Writing IEP Goals for Generalization (after Panagos, 2008) TraditionalPhonologicalSystemic Adam will produce the /t/ sound with 90% accuracy over two trials. Adam will produce the /d/ sound with 90% accuracy over two trials. Adam will suppress alveolar backing at the 90% level of correct articulation in probe lists over two trials. Adam will expand his word-initial inventory of singletons and clusters by a minimum of 25% on a general speech test by addressing /d,f, ʧ,st/ using a multiple oppositions approach.