ABSTRACT

USING OPTIMALITY THEORY TO IDENTIFY RULE-BASED VARIABILITY IN A

CHILD WITH SUSPECTED CHILDHOOD APRAXIA OF SPEECH: A SINGLE­

SUBJECT CASE STUDY

By

Melissa N. Posod

May 2013

The framework of Optimality Theory has been recently used to develop

constraint-based approaches to the analysis of speech patterns produced by children with

phonological disorders. A significant benefit of this type of nonlinear analysis is the

power to predict interword and intraword variability of phonological productions. Such

variability, also known as inconsistency, is a speech characteristic frequently cited by

researchers and clinicians as one that (a) critically aids in differentially diagnosing

childhood apraxia of speech and (b) supports the theoretical perspective that childhood

apraxia of speech is a motor speech disorder. This study applies a constraint-based

approach to the phonological analysis of the speech of a single child suspected to present

with childhood apraxia of speech. Transcriptions of the participant’s speech were

obtained from therapy notes written by the clinicians providing his speech services. A

thorough phonological analysis of the sample was performed yielding a consonant

inventory, two quantitative measurements of variability, and several constraint-based

predictions of variability at the segmental and prosodic levels. The results of this study

confirm variability as a characteristic of this child’s speech. Relatively common and rare

variations were successfully predicted by a phonological constraint hierarchy, revealing a

rule-based deficit discordant with the theoretical perspective that childhood apraxia of

speech is a pure motor speech disorder. It is suggested that the results presented in this

study indicate a breakdown in the transformational stage of speech production similar to

that of phonological disorders. Implications of this theoretical perspective for future

research and clinical practice are discussed.

2

USING OPTIMALITY THEORY TO IDENTIFY RULE-BASED VARIABILITY IN A

CHILD WITH SUSPECTED CHILDHOOD APRAXIA OF SPEECH: A SINGLE­

SUBJECT CASE STUDY

A THESIS

Presented to the Department of Communicative Disorders

California State University, Long Beach

In Partial Fulfillment

of the Requirements for the Degree

Master of Arts in Communicative Disorders

Committee Members:

Geraldine P. Wallach, Ph.D. (Chair)Lei Sun, Ph.D.

Jennifer Ostergren, Ph.D.

College Designee:

Carolyn Conway Madding, Ph.D.

By Melissa N. Posod

B.A., 2009, University of California, Riverside

May 2013

UMI Number: 1523088

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TABLE OF CONTENTS

Page

LIST OF TABLES....................................................................................................... v

LIST OF FIGURES..................................................................................................... vii

CHAPTER

1. INTRODUCTION............................................................................................ 1

2. OVERVIEW OF OPTIMALITY THEORY................................................... 4

Markedness and Faithfulness: Two Forces Behind Constraints.............. 4Constraint Ranking: Conflict Resolution by Strict Domination.............. 7The Architecture of Optimality Theory Grammar.................................... 14

3. DESCRIPTIVE STUDIES: CONSTRAINT-BASED ANALYSES OF VARIATION IN PHONOLOGICAL DISORDERS...................................... 19

Single-Subject Case Studies...................................................................... 19Group Case Study...................................................................................... 24

4. CHILDHOOD APRAXIA OF SPEECH......................................................... 28

Descriptive Studies: Symptomatology of Childhood Apraxia of Speech. 29Descriptive Studies: Variability in Childhood Apraxia of Speech 35Theoretical Perspectives of Childhood Apraxia of Speech...................... 38

5. METHODS....................................................................................................... 44

Purpose....................................................................................................... 44Design........................................................................................................ 45Participant.................................................................................................. 45Procedure................................................................................................... 46

6. RESULTS.......................................................................................................... 49

iii

CHAPTER Page

Whole-Word Variability........................................................................... 49Consonant Inventory................................................................................. 49Nonlinear, Constraint-Based Phonological Analysis................................ 52

7. DISCUSSION.................................................................................................. 66

Limitations................................................................................................. 71Implications................................................................................................ 72

APPENDIX: GLOSSARY OF COSTRAINTS........................................................... 77

REFERENCES............................................................................................................. 82

iv

LIST OF TABLES

TABLE Page

1. Simple Domination................................................................................... 8

2. Markedness Dominates Faithfulness........................................................ 9

3. Faithfulness Dominates Markedness........................................................ 9

4. Severity of Violation Determined by Strict Domination.......................... 12

5. Severity of Violation Determined by Strict Domination.......................... 12

6. Intraword Variability by Equal Ranking................................................... 13

7. Variation in Cluster Reduction of Target green........................................ 26

8. Variation in Cluster Reduction Patterns.................................................... 26

9. Selection Criteria for CAS in Descriptive Research................................. 31

10. Sample of Repeated Words and Their Measures of Variability............... 47

11. Participant’s Consonant Inventory Between Ages 4;4 and 4 ;8 ................ 50

12. Constraint Rankings for Phonological Processes..................................... 52

13. Place Harmony Intraword Variation for Target Nemo /nimo/.................. 53

14. Place Harmony Intraword Variation for Target bandaid /baendeid/ 53

15. Place Harmony Intraword Variation for Target cinnamon /sinomin/ 54

16. Variation in Cluster Reduction................................................................. 55

17. Interword Variation of 1)1 in Onset for Target yard /yod/........................ 56

18. Interword Variation of 1)1 in Onset for Target yours /js-z/........................ 56

19. Interword Variation of 1)1 in Onset for Target you /ju /............................. 56v

TABLE Page

20. Interword Variation of Labial Continuants in the Coda for Target stuff

/stAf/ ....................................................................................................... 57

21. Interword Variation of Labial Continuants in the Coda for Target leaf

/lif/ ....................................................................................................... 57

22. Interword Variation of Labial Continuants in the Coda for Taget soft

/soft/ ....................................................................................................................... 58

23. General Prosodic Hierarchy...................................................................... 60

24. Peak and Margin Restrictions for Target Chick-fll-a /tjikfalei/............... 62

25. Peak and Margin Restrictions for Target crocodile /krakadail/............... 62

26. Peak and Margin Restrictions for Target fine /fain/................................. 62

27. Word Shape Variations for Target salami /salami/.................................. 64

28. Word Shape Variations for Target balloon /balun/................................... 64

29. Markedness Constraints............................................................................. 78

30. Faithfulness Constraints............................................................................. 80

vi

LIST OF FIGURES

FIGURE Page

1. Simplified diagram of the architecture of optimality theory..................... 16

CHAPTER 1

INTRODUCTION

Formal phonological theories have made significant contributions to our

understanding of both typical and disordered language acquisition. These linguistic

frameworks have been implemented by speech-language pathologists for their ability to

account for a number of factors: (a) differences between children’s productions and adult

productions; (b) generalizations and variability both within and between developing

phonological systems; and (c) diachronic developmental changes to the system (Ferguson

& Gamica, cited in Barlow & Geirut, 1999). For approximately 40 years, the framework

dominating the literature on phonological acquisition has largely been the derivational

model of generative phonology proposed by Chomsky and Halle (1968; see also Dinnsen,

2008). This particular framework sought to describe systematically the transformation of

a speaker’s underlying mental representation of a word to his/her production of a word

(i.e., surface form) on the premise that phonological representations consist of linear

strings of segments in a single dimension (Clements & Keyser, 1983). In order to map

this journey, the derivational model proposed transformational rules that linearly derive

the surface form from the mental representation (Chomsky & Halle, 1968). The

derivational model has influenced several advances in the assessment and treatment of

phonological disorders, such as phonological process analyses (Shriberg & Kwiatkowski,

1997) and minimal pairs treatment (Weiner, 1981).

More recently, a multi-dimensional outgrowth of generative phonology, known as

Optimality Theory (Prince & Smolensky, 1993), has been integrated into the literature

addressing typical and disordered phonological acquisition. Optimality Theory offers to

the field a unique, multidimensional view of generative phonology. While it does

maintain the aim of providing a theoretical framework for mapping speakers’ underlying

representations to their surface forms, Optimality Theory replaces linear transformational

rules with a process involving a hierarchy of phonological constraints in conflict with

each other. It has been found to be useful not only in assessing and treating phonological

disorders of varying severities (Barlow, 2001; Dinnsen & Geirut, 2008; Dinnsen &

O’Connor, 2001; Tyler & Figurski, 1994), but also in understanding typical language

acquisition (Barlow & Geirut, 1999; Dinnsen, 2008; Dinnsen & O’Connor, 2001; Jarosz,

2010). It has been particularly useful in predicting outcomes of treatment of multiple and

rare phonological processes, such as spirantization and final consonant insertion (Dinnsen

& Gierut, 2008; Dinnsen & O’Connor, 2001), in addition to accounting for pervasive

variability within and between single-word productions made by children with

phonological delay (Barlow, 2001; Chin, 2007; Ulrich, Stemberger, & Bernhardt, 2008).

Despite this initial success in understanding the underlying nature of phonological

disorders, constraint-based analysis has not yet been used to analyze the speech of

children with suspected childhood apraxia of speech (CAS). Severe, rare, and persisting

speech errors have been known to be associated with this controversial disorder (Forest,

2003; Shriberg, Aram, & Kwiatkowski, 1997). Inconsistent productions is one type of

error that is often included as a primary characteristic and cited as evidence of a pure

motor speech disorder (Strand, 2001). Currently, however, there is a lack of consensus as

to what characteristics differentiate childhood apraxia of speech from other

developmental phonological disorders and where the loci of the deficit can be found.

Because Optimality Theory has been applied to the analysis of variable phonological

output in children with phonological disorders, it may also be useful in accounting for

similar variability in those suspected of having childhood apraxia of speech.

3

CHAPTER 2

OVERVIEW OF OPTIMALITY THEORY

Of those linguistic frameworks seeking to describe the systematic organization of

human speech sounds, Optimality Theory poses a distinctly unique model. First

proposed by Prince and Smolensky (1993), Optimality Theory differs from the classic

model of Generative Phonology in its description of an architecture of phonology

constructed out of dynamic relationships between grammatical constraints. Rather than

deriving surface forms using transformational rules, the proposed internal components

generate possible output forms (also known as “candidates”) and evaluate how

harmonious these are with the hierarchical ranking of the grammatical constraints. In this

way, the output is not viewed as wholly erroneous, but rather as in agreement with the

organization of structural rules within the phonological system. In the proceeding

overview, the two key characteristics of Optimality Theory, phonological constraints and

constraint ranking, are described, followed by an outline of the mechanical components

of the framework.

Markedness and Faithfulness: Two Forces Behind Constraints

Within the framework of Optimality Theory, every natural language grammar is

assumed to have inherent phonological constraints that define the structural complexity

of candidate forms (Kager, 1999). Features of the underlying mental representation of a

4

word are changed according to the structural requirements of the constraint, so that the

output form either looks different from or resembles the input form. The two forces

behind constraints are called “markedness” and “faithfulness” and are inherently in

conflict with one another. Markedness is a quality in which a linguistic form is either

marked, possesses a feature that contrasts with another form, or unmarked, does not

possess a feature that contrasts with another form. Language systems generally favor

simpler, unmarked forms over marked forms so, it follows that, markedness constraints

push for the neutralization of those features by which contrast and complexity are created

(Dinnsen, 2008; Kager, 1999). An example of a markedness constraint, taken from child

language development, is codas are not allowed in output forms and is written as

*CODA (Dinnsen, 2008; refer to the appendix for a glossary of constraints). This

constraint describes the coda position of a syllable to be a marked form and, therefore, it

is mandated that no final consonants be produced. The challengers to these markedness

constraints are the faithfulness constraints. These push for the requirement that

contrastive features be preserved so that the resulting output form is not changed from its

original input form (Dinnsen, 2008; Kager, 1999). Faithfulness constraints can range

from maximum faithfulness (e.g.., all phonological segments are preserved in the output

form), to the preservation of one feature (e.g., only the feature of [voice] is preserved in

the output form; Kager, 1999). An example of a faithfulness constraint is every segment

o f the input has a correspondent in the output and is written as MAX (Dinnsen, 2008;

Kager, 1999). This constraint describes the preservation of phonological segments in the

output form and, therefore, does not allow deletion of segments (e.g., final consonant

deletion).

The inherently conflicting nature of markedness and faithfulness necessitates that

every surface form must violate a constraint (Kager, 1999). That is, any output which is

faithful to features of its input will violate a markedness constraint and any output which

neutralizes a marked feature of its input will violate a faithfulness constraint (Kager,

1999). Quite interestingly, it is this conflicting interaction between the markedness and

faithfulness constraints which creates a system of balanced complexity that is both

functional and manageable. For example, a system lacking constraints on marked

phonological elements would produce such a high number of combinations of segments

that the lexicon would swell to an unmanageable 300 billion potential items (Kager,

1999). Conversely, a system lacking faithfulness to the contrastive features of its input

forms is predicted to generate a mere 36 possible items for its lexicon (Kager, 1999). By

forming relationships of dominance between the two types of constraints and arranging

them into a single hierarchy, the right amount of marked contrast needed for a

meaningful, practical system is generated.

The establishment of this hierarchy of constraints can be seen in language

development. In a typical, fully developed adult system, a rich lexicon is expressed with

contrastive output forms generated by a hierarchical arrangement whereby faithfulness

generally dominates markedness constraints (Barlow, 2001). Because of this

arrangement, adult productions are more complex and retain a high amount of contrast

between phonological elements. During the initial stages of language development in

children, however, markedness generally dominates faithfulness constraints (Barlow,

2001; Tesar & Smolensky, 1996). This type of arrangement produces mostly unmarked

forms that lack the variety of contrasts found in adult output forms and are generally

6

described as “simplified”. Language development has, therefore, been described as a

process by which markedness constraints are demoted and reranked within the hierarchy

(Barlow, 2001; Tesar & Smolensky, 1996; Ullrich et al., 2008). This process of

demotion has implications for how delay in the development of phonological systems is

understood. Instead of the perception that persisting or uncommon phonological patterns

are errors produced by a dysfunctional phonological system, Optimality Theory offers the

perception that these productions are, in fact, harmonious with the hierarchical

arrangement of the system’s phonological constraints. The system is functional, but it is

viewed as delayed in its progression through the developmental demotion of markedness

constraints. In order to better understand this view of child speech development, the

nature of the hierarchical arrangements of both types of constraints is reviewed.

Constraint Ranking: Conflict Resolution bv Strict Domination

The second key characteristic of Optimality Theory is a conflict resolution device

known as constraint ranking. As has been briefly described, markedness and faithfulness

constraints are intrinsically in conflict with each other. To resolve this conflict, they must

be arranged into a hierarchy of dominance through which an input form may be

successfully processed (Kager, 1999). It is the principle of strict domination that

ultimately resolves conflict and guides the selection of the most optimal output candidate

(Kager, 1999).

An inevitability of domination rankings, and a significant characteristic of the

selection process, is the violation of constraints. Despite the universal instinct of systems

to produce perfect outputs (i.e., forms that do not violate constraints), violation must

occur for an output form to surface (Kager, 1999). The optimal output form is considered

7

to be that which most avoids violating the higher-ranked constraints and is, therefore,

closer to resembling perfection (Kager, 1999). Put in a different way, the higher a

constraint is ranked, the more it will be obeyed. Lower ranked constraints will, therefore,

endure higher tolerance of violations against them. In conventional Optimality Theory, a

“tableau” is typically constructed to describe these domination rankings and the output

selection process. A template is shown in Table 1. Here we see that a list of possible

output forms (icandidatea, candidateb) is arranged vertically in a non-specific order. The

phonological constraints (Cl, C2) are arranged horizontally according to their domination

in the hierarchy, namely left (highest-ranking) to right (lowest-ranking; Kager, 1999).

This dominance may also be written as *CODA» MAX, meaning the constraint

*CODA is ranked over the constraint MAX. Because candidateb violates the higher-

ranked constraint (as indicated by the asterisk), it is immediately dismissed as an optimal

TABLE 1. Simple Domination

Underlying c, c2Representation

e.g., /bed/ e.g., *CODA e.g., MAX(no final consonant) (no deletion of

segments)

^Candidates *e.g. /be/

Candidateb *!e.g., /bed/

8

output (as indicated by the exclamation point; Kager, 1999). Candidatea, on the other

hand, does not violate the higher-ranked constraint and is selected as the optimal output

form (as indicated by the Kager, 1999). In the example above, the outcome of this

arrangement is the selection of /be/ for the target bed. The ranking of a constraint

banning final consonants over a constraint preserving all segments of an input in the

output is a formula for what is commonly known as final consonant deletion.

Using this tableau template, let us look at an illustration of the influence of

various sets of rankings on the selection of the output.

TABLE 2. Markedness Dominates Faithfulness

/koum/ comb: *k IDENT [place]

^/toum / *!

/koum/ *

Note: Based on research by Dinnsen (2008).

TABLE 3. Faithfulness Dominates Markedness

/koum/ comb: IDENT [place] *k

/toum/ *!

/koum/ *

Note: Based on research by Dinnsen (2008).

9

In Table 2, we have a clear example of a markedness constraint dominating a

faithfulness constraint. In the case of this arrangement, the target form (i.e., /koom/)

violates the higher ranked k* and is not selected as the optimal output form. Instead, the

winner is /toum/ which avoids this violation in favor of a less serious one (i.e., violation

of IDENT[place]). The winning candidate is harmonious with the constraint ranking of

this particular phonological system. In Table 3, we see that a systematic change must

occur before the underlying form surfaces intact. With the demotion of the markedness

constraint below the faithfulness constraint comes the selection of the candidate retaining

the complexity of its underlying representation. This output form preserves the

phonological contrast that differentiates itself from that of tome, for example, and is also

harmonious with the hierarchy. As we can see, the system-wide shift in constraint

rankings accounts for this difference in output production and highlights the significance

of constraint ranking in this framework. When the markedness constraint banning velars

dominates a faithfulness constraint preserving the place of articulation, the output

produced is one that exhibits what is commonly known as fronting.

Not all conflict resolution and output selection are as simple as one candidate

violating the highest-ranked constraint and one candidate avoiding violation of that

constraint. There may be situations where all candidates violate the higher-ranked

constraint or where constraints are equally ranked between each other.

As stated earlier, crucial to violation evaluation is the principle of strict

domination. No amount of lower-ranked constraint fulfillment can compensate for the

violation of a single higher-ranked constraint. That is, a candidate preserving one

distinctive feature of the input may still be selected over a candidate preserving three

10

distinctive features. It is the dominant ranking of a constraint that dictates the severity of

violations against it. For an example, let us turn to Table 4. Candidatea /ta/ is closer in

its approximation of the target Tom and also incurs just one violation (i.e., the highest

ranked constraint). Candidateb /ka/ is further from the target (i.e., deletes the final

consonant and backs the onset) and incurs multiple violations (i.e., all lower ranked

constraints). Despite violating more constraints, candidateb must be selected as a more

optimal output form as it avoids violating the higher ranked constraint. Here, it is not

quantity that measures the severity of violation but rather type (i.e., violation of a higher

ranked constraint versus a lower ranked constraint). There are cases, however, in which

the quantity of violations may also influence this measure of severity. If all candidates

incurred a violation of the highest ranked constraint, the optimal candidate would then be

selected by the quantity of violations against this constraint. That is, the candidate

holding the least amount of violations against a higher-ranked constraint wins selection.

This is illustrated in Table 4. Both Candidatea /bet/ and Candidateb /pet/ violate the mid­

ranked constraint IDENT [voice]. Candidateb violates this constraint in two ways: (a)

devoicing the onset and (b) devoicing the coda. Candidatea violates this constraint in just

one way (i.e., devoiced coda) and, therefore, less severely. In this way it is understood

that elimination is not simply a consequence of the amount of constraint violations

incurred but rather a consequence of the severity in which higher ranked constraints are

violated.

Of particular relevance to child speech development are those situations in which

two or more constraints are ranked equally and possess mutual dominance in the

hierarchy. That is, violation of one constraint is determined to be equally severe to

11

violation of another constraint in the same ranking (Barlow, 2001). Equal rankings

between constraints have been identified as responsible for variability in output forms

TABLE 4. Severity of Violation Determined by Strict Domination

/tarn/ Tom *t/[back]1 *k IDENT [place]

a. /ta/ *!

b. ^ /ka/ * *

Note: Adapted from Dinnsen (2008).

1 coronal consonants are not allowed before back vowels

TABLE 5. Severity of Violation Determined by Strict Domination

/bed/ bed *VOICED-

CODAj

IDENT [VOICE]2 VOP3

a. ®“/bet/ * *

b. /pet/

c. /bed/ *! **

Note: Adapted from Kager (1999).

No voiced coda obstruents. The voice feature of corresponding segments must be identical.3 No obstruent must be voiced.

12

(Barlow, 2001; Chin, 2007). Table 6 illustrates multiple outcomes resulting from an

equal ranking of constraints (as indicated by a dotted line). In this example, an equal

ranking of a markedness and a faithfulness constraint (i.e., *CODA, MAX) is responsible

TABLE 6. Intraword Variability by Equal Ranking

/5is / this DEP1 *CODA2 MAX3

a. /dis/ *

b. /di/ *

c. /diso/ *!

Note: Adapted from Barlow (2001).1

Segments found in the output must also be in the input (no insertion). No coda.3 Segments found in the input must also be in the output (no deletion).

for the selection of two optimal output forms. That is, the child produces both [dis] and

[di] for the target this. Noteworthy is that the variation in output forms is not random and

is restricted to an exclusive set of [dis] and [di]. Other variations of the surface form

(e.g., /diso/) cannot surface due to a violation of a higher-ranked constraint.

As we see, strict domination in constraint ranking is essential to the process of

elimination and selection of output candidates. Conflict between constraints is resolved

by dominant rankings and the constraint hierarchy provides a way for output candidates

to be marked for their violations in a measureable way. That is, an output form can be

understood in relation to its fellow competing candidates as a form in better harmony

13

with the rules of the phonological system. Elimination of candidates is, therefore,

determined by the severity of their violations against constraints ranked high in

importance for harmony. This measure of severity is always determined by the position

of violated constraints within the hierarchy and may also consider the quantity of such

violations. It is also entirely possible that multiple constraints share mutual dominance

through equal ranking and produce more than one output form. Yet, even in these cases,

the uncompromising principle of strict domination is firmly abided and the variations of

output forms successfully predicted.

The Architecture of Optimality Theory Grammar

As stated earlier, Optimality Theory proposes a novel mechanism for mapping an

input form to an output form (Kager, 1999). This mechanism consists of two main

components: the Generator and the Evaluator. Each takes the underlying representation

of a word (i.e., the input form) and processes it in its own separate way. To better

understand their functional capabilities, the characteristics of the mental lexicon and its

role in input selection is first reviewed.

The mental lexicon is described as consisting of the underlying representation of

all contrastive morphemes with properties important to the domains of phonology,

morphology, syntax, and semantics (Kager, 1999). Differing from traditional

derivational models, Optimality Theory finds no changes to be made at this level and, as

such, no phonological constraints describe the structure of the underlying input form.

Subsequently, the mental lexicon contains the underlying representation of lexical items

untransformed by language-specific rules (or else child-specific rules) and in its rawest

form. The mental lexicon is, therefore, said to express Richness o f the Base (Prince &

14

Smolensky, 1993). To illustrate, the English language does not contrast oral and nasal

vowels meaningfully, but richness of the base means that this option for contrasts always

remains available in the underlying representation of a word (Kager, 1999). This type of

contrast never surfaces in the speech of English speakers, however, due to the language-

specific arrangement of the constraint hierarchy that does not require this contrast. The

significance of this for child speech development is that the underlying representation of

the phonological properties of words is never viewed as disturbed or incomplete. Instead,

richness of the base describes an intact representational form complete with all

contrastive properties. This raw input form, as specified by the mental lexicon, is then

sent for processing by the Generator and the Evaluator for changes to be made that will

transform the underlying representation into one that is harmonious with both language-

specific and child-specific rankings of phonological constraints.

The Generator is an essential component to the process of output selection. It is

tasked with the sole charge of compiling all possible output forms that could potentially

be mapped to the input form (Kager, 1999). That is, any possible approximation of the

underlying phonological form of a word is gathered for processing. This is made

possible by a core characteristic of the Generator known as Freedom o f Analysis. By

generating candidates using combinations of any and all phonological structures

produced within the limits of human language (e.g., segmental and prosodic features), the

Generator is able to create an infinite set of possible output candidates (Prince &

Smolensky, 1993). These are then sent to the Evaluator for final processing.

The Evaluator is the last component of the mechanism and is the most central to

the principle of constraint ranking. Its function is to evaluate each generated candidate

15

for their degree of harmony with the constraint ranking of the phonological system

(Kager, 1999). To accomplish this, the Evaluator is designed with three components: (a)

the hierarchy of all constraints belonging to Universal Grammar as arranged by language-

specific rankings; (b) a device for marking output forms in violation of these constraints;

and (c) a device for evaluating the harmony of output forms. It is the latter device which

does the actual elimination of candidates and selection of the single, most optimal output

form.

MentalLexicon

input/koum/

Generator

GEN

------ > /toum/------ > /koum/_/nnnm/

Evaluator

LEX^ /puuiii/

/fnnm / EVAL^ /iUUIll/

FIGURE 1. Simplified diagram of the architecture of Optimality Theory.

Adapted from Barlow (2001).

Together, these parts form the mechanism by which surface forms are mapped to their

underlying mental representations. First, the underlying form of a word, as it is

phonologically represented in the mental lexicon (e.g., /koum/comb), is plugged in to the

Generator. This device then gathers together an infinite list of candidates (e.g., /koum/,

/toum/, /poum/, /foum/, etc.) to be considered for selection as the most optimal output

form. These are then sent through the Evaluator. In this final stage of the process, the

Evaluator enforces the consequences of the constraint hierarchy by first marking

candidates for their violations against constraints and then selecting the candidate with

the least severe of violations to surface. As we can see, instead of a linear process

16

described by transformational rules, the architecture of an Optimality Theory grammar

offers a framework designed for multidimensional processing of these linguistic forms.

Summary

Optimality Theory is a unique offshoot of generative phonology and has the

ability to contribute to clinical phonological analyses in a distinctive way. Contrary to

the derivational model that dominates the area of language acquisition, Optimality

Theory does not perceive output forms as outcomes of isolated phonological processes

(Dinnsen & O’Connor, 2001). Each surface form is, instead, interpreted as a

manifestation of many conflicting constraints relatively arranged in a hierarchy belonging

to the innate grammar (Barlow & Geirut, 1999; Geirut & Morrisette, 2005). These

constraints either change elements of the mental representation so that the output looks

different from the input (markedness constraints) or they preserve elements so that the

output resembles the input (faithfulness constraints) (Kager, 1999). Ranked and arranged

in a hierarchy of dominance, constraints determine what candidate form surfaces (Barlow

& Geirut, 1999; Kager, 1999). The most optimal output form is one that violates the

higher ranked constraints least severely (Kager 1999). Hierarchical ranking by strict

domination also gives us an alternative perspective of phonological error patterns.

Instead of viewing an errored production of a target word as the outcome of an

assimilation process, for example, we can analyze an assimilated production as an

optimal output form adhering to the rules of the internal phonological system.

Furthermore, richness of the base views the underlying representation of a word as raw

and untransformed by the innate grammar. Any changes made to this form must,

therefore, occur during the processing of forms through the Generator and Evaluator. In

this way, Optimality Theory offers us a means to finely focus our analyses and to better

understand the systematic processes behind the transformation of underlying

representations to surface forms.

18

CHAPTER 3

DESCRIPTIVE STUDIES: CONSTRAINT-BASED ANALYSES OF VARIATION

IN PHONOLOGICAL DISORDERS

Much of the formal research utilizing a constraint-based analysis to describe atypical

speech patterns and development has been conducted over the past fifteen years (Barlow,

2001; Barlow & Gierut, 1999; Chin, 2007; Dinnsen & Barlow, 1998; Dinnsen & Gierut,

2008; Dinnsen & O’Connor, 2001; Gierut, 2001; Geirut & Morrisette, 2005; Ullrich,

Stemberger, & Bernhardt, 2008). Of these, three case studies are known to the author to

have attempted to describe variability in the productions of children with phonological

disorders. Constraint-based analyses of interword and intraword variability have

accounted for this type of persistent error as a consequence of ranked constraint

interactions and, therefore, have contributed to a finer description of the atypical

phonological system as a whole.

Single-Subject Case Studies

In an attempt to describe the language development of a young child with

phonological delay, Ullrich et al. (2008) conducted a longitudinal case study analyzing

changes made to the phonological system without the influence of therapy. While a brief

period of variation in speech production is common in typical language development,

persistent variation is atypical and was a feature of the participating 3-year-old’s speech.

19

Variable productions are said to be produced during times of systematic change in

language development (Ferguson & Farwell, cited in Ullrich et al., 2008) and it was

determined that a phonological process analysis would not sufficiently describe such

positive change in this child. That is, phonological process analysis is restricted in

viewing longitudinal variability as an isolated regression uncorrelated with a systemic

change, such that variation of a target is not observed as consequential to improvement in

the phonological system. In order to obtain a more detailed description of the

longitudinal variability in this child, a variety of data collected over a nine month period

was analyzed with a constraint-based analysis. Data included responses on a

standardized speech and language test (SETK 3-5; Grimm, 2001) and a connected speech

sample collected from initial assessment, three connected speech samples collected

monthly over a three month period, and responses to a single-word repetition task and a

connected speech sample collected from a final follow-up assessment. From these data,

consonant inventories and a measure of Percentage Consonant Match (PCM) were

gathered. Results of this study showed that both longitudinal variability and concurrent

intraword variability could be accounted for as consequences of a positive change in the

child’s phonological system. This variation involved a decrease in production of coronal

consonants, including stops, fricatives, affricate /ts/, and liquid /l/ that could be correlated

with an overgeneralization of the [dorsal] place feature. This was seen in two contexts.

First, /t,d/ were substituted by /k,g/ near labials /p,b,m/. An example of this is in the

native German-speaker’s productions of [bote] and [boke] for the target word Butter

/bote/. Such variation was accounted for by demotion of the markedness constraint

20

NOT[Dorsal] within the child’s phonological system which led to a change in the

constraint hierarchy from

NOTIDorsa!l»NOT[Labial]»NO SEQUENCE [Labial...Coronal]»

SURVIVED [Coronal] »N O T [Coronal]

to

NOT[Labial]»NO SEOUENCEfLabial...Coronall»NOTrDorsall»

SURVIVED[Coronal]»NOT[CoronaI].

With demotion of NOT[Dorsal] came allowances for the [+dorsal] feature in output

segments. In this case, the output form for the target Butter /bote/ surfaced as [boke] and

[bote] during the demotion of this markedness constraint.

In the second context, coronal fricatives, affricates, and liquids were substituted

by dorsal stops. An example of this being the production of Tasse /tasa/ (‘cup’) as both

/tata/ and /taka/. Both of these outputs substituted /s/ with segments that do not express

the manner feature [+continuant]. These substitutions do, however, vary in their place of

articulation (i.e., [+dorsal] or [+coronal]). Accounting for a cross-category link between,

in this case, an increase in the surfacing of place feature [+dorsal] and a decrease in the

surfacing of [+continuent] required the same demotion of NOT [Dorsal]. In this case, a

demotion of this markedness constraint allowed activation of mid-ranked constraints

affecting the [grooved] feature affecting coronals. Specifically, the hierarchy changed

from

NOT CO-OCCURRING[+continuant,-sonorant]» NOT[Dorsall»

NOT[Labial]» IDENT[+grooved]» SURVIVED [Coronal]»

21

NOT [Coronal]

to

NOT CO-OCCURRING[+continuant,-sonorant]»NOT[Labial]»

IDENT 1+groo vedl» NOT [Dorsall »SU R V I VED1 Coronall »N O T [ Coronall

Here the demotion of NOT [Dorsal] activated allowance of segments that preserved the

grooved feature of the tongue tip but were still lacking the manner feature [+continuant].

Because it was becoming more important for the output to preserve the grooved feature

than it was to restrict production of the dorsal feature, substitutions moved between the

dorsal /k/and grooved coronal /t/ that still satisfied the restriction on continuants (i.e., /s/).

Overgeneralization of the [dorsal] place feature in longitudinal variability for this

participant was successfully explained by a demotion of the markedness constraint

banning [+dorsal]. This change could also be correlated with the positive effect of

increasing accurate productions of target dorsals in addition to the negative effect of

decreasing the production of marked coronals in specific contexts. Variation in this

regard was described by changes made to the child’s developing phonological system in

order to increase the accuracy of matching adult forms.

In another single-subject case study, intraword and interword variation in

productions taken from a single point in time was analyzed with a constraint-based

approach. Barlow (2001) collected single-word responses from a 3-year-9-month-old

child using the Bankson-Bemthal Test of Phonology. Results highlighted typical

simplifications from developmental phonological processes (e.g., final consonant

deletion, stopping, gliding, etc.) in addition to variations in production patterns both

within and between word productions. By her analysis, intraword variation could be

22

explained by an equal ranking of a markedness constraint (i.e., *CODA) and faithfulness

constraint (i.e., MAX). That is, the ranking

DEP»*CODA, MAX

selected both outputs with and outputs without final consonants as optimal forms. The

outcomes of this kind of equal ranking is illustrated in Table 5 by the selection of both

/dis/ and /di/ for the target word this. Further support for this arrangement of the equally

ranked *CODA and MAX constraints below DEP (i.e., no insertion of segments) came

from a lack of evidence in the sample of similar variation in the production of open

syllable targets. For example, the target shoe was never produced with a final consonant

(e.g., /tut/). The dominant position of constraint DEP successfully predicted the presence

of open and closed syllable outputs for closed syllable targets in addition to the notable

absence of closed syllable outputs for open syllable targets. In other words, the equal

ranking of two constraints here allow for a systemically contained type of variation in

final consonant production.

In contrast, interword variation of consonant cluster productions in the same

sample was not found to be an attribute of equal dominance between constraints.

Productions such as [kwaun] for the target clown and [le] for the target sled indicated

variation in preserving segment slots in consonant clusters. The constraint hierarchy

identified to account for this variability was

*FRICATIVES»MAX»*COM PLEX.

First, the dominance of the faithfulness constraint preserving all segments of an input

form (i.e., MAX) over the markedness constraint banning clusters (i.e., ^COMPLEX)

allows productions of clusters, such as /kwaun/, to surface. However, it is the overall

23

dominance of the constraint banning fricatives (i.e., *FRICATIVES) that allows for

deletion of this particular class of segments in clusters (i.e., the deletion of Is/ in the

production [le] for sled). Overall, the complete ranking of relevant constraints in this

child’s system was determined to be:

^FRICATIVES, DEP, *LIQUIDS-[r]»MAX, *CODA, IDENT[Continuant]

»*LIQUID-[1], IDENT [Consonantal], ^COMPLEX.

In identifying this particular constraint hierarchy, two discoveries were made that

remain otherwise hidden from a linear phonological process analysis. Firstly, a strictly

defined relationship between highly ranked markedness constraints in the child’s system

could be identified as the source of interactions between phonological processes (e.g.,

cluster reduction and final consonant deletion in the production of [le] for sled).

Secondly, intraword and interword variability could be accounted for as nonrandom,

systemically contained sets of variants produced by the constraint hierarchy of that

child’s system. In other words, the completeness of a constraint ranking is not only

apparent in its prediction of what variants will surface for a given target, but also in its

prediction of what productions will not surface.

Group Case Study

One group case study is known to the author to use a constraint-based analysis to

describe variation in a group of children exhibiting patterns of phonological

simplification. In his study, Chin (2007) investigated intragroup variation in the

production of consonant clusters by pediatric cochlear implant users. Participants

included eleven children between the ages of 6;4 and 16;5 years at the time of testing.

All used a cochlear implant for at least five years between the ages of 5 and 11 ;6 years.

24

For each participant, single-word responses for 107 words were elicited by a

confrontation naming task. These were analyzed for variation in the number of segments

realized, variation in the type of reduction of consonant clusters, and faithfulness to

segments and features using a constraint-based approach. The first measure revealed

three varieties in the group’s production of consonant clusters. These were: (a) reduction

to a single stop (e.g., [gin] green)-, (b) no reduction (e.g., [grin] green)-, and (c) vowel

epenthesis (e.g., [gorin] green). Differences between varieties were attributed to three

different combinations of rankings between three constraints (see Table 7).

As illustrated, variation in the number of segments realized in the output forms is

associated with the relative rankings of three constraints. It is also noteworthy that

intraword variability is again accounted for here by equal rankings between constraints,

just as previously illustrated by Barlow (2001). In regards to the second measure, two

varying rankings of the markedness constraints on types of segments allowed at the

syllable margin (i.e., *M/Sonorant: no sonorants at the syllable margin, and

*M/Obstruent: no obstruents at the syllable margin) are implicated in variants of cluster

reduction patterns. These and their corresponding rankings are displayed in Table 7. As

is shown, the less common reduction to a sonorous segment in the consonant cluster is

made possible by systems whose hierarchy ranks a ban on the alternative segment’s type

higher than a ban on sonorants at the margin. In this case, a ban on the place feature

[dorsal] reduces the word form for clock to /lak/ rather than the more commonly expected

/kak/. The last measure in this study examined the relationship between the markedness

constraint banning /r/ (i.e., *R) and the faithfulness constraint preserving all features of

the input (i.e., IDENT [feature]) and its influence on variations in consonant clusters

25

TABLE 7. Variation in Cluster Reduction of Target green

No. of Segments Constraint-ranking Example (target: green)

1 Segment ^COMPLEX,

DEP»M AX[gin]

2 Segments MAX,

DEP»*COMPLEX

[grin]

3 Segments ^COMPLEX,

M AX»DEP

[gorin]

TABLE 8. Variation in Cluster Reduction Patterns

Reduction Constraint-ranking Example

Type

Reduction to *COMPLEX»*M/SONORANT»*M/OBSTRUENT [bAj] for

less sonorous brush

segment

Reduction *COMPLEX»*DORSAL»*M/SONORANT» [lak] for

conflicted *M/OBSTRUENT clock

with sonority

containing liquids. It was found that one child exhibited gliding of liquid clusters with /r/

(e.g., [bwAj] for target brush) but not liquid clusters with /l/ (e.g., [klok] for target clock).

To account for this, the author identified a constraint ranking whereby *R dominated

IDENT [feature]. This ranking describes a greater importance in banning /r/ than in

preserving the feature of [+liquid] for approximants and, therefore, successfully predicts

the variations in liquid cluster productions seen in this study. It was concluded here, as in26

the previously reviewed case studies, that variation in productions could be accounted for

as consequences of constraint-based operations belonging to the speaker’s phonological

system. Instead of considering these variations as isolated, random errors, an expanded,

constraint-based analysis offered a more complete interpretation of these as harmonious

productions that can be systematically predicted. This would mean, for example, that

variation in a child’s production of a given word is, in fact, consistent with the child’s

internal phonological system and that a description of variants as ‘inconsistences’ does

not fully account for the rule-based selection of particular variants over others.

A review of the handful of descriptive studies found to use a constraint-based

analysis to describe variability in speech productions in children with phonological delay

highlights the versatility of the Optimality Theory framework. Whether accounting for

intraword or interword variability, diachronic or synchronic variability, and within or

between system variability, constraint-based analysis has the ability to reveal previously

hidden systemic causes.

27

CHAPTER4

CHILDHOOD APRAXIA OF SPEECH

When discussing persistent variability in speech production, the diagnostic label of

CAS is likely to come to mind. Inconsistency of speech sound production, especially in

repeated productions, has long been considered to be one of, if not also the primary

symptom of CAS by researchers in the field (Davis, Jakielski, & Marquardt, 1998;

Maassen, Groenen, & Crul, 2003; Velleman & Strand, 1994; Yoss & Darley, 1974). First

on the list of signs or symptoms of CAS published in a position statement by ASHA

(2007) is “makes inconsistent sound errors that are not the result of immaturity”.

Additionally, a survey of speech-language pathologists working with children found that

inconsistent productions was the characteristic identified most by clinicians to be

necessary in diagnosing CAS (Forrest, 2003). Despite there being no standardized

measure or definition of variability, the characteristic persists as one of the more

frequently cited markers identified on diagnostic checklists for CAS. It is also often cited

as an attribute of a motor programming deficit (Darley, Aronson, & Brown, 1975;

Marquardt, Jacks, & Davis, 2004; Shriberg et al., 1997), although reports of variability in

the speech productions of typically developing children and those with other speech

disorders have also been made (Barlow, 2001; Betz & Stoel-Gammon, 2005; Chin, 2007;

Dinnsen & Barlow, 1998; Marquardt et al., 2004; Shriberg et al., 1997; Ullrich et al.,

2008). Over the past decade, some researchers have challenged the inclusion of

28

variability as a distinctive sign of CAS and as a significant attribute of a pure motor

speech disorder (Ball, Bemthal, & Beukelman, 2002; Jacks, Marquardt, & Davis, 2006;

Marquardt, Sussman, Snow, & Jacks, 2002; Shriberg, Lohmeier, Strand, & Jakielski,

2012; Staiger, Finger-Bert, Aichert, & Ziegler, 2012). To better understand variability

under the controversial diagnostic label of CAS, this section will review the

characteristics forming diagnostic checklists, the multiple definitions of variability and

the results of differing measures, and the differing theoretical perspectives derived from

these diverse checklists.

Descriptive Studies: Symptomatology of Childhood Apraxia of Speech

Early formal research on CAS, namely Yoss and Darley (1974), described a pediatric

articulation disorder that was perceived apraxic. The symptomatology in which this

disorder, then termed developmental apraxia o f speech, differed distinctly from

functional articulation disorders was identified to be a collection of five speech

characteristics: (a) slow rate of diadochokiesis with incorrect syllable sequence; (b)

greater errors producing polysyllabic words; (c) a combination of two- and three-feature

errors, prolongations, repetitions of sounds or syllables, distortions, and additions on

repeated speech tasks; (d) distortions, one-place feature errors, additions, and omissions

in spontaneous speech; and (e) altered prosody (e.g., slow rate and equal stress). These

characteristics were claimed to be evidence of a motor programming/planning deficit

resembling adult, acquired apraxia of speech. Although described in different terms

before Darley began his research, it is this account that has dominated in the literature as

the traditional description of CAS (Strand, 2001).

29

To date, there is little agreement among researchers as to what speech behaviors

characterize this disorder (Shriberg, Campbell, Karlsson, Brown, McSweeny, & Nadler,

2003). A review of descriptive research conducted over the past fifteen years is

congruent with this finding. In Table 9, a compilation of characteristics used to select

participants in these studies is shown.

30

TABLE 9. Selection Criteria for CAS in Descriptive Research

CHARACTERISTIC RESEARCHERSInconsistent speech sound errors/production

Ball, Bemthal, & Beukelman, 2002; Jacks, Marquardt, & Davis, 2006; Maassen, Groenen, & Crul, 2003; Marquardt, Jacks, & Davis, 2004; Marquardt, Susman, Snow, & Jacks, 2002

Restricted consonant inventory Bums, 2011; Marquardt, Susman, Snow, & Jacks, 2002

Prosodic abnormalities Ball, Bemthal, & Beukelman, 2002; Jacks, Marquardt, & Davis, 2006; Marquardt, Jacks, & Davis, 2004; Marquardt, Susman, Snow,& Jacks, 2002; Shriberg, Campbell,Karlsson, Brown, McSweeny, & Nadler, 2003; Shriberg, Lohmeier, Strand, & Jakielski, 2012

Reduced fluency Bums, 2011Difficulty sequencing speech movements and/or syllables

Ball, Bemthal, & Beukelman, 2002;Maassen, Groenen, & Crul, 2003; Marquardt, Susman, Snow, & Jacks, 2002; Nijland, Maassen, Van der Meulen, Gabreels, Kraaimaat, & Schreuder, 2003

Reduced performance on word repetitions

Bums, 2011; Nijland, Maassen, Van der Meulen, Gabreels, Kraaimaat, & Schreuder, 2003

Poor diadochokinetic performance Maassen, Groenen, & Crul, 2003Slow diadochokinetic rates Shriberg, Lohmeier, Strand, & Jakielski,

2012Slow rate of speech Shriberg, Lohmeier, Strand, & Jakielski,

2012Increased difficulty with multi-syllabic words

Ball, Bemthal, & Beukelman, 2002; Shriberg, Lohmeier, Strand, & Jakielski, 2012

Groping Ball, Bemthal, & Beukelman, 2002; Maassen, Groenen, & Crul, 2003; Shriberg, Lohmeier, Strand, & Jakielski, 2012

Severely unintelligible Maassen, Groenen, & Crul, 2003Moderate/severe phonological disorder Bums, 2011; Davis, Jakielski, & Marquardt,

1998Articulation errors with a motor component

Ball, Bemthal, & Beukelman, 2002

Single syllable production limitation Bums, 2011

31

TABLE 9. Continued

CHARACTERISTIC RESEARCHERSVowel distortions/errors Ball, Bemthal, & Beukelman, 2002; Jacks,

Marquardt, & Davis, 2006; Marquardt, Jacks, & Davis, 2004; Shriberg, Lohmeier, Strand, & Jakielski, 2012

Epenthetic schwa Shriberg, Lohmeier, Strand, & Jakielski, 2012

Voicing errors Shriberg, Lohmeier, Strand, & Jakielski, 2012

High rate of speech sound errors Maassen, Groenen, & Crul, 2003; Nijland, Maassen, Van der Meulen, Gabreels, Kraaimaat, & Schreuder, 2003

High rate of omissions Jacks, Marquardt, & Davis, 2006; Marquardt, Jacks, & Davis, 2004; Nijland, Maassen, Van der Meulen, Gabreels, Kraaimaat, & Schreuder, 2003

High rate of substitutions Nijland, Maassen, Van der Meulen, Gabreels, Kraaimaat, & Schreuder, 2003

Distorted substitutions Shriberg, Lohmeier, Strand, & Jakielski, 2012

Syllable segregation Shriberg, Lohmeier, Strand, & Jakielski, 2012

Delayed initiation of articulatory movements

Ball, Bemthal, & Beukelman, 2002

Hypemasality and/or hyponasality Ball, Bemthal, & Beukelman, 2002; Bums, 2011

Unsuccessful self-correction attempts Ball, Bemthal, & Beukelman, 2002Oral apraxia Ball, Bemthal, & Beukelman, 2002; Bums,

2011Lack of progress in treatment Ball, Bemthal, & Beukelman, 2002; Davis,

Jakielski, & Marquardt, 1998Expressive language delay Marquardt, Susman, Snow, & Jacks, 2002;Cognition within normal limits Nijland, Maassen, Van der Meulen,

Gabreels, Kraaimaat, & Schreuder, 2003

As we can see, there is a sizeable collection of behaviors that are not uniformly

included on diagnostic checklists. Of the 30 characteristics used as criteria for selection

32

of CAS participants in these descriptive studies, only four were used by four or more

studies. These are (a) inconsistent speech sound errors/production, (b) prosodic

abnormalities, (c) difficulty sequencing speech movements and/or syllables, and (d)

vowel distortions/errors. Differences between criteria specifications extend beyond what

characteristics are included on the checklist to the amount and type of characteristics

needed to be present in order to receive the diagnosis. Some require that a child present

with a minimum amount of characteristics from a comprehensive list, while others

suggest that a specific set of core characteristics must be present for a diagnosis of CAS.

For example, Davis et al. (1998) proposed a core set of differential determiners derived

from results of a group case study that contained (a) limited consonant and vowel

repertoires, (b) inconsistent production of complex word shapes, (c) error variability in

conversation and in single-word productions, and (d) multiple suprasegmental

differences. Shriberg et al. (2003) reviewed reference data from a database of children

with a speech disorder and identified a different set of five markers specific for suspected

CAS. These are (a) articulatory groping, (b) metathesis, (c) inconsistencies on repeated

targets, (d) increased deletions relative to severity of involvement, and (e) increased

vowel errors relative to severity of involvement. In an earlier study, however, Shriberg et

al. (1997) found that only one of nine proposed core markers significantly distinguished a

group of children diagnosed with CAS from peers with a speech delay. Of segment

production measures, phonological process analysis, single-sound analyses, and error

variability, the measure that reached statistical significance was that of inappropriate

stress. It is noteworthy that all three studies included a form of variability in production

on their list of core determiners of CAS.

33

It should also be noted that compounding the struggle to understand the

descriptive nature of the disorder are the diagnostic checklists themselves. These have

been criticized for their lack of specificity in differential diagnosis in addition to their

inability to capture relationships among proposed diagnostic markers (Shriberg et al.,

2003). For example, a limited inventory of consonants and significant vowel distortions

may lead to reduced intelligibility, especially in the context of utterances of increased

length. A linear list of characteristics and contexts fails to acknowledge these

hierarchical connections. A few published speech and language profiles (Jacks et al.,

2006; Marquardt et al., 2004) and clusters of communication deficits (Ball et al., 2002)

have established some documentation of co-occurring characteristics but with little

explanation of their possible relationships. The longitudinal study by Jacks et al. (2006),

stands out as one that did investigate and identify a relationship between two

characteristics observed in the profiles of participants with CAS. Their multiple

regression analysis found that syllable shape accuracy accounted for 87% variance in

consonant accuracy, suggesting that the high rate of omissions (i.e., final consonant

deletion) was likely due to a deficit in forming accurate syllable shapes and was not an

isolated feature. Other quantitative information on these relationships is yet to be

gathered.

Overall, the literature is full of conflicting diagnostic checklists assembled from a

vast pool of speech, non-speech motor, and language characteristics. Although a few

markers appear with greater frequency than others, there is a general lack of consensus

among researchers and clinicians as to what set of characteristics can differentially

diagnose CAS from other developmental speech disorders. As will be illustrated further,

34

this has led to differing theoretical interpretations as to the nature of the disorder and,

ultimately, to the overall controversy of CAS as a diagnostic label.

Descriptive Studies: Variability in Childhood Apraxia of Speech

Variability in speech production is one of the characteristics included on

diagnostic checklists for CAS by many researchers and clinicians in practice. Although

also identified as characteristic of moments of developmental change in typically

developing children and children with phonological delays, the ubiquity of production

and error variability in characterizations of the speech of those with CAS may be due to a

lack of standardized, operational definitions of either consistency or variability

(Marquardt et al., 2004; Staiger et al., 2012). Without a unified definition, results of

studies investigating the nature of variability in CAS and the utility of variability as a

differential marker may be incongruent.

In their study identifying speech characteristics contributing most to CAS subject

selection certainty, Davis et al. (1998) defined error variability as a lack of consistent

patterns in both segmental productions and same-word repetitions. In order to test the

ability of various theoretical bases of CAS symptomatology to predict differential

characteristics, the speech of a small group of five children diagnosed with either CAS or

suspected CAS was analyzed. Data were collected through a comprehensive diagnostic

protocol that included both spontaneous speech sampling and responses collected from

single-word articulation testing. Results were reported for phonetic inventory, error type

and variability, suprasegmental qualities, and language skills. One of these participants

received confirmation of CAS by exhibiting a set of distinguishing characteristics. The

first of these being variable productions and the others being suprasegmental variability

35

and vowel errors. The conclusion of the study presented three contexts of variability (i.e.,

variability in the production of complex word shapes, in conversation, and in single

words) as differential determiners of CAS.

A narrower, operationalized measure of variability was used by Shriberg et al.

(1997) to calculate error variability in their comparative study. A ratio of the most

frequent error class produced per word to the total number of tokens of the word

produced measured the intraword consistency of an error pattern. This measure was used

to analyze speech sampled from 14 children with suspected CAS and 73 children with

speech delay at the conversational level. By their account, error variability did not

distinguish the suspected CAS group from the speech delay group. In fact, the speech

profiles assembled from additional measures of percent consonant correct, phonological

processes, and even vowel production accuracy did not highlight a unitary difference

between the groups. Instead, a collection of stress measures identified the characteristic

of inappropriate stress as significant in distinguishing the group of children with

suspected CAS from the group with speech delay.

In a group case study conducted by Marquardt et al. (2004), operationalized

measures of both variability and consistency were used to describe diachronic changes in

phonetic variability in CAS. By their definition, variability is perceived as repetitions of

any production that vary in the absence of contextual change. Quantitatively, variability

is calculated here by ratios of total token variability (i.e., total variant productions : total

tokens produced) and error token variability (i.e., number of error variants : total

incorrect token productions). The latter ratio differs from that used by Shriberg et al.

(1997) by comparing variants to the total of erred productions rather than the total of all

36

token productions. Furthermore, their analysis added measures of consistency using

ratios of token accuracy (i.e., total number of correct productions : total number of token

productions) and target stability (i.e., total number of same token productions : total

number of token productions). Data investigated here were collected from three children

between the ages of 4;6 and 5;6 diagnosed with CAS across three different points in time

from spontaneous speech samples and single word articulation test responses. Results of

both total token variability and error token variability were shown to be significantly

higher than those expected in typical speech development. Despite the fact that these

participants received speech treatment across the period of the study, this type of whole-

word variability across repeated assessment was suggested by the authors to be a possible

diagnostic marker.

Another study also used multiple formulas in their analysis of variability in

speech productions of children with CAS. Betz and Stoel-Gammon (2005) developed

three formulas in an attempt to measure different aspects of variability in whole-word

productions. These calculated the (a) proportion of errors, (b) consistency of error types,

and (c) consistency of the most frequent error type. Similar to the error variability

measure used by Marquardt et al. (2004), these formulas used ratios containing a

denominator of total erred productions. Unique to this study, however, is the collection of

tokens within a uniform phrasal context rather than spontaneous speech samples.

Productions of five target words were elicited in isolation and in two carrier phrases of

varying length (i.e., ‘It’s a ’ and ‘It’s a very big ’) from one child diagnosed with

CAS (age4;2), one child diagnosed with speech delay (age 5; 10), and one typically

developing child (age 5;0). Results indicated that the CAS group did not produce a

37

higher percentage of error variability in comparison to the group with speech delay and,

therefore, could not confirm this characteristic as a diagnostic marker for CAS.

Although many descriptive studies include variability on their diagnostic

checklists and participant selection criteria, relatively few have formally defined the

characteristic or utilized an operationalized formula in their analyses. Those that have

defined variability are not uniform in their outline of the level (e.g., phoneme, word) or

context (e.g., repeated phrase or spontaneous speech) in which the behavior may be

observed. Neither are operational formulas uniform in their ratio type. Without a

standardized definition of variability by which measurements may be taken, it is expected

that results presented across studies differ in their identification of the characteristic as a

diagnostic marker.

Theoretical Perspectives of Childhood Apraxia of Speech

The confusion regarding differential diagnosis of CAS contributes to the

formation of differing theoretical perspectives attempting to predict the reported

symptomatology. Indeed, there is an undeniable circularity to the classification process

in which participant selection criteria for explanatory research studies align with

theoretical perspectives (Davis et al., 1998; Shriberg et al., 2012; Staiger et al., 2012).

Guyette and Diedrich (1981) once called CAS the diagnosis looking for its population

(cited in Shriberg et al., 2012). However, with a clinical need to classify children

exhibiting severe, rare, and persisting speech errors (Forest, 2003; Shriberg et al., 1997),

there is a strong impetus to identify a diagnostic marker and locate the underlying deficit.

First, it should be mentioned that the type and amount of criteria shaping these

investigations vary in their scope and may also contribute to this circularity. In their

38

review of the literature, Shriberg et al. (1997) identified three variations of classification

hypotheses. The first, and most prominent, is the perspective that there is a single

measureable characteristic by which those with CAS may be distinguished from those

with other speech disorders. A second, increasingly popular perspective is that CAS is a

syndrome involving a cluster of symptoms. It is not necessary for all symptoms of the

cluster to be present, nor is it necessary for a single symptom to be present for a child to

receive the diagnosis. Crary (1993), for example, expanded from this view and purported

that CAS is a part of a continuum of impairments extending from speech across motor

and language skills (cited in Marquardt et al., 2004). The third divides CAS into

subtypes that are each defined by a specific profile of behaviors. This perspective differs

from the second in that subtypes are strictly defined by a closed cluster of symptoms

rather than a variable set of symptoms undefined by a distinct collection. These clusters

are not yet thoroughly developed in the literature. Such varying diagnostic perspectives

can define the scope of an investigation in a way that refers to the theoretical perspective

held by the authors. For example, a study investigating lexical stress patterns as a

diagnostic marker for CAS (Shriberg et al., 2003) interprets its findings as support for the

theory that CAS is a motor programming disorder. A different study investigating

articulation, vocabulary, language comprehension, and social skills in children with CAS

concludes that the disorder involves a constellation of impairments in the areas of speech,

language, and social skills (Ball et al., 2002).

The overall purpose of these many theoretical perspectives is to locate the

processing stage of the deficit manifest in the reported speech characteristics. These

stages are well described by the mechanical model of speech production presented by

39

Shriberg et al. (1997). In this model, six processing stages are grouped within the

traditional phases of input, organization, and output. The input phase is comprised of the

auditory-temporal processing stage, whereby auditory information is analyzed for rapid

temporal features, and the perceptual-memorial stage, whereby phonemes are assimilated

into the phonological system. The organization phase is comprised of the

representational stage, by which underlying representations are constructed, and the

transformational stage, by which these representations are altered to be harmonious with

morphophonemic, allophonic, and sociolinguistic rules. The final output phase involves

the process of selecting and retrieving phonological representations before sequencing

prearticulatory movements for the speech production of these representations. Of these

processing stages, the majority have been proposed as the locus of deficit in CAS with

little consensus among researchers. Reliable and valid evidence in broad support of one

of these theoretical proposals is currently lacking in the literature.

While the perspective of CAS as a motor programming deficit has dominated the

literature, especially during the earlier years of research in this area, there is a growing

interest in the theory that the loci of deficit can be found before the output phase in the

representational stage of speech production. Marquardt, Sussman, Snow, and Jacks

(2002) critiqued the former perspective for failing to consider a higher-order etiology

from surface-level errors of production (e.g., omissions, additions, revisions). The

interpretation of these errors as indicative of a deficit in the sequencing of segments is

seen as being limited in its explanatory power. Instead of a deficit in motor

programming, they propose that a delay in the development of the neural substrates

underlying phonological representations is responsible not only for production errors but

40

perceptual errors as well. The appeal of this theory is that it has the potential to explain

not only segmental-level errors but also syllabic- and suprasegmental-level errors.

Support for this was shown in results from their investigation of differences in the

perception of ‘syllableness’ by typical-developing children and children with CAS. The

CAS group performed lower than the control group on all tasks (i.e., detecting syllables

and judging intra- and inter-syllabic positions) and responses from typical-developing

control group participants exhibited organized syllabic constructs. These findings were

taken to suggest that the sequencing of speech sound segments in CAS is not organized

by well-formed syllabic frames. This kind of breakdown in the structural integrity of the

syllabic frame points to a deficit in underlying representations rather than a pure motor

speech deficit.

Velleman and Strand (1994) also described ‘frames’ in which the structure of the

syllable organizes speech sound segments by highlighting the hierarchical nature of

phonological organization. They uphold that CAS involves an impairment in generating

well-formed frames which, in turn, leads to ill-formed motor plans. Evidence for this

was presented by Jacks et al. (2006) in their study on the longitudinal change in

consonant and syllable patterns produced by children with CAS. High rates of omissions,

substitution errors, and inaccurate word shape productions were seen as patterns expected

in younger, typically-developing children. The types of errors and the relationship found

between syllable patterns and consonant accuracy were seen as projections of a delay in

the development of the representational substrates underlying the formation of the

appropriate syllabic frames.

41

As we see, this emerging theoretical perspective looks beyond the level of motor

programming speech sound segments to discover a more general cognitive-linguistic

deficit preceding this stage of production. The difference in these two perspectives has

implications for further research in this area as well as clinical treatment of the disorder.

Because children suspected to have CAS are often those making slow progress in

treatment, it is of great importance that descriptive and explanatory research investigate

the prediction power of all theoretical perspectives and identify markers that can

differentially diagnose CAS reliably.

Summary

In lieu of a gold standard protocol, diagnostic checklists of observed behaviors are

used by researchers and clinicians for assessing and diagnosing CAS. Currently, there is

a general lack of consensus among researchers on the descriptive nature of CAS and

these lists remain limited in their ability to identify true positives (Shriberg et al., 2012).

If the nature of the disorder is to be understood and if the diagnostic label is to be

clinically useful for assessment and treatment purposes, an operationalized and

standardized set of core characteristics with a high percentage of sensitivity and

specificity is needed (Shrieberg et al., 2012). Standardizing definitions of speech

behaviors, investigating conditional relationships between markers will also aid in

locating the deficit at a specific processing stage in speech production.

Traditionally, the theory that CAS is a deficit of motor programming articulatory

gestures has dominated the literature (Darley et al., 1975; Nijland et al., 2003; Shriberg et

al., 2003; Yoss & Darley, 1974). A growing interest has been seen, however, in the

theoretical perspective citing a deficit or delay in the development of neural substrates

42

underlying phonemic representation (Dinnsen & Barlow, 1998; Jacks et al., 2006;

Marquardt et al., 2002; Velleman & Strand, 1994). Instead of a pure motor disorder, this

model identifies a cognitive-linguistic deficit that predicts difficulties programming

articulatory gestures for speech. Locating the origin of deficit in CAS is important not

only in guiding researchers in their search for diagnostic markers but also in the clinical

assessment and treatment of this population.

43

CHAPTER 5

METHODS

Purpose

The purpose of this study is to explore the possible contributions of Optimality

Theory to the body of descriptive research on CAS. Although there is no unified

consensus on what set of behaviors may be considered to be core characteristics of the

disorder, variability in speech production is commonly included on the lists of participant

selection criteria used by researchers and on the lists of characteristics necessary in

clinical diagnosis. If variation in the speech productions of a child with suspected CAS

can be accounted for as rule-governed using a constraint-based analysis, this would result

in two major implications. Firstly, the results of the analysis may provide empirical

support for the theoretical proposal that the core deficit of CAS is one affecting a

cognitive-linguistic stage rather than the motor programming stage. Because the motor

programming stage of speech production occurs after the phonological representation of a

target is retrieved and transformed, motor speech errors would not exhibit a systematic

pattern of variation. It is instead expected that motor speech errors would occur

randomly and would not be predicted by any grammatical rule. Secondly, predictable

variation in speech production would provide clinical implications for the assessment and

treatment of CAS. Clinicians may want to remove the characteristic of error variability

from their diagnostic checklists of characteristics believed to differentiate children with

CAS from those with a severe phonological disorder. Because variation is produced by

children with phonological disorders, it is not a distinctive characteristic of CAS and,

therefore, may further reduce the sensitivity of this diagnostic tool. When selecting

treatment targets, knowledge of variation as rule-based can aid the clinician in his or her

development of a more efficient intervention plan with specified targets aimed at

demoting those phonological constraints governing the error patterns.

Design

A single-subject case study design was selected for this study because of the nature of

this investigation. Studies attempting to describe and measure the presence of speech,

non-speech, and language deficits in children with CAS or suspected CAS benefit from a

group design. The present study seeks to describe the nature of a speech characteristic

produced by an individual phonological system using an experimental analytical

approach. Crucial to this analysis is the identification of interactions and relationships

between the idiomorphic rankings of constraints. The case study design allows this kind

of in-depth observation of a particular phonological system to be made.

Participant

The participant is a male child receiving speech therapy at a private practice in

Placentia, California. He was selected following a request made by the author to the

supervising clinician at the private practice for access to diagnostic and treatment data

collected from a child diagnosed with or suspected to exhibit CAS. At the time the data

used in this study was collected, the participant was between the ages of four years, four

months and four years, eight months. He had been receiving speech and language

45

services inconsistently for a period of approximately two years. Therapy addressed a

delay in speech development determined by the provider to be characteristic of CAS.

The speech behaviors informally cited by the provider to influence her suspicion

of the disorder were: (a) inconsistent error productions across repeated trials of the same

word; (b) difficulty sequencing segments and syllables; (c) reduced intelligibility with

increased utterance length; and (d) unusual substitution errors. These characteristics

correlated with those appearing on the list of characteristics used in making a diagnosis of

CAS collected by Forrest (2003) in her survey of practicing clinicians. Although this

study does not address treatment effects, it is worth noting that the treatment approach

used at this time was one that targeted segmental errors (e.g., producing velars in medial

word position) using repetition drills of words and phrases.

Procedure

Data Collection

The data were obtained by the author from the participant’s clinical file at the

private practice. These data included broadly transcribed responses to word and phrase

repetition tasks, transcriptions of words and phrases produced in connected speech, and

qualitative descriptions of speech production errors. A total of two clinicians recorded

the data during treatment sessions and used the information for diagnostic purposes as

well as for measuring the response to treatment. Each clinician contributed to the data

collection in a different way. One clinician documented speech production accuracy

using qualitative descriptions and binary scores (i.e., a trial was performed either

correctly or incorrectly). The other clinician documented speech production accuracy

46

with broad transcriptions of whole-word productions during repetition tasks and moments

of spontaneous speech.

Data Analysis

The speech samples were reviewed and repeated target words were selected for

analysis. These were any target productions produced more than once. Three types of

data analysis were performed. The first analysis quantitatively measured the rate of

whole-word variability in repeated productions using two operationalized formulas

developed by Marquardt et al. (2004). These are total token variability and error token

variability (see examples in Table 10). Total token variability measured the

TABLE 10. Sample of Repeated Words and Their Measures of Variability

Example Target Token 1 Token 2 Token 3 Token 4 TotalToken

Variability1

ErrorToken

Variability2

1 ‘name’/neim/

[meim] [meim] [neim] [neim] (2-1/4-1)

33%

(1-1/2-1)

0%2 ‘daffodil’

/daefodil/[baesAbo] [daefAdil] [daedAdio] [daesfAdio] (4-1/4-1)

100%

(3-1/3-1)

100%3 ‘water’

/wcuW[war&] [ware*] [waro-] (1-1/3-1)

0%

(0-1/3-1)

0%1 (# variants produced - 1 degree of freedom/# tokens produced-1 degree of freedom).2 (# incorrect variants produced - 1 degree of freedom/# incorrect tokens produced-1

degree of freedom).

percentage of variability in all productions and was defined as the number of variants

produced compared to the total number of tokens produced. Error token variability

47

measured the percentage of variability in incorrect productions and was defined as the

number of variants produced compared to the total number of incorrect tokens produced.

The second analysis compiled a phonemic inventory of consonants produced by the child

in these samples so as to better describe the child’s phonological system and the

phonemes acquired. Lastly, a qualitative analysis of intraword variants used a

constraint-based phonological approach to account for their phonological differences.

48

CHAPTER 6

RESULTS

Quantitative and qualitative analyses of the data yielded a rate of variability in all

token productions and error token productions, a consonant inventory, and a complete

phonological analysis.

Whole-Word Variability

A total of 52 repeated target words were produced in the speech sample. From

these, a total of 73 tokens were produced. Analysis of intraword variability among these

targets yielded total token variability and error token variability.

Total Token Variability

Of all tokens that were produced both correctly and incorrectly, variability of

productions was calculated to be at a rate of 74%.

Error Token Variability

Of those tokens that were produced incorrectly, the variability in production was

calculated to be at a rate of 52%.

Consonant Inventory

Analysis of all productions transcribed in the treatment notes yielded a complete

inventory for all consonants expected to be acquired by a speaker of American English

during the age of 4-5 years. Results are shown in Table 11. The inventory is organized

49

TABLE 11. Participant’s Consonant Inventory Between Ages 4;4 and 4;8

Phoneme Onset slot Acquisition Coda slot Acquisitionstatus status

BILABIALS

Plosives /p/ [pwiz] please X [tip] sleep X/b/ [bAbogAm]

bubblegumX [web ]web X

Nasal /m/ [muf] move X [denim] denim XApproximant /w/ [siwid] seaweed X N/A

LABIODENTALS

Fricatives HI [fen] friend X [bAf] buff XM [hevi] heavy X [haev] have X

DENTALS

Fricatives /e/ [nAsi] nothing 0 [>skwet] 0/a / [Aj&said] other 0 earthquake 9

side (no example)ALVEOLARS

Plosives N [tisu] tissue X [fast] fa t X/c [demm] denim X [fud ]food X

Nasal /n/ [nau] now X [sAdon] sudden XFricatives /s/ [sAdon] sudden X [dis] this X

/z/ (no example) 9 [siz] cheese X/r/ allophones

Alveolar [wedi] ready 0 N/A 0approximant [a]

Rhotacized [3-skwet] X [kcr-] car Xvowel [<>] earthquake

LateralApproximant /!/ [lido] little X [bado] bottle 0POST-ALVEOLAR

Fricatives /J7 [tisu] tissue 0 [tofis] starfish 0

PALATO-ALVEOLARS

Affricates /tJ7 [tsaimifud] Chinese 0 [kraets] scratch 0food

/<fe/ [daPnt] giant 0 (no examples) ?PALATALS

50

TABLE 11. Continued

Phoneme Onset slot Acquisitionstatus

Coda slot Acquisitionstatus

Approximant /j/ [ju] you X N/A

VELARS

Plosives /k/ [kakadaido] X [sto-k] stork X/g/ crocodile

[gas] golfX [pig] pig X

Nasal /g/ [go-pagan]watermelon

X* [haidig] hiding X

GLOTTALS

Allophonic plosive /?/

N/A [itsga?aut] i t ’s got out

X

*not phonotactically allowed in American English

by occurrence of the phoneme within the syllable. A multidimensional understanding of

the phonological system benefits from viewing the phoneme by its occupancy of syllable

slots rather than by the traditional measure of word position (e.g., initial, medial, and

final word position). Furthermore, the syllable is a unit of measure consistently used by

researchers utilizing a constraint-based approach (Barlow, 2001; Chin, 2007; Dinnsen &

Gierut, 2008; Ullrich et al., 2008).

The participant demonstrated acquisition of all bilabial, labiodental, palatal, and

velar phonemes in all syllable slots phonotactically allowed by American English

phonology. The alveolar plosives and nasals appeared in all allowed positions with the

alveolar fricatives appearing in all documented positions. The alveolar approximant, the

post-alveolar fricative, and the dental fricatives do not appear in the data at all and are not

51

a part of this child’s inventory. The same appears to be true for palato-alveolar fricatives,

however, a paucity in the data cannot confirm this. Finally, it is worth noting that the

participant’s inventory includes the unusual occurrence of /rj/ in the onset slot. This

sound is restrained by the phonotactic rules of the English language from the onset and is,

therefore, highly rare in the speech of English-speakers.

Nonlinear. Constraint-Based Phonological Analysis

A phonological analysis of the data revealed several active phonological

processes causing simplification of adult target forms. These are gliding, vocalization,

cluster reduction, depalatalization, place assimilation, and weak syllable deletion. A

nonlinear, constraint-based approach accounts for these by a general dominance of

markedness over faithfulness constraints.

TABLE 12. Constraint Rankings for Phonological Processes

PhonologicalProcess

Constraint Ranking Examples

GlidingVocalization

* LIQUIDS [l,r]»IDENT [consonantal] wis/leaf; swAg/slug kaedopido/caterpillar

Cluster reduction * COMPLEX»M AX wok/brokeDepalatalization * PAL AT ALS»IDENT[anteriorl ssd^siz/chedder cheese

Place assimilation AGREE[place]»IDENT[place] mimo/Nemo;hagagz/hotdogs

Weak syllable deletion

FOOT-F ORM »M AX fami/salami

For many utterances, a simple dominance ranking between one markedness and one

faithfulness constraint is sufficient in accounting for differences between the input and

output forms (see Table 12). For other productions in this sample, a more complex

52

ranking of multiple constraints must be constructed. This is particularly true for

interword and intraword variation as well as for productions exhibiting interactions

between phonological processes. Because variation in production is the focus of this

study, the following sections will provide a more in-depth account of how constraint

rankings can account for variations between and within words.

Intraword variability

Of the phonological processes identified in the sample, place harmony and cluster

reduction were not consistently active in all tokens. That is, a given token production

could either be predicted by one of these phonological processes or else they could not be

predicted. Such intraword variation can be sufficiently accounted for by equal rankings

of constraints.

Place Harmony. There were several examples of variation of place harmony

within repeated tokens. For all of these, it appears that an equal ranking between the

markedness constraint AGREE [labial] and the faithfulness constraint IDENT [place] is

responsible for all variants. For the examples illustrated in Tables 13-15, candidates

faithful to the underlying representation and candidates marked by labial assimilation

both surface as variants in repeated token productions. This happens as a result of equal

rankings between the markedness constraint and faithfulness constraint dealing with the

TABLE 13. Place Harmony Intraword Variation for Target Nemo /nimo/

Nemo IDENT [ manner] AGREE [labial] i IDENT [placel®°/nimo/ * iI^/mimo/ ! */bibo/ *! i *!

53

TABLE 14. Place Harmony Intraword Variation for Target bandaid /baendeid/

Bandaid IDENT [manner] AGREE [Iabiall IDENT [placel®°/b^nbeid/ *^/baendeid/ */maendeid/ *!

TABLE 15. Place Harmony Intraword Variation for Target cinnamon /sinomin/

Cinnamon IDENT [manner] AGREE [labial] IDENT [placel^/simAmin/ *^/sinAmin/ */sibAmin/ *! *

[place] feature of surface forms. On the other hand, other kinds of variants containing

segment substitutions that are not faithful to preserving the manner of the input segment,

do not ever surface in the sample. For example, the faithfulness constraint demanding

that output segments preserve the manner feature of their corresponding input segments

(i.e., IDENT [manner]) is ranked above the markedness constraint demanding labial

harmony (i.e., AGREE[labial]). Because of this domination, a [labial] plosive Ibl cannot

surface as a substitute (e.g., /sibAmin/ for target cinnamon) despite being harmonious

with the constraint requiring [labial] assimilation.

Some productions are not simplified and surface as entirely faithful to the input

form (e.g., /sinAmin/ for target cinnamon). As has been documented in other studies

describing variation in typical and atypical phonological development (Barlow, 2001;

Chin, 2007; Dinnsen & Gierut, 2008; Ullrich et al., 2008), this may be a sign of

systematic change whereby markedness constraints are demoted below faithfulness

constraints. As seen here, although tokens of a given target are variable, these variants

54

are not random and can be sufficiently predicted by the strict domination of constraint

rankings. For example, the possible candidate /sibomin/ does not surface as a variant due

to its violation of the highest ranking constraint demanding the preservation of the

manner feature.

Cluster reduction. Cluster reduction is another phonological process that is not

consistent across repeated token productions in the sample. The patterns of this kind of

simplification range from reduction to the most sonorous segment to reduction to a single

segment containing features from both cluster elements (i.e., coalescence). Cluster

reduction involving place assimilation was the only pattern exhibiting variation. An

example is shown in Table 16.

TABLE 16. Variation in Cluster Reduction

Sleeping *LIQUID-[1]

IDENT[manner]

*COMPLEX

AGREE[labial]

IDENT | DEP [place] |

MAX

^/fipirj/ *1

*^/swipiq/ * **/lipirj/ *! ** | */solipirj/ *! *** | */ slipirj/ *! * *** i

i

Here we see that both a consonant cluster in onset and a singleton onset are produced as

variants of the same target word. This can only happen if the markedness constraint

barring complex onsets (i.e., *COMPLEX) and the faithfulness constraint requiring all

cluster segments to surface (i.e., MAX) are equally ranked. The adult form of the target,

in addition to other candidates (e.g., /lipirj/ and /sslipiq/) cannot surface as variants,

however, due to their violations of the high ranking *LIQUID-[1]. An equal ranking of

55

the markedness and faithfulness constraints dealing with place harmony accounts for the

reduction of the cluster [si] to [f]. A labiodental fricative satisfies the highly ranked

IDENT[manner] as well as the AGREE[labial] constraint in a way that is more

harmonious than any other substitution candidate. As such, the variants of the target

sleeping which surfaced in this speech sample are sufficiently predicted by the dominant

ranking of *LIQUID-[1] over the equally ranked * COMPLEX, DEP, and place harmony

constraints illustrated above.

Interword variability

Another type of variation present in the sample is that which occurs across targets.

While intraword variability could be discussed within the context of common

phonological processes, interword variability observed in this child’s speech presents

itself outside the context of such common error patterns. The patterns discussed here

TABLE 17. Interword Variation of /j/ in Onset for Target yard /jcvd/

Yard IDENT [manner] *LIQUID-fU *j/[-high] IDENT [roundl^/wa-d/ */jod / *!/lod / *!

TABLE 18. Interword Variation of /j/ in Onset for Target yours l)3-zl

Yours IDENT [ manner] *LIQUID-fll *j/[-high] IDENT [roundlt®=/w3-z/ */jS'Z / *!/ l^ z / *!

56

TABLE 19. Interword Variation of /j/ in Onset for Target you /ju/

You IDENT [manner] *LIQUID-[11 *j/[-high] IDENT f roundl^ /ju //wu/ *!/hi/ *!

involve the banning of /j/ in the onset, the banning of labial continuants in the coda, and

the dissimilation of features. Examples for discussion are illustrated in Tables 17-22.

An unusual pattern that bans the palatal approximant /j/ from the onset slot

occurred across a set of targets collected in the sample (see Tables 17-19). This pattern,

however, was not consistent across target forms containing /j/ in the onset. A constraint-

based analysis revealed that this variation was determined by the nucleus of the syllable.

That is, the palatal approximant could surface in the onset when it was attached to a

[+high] vowel. For all other vowels, /j/ transformed into the labio-velar approximant /w/.

No other manner of surface substitutions appeared in the sample because the faithfulness

constraint for manner is ranked above all other markedness constraints and must be

strictly abided. Lateral approximants do not surface as a substitute due to the high

ranking of the *LIQUID-[1] markedness constraint. As a consequence of this

hierarchical arrangement, /w/ must substitute /j/ in this particular phonological

environment as the most optimal output segment.

Another unusual error pattern present in the sample is the banning of the labial

continuant til from the coda. Many productions of targets containing /f/ in coda were

produced by substituting this segment with the coronal continuant /s/. The consistency

with which this substitution was made can be predicted by the high ranking of

57

TABLE 20. Interword Variation of Labial Continuants in the Coda for Target stuff /stAf/

Stuff ‘LIQUID-HI

‘COMPLEX IDENT[manner] DISSIMILATION CODA-COND

IDENT [place]

®°/dAS/ */d A f/ *!/dAt/ *! */stAf/ *! *

TABLE 21. Interword Variation of Labial Continuants in the Coda for Target leaf /lif/

Leaf ‘LIQUID-[11

‘COMPLEX IDENT[manner] DISSIMILATION CODA-COND

IDENT [place]

^/w is/ */wif / *! */wip/ *! * */lif/ *! *

TABLE 22. Interword Variation of Labial Continuants in the Coda for Target soft /soft/

Soft ‘LIQUID-[11

‘COMPLEX IDENT[manner] DISSIMILATION CODA-COND

IDENT [place]

^/saf/ *

/sas/ *! *

/sat/ *! *

/saft/ *! *

IDENT [manner]. Both /f/ and /s/ contain the manner features [+strident] and

[+continuant] and a substitution of /s/ for /f/ does not violate this constraint. On the other

hand, /f/ in coda does violate the markedness constraint banning labial continuants from

the coda (i.e., CODA-COND) ranked just below the faithfulness constraint preserving

manner and just above the faithfulness constraint preserving place. Because of the

position of CODA-COND between these two faithfulness constraints, /f/ does not often

surface in coda. An exception to this, however, is seen in Table 22. Here we notice that58

a ban on identical consonants within a word (i.e., DISSIMILATION) is ranked above

both CODA-COND and IDENT [place]. In order to be harmonious with the ranking of

DISSIMILATION, /f/ is allowed to surface in those cases where /s/ already occurs

within the word (e.g., /saf/ surfaces instead of variant /sas/). As such, this is the only

environment where /f/ in coda is produced in the sample. Again, variability in this

child’s productions can be sufficiently predicted across a variety of words.

Word shape simplification and variation

Initially, this analysis focused primarily on accounting for variations that occurred

at the segmental level in the form of substitutions and deletions. As the analysis

continued, it became rapidly apparent that variations of word shapes in this sample could

not be ignored. This level of variation is not sufficiently explained by constraints ruling

over the segmental tier. In order to account for phonological constraints operating on

elements organizing syllables, we must appeal to the levels of the prosodic structure

hierarchy (see Table 23). This hierarchy is hypothesized to organize prosodic elements

by domination, such that segments are dominated by CV elements, CV elements by

syllables, syllables by feet, and so on (Raimy & Cairns, 2009). Of importance to this

analysis is the CV tier, which defines the functional positions of peaks (e.g., typically

vowels) and margins (e.g., typically consonants) within the syllable, and the metrical foot

tier, which is responsible for responsible for organizing the stress patterns of words by

the rules of a given language (Clements & Keyser, 1983).

It is important to review that the syllable itself is a prosodic unit detected by its

perceived amplitude and separately organized around an amplitude peak. This peak is

also known as the nucleus and must be present in order for a syllable to be perceived.

59

Other segments that might also belong to the syllable are the onset and coda which are

called margins. Each syllable carries its own weight which is determined by the rhyme

(i.e., nucleus or nucleus+coda) and defined by the timing measuring unit known as the

mora (p.). A light syllable has a short rhyme and is termed monomoraic. An example of

this is the word the, which is a CV word shape consisting of a short vowel. A heavy

syllable has a long rhyme and can be bimoraic or trimoraic. For example, the word tie is

a bimoraic syllable with a CV word shape consisting of a diphthong and the word tire is a

trimoraic syllable with a CVC word shape consisting of a diphthong and a coda (Lavoie

TABLE 23. General Prosodic Hierarchy

Intonational Phrase tier

IPhonological Phrase tier

IProsodic Word tier

I

Foot tier

Syllable tier

CV tier

ISegment tier

Note: Adapted from Goldsmith, Riggle, and Yu, 2011; Clements and Keyser, 1983.

60

& Cohn, 1999). Timing slots holding morae are found at the CV tier. It is worth

highlighting that the word shape itself does not determine how many morae a syllable

will have. Rather, it is the timing of the segments holding the C and V positions that

determine this weight. For example, a CV word shape may be monomoraic or biomoraic

(e.g., the difference between the word the and the word tie). In order to understand the

simplification of word shapes produced in this study’s data, and the variation in this

simplification, we must appeal to the phonotactics involving the prosodic units of the

metrical foot and the mora.

Two types of phonotactic restrictions on word shapes were found to occur in this

sample. The first restriction is one that concerns the margins of syllables. In Tables 24-

26, we see a tableau arranging constraints for this element of syllable structure. The

hierarchy is such that the markedness constraints NoSeq[M2,Ml], which bans a

sequence of M2 (i.e., singleton coda margin) and Ml (i.e., singleton onset margin) within

a word shape, and *3p<r, which bans superheavy syllables, are ranked above faithfulness

constraints. Dominance of NoSeq[M2,Ml] prevents word shapes such as CVCCVCV

and CVCVCCV from surfacing but not CVCVCV or CVCVCVC. In Table 24, this

results in the variants /tikAlik/ and /tsikAlei/ as optimal surface forms for the target

“Chick-fil-a”. The word shapes of these outputs are CVCVCVC and CVCVCV

respectively, which successfully avoid the target word shape of CVCCVCV while also

preserving the moraic weight of the penultimate and ultimate syllables. That is, the initial

syllable /tik/ loses a mora with the deletion of the coda, but the syllabic weight of the

other syllables are preserved. Other examples of avoiding a sequence of M2 (i.e. coda)

61

and Ml (i.e., onset) in the sample include deletion of the /l/ in the production [aefAbst] for

alphabet, deletion of /n/ in the production [etonA] for antenna, and deletion of /d/ and /g/

in the production [fainAmimo] for Finding Nemo. Examples in Tables 24 and 25 best

illustrate the consequences of dominance of *3po. Because the target form for the word

crocodile contains a diphthong and dark /l/ in the rhyme, it cannot surface. With the

faithfulness constraint FILL (i.e., no addition of segments to a syllable structure) ranked

low in the hierarchy, a surface form that adds a vowel to the final rhyme is a good

candidate. In order to surface, however, this epenthetic change cannot add morae to the

output form (i.e., violation of WT-IDENT-IO). The output surfaces as the form

/kakodaido/ which preserves the weight of the final syllable without violating the rule

against margin syllabification. The more unusual production of [faido] for the word fine

can also be accounted for by this constraint hierarchy, as this outut form avoids a

monomoraic consonant while preserving moracity. Common to these examples is the

ranking of constraints governing the prosodic organization of syllables and word shapes

over constraints governing faithfulness to the segments of the word. In this particular

TABLE 24. Peak and Margin Restrictions for Target Chick-fil-a /tjikfolei/

Chick-fil-a NoSeq[M2,Ml1

*3|«r WT-IDENT-IO

PARSE FILL

^/tikolik/ * * *®“/tsikolei/ * */tikoli/ **i */tsikofl/ *! ** */tfikfolei/ *!

62

TABLE 25. Peak and Margin Restrictions for Target crocodile / krakodail/

Crocodile ‘ COMPLEX NoSeq[M2,Ml] *3]Uflr WT-IDENT-IO PARSE FILL®°/kak9daido/ * */kakodai/ *! */kakadaid/ *! * */ krakodai8!/ *! *

TABLE 26. Peak and Margin Restrictions for Target fine /fain/

Fine *3iut WT-IDENT-IO PARSE 1 FILL/faida/ 1 *

/far/ *! * i/fain/ *! |

case, adding or deleting segments are allowed by the phonological system as long as

these segmental changes assist in satisfying higher-ranked prosodic constraints.

The second restriction for word shapes found in this sample is one that concerns

the metrical foot. The foot is a prosodic unit which combines two alternating elements in

order to form lexical stress (Gussenhoven, 2004; Kager, 1999). A foot with a stress

pattern of strong-weak is trochaic while a foot with a stress pattern of weak-strong is

iambic (Gussenhoven, 2004). Trochaic feet can either be syllabic trochees, whereby two

syllables are combined (e.g., HOTdog), or moraic trochees, whereby two morae are

combined to make a single heavy syllable (e.g., RAT). The difference between these

trochees is that only the moraic trochee can be produced in a single syllable.

Crucial to understanding other puzzling productions collected from the participant

are the faithfulness constraint MAX-o and the markedness constraints FT-TROCHEE

and ALL-FT-LEFT. The faithfulness constraint MAX- <r requires that all syllables

from the input surface in the output. Preservation or deletion of syllables loosely

63

interacts with rules governing the prosodic foot. Because bimoraic trochaic feet can be

mono- or bi-syllabic, preservation of the metrical foot need not require that all syllables

surface. As is illustrated in Table 27, it is of greater importance to the participant’s

phonological system that the metrical foot surface in the output than it is to preserve all

syllables of the input. In fact, it appears that the system prefers to deliver trochaic feet in

as few syllables as possible. For example, the deletion of a weak peak in both [bju:n] and

[bwu:m] for target balloons and the deletion of the weak syllable in the target salami. An

equal ranking of ALL-FT-LEFT with MAX-cf also influences the deletion of weak

syllable peaks that do not belong to any metrical foot. ALL-FT-LEFT demands that

every foot be positioned at the left edge of a word so that any weak peaks that appear

word-initially in the input do not surface in the output. In Table 27, both bisyllabic and a

trisyllabic variants for salami surface as optimal output forms and are accounted for by

this equal ranking. Shared dominance here means that preservation of syllables can co­

occur with the deletion of word-initial weak peaks. Finally, a high ranking of FT-

TROCHEE means that this child’s system mandates that the metrical foot of a given

target be trochaic at all costs. This correctly predicts the absence of reduced word shapes

TABLE 27. Word Shape Variations for Target salami /salami/

Salami *LIQUID-1 FT-TROCHEE ALL-FT-LEFT MAX-a®“/fami/ *^/sajami/ */sala/ *!/salami/ *! *

64

TABLE 28. Word Shape Variations for Target balloon /bolu:n/

Balloon *LIQUID-I FT-TROCHEE ALL-FT-LEFT

MAX-tr

^/bjuin/ *®°/bwu:m/ */bowu/ *!/bolu:n/ *! *

that changes the parsing of feet from trochaic stress patterns to iambic stress patterns

(e.g., the form /sola/ for salami does not appear in the sample).

A constraint-based analysis of the word shapes and syllable structure of

multisyllabic productions in this sample revealed the internal structure of phonological

constraints that produced not only unusual surface forms but variations in these forms.

Because these productions did not reduce word shapes in the conventional way (e.g.,

weak syllable deletion), a constraint-based analysis was used to understand the process

behind not just syllable deletions but also unusual syllable insertions.

65

CHAPTER 7

DISCUSSION

Speech samples of both spontaneous speech and single-word repetitions produced

by a 4-year-4-month-old boy collected within treatment sessions across a period of four

months were analyzed for variability in production. Two operationally-defined,

quantitative measures of variability revealed rates above 50% for both total token

variability and error token variability. These results appear to support the claim that

overall variability in token productions is high in the speech of children with suspected

CAS. Moreover, a high rate of error variability would suggest that predictability of

variants is much more difficult to define in the speech produced by this population of

children. A deep phonological analysis of these utterances confirms this by the way that

errors and their variants could not be predicted by common phonological processes alone.

Of those common phonological processes found in the sample, place harmony and

cluster reduction by coalescence exhibited the most variation in their patterns. That is,

target words predicted to surface as forms described by one of these processes were not

always the only forms to surface (e.g., the variants [fami] and [salami] for target salami).

This kind of intraword variability was successfully accounted for by a constraint-based

analysis revealing an equal ranking among markedness and faithfulness constraints (i.e.,

AGREE [labial], IDENTJplace] and ^COMPLEX, UNIFORMITY, DEP, MAX).

66

Variation by equal rankings has been previously described in constraint-based analyses of

intraword variability in the speech of children with phonological disorders (Barlow,

2001; Chin, 2007; Ullrich et al., 2008). Because variation in this child’s production of

targets involved producing the adult form on some occasions and a form exhibiting a

clear pattern of phonological processes on other occasions, variation may be interpreted

as a sign of positive change to the phonological system. For example, the markedness

constraint responsible for place harmony appeared to be in the process of demotion below

its opposing faithfulness constraint. As mentioned earlier, the ranking of a fully

developed adult system is that which arranges faithfulness constraints in domination of

markedness constraints. This child’s system appears then to be in the process of

achieving a more accurate approximation of the adult system rankings. The same

positive change could also be seen in the case of cluster reduction. Variation was,

however, different in that error productions exhibited both demotion of a markedness

constraint (i.e., banning complex onsets) and persistence of a highly ranked constraint for

gliding. That is, two phonological processes were active in the production of tokens for

this kind of target with only one of those processes exhibiting signs of change.

Therefore, an incomplete demotion of *COMPLEX allowed a cluster to occasionally

surface in the onset position. A higher-ranked ban on liquid /l/, however, meant that this

cluster would still be an error form (i.e., the glided /sw/ form for an /si/ onset).

Another notable type of variation found in this participant’s speech sample was

that of inconsistent interword production of two rare phonological patterns. The first

pattern appeared to substitute labio-velar approximant /w/ with the palatal approximant /j/

in the onset slot of most but not all surface forms. In this case, variation was accounted

67

for by the strict domination of a markedness constraint banning /j/ before vowels

containing the feature [-high] over a faithfulness constraint preserving the feature

[round]. This ranking was able to account for the difference between the output form

/wa-z/ yours and the output form lyxl you. The second pattern exhibiting interword

variation was the substitution of the coronal continuant /s/ for the labiodental continuant

/f/ in the coda slot of most but not all surface forms. In contrast to the pattern of place

assimilation discussed earlier, variations in this pattern appeared to center around a

constraint ordering the dissimilation of segments belonging to the same syllable.

Specifically, the ranking of

IDENT [manner] »DISSIMIL ATION»COD A-COND»IDENT [place]

sufficiently predicted the variants /f/ and /s/ in the coda by disallowing this substitution in

those cases where it would mean the double occurrence of /s/ within the same syllable.

More importantly, this ranking also predicted that no other substitution variant may

surface that did not preserve the manner of the segment it substituted (e.g., /p/ or /t/). By

predicting what we do and do not see surface in a speech sample, a more complete

picture of the child’s internal system is illuminated.

While intraword and interword variation involving phonological segments has

been previously accounted for by other researchers investigating variation in children

with phonological disorders, this study was also able to extend such accountability to the

prosodic elements of speech. Variation in word shapes produced by the participant was

noted to involve changes to prosodic units located above the segmental tier in the

prosodic hierarchy. These changes altered the overall shape of some output forms in a

way that could not be sufficiently described by either phonological processes or

68

constraints governing phonological segments. In order to account for phonological

reduction and variation at the higher prosodic levels, a hierarchical arrangement of those

phonotactic constraints governing the organization of syllable peaks and margins and

those governing the organization of timing units (i.e., morae) had to be constructed. For

example, a highly ranked markedness constraint banning the weight of three morae in a

syllable (i.e.,*3po) accounted for the unusual surface shape /faido/ for target fine.

Unusual word shape variants that surfaced for the word Chick-fil-a were predicted by a

highly ranked markedness constraint governing segment organization within a syllable

(i.e., NoSeq[M2,Ml]) in addition to an equal ranking of the faithfulness constraints DEP

and MAX. Variants that surfaced either inserted (i.e., CVCVCVC) or deleted (i.e.,

CVCVCV) segments in order to satisfy the markedness restriction on margin sequences.

Further prosodic irregularities involved variation in the production of target forms with

weak initial syllables outside of the iambic foot pattern. This too was accounted for by

an equal ranking in constraints (i.e., *ALL-FT-LEFT and MAX-«) that were

collectively dominated by a markedness constraint (i.e., FT-TROCHEE). The outcome

of this arrangement was such that surface forms varied in their preservation of all

syllables at the expense of parsing only trochaic feet.

A traditional phonological analysis would not have been able to account for such

syllable reduction patterns either descriptively or predictably. The only phonological

process made available by a linear analysis is syllable deletion (i.e., either weak or

strong) which describes deletion of all segments in a syllable rather than syllable peaks.

Because syllable reduction patterns like those produced in the present data would not be

predicted by this phonological process, they might be deemed unruly and random by a

69

linear analysis. By incorporating the nonlinear model of the prosodic hierarchy into a

constraint-based analysis, however, syllable reduction by deletion and insertion of

syllable peaks and margins are successfully predicted and deemed disciplined by a strict

hierarchy of phonological constraints.

Accountability for not just variability but also unusual error patterns that are not

successfully described by a linear phonological process analysis is one of the significant

benefits of a constraint-based analysis. What might have typically been described simply

as high rates of variability or high rates of omissions and substitutions, as is consistent

with frequently cited characteristics of CAS, can in this way be understood as a

consequence of a complex, systematic arrangement of phonological and phonotactic

rules. One of the difficulties in understanding a child’s phonological system is that we

can only look at traces of the transformation of an item from its underlying form to its

surface form. By further viewing these traces merely as shadows, we do not see the light

that defines them. A constraint-based analysis is useful in the way we can begin to see

not only the forms that surface but also the forms that do not. This kind of information

aids in revealing a depth of dimension involving connections between ostensibly simple

omissions or substitutions of segments and higher order prosodic elements of

phonological structure. By utilizing a finer phonological analysis, we are able to better

understand the complex nature of a given phonological system and, thus, the nature of the

disorder affecting it.

70

Limitations

Although the phonological variation and rare phonological error patterns

described here appeared to be accounted for by a constraint-based phonological analysis,

there were some restrictions to the study.

Firstly, the participant received speech treatment at the time the speech samples

were transcribed. Intervention was not examined in this study, but it cannot be ruled out

that intervention might have influenced the rate of variation produced within and between

token word productions. Furthermore, many of the words transcribed in the therapy

notes obtained by the author were produced during a therapeutic task of drill-and-kill. To

increase the likelihood that the phonological analysis of variation would reflect the

spontaneous production of output forms, transcriptions of tokens produced first in a series

of repetitions and tokens marked as “spontaneous” in the data were the only tokens

included in this analysis.

Secondly, the data collected by the two therapists treating the participant were not

transcribed simultaneously. That is, each therapist collected data from sessions that they

held with the child separately. In this way, interrater reliability could not be calculated.

Future case studies should employ a data collection procedure that ensures interrater

reliability and, therefore, the consistency of this kind of perceptual data.

Lastly, the data used in this study was not systematic in its collection of

productions of all possible segments and word shapes. Due to the nature of the data

collection, there was an inevitable paucity in opportunities to examine the scope of

possible output forms. A larger sample that used a systematic approach aimed at eliciting

an extensive amount of phonotactic environments from the participant would provide a

71

richer pool of data from which a more thorough understanding of the child’s

phonological system might be constructed. Future studies would be advised to elicit a

larger range of variations of all phonotactic environments allowed in the given language.

Implications

The results of this study hold implications for the theoretical proposal that CAS is

a pure motor speech disorder and clinical implications for the differential diagnosis and

treatment of CAS.

The phonological patterns involving the prosodic units of speech in the data

presented provide the most telling evidence of what processing level of speech

production the locus of deficit for CAS may lay. Prosodic abnormalities are frequently

cited by researchers and clinicians as distinctive to CAS (Ball et al., 2002; Jacks et al.,

2006; Marquardt et al., 2004; Marquardt et al., 2002; Shriberg et al., 2003; Shriberg et al.,

2012), and the results of a constraint-based analysis seem to confirm a disturbance in

prosody as it would be defined by rare and variable patterns occurring at the level of the

CV tier (i.e., the organization of amplitude peaks and margins of syllables) and the

metrical foot tier (i.e., lexical stress patterns). Because the data used in this study could

not convey prosodic information above the level of the foot, a complete account of

prosodic abnormalities was beyond the scope of this analysis. What could be said about

word shape variation, however, suggests that the complexity of syllabic frames is

severely restricted in this child’s phonological system. Evidence for this developmental

delay is seen in the simplification of the internal structure of the syllable so that any

complex sequences of consonant margins in a multisyllabic word did not easily surface.

Word shape was further restricted, however, by constraints on the location of the foot

72

within the word. Such limitations point to a delay in the development of complex word

shapes and stress patterns in this child’s phonological system.

It is this simplification of syllable and prosodic foot sequences, in addition to

variability in productions, that most strongly imply the nature of CAS and its theoretical

locus of deficit. As mentioned in the literature review, there is an emerging perspective

of CAS as a deficit in the cognitive-linguistic processes of speech production, namely, in

the development of the neural substrates representing the syllabic frame (Jacks et al.,

2006; Marquardt et al., 2002; Velleman & Strand, 1994). This has been variably

described as interfering in the accessibility of these representations and in the

phonological encoding of these representations. The results of the present analysis

provide limited evidence of CAS as a cognitive-linguistic deficit rather than a pure motor

speech deficit. Specifically, the simplified sequencing of syllables within a restricted

lexical stress pattern highlights a distinct reduction in the structural complexity of the

syllabic frame used to organize the word shapes of lexical items. Such simplifications

are not sufficiently described by a motor programming deficit, which fails to predict the

simplification patterns seen in this participant’s speech. Similarly, a disturbance in the

underlying representation of segments and syllables also does not seem to predict the

results of this study. Because Optimality Theory assumes the principle richness o f the

base, a disturbance in the underlying representation of a lexical item implies that the

transformation of these representations by internal grammatical rules would not

necessarily produce predictable outcomes. The fact that a constraint-based analysis could

account for changes to and variations in the organization of prosodic units within words

seems rather to imply that the underlying representation of these units is not disturbed.

73

Rather, what shows in the data is a disturbance in the development of the ranking of those

phonological constraints governing syllable structure and word shapes. This suggests

that the locus of deficit in CAS lies in the transformational stage of speech processing,

whereby the underlying representation of a word is transformed by phonological

constraints belonging to the innate grammar. This is similar to the locus of deficit of

phonological disorders. The difference between the two, however, may be that children

with CAS exhibit disordered development in the prosodic organization of speech in

addition to segmental disturbances. Overall, CAS may be better understood as more so a

deficit in cognitive-linguistic competence than in motor performance.

Clinically, this interpretation of prosodic abnormalities in addition to the evidence

of variation presented above hold implications for the differential diagnosis and treatment

of CAS. Firstly, clinicians might consider including the assessment of higher-level

prosodic elements of speech in their diagnostic protocol. Prosodic abnormalities have

been frequently cited as distinctive to the speech produced by children presenting with

suspected CAS and the results of this study were congruent with this description.

Additionally, it appeared in this study that disruptions in the organization of prosodic

units are responsible for the more unusual variant forms produced by children belonging

to this population. By assessing not only the segmental but also the prosodic units of

speech, a different dimension of the child’s internal system is revealed. This kind of

insight can help guide treatment target selection that can be used in a more efficient

intervention program.

Variation in repeated productions both within and between target words is another

frequently cited characteristic used to differentially diagnose CAS (Ball et al., 2002;

74

Jacks et al., 2006; Maassen et al., 2003; Marquardt et al., 2004; Marquardt et al., 2002).

Although the data collected here confirmed variability in the speech production of a child

with suspected CAS, these results do not necessarily support the claim that variability is a

characteristic that differentiates CAS from a severe phonological disorder. Variation in

the productions made by the participant in this study was accounted for in the same way

that previous researchers accounted for variation in the productions made by children

with phonological disorders, namely, an equal ranking of constraints within the hierarchy

belonging to the child’s phonological system. Because children with phonological

disorders exhibited the same rule-based variation as the child in this study, it is suggested

that variation in production be considered for removal from the checklist of distinctive

characteristics of CAS. If the characteristic is shared by populations, it would not appear

to be sensitive enough to identify true positives of CAS. Furthermore, the emerging view

of variation as a systematic outcome of equally-ranked phonological constraints can aid

clinicians in better treatment planning. By viewing variation as rule-based and often a

positive indication of change within the phonological system, clinicians might be advised

to select treatment targets that would systematically target constraint demotion highly

specific to the child’s system (e.g., demotion of the constraint banning /£I in the coda by

choosing targets susceptible to dissimilation) rather than those targeting the linear

sequence of segments (e.g., final /f/).

Further research into the rankings of phonotactic constraints affecting the

organization of prosodic units is needed in order to better understand the nature of CAS

and how to assess and treat it. A more thorough inquiry into the prosodic abnormalities

demonstrated by children in this population may reveal a deficit in an area of language

75

competence qualitatively distinctive to this population. Past research has already begun

to identify stress as a possible diagnostic marker (Shriberg et al., 2003). The current

study provides an example of how Optimality Theory offers a framework that provides

researchers with the kind of precision in phonological analysis needed to locate the

systemic etiology of the vaguely defined speech production errors commonly cited as

characteristic of CAS.

76

APPENDIX

GLOSSARY OF CONSTRAINTS

77

TABLE 29. MARKEDNESS CONSTRAINTS

CONSTRAINT MEANING

*CODA No coda allowed

^COMPLEX No consonant clusters allowed

*LIQUIDS-[1] No liquid [1] segments allowed

*LIQUIDS-[r] No liquid [r] segments allowed

*R

*k No dorsal consonants allowed

NOT[Dorsal]

*DORSAL

NOTfLabiall No labial consonants allowed

NOTfCoronall No coronal consonants allowed

*t/[back] Coronal consonants are banned before back vowels

*VOICED-CODA No voiced coda consonants allowed

NOSEQUENCEfLabial.. .Coronall

No sequence of labial consonants before coronal consonants

NOT CO-OCCURRING [+continuant, -sonorant]

No segment may contain both [+continuant] and [-sonorant] features

*FRICATIVES No fricatives allowed

*M/Sonorant No sonorants may occur in the syllable margin

*M/Obstruent No obstruents may occur in the syllable margin

*PALATALS No palatal consonants allowed

AGREE [place] Segments of the output must agree in place of articulation

78

TABLE 29. Continued

CONSTRAINT MEANING

AGREE [labial] Segments of the output must agree in the labial feature

*j/[-high] 1)1 cannot occur before a [-high] vowel

NoSeq[M2,Ml] No sequence of a final syllable margin before an initial syllable margin

No trimoraic syllables

ALL-FT-LEFT Every foot must stand at the left edge of the prosodic word

DISSIMILATION Identical consonants are banned within a word

CODA-COND No labial continuants in the coda

VOP No obstruent must be voiced

FT-TROCHEE The prosodic foot of the prosodic word must surface as a trochee

79

TABLE 30. FAITHFULNESS CONSTRAINTS

CONSTRAINT MEANING

MAX No deletion of segments

IDENT [place] Corresponding segments must have identical place features

IDENT [voice] Corresponding segments must have identical voice features

DEP No insertion of segments

SURVIVED [coronal] The coronal place feature of input segments must surface in output segments

IDENT [+grooved] The output must be faithful to the [+grooved] feature for coronal consonants or else the segment must have some other place of articulation.

IDENT [continuant] No changes may be made to the [continuant] feature of a segment

IDENT [consonantal] No changes may be made to the [consonantal] feature of a segment

IDENT [feature] No changes may be made to any feature of a segment

IDENT [anterior] No changes may be made to the anterior placement of a segment

IDENT [manner] No changes may be made to the manner feature of a segment

UNIFORMITY No element of the output has multiple correspondents in the input (no coalescence)

IDENT [round] No changes may be made to the manner feature of [round]

WT-IDENT-IO No changes may be made to the weight of a syllable

80

TABLE 30. Continued

CONSTRAINT MEANING

PARSE Underlying segments must be parsed intosyllable structure

FILL Syllable positions must be filled withunderlying segments

MAX-o No deletions of syllables

81

REFERENCES

82

REFERENCES

American Speech-Language-Hearing Association. (2007). Childhood apraxia o f speech [Position statement]. Retrieved from www.asha.org/policv.

Ball, L. J., Bemthal, J. E., & Beukelman, D. R. (2002). Profiling communicationcharacteristics of children with developmental apraxia of speech. Journal o f Medical Speech-Language Pathology, 10(4), 221-229.

Barlow, J. A. (2001). Case study: Optimality theory and the assessment and treatment of phonological disorders. Language, Speech, and Hearing Services in Schools, 32, 242-256.

Barlow, J. A. & Gierut, J. A. (1999). Optimality theory in phonological acquisition. Journal o f Speech, Language, and Hearing Research, 42, 1482-1498.

Betz, S. K. & Stoel-Gammon, C. (2005). Measuring articulatory error consistency inchildren with developmental apraxia of speech. Clinical Linguistics & Phonetics, 79(1), 53-66.

Bums, M. (2011). Apraxia of speech in children and adolescents: Applications of neuroscience to differential diagnois and intervention. Percpectives on Neurophysiology and Neurogenic Speech and Language Disorders, 21, 15-32.

Chin, S. B. (2007). Variation in consonant cluster production by pediatric cochlear implant users. Ear and Hearing, 2§.(2-suppl.), 7S-10S.

Chomsky, N. & Halle, M. (1968). The sound pattern o f English. New York, NY: Harper and Row.

Clements, G. N. & Keyser,S. J. (1983). CV Phonology: A generative theory o f the syllable. Cambridge, MA: MIT Press.

Darley, F. L., Aronson, A. E., & Brown, J. R. (1975). Motor speech disorders. Philadelphia, PA: W. B. Saunders.

83

Davis, B. L., Jakielski, K. J., and Marquardt, T. P. (1998). Developmental apraxia of speech: Determiners of differential diagnosis. Clinical Linguistics & Phonetics, 72(1), 25-45.

Dinnsen, D. A. (2008). Fundamentals of optimality theory. In D. Dinnsen & J. A. Gierut (Eds.), Optimality Theory, phonological acquisition and disorders. Oakville, CT: Equinox Publishing Ltd.

Dinnsen, D. A., & Barlow, J. A. (1998). Root and manner feature faithfulness in acquisition. Proceedings o f the Annual Boston University Conference on Language Development, 22(1), 165-176.

Dinnsen, D. A., & Gierut, J. A. (2008). The predictive power of optimality theory forphonological treatment. Asia Pacific Journal o f Speech, Language, and Hearing, 77(4), 239-249.

Dinnsen, D. A., & O’Connor, K. M. (2001). Implicationally related error patterns and the selection of treatment targets. Language, Speech, and Hearing Services inSchools, 32, 257-270.

Forrest, K. (2003). Diagnostic criteria of developmental apraxia of speech used byclinical speech-language pathologists. American Journal o f Speech-Language Pathology, 12, 376-380.

Gierut, J. A. (2001). A model of lexical diffusion in phonological acquisition. Clinical Linguistics & Phonetics, 25(1), 19-22.

Gierut, J. A., & Morrisette, M. L. (2005). The clinical significance of optimality theory for phonological disorders. Top Language Disorders, 25(3), 266-280.

Goldsmith, J., Riggle, J., & Yu, A. (2011). The handbook o f phonological theory. (2nd Ed.), West Sussex, England: Wiley.

Gussenhoven, C. (2004). Research Surveys in Linguistics Series: The phonology o f tone and intonation. Cambridge, MA: Cambridge University Press.

Jacks, A., Marquardt, T. P., & Davs, B. L. (2006). Consonant and syllable structurepatterns in childhood apraxia of speech: Developmental change in three children. Journal o f Communication Disorders, 39, 424-441.

84

Jarosz, G. (2010). Implicational markedness and frequency in constraint-basedcomputational models of phonological learning. Journal o f Child Language, 37, 5 65-606.

Kiparsky, P. (1998). Sievers’ law of prosodic optimization. In J. Jasanoff, H. C. Melchert, & L. Olivier (Eds.), Mir Curad.Studies in Honor o f Calvert Watkins. Innsbruck, Germany: Innsbrucker Beitraege zur Sprachwissenschaft.

Kager, R. (1999). Optimality Theory. Cambridge, MA: Cambridge University Press.

Lavoie, L. & Cohn, A. (1999). Sequisyllables of English: The structure of vowel-liquid syllables. Proceedings o f the XlVth International Congress o f Phonetic Sciences, 109-112.

Maassen, B., Groenen, P., & Crul, T. (2003). Auditory and phonetic perception of vowels in children with apraxic speech disorders. Clinical Linguistics & Phonetics, 17(6). 447-467.

Marquardt, T. P., Jacks, A., & Davis, B. L. (2004). Token-to-token variability indevelopmental apraxia of speec: 3 longitudinal case studies. Clinical Linguistics & Phonetics, 18(2), 127-144.

Marquardt, T. P., Sussman, H. M., Snow, T., & Jacks, A. (2002). The integrity of the syllable in developmental apraxia of speech. Journal o f Communication Disorders, 35, 31-49.

Nijland, L., Maassen, B., Van der Meulen, S., Gabreels, F., Kraaimaat, F. W., &Schreuder, R. (2003). Planning syllables in children with developmental apraxia of speech. Clinical Linguistics & Phonetics, 77(1), 1-24.

Prince, A., & Smolensky, P. (1993). Optimality Theory: Constraint interaction ingenerative grammar (Technical report 2). Piscataway, NJ: Rutgers University Center for Cognitive Science.

Raimy E., & Cairns, C. (2009). Contemporary views on architecture and representations in Phonology. Cambridge, MA: MIT Press.

Shriberg, L. D., Aram, D. M., & Kwiatkowski, J. (1997). Development apraxia of speech:

85

II. Toward a diagnostic marker. Journal o f Speech, Language, and Hearing Research, 40, 286-312.

Shriberg, L.D., Campbell, T. F., Karlsson, H. B., Brown, R. L., McSweeny, J. L., & Nadler, C. J. (2003). A diagnostic marker for childhood apraxia of speech: the lexical stress ratio. Clinical Linguistics & Phonetics, 17(7), 549-574.

Shriberg, L. D., & Kwiatkowski, J. (1997). Developmental apraxia of speech: I.Descriptive and theoretical perspectives. Journal o f Speech, Language, and Hearing Research, 40, 273-285.

Shriberg, L. D., Lohmeier, H. L., Strand, E. A., & Jakielski, K. J. (2012). Encoding, memory, and transcoding deficits in childhood apraxia of speech. Clinical Linguistics & Phonetics, 26(5), 445-482.

Staiger, A., Finger-Berg, W., Aichert, I., & Ziegler, W. (2012). Error variability inapraxia of speech: A matter of controversy. Journal ofSoeech, Language, and Hearing Research, 55, S1544-S1561.

Strand, E. (2001). Darley’s contributions to the understanding and diagnosis of developmental apraxia of speech. Aphasiology, 15, 291-304.

Tesar, B., & Smolensky, P. (1996). Learnability in Optimality Theory. (Technical Report JHU-CogSci-96-3). Baltimore, MD: Department of Cognitive Science at Johns Hopkins University.

Tyler, A. A., & Figurski, G. R. (1994). Phonetic inventory changes after treatingdistinctions along an implicational hierarchy. Clinical Linguistics & Phonetics, 8, 91-108.

Ullrich, A. A., Stemberger, J. P., & Bernhardt, B. M. (2008). Variability in a German­speaking child as viewed from a constraint-based nonlinear phonology perspective. Asia Pacific Journal o f Speech, Language, and Hearing, 11(4), 221- 238.

Velleman, S. L., & Strand, K. (1994). Developmental verbal dyspraxia. In J. E. Bemthal & N. W. Bankson (Eds.), Child Phonology: Characteristics, Assessment, and Intervention with Special Populations. New York, NY: Thieme Medical Publishers, Inc.

86

Weiner, F. F. (1981). Treatment of phonological disability using the method ofmeaningful minimal contrast: Two case studies. Journal o f Speech and Hearing Disorders, 46, 97-103.

Yoss, K. A., & Darley, F. L. (1974). Developmental apraxia of speech in children with defective articulation. Journal o f Speech and Hearing Research, 17, 399-416.

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