Truncation Without Shape Constraints: The Latter Stages of Prosodic ...

LANGUAGE ACQUISITION, 8(1), 23–67 Copyright © 1999/2000, Lawrence Erlbaum Associates, Inc.

Truncation Without Shape Constraints: The Latter Stages of Prosodic Acquisition Margaret M. Kehoe Department of Speech Communication Pennsylvania State University

This article evaluates the claim of uniform size and shape restrictions in prosodic development using a cross-sectional database of English-speaking children’s multisyllabic word productions. Several of the youngest children in the study were limited by a bisyllabic output constraint, consistent with 1 stress-foot, and one of the oldest children produced output forms, consistent with 2 stress-feet, suggesting that uniform shape may occur at the earliest stages of prosodic development and on an individual basis for certain children. In the majority of cases, however, input–output correspondence between stressed and word-final syllables played the greatest role in explaining output patterns. Consequently, the article explores optimality accounts of truncation that do not assume a size restriction. Children’s increasing faithfulness to unstressed syllables can be explained by different constraint rankings that relate to edge alignment, syllable structure, and foot structure.

1. INTRODUCTION During phonological development, children exhibit a variety of prosodic processes in their productions of multisyllabic words: They delete syllables, add syllables, and alter stress patterns in systematic ways within words. Despite the wide array of prosodic processes that children display, child language researchers have often noted that children’s word productions conform to a consistent size and rhythmic pattern (Archibald (1995), Demuth (1995; 1996a; 1996b; 1996c), Demuth and Fee (1995), Fee (1995; 1996a; 1996b), Fikkert (1994), Pater and Paradis (1996), Wijnen, Krikhaar, and den Os (1994)). Around the age of 2 years, for example, it has been frequently observed that children’s productions are maximally bisyllabic and conform to a trochaic stress pattern (Demuth and Fee (1995), Pater Requests for reprints should be sent to Margaret Kehoe-Winkler, Avenue de Bel-Air 74, CH–1225, Chêne-Bourg (Geneva), Switzerland.

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(1997), Pater and Paradis (1996)). The claim of uniform size and shape restrictions in development forms the basis of two prominent theories of prosodic acquisition—namely, Fikkert’s parametric account of stress acquisition and Demuth and Fee’s prosodic hierarchy account. The goal of this article is to examine the notion of shape restrictions in a cross-sectional database of English children’s multisyllabic word productions. By shape restrictions, I refer to the claim that during development, the size and shape of children’s productions conform to prosodic (i.e., syllable or foot) or templatic (i.e., two stress-feet) units irrespective of target form. I expand on previous analyses by offering an account of prosodic development that places greater emphasis on the identity relation between the target and the output and that does not necessarily imply shape restrictions. This study focuses on the latter stages of prosodic development, the stages in which children produce one stress-foot or greater. The analysis shows that reduction to a single stress-foot is present in some of the very youngest children’s productions and augmentation to two stress-feet is present in one of the older children’s productions, suggesting that uniform shape may occur at the earliest stages of prosodic development and on an individual basis for certain children. In the majority of cases, however, there is a strong correlation between the prosodic shape of the target word and the child’s output, providing little evidence for shape restrictions at the latter stages of development. The findings support a view of prosodic development as largely one of expanding prosodic and segmental faithfulness between input and output: Children at the latter stages of prosodic acquisition display faithfulness to stressed syllables and syllables at word edges and variable faithfulness to nonfinal, unstressed syllables. This lack of faithfulness can be explained by different constraint rankings that relate to edge alignment, syllable structure, and foot structure. The article is divided as follows: In the remainder of this section, I provide a brief survey of basic principles in prosodic theory and English stress insofar as they are relevant to later discussion. In the second section, I present an overview of two main approaches to prosodic development and discuss empirical evidence for shape restrictions in development. In the third section, I describe the database. In the fourth section, I analyze the data. In the fifth section, I explore formal accounts of the findings. In the sixth section, I consider why the findings of the English study differ from previous findings, in particular, Fikkert’s (1994) longitudinal study of Dutch children’s prosodic development. 1.1. Prosodic Hierarchy Recent work in prosodic theory recognizes a hierarchical arrangement of prosodic units at and below the word level, referred to as the prosodic hierarchy (McCarthy and Prince (1986; 1993b), Nespor and Vogel (1986), Selkirk (1984)). These units include the mora (m), the syllable (s), the foot, and the prosodic word. Each level in the hierarchy is composed of units from the level directly below. The lowest level is

PROSODIC ACQUISITION

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characterized by the mora, a subsyllabic constituent that determines syllable weight. Light syllables contain one mora and heavy syllables contain two moras. Languages differ, however, in which segments are counted as moraic; in English, coda consonants as well as vowels count as moraic, whereas in Lardil, only vowels count as moraic. An alternate way of representing subsyllabic structure is via onset-rhyme constituency (McCarthy (1979), Selkirk (1982)). The onset dominates all prevocalic elements and the rhyme all other elements. The rhyme is further divided into the nucleus and coda. In recent linguistic theory, onsets and rhymes have no constituent status but are frequently used for descriptive purposes. Syllables are grouped together into feet, the principal unit of stress representation. A general condition on foot form determines that feet must be binary at some level of analysis (McCarthy and Prince (1986; 1993b)). Thus, a foot can contain either two syllables or one bimoraic syllable. Given foot binarity, single light syllables are unfootable and are dominated by the next level of prosodic structure, the prosodic word. Considerable crosslinguistic evidence attests to a restricted inventory of feet type in the stress systems of the world, which vary along parametric dimensions (Halle and Vergnaud (1987), Hayes (1985; 1995), Kager (1989)). Two main parameters are foot headedness and quantity sensitivity. Feet may have the stressed syllable on the left or right and are labeled according to terms in traditional metrics: Left-headed feet are trochaic and right-headed feet are iambic. If stress is attracted to syllables that are heavy, the stress system is quantity sensitive; if stress is unconcerned with syllable weight, it is quantity insensitive. Finally, feet are organized into prosodic words. The smallest prosodic word is referred to as the minimal word and is derived from the prosodic hierarchy taken together with the foot binarity condition. Because the prosodic word must contain a foot, and because a foot must be either bimoraic or bisyllabic, a prosodic word must contain at least two moras or two syllables. 1.2. English Stress English has a Latinate stress system. The main generalization of stress in English nouns is that primary stress falls on the penult if it is heavy and on the antepenult if the penult is light. In English, a consonant (C) followed by a lax vowel (V, i.e., CV) is light and all other syllables (e.g., CVV, CVC, or CVVC) are heavy. The basic component of the English stress rule is a quantity-sensitive trochaic foot (moraic trochee) parsed from the right side of the word with the additional stipulation that final syllables in English nouns are extrametrical.1 1 1This

analysis does not take into account those nouns in English that receive stress on the final syllable. In metrical stress theory, nouns with word-final long vowels are subject to a rule of long vowel stressing, which in the exceptionless case precedes extrametricality (Hayes (1985)). This results in word-final secondary stress. Nouns that receive primary stress on the final syllable are exceptional stress forms. See Hayes (1985), Halle and Vergnaud (1987), Kager (1989), and Pater (1995) for detailed discussions of English stress.

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This rule derives the patterns shown in (1). Stress representation is based on Hayes’s (1995) metrical stress theory. The bottom line indicates extrametricality and foot construction, and the line above indicates word layer construction. Primary stress falls on the penultimate syllable in agenda but on the antepenultimate syllable in cinema because the penult is light. (1) a. ( X . (X) E gXn “agenda”

) dE

b. (X ) (X .) mE sÍ nE “cinema”

More recent developments in linguistic theory, within the research program of optimality theory, eschew rules in favor of constraints that apply to the surface or output form (McCarthy and Prince (1993b), Prince and Smolensky (1993)). The basis of optimality theory is a universal set of violable constraints that are hierarchically arranged with respect to one another. Constraints are of two main types: structural constraints that regulate the wellformedness of the output, and faithfulness constraints that regulate the relation between input and output. An optimality analysis of primary stress in English nouns includes the constraints listed in (2). The analysis is adapted from Pater (1995). (2) FtBin Troch Nonfinality AlignHead Right Parse-s

Feet are binary at some level of analysis (m, s). Rhythmic type = Trochaic. No prosodic head is final in the prosodic word. Align the right edge of the prosodic word with the right edge of the head of the prosodic word. Syllables must belong to feet.

The tableau in (3) displays the constraint hierarchy that selects the optimal candidates for the input forms agenda and cinema. The optimal candidates satisfy (i.e., do not violate or minimally violate) the highest ranking constraints. Standard optimality conventions are employed. Constraint violations are indicated by asterisks, and violations that exclude a particular candidate are indicated by an exclamation mark; the optimal candidate is denoted by a check mark; constraints separated by a solid line are ranked with respect to one another, and constraints separated by dashed lines are unranked. Penultimate stress in agenda arises largely through the interaction of two constraints: Nonfinality and AlignHead Right (AlignHead-R). Nonfinality prevents the head foot of the prosodic word from being in word-final position, whereas AlignHead-R requires that the primary stressed syllable be as close to the right edge of the word as possible. The optimal candidate (a) contains primary stress on the penultimate syllable, satisfying Nonfinality and incurring only a single violation of AlignHead-R. Note that the optimal candidate (a) contains two unparsed


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syllables, whereas candidate (b) contains only one, suggesting that Parse-σ must be lower ranked than Nonfinality and AlignHead-R. (3) Primary stress assignment in English nouns FtBin, Troch, NonFinality >> AlignHead-R >> parse-σ

Antepenultimate stress in cinema requires, in addition, the action of two-foot form constraints, FtBin and Troch. Penultimate stress is now not possible either due to violations of Nonfinality (candidate (b) that contains a head foot in final position), violations of FtBin (candidate (c) that contains a monomoraic foot), or violations of Troch (candidate (d) that contains an iambic foot). Candidate (a) is the optimal candidate, satisfying foot form constraints and Nonfinality although incurring violations of lower ranked AlignHead-R. An analysis of secondary stress in English requires additional constraints to those in (2). See Pater (1995) for an analysis of secondary stress, which shows that the nonuniform weight-to-stress and stress-stem preservation effects can be accounted for by the optimality tenets of minimal violation and constraint ranking. 2. LITERATURE REVIEW 2.1. Development of Prosodic Structure In this section, I contrast two approaches to the development of prosodic structure. The first approach, exemplified by the theories of Fikkert (1994) and Demuth and Fee (1995), proposes that prosodic units are projected over time and that, at any given time in development, children’s outputs will be constrained by the amount of prosodic structure that is available to them. For example, if at a

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given stage children’s prosodic structure consists only of a foot, then children’s output, regardless of input, will be maximally one foot. The other approach, which is not as well articulated in the literature but is consistent with recent input–output correspondence in optimality theory, proposes that there is a more direct relation between the target and the child’s output and that constraints that govern faithfulness to prosodic heads and alignment with edges will determine prosodic shapes over time. In the following paragraphs, I describe the two approaches, which I refer to as the prosodic structure and correspondence accounts, in more detail. 2.1.1. Prosodic structure accounts. The central claim of the prosodic structure account is that children’s prosodic representations are initially limited and over time become more sophisticated being constrained by structural principles in development. In Fikkert’s (1994) theory development involves expansion of the child’s prosodic template, whereas in Demuth and Fee’s (1995) theory, development proceeds according to the units of the prosodic hierarchy with higher level units projected over time. This study is concerned with the later stages of Demuth and Fee’s approach only, summarized in (4). (4) Later stages in the development of prosodic structure Stage 3: Stress-Feet a. One Stress-Foot b. Two Stress-Feet—each with primary stress c. Feet—one primary stress per word Stage 4: Phonological Words Extrametrical syllables permitted In terms of stages of acquisition, Fikkert (1994) and Demuth and Fee (1995) made relatively similar predictions. They both proposed there would be a stage in prosodic development in which children’s productions conform to one stress-foot and a later stage in which children’s productions conform to two stress-feet.2 The two stress-feet stage is first characterized by level stress and then by the acquisition of word-stress prominence. Both sets of investigators observed that children employ a variety of means to satisfy constraints on prosodic structure, including truncation and syllable epenthesis. They also observed overlap between prosodic patterns at each stage and noted that forms characteristic of earlier and later stages may co-occur at any one time. A hypothetical example of stages of acquisition based on Fikkert’s account are shown in Table 1 for the English words giRAFFE, 2 2Although

in Fikkert’s (1994) theory the template expands from one to two feet, there is not necessarily uniformity of output shape for two stress-feet. For example, SWW words are realized as a single foot across all stages of development. This differs from Demuth and Fee’s (1995) approach, which claims shape uniformity for the two stress-feet stage.


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TABLE 1 Stages of Acquisition Based on Fikkerts (1994) Theory of Prosodic Acquisition Using Hypothetical English Data Target Words Stage 1 2 3 4

giRAFFE

baNAna

AvoCÁdo

[ræf] [d^íræ] [d^íræ' f] [dÊræ' f]

[næ'nE] [næ' nE] [b8' næ' nE] [bEnæ' nE]

[ka'do] [ka'do] [a'vEka'do] [a! vEka'do]

baNAna, and AvoCAdo. In general terms, the shape of productions at Stages 1 and 2 are consistent with one stress-foot, and the shape of productions at Stages 3 and 4 are consistent with two stress-feet. Depending on the target, children will produce unfooted syllables at Stage 4, consistent with Demuth and Fee’s phonological word stage. Despite the similarities between Fikkert’s (1994) and Demuth and Fee’s (1995) theories, they differ in several important respects. One difference is that Fikkert, via the theoretical device of prosodic circumscription, made stronger claims than Demuth and Fee on the relation between the adult target and the child’s production. At Stage 1 in Fikkert’s theory, children’s forms consist of either a single syllable or a bisyllabic form, equivalent in content to the rightmost foot of the adult target. If the adult foot is monosyllabic, then at Stage 2 another syllable from the adult target is circumscribed, and this, along with the previously circumscribed syllable, is mapped to the child’s template, again producing a trochaic contour. In contrast, Demuth and Fee observed that “segments may be drawn from any part of the target word” to satisfy constraints on prosodic structure, although they add they are “largely drawn from stressed syllables” (p. 39). A second crucial difference between the two theories is in their conceptualizations of development. Fikkert (1994) offered an elaborate account of stress development couched within a parametric framework. Transition from one stage to the next involves the setting of metrical parameters based on linguistic cues in the input. Demuth and Fee (1995) offered a far less detailed account. They considered two explanations for children’s restricted word shapes in development. One is that children do not have access to all linguistic structure; they first have access to the syllable but not the foot, and the foot but not the prosodic word. This is akin to maturational accounts in syntax acquisition that assume that linguistic principles “grow” over time (Borer and Wexler (1987)). The other explanation is that children have access to the entire prosodic hierarchy but exploit only part of it due to high-ranking constraints that yield unmarked prosodic forms (Demuth (1995)). This explanation is consistent with optimality theoretical approaches that conceptualize development as constraint reranking in accordance with the grammatical requirements of the target language.

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2.1.2. Correspondence account. The main claim of the correspondence account is that the identity relation between the adult target and the child’s output is the primary factor in determining children’s prosodic patterns. Given this view, prosodic development is seen as expanding prosodic (and segmental) faithfulness between input and output rather than reflecting the expansion of metrical templates or the projection of prosodic units over time. This viewpoint is not new and has been repeatedly voiced over the years in the common observation that children’s multisyllabic word attempts, at least in English, include stressed syllables and syllables in word-final position (Blasdell and Jensen (1970), Echols and Newport (1992), Klein (1981)). What is perhaps newer is the more principled treatment of input–output correspondence in optimality theory and the observance that adult languages display similar types of identity effects. Correspondence theory extends optimality theory’s original notion of faithfulness by including the insight that prosodic structure itself exists in correspondence relations (McCarthy (1995), McCarthy and Prince (1995)). In correspondence theory, ranked constraints apply to correspondent elements demanding completeness of correspondence, contiguity and linearity of mapping, and anchoring at the edge. Two main features distinguish an optimality or correspondence approach from a prosodic structure account. First, there is no need for maturation of prosodic structure as entertained by Demuth and Fee (1995). Under an optimality account, children have access to the entire prosodic hierarchy right from the outset. Their immature prosodic outputs arise from independently motivated constraints on prosodic structure. Second, the input form is assumed to be fully prosodified, because by its very nature, prosodic faithfulness presupposes that the two correspondent elements contain prosodic structure (McCarthy (1995)).3 Given the wealth of perception data indicating that children are sensitive to prosodic phenomena from an early age (Jusczyk, Cutler, and Redanz (1993)), I take as my starting point the assumption that children have access to prosodic structure in the input. Already, several investigators have formalized content preservation findings in child truncation using a correspondence framework (Pater (1996), Pater and Paradis (1996)). Children’s preservation of stressed and word-final unstressed syllables can be explained by high-ranking constraints that demand faithfulness to prosodic heads and edges of domains. A further corollary of this account, however, is that the bisyllabic size restriction in truncation may result from faithfulness effects between input and output. That is, children’s faithfulness to prosodic heads and word edges combined with the infrequency of multisyllabic words in children’s corpora (see section 2.2) may give the appearance that output forms are always bisyllabic and conform to a trochaic pattern. 3 3In child phonology, the standard view is that the input is the adult surface form minus any perceptual losses; the output is the child’s production.


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Because no full-scale correspondence account has yet been proposed, stages of development are not presented. Given high-ranking constraints that demand faithfulness to stressed syllables and word edges, the prediction is that output forms of varying size will occur at any one time, and these forms will vary systematically with input, as shown in (5). (5) Productions WS4 WSW SWS' W

of varying size giRAFFE baNAna AvoCAdo

according to correspondence account /dÎræ' f/ [ræf] /bEnæ' nE/ [næ' nE] /a!vEka'do/ [8! ka'do]

2.1.3. Combined account. It is also possible that a third alternative exists—namely, that prosodic development is characterized by both shape constraints and correspondence. Given an optimality framework in which individual variation is captured by different sets of constraint rankings, shape constraints may exist for some children and not for others. Alternatively, shape constraints may exist at the earlier stages of development and be later superseded by correspondence effects. A possible scenario could be that there is an early stage in which children’s outputs are consistent with a single foot but no later stage in which outputs are consistent with two feet. Rather, correspondence effects characterize children’s outputs after the one stress-foot stage. In section 2.2, I review evidence for shape constraints in prosodic development. 2.2. Empirical Evidence for Shape Constraints in Prosodic Development Evidence for shape restrictions in prosodic development comes from the finding that children display prosodic shape uniformity regardless of target form. That is, children systematically reduce long words (i.e., words of three syllables or more) to one stress-foot, or expand short words (i.e., words with one stressed syllable such as WSW and SWW) to two stress-feet. Although it is frequently reported that children’s productions around the age of 2 years are maximally bisyllabic and conform to a trochaic stress pattern, a closer examination of the literature often reveals that the corpora children produce at this age contain very few long target words, thus not permitting a true test of a size constraint in production. For example, Holmes (1927) noted that his daughter Molly, at age 23 months, consistently 4 4 Throughout the article, the stress patterns of target words are indicated by the following notation: S is a stressed syllable and W is an unstressed syllable. When there is more than one stressed syllable in a word, primary stress is indicated by S' . Target lexical items are italicized, and primary and secondary stressed syllables are denoted by uppercase lettering. Phonetic transcription complies with the International Phonetic Association, with the exception of stress diacritics, in which the American system of placing the diacritic above the stress-bearing vowel is employed.

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reduces words of more than two syllables to two syllables. However, if we examine Molly’s corpus at this age, we find only 4 out of 28 words that are three syllables or longer, and only one example is particularly telling because the deletion of an unstressed syllable in the words BUffaLOES, MAjorie, and CHOcolate will naturally result in a two-syllable form; only the form [abi] for AUtoMObile is suggestive of a size constraint because the child deletes both a stressed and unstressed syllable. The absence of long words in young children’s inventories may suggest selection and avoidance (Schwartz and Leonard (1982)) or simply reflect the low frequency of multisyllabic words in the ambient language. Dobrich and Scarborough (1992) found that children ages 2 to 5 years did not avoid producing multisyllabic words, but the overall proportions of multisyllabic productions was very low, less than .10. Wijnen et al. (1994) found no evidence of rhythm-based lexical selection in two Dutch children’s productions; rather, the proportions of rhythmic types in the children’s speech closely resembled those in their respective mothers’ speech. Thus, there does not appear strong evidence for the “de-selection” of long or rhythmically marked forms, but the generalization that these forms are infrequent in young children’s repertoires is supported. Fikkert’s (1994) database represents the most convincing evidence for shape restrictions because she provided numerous examples attesting to the presence of templatic effects in a wide array of subjects. However, she acknowledges that words longer than three syllables were infrequent in her database. Empirical support for Demuth and Fee’s (1995) theory largely rests on Fikkert’s database and from published databases in English, such as Smith’s (1973) in-depth study of Amahl. In fact, a close analysis of Amahl’s productions shows little support for the view of prosodic development that Demuth and Fee proposed. Even at the earliest period of data collection (i.e., Smith’s Stages 1–6), Amahl’s corpus contains prosodic patterns consistent with several stages of prosodic development (e.g., one stress-foot, two stress-feet, and phonological word), and examination of both target and output forms reveals strong input–output effects. More recently, two case studies attest to the presence of a monosyllabic rather than a bisyllabic stage in prosodic development. Salidis and Johnson (1997) reported on an English-speaking child named Kyle who, before the age of 17 months, consistently reduced all multisyllabic words to a single syllable, and Lohuis-Weber and Zonneveld (1996) reported on a Dutch child named Joost who progressed through three stages of development: monosyllabic words, polysyllabic words, and words containing the accurate number of syllables. In the case of Joost, Lohuis-Weber and Zonneveld observed that, in his second acquisitional stage, Joost produces heavy syllables from the adult form while maintaining the target stress contour. Thus, final-stressed words such as TEleFOON /tèlEfón/ are realized with final stress, and exceptionally long words such as CHOcoLAdeMELK /òòcoládEmèlk/ are produced as trisyllabic forms. In short, be-


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yond the one-syllable stage, Joost’s patterns appear strongly determined by prosodic salience or correspondence effects. 2.3. Purpose of the Current Study To evaluate the claims of the prosodic structure and correspondence accounts, the current analysis investigates the relation between the adult target and the child’s output in the multisyllabic inventories of over 40 English-speaking children. If a prosodic structure account holds, there should be a weak relation between input and output, and the child’s own word shape constraints (one stress-foot, two stress-feet) at a given stage in development will determine output form. If a correspondence account holds, there should be a strong relation between input and output, and faithfulness to prosodic heads and word edges will determine output shape. If a combined account holds, there may be an early stage in which output forms are constrained, for example, to the size of one foot, but no later stage in which output forms are similarly constrained. Alternatively, shape constraints may vary on a child-to-child basis: Some children’s patterns may be consistent with shape constraints, other children’s primarily correspondence. This analysis depends crucially on the inclusion of long multisyllabic words and words with marked stress patterns allowing a separation of the two main accounts. Given the possibility of overlap between stages, I assume that the majority of patterns in each child’s corpus conforms to a single stage in that child’s prosodic development.

3. DATABASE The data come from a series of studies at the University of Washington in which children of various ages produced multisyllabic words. The bulk of the analysis is based on Kehoe’s (1995) dissertation study that tested 22-, 28-, and 34-month-old children’s (n = 18; six children at each age range) productions of three- and four-syllable words. Reference is made to two additional data sources: an earlier pilot study (Kehoe (1994)) that tested 27-month-old (n = 11) and 30-month-old (n = 10) children’s productions of multisyllabic words, and Kehoe, Stoel-Gammon, and Buder’s (1995) acoustic study of stress acquisition. This study focused on productions of one- and two-syllable words in a group of 18-, 24-, and 30-month-old children, but some of the younger children (three children at 18 months, six children at 24 months) produced three-, four-, and five-syllable words as well. These words are considered in this analysis. The main data set (Kehoe (1995)) is referred to as Data Set A; the additional sources (Kehoe (1994), Kehoe et al. (1995)) are referred to collectively as Data Set B. All children were within a 1-week interval of their age and received scores between the 20th and 80th per-

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KEHOE TABLE 2 Examples of the Stimulus Words

Number of Syllables

Stress Pattern

Two

WS SS' S' WS SWS'

Three

SWW WSW S' WSW SWS'W WSWW WS' WS SS'WW WSWS' W SWS' WW

Four

Five

Note.

Examples of Stimulus Words

Data Set

giRAFFE, guiTAR RACCOON, SHAMPOO CROcoDILE, TElePHONE KANgaROO, CHIMpanZEE Elephant, Animal toMAto, poTAto AlliGAtor, CAterPIllar CINdeRElla, AvoCAdo biNOculars, piNOcchio oRANGuTAN RHINOceros tyRAnnoSAUrus HIppoPOtamus

B B A A A A A A B B B B B

and and and and and and

B B B B B B

S = stressed syllable; W = unstressed syllable; S' = primary stress.

centile for their age range on the vocabulary section of the MacArthur Communicative Developmental Inventory: Toddlers (Fenson et al. (1991)). Examples of the stimulus words in Data Sets A and B are given in Table 2. Note that the stimulus set does not include monosyllabic or SW forms because these forms offer less useful information on shape constraints.5 The number of multisyllabic words in each child’s inventory (separated according to spontaneous and imitated productions) are listed in the Appendix. This count includes only productions of stress patterns listed in Table 2. The data for all children were collected in a similar way. Children were tested in two 45-min sessions separated by a 1-week interval. In each session, they participated in games and elicitation tasks in which they were encouraged by an experimenter and parent to produce multiple tokens of stimulus words. Children’s productions of target multisyllabic words were recorded, digitized, and subjected to acoustic and perceptual analysis. Productions were phonetically transcribed with particular attention given to the assignment of primary stress. A subset of the data (15%–20%) was reanalyzed, and reliability scores for stress placement and syllable presence exceeded 80% (see Kehoe and Stoel-Gammon (1997b)). Two aspects of the database are noteworthy: 1. The data are cross-sectional and therefore cannot adequately address issues pertaining to developmental stages of acquisition, although the typology of patterns present in the data offers tentative information on developmental stages. 5 5Monosyllables

and SW forms can potentially offer information on shape constraints. Monosyllables can be epenthesized or reduplicated, and SW forms can be truncated. In this study, there were numerous productions of monosyllables and SW forms, and shape alterations were uncommon with the exception of 24f6 (see Table 3), who tended to truncate SW words.


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2. The database consists of both spontaneous and imitated productions. A production was classified as an imitation if an adult model closely preceded the child’s production. Without relying on imitated data it would have been impossible to ensure that the data contained an adequate representation of “longer” multisyllabic words. To make sure that the prosodic effects reported in this study are not a product of imitation, careful attention is paid to the distinction between spontaneous and imitated productions. Whenever both spontaneous and imitated productions exist for a given word in a child’s inventory, reference is made to spontaneous tokens only. Only imitated productions that resemble spontaneous productions are presented. 4. DATA ANALYSIS 4.1. Evidence for Prosodic Structure Account 4.1.1. One stress-foot stage.6 In the analysis, I first examine whether there is a stage in prosodic development in which children consistently reduce multisyllabic words to a single syllable or bisyllabic trochaic form, consistent with one stress-foot.7 Results show that a bisyllabic maximum is not easy to find, but tentative evidence exists in the speech of some of the younger children. I then examine content preservation patterns in terms of correspondence effects. There were four children (two children age 18 months, two children age 24 months) in the study who displayed a bisyllabic maximum in truncation. Representative examples (all spontaneous productions) are given in Table 3. Throughout the tables and text, participant designation is as follows: 18m4 is an 18-month-old male child. Number 4 refers to child identity. Productions of SW words are included for comparison. Unfortunately, this set of children did not produce many multisyllabic words, making the current results tentative. The crucial example is AlliGAtor, and to the extent that it was not often produced as a two-syllable form in other children’s productions, but is in these children’s productions, it suggests that a size restriction is operative. Two other 22-month-old children (22m1 and 22m3) displayed an interesting pattern of truncation, which although not consistent with a size restriction, still conformed to a systematic shape. WSW, SWW, and S'WS words were reduced to 6 6Although

this study concentrates on the latter stages of prosodic development, some readers may be interested to know what children have already learned to date in their prosodic development. In terms of syllable structure, all the older children showed awareness of vowel length distinctions, had acquired codas, and appeared to know that codas were moraic. They also produced consonants in extraprosodic positions. This was not the case with the younger children. As can be seen in Tables 3 and 4, not all the younger children had acquired codas, or if they had, they produced them only in word-final position. Most children produced tense and lax vowels appropriately, but the limited nature of the data set makes it difficult to determine whether they had truly acquired this distinction. 7 Quantity is not taken into consideration in the classification of one stress-foot. A stress-foot 7 could be bimoraic or greater than bimoraic.

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BUnny [b8'ni] PICture [pa'kIs] giRAFFE [d3f], [-\æf] baNAna [næ' næ] Elephant [a'fInt], [3' lbInt] ÁlliGAtor [æ' we], [æ' gu]

18m4

BAby [bébi] KItty [ki+] giRAFFE [wa] baNAna [næ'n8], [næ' næ] PEEkaBÓO [bu+] ÁlliGAtor [æ' gi], [a'gi]

18f4 BUbbles [b8'bo] HAmmer [hæ'm7] DOggie [da'I.i] giRAFFE [va], [wa] baNAna [na'n8] Elephant [a'IsE], [æ' fE] ÁlliGAtor [æ' g#], [æ'de]

24m6

TABLE 3 Productions of 18- and 24-Month-Old Children Who Display a Size Restriction

Baby [be] KItty [ki+] BUnny [bãI] YEllow [wo] giRAFFE [waIs], [bas] SHAMPÓO [pu+] ÁlliGAtor [ge], [ge+]

24f6


37

two-syllable forms (e.g., 22m1 produced baNAna as [ba'dIn], Elephant as [a'-\v3n], and TElePHONE as [k3'f8m]); SWS' words were reduced to one-syllable forms (e.g., KANgaROO was produced as [wu+]), and S'WSW words were often produced as three-syllable forms (e.g., AlliGAtor was produced as [h3' g#! dE]). What seems to be important in these children’s productions is that primary stress is always aligned with the left edge of the prosodic word, not that their outputs are maximally bisyllabic. Examples are provided in Table 4. (S) and (I) refer to whether the production is spontaneous or imitated, respectively. Numbers beside phonetic examples indicate that there were multiple instances of that particular rhythmic form, where rhythmic form denotes productions with the same number of syllables and primary stress placement. When segmental variation exists for a rhythmic form, two separate examples are presented. Two generalizations are apparent in children’s content preservation patterns. The first is that when children’s output patterns are monosyllabic, they generally produce the rightmost stressed (or heavy) syllable of the target form. The second is that when children’s output patterns are bisyllabic, two options are possible: Children may produce the rightmost stressed and the word-final unstressed syllable, or they may reproduce two stressed syllables. Which option they take is often influenced by the position of primary stress. When primary stress is retracted from the end of the word, children show a tendency to produce two stressed syllables, as exemplified by the truncations [æ' gi] or [æ' ge] for AlliGAtor in several children’s productions (see Table 3). TABLE 4 Productions of Two 22-Month-Old Children Who Do Not Display a Size Restriction Participants Stimulus Words baNAna Elephant TÉlePHONE CRÓcoDILE KANgaRÓO CHIMpanZÉE ÁlliGAtor HÉliCOPter

22m1 [ba'dIn] (S) 3 [ba'+d3n] (S) [a'-\v3n] (S) 6 [h8'wi+] (S) [k3'f8m] (I) [3'b8'n] (I) 2 [dæ' d8] (S) 4 [wu+] (I) 6 [hu+] (I) [zi+n] (S) 3 [h3'g3! dE] (I) 4 [-\ígè27] (I) [a'-\gEdida] (S)

22m3 [næ' n8] (S) 4 [næ' n8] (S) [æ+] (S) 6 [va'bo] (S) [g3'+-\o] (I) [gu+] (S) 3 [gwu] (S) [zi+] (S) 2 [æ' gè.8] (S) 2 [æ' +g3r] (S) 2 [æ' g3! .8] (S) [3'+g3!.8] (S)

Note. (S) = spontaneous production; (I) = imitated production. Numbers beside phonetic examples indicate that there were multiple instances of that particular rhythmic form.

38

KEHOE

The influence of primary stress on truncation can be seen in the older children’s productions as well. Occasionally, children reverted to primitive forms consistent with a foot, even though the majority of their productions were consistent with a more advanced prosodic stage. In a greater number of cases, primitive forms occurred as productions for target forms in which the rightmost stressed syllable received primary stress. Examples are presented in Table 5. Also note the different preservation patterns between the two sets of words. When primary stress was retracted from the end of word, children often preserved both stressed syllables; when primary stress was situated rightmost in the word, children preserved the rightmost stressed syllable and the final syllable.8,9 The results suggest that two faithfulness effects operate at the early stages of prosodic development. They are summarized in (6). (6) 1. Be faithful to the rightmost stressed syllable (and word-final syllable if present). 2. Be faithful to the primary stressed syllable and the next most “prosodically prominent syllable” that follows in the word (i.e., the syllable with secondary stress or the word-final syllable). The first faithfulness effect is well documented and achieves the same result as prosodic circumscription in Fikkert’s (1994) model of stress acquisition. A variety of sources indicate that children attend first to the rightmost stressed syllable of the target, regardless of whether it receives primary or secondary stress (Archibald (1995), Fikkert (1994), Kehoe and Stoel-Gammon (1997a), LohuisWeber and Zonneveld (1996)). These results suggest that there is a later stage in which children’s awareness of the distinction between primary and secondary stress leads them to focus on stressed elements leftward in the word. If primary stress and the right side of the word coincide, they may not proceed further leftward, as suggested by the concurrent presence of monosyllabic forms for SWS' words and bisyllabic forms for S' WS words in several children’s productions. Some of the children (18f4, 18m4, and 24m6) are already aware of the distinction between primary and secondary stress and still produce only bisyllabic forms (i.e., they are faithful to stressed syllables and syllables at word edges in their truncations of Elephant and are faithful to stressed syllables and not word edges in their truncations of AlliGAtor), which indicates that they are limited by a size constraint on output. There are other children, however, who note the distinction between primary and secondary stress and are not limited by the same size constraint on output—for example, 22m1 and 22m3, who produce monosyllabic, only exception to this is 27m5’s production of tyRAnnoSAUrus as [twæ' sas], which seems to suggest preservation of the two stressed syllables of the target form but with stress shift to the initial syllable. 9 Table 59 considers only productions of chimpanzee with penultimate main stress (e.g., [tòÌmpæ'nzi]). The other pronunciation of chimpanzee in the database was final syllable main stress (e.g., [tòÌmpEnzí+]). 8 8The


39

TABLE 5 Truncation Patterns Consistent With a Single Foot in the Productions of Older Children Primary Stress Left

Primary Stress Right

ÁlliGAtor 27f4 [æ' gwId] (I) 30m4 [e-\] (I), [æ' ge] (I) 2 34m1 [æ' d3] (S) 34m3 [géd7] (S)

CHIMPÁNzee 27f4 [pæ' nzi] (I) 27m5 [pæ' nzi] (S) 27f6 [pæ' nzi] (S) 3 30m6 [pæ' nzi] (I) 2

HÉliCOPter 27f6 [ka'pt7] (S) 27m5 [h3'kapt] (S) 34f3 [a'lkat] (S)

AvoCÁdo 27f3 [ka'do] 27f6 [ka'do] 28f1 [ka'do] 28f2 [va'do]

CÁterPIllar 27m2 [kæ' p#] (S)

(S) 3 (I) 2 (S) 3 (S)

CINdeRÉlla 34f3 [sw8'lE] (S) RHINÓceros 27f3 [na'sE] (I), [na'srIs] (I) 27f5 [na'swE] (I), [a'ndwIs] (I) 27f6 [sa'swIs] (I) 2 30f5 [na'sIs] (S) 30m4 [wa'wIs] (S) STEgaSÁUrus 27f4 [st$'rIs] (I) 27f6 [s$'wIs] (S) tyRAnnaSÁUrus 27m5 [sa'.Es] (S), [twæ' sas] (S) HIppoPÓtamus 27f6 [pa'mIs] (I), [pa'mI] (S)

Note.

(S) = spontaneous production; (I) = imitated production.

bisyllabic, and trisyllabic forms (see Table 4). The main pattern in these children’s productions is that primary stress is always leftward in the word. Presumably, the next stage of development is one in which children are faithful to all stressed syllables regardless of which position in the word they occur and regardless of primary or secondary stress. In section 4.1.2 I investigate the two stress-feet stage in prosodic development. 4.1.2. Two stress-feet stage. In this section, I examine whether there is a stage in prosodic development in which children’s output patterns are consistent with two stress-feet. To start, I present representative examples from two of the older children in the study, a 27-month-old child (27m6) in Data Set B and a 28-month-old child (28f1) in Data Set A. Already these patterns illustrate one problem inherent in the prosodic structure account—namely, the concurrent pres-

40

KEHOE TABLE 6 Productions of a 27- and 28-Month-Old Child Showing the Concurrent Presence of One and Two Stress-Feet Forms 27m6

Stimulus Words giRAFFE RACCÓON baNAna toMAto Elephant TÉlePHONE DÍnoSAUR KANgaRÓO ÁlliGAtor HÉliCOPter AvoCÁdo HIppoPÓTamus

One Foot

28f1 Two Feet

One Foot

Two Feet

[dwæf] (S) 7 [ba'ni] (S) 4 [médo] (S) [3' lIf] (S) 6 [da'Ins$! ] (I) 2

[ræ! kún] (S) 4

[da'InEs$! ] (I) 2 [kæ! nnoja'] (S) 4 [æ' bIg3!r] (S) 3 [ha'ka!p7] (S) 3 [a!ka'do] (S) 3 [hÌpopa'mIs] (S) 4

[n3'+n8] (S) 5 [médo] (S) 4 [a'fIt] (S) 5 [t3' lfo] (S) 4 [da'In1$!] (I)

[ka'do] (S) 3

[da'InEsa!] (S) 5 [k3!nEwú] (S) 5 [æ' dEgèd7] (S) 5 [ha'pka!pd7] (S) 4 [èka'do] (S) 3


ence of one and two stress-feet forms. At a time when children are clearly beyond a one-foot constraint, they continue to produce many target forms as one foot. For example, Table 6 shows that 27m6 produces the words giRAFFE, baNAna, toMAto, Elephant, and sometimes DInoSAUR as one foot; 28f1 produces the words baNAna, toMAto, Elephant, and TElePHONE consistently as one foot, and she alternates between one and two stress-feet for DInoSAUR and for AvoCAdo. The remaining words in each child’s inventory are produced as two feet. This is not a case of simple variability, in which forms characteristic of preceding and following stages co-occur, because the same words tend to be reduced and not reduced by all children. In general, target words that contain a single stressed syllable and an initial unfooted syllable (i.e., WS and WSW words) are produced as a single foot for a long period in development; other words include Elephant, TElePHONE, and DInoSAUR, three-syllable words that contain intervocalic sonorants. I have elsewhere postulated (Kehoe and Stoel-Gammon (1997b)) that the high truncation rate in these words reflects sonority effects on truncation. The concurrent presence of prosodic forms consistent with one and two stress-feet and the fact that these output patterns are strongly correlated with input make it difficult to detect a true two stress-feet stage in development.10 10 10It is possible to reconcile the concurrent presence of one and two stress-feet patterns in a prosodic structure account if we allow children to remain at earlier stages of development for some target words and later stages of development for other target words. The alternate approach is to account for all forms in terms of a single grammar. One grammar, however, cannot account for all within-subject variation, particularly in the case of variation for the same target word.


41

The only evidence for a two stress-feet stage in prosodic development can be found in the prosodic patterns of a single child, 28m2. Across a wide array of input forms, 28m2 displayed a striking tendency to produce output forms consistent with two stress-feet. Patterns that are particularly suggestive of an output template are his productions of poTAto, toMAto, Elephant, DInoSAUR, and TElePHONE, shown in (7). Whereas other children of this age tended to truncate these words, 28m2 either preserved all syllables of the target form or added a syllable to his truncated production resulting in a three-syllable output. Note that his patterns were additionally intriguing because, unlike the majority of children acquiring English, he produced a large percentage of his words with word-final main stress and with an iambic rather than a trochaic pattern (Kehoe (1996)). There was variability in his productions, however, and his three-syllable forms consisted of two templatic patterns: (WS S') or (SW S'). To the extent that 28m2’s outputs exhibit a weak correlation with input, there is further support for shape constraints in prosodic development. (7) Productions by 28m2 suggestive of shape constraints poTAto

[tètetó+] [hèti tó] [tètI tó]

toMAto

[hEtè tó]

Elephant

[af ít hÍt] [3f Ínt Ít] [afÍ\- tÍt] [ka'Igo ja'u] [ka!IkEra'I.8] [ab8'tEp*! s] [ap8! pÍs] [a!pIt pís] [had8! 8d#'] [a!t8 t#']

CROcoDILE OCtopus

AlliGAtor

DInoSAUR

[naInÌs h$'r]11 [ha!In8s$']

TElePHONE

[t3v8! h8'm] [t3! ljEm h8'm] [t3' d8 tó+]

CHIMpanZEE

[tÍmztí+] [tÌmti tÍ+] [k8wa! ó+] [k$!IjE ó+]

KANgaROO

CINdeRElla

[hEla! bEla'] [lá* pEla']

Apart from this one child, the bulk of the results show that most children, beyond the one stress-foot stage, do not display evidence of shape uniformity. Instead, they produce output forms that are highly correlated with input and that cannot be easily captured by a word-shape constraint. In the following section, I provide evidence for a view of the latter stages of prosodic development as largely one of correspondence. Specifically, I concentrate on children who are beyond a bisyllabic maximum in their output patterns. I focus predominantly on truncation patterns but address the issue of stress shift in section 5.3. 11 11Spaces

in the phonetic transcription indicate an intraword pause (e.g., [nanÌs h$'r]).

42

KEHOE

4.2. Evidence for Correspondence Account The essential finding of this database is that children at the latter stages of prosodic acquisition display faithfulness to stressed syllables and variable faithfulness to unstressed syllables. Consistent patterns in the inventories of individual children suggest a developmental pattern in the acquisition of unstressed syllables. First, children acquire unstressed syllables at the right edge of the word, then at the left edge of the word, and then word internally, although some word-internal syllables emerge before left-edge syllables and some after. I present evidence for this developmental pattern and then discuss each developmental state in more detail. 4.2.1. Developmental patterns: overview. Table 7 presents productions of two children (22f1 and 34m3) whose patterns consist predominantly of stressed and right-edge unstressed syllables. Across a variety of input forms (e.g., WSW, SWW, S' WS, SWS', S'WSW, and SWS'W), only these syllables are produced. 22f1 TABLE 7 Productions of Children Who Preserve Mainly Stressed and Right-Edge Unstressed Syllables Participants Stimulus Words baNAna toMAto Elephant OCtopus TÉlePHONE CRÓcoDILE KANgaRÓO ÁlliGAtor HÉliCOPter AvoCÁdo

22f1a [næ' nE] (S) 5 [næ' n8] (I) [médo] (I) (4) [mé+na] (I) [a'fInt] (I) 4 [a'fIt] (I) [a'-\f3s] (S) [a'-\fIs] (I) [ba'bò] (I) [p8!fó] (I) 3 [a'kIda'l] (I) 2 [-\æ!ku-\a'*] (I) 2 [wa'wu] (I) 2 [fa'wa'] (I) [æ' gæ!d7] (I) 4 [æ'-\g3!27] (I) [æ' \-ka! p7] (I) 4 [a'ha!p7] (I) [a!-\ga'r7] (S) [a! Iga'do] (I)

34m3 [na'n8] (S) 6 [næ' n8] (S) [médo] (S) 6 [mégo] (S) [-\8' fInt] (S) 6 [a'fInt] (S) [a'-\p*s] (S) 6 [a'p*s] (S) [ka'fo] (S) 6 [ka'fon] (S) [kra'kda! I.o] (S) 4 [ka'-\dè.7] (S) [kæ! nrú+] (S) 4 [kæ' nrú] (S) [æ' gèj7] (I) 4 [æ' \-gèd7] (I) [h3'+ha!d7] (S) 6 [-\a'hA!du] (S) [8! ka'go] (S) 5 [æ! ta'do] (S)

Note. (S) = spontaneous production; (I) = imitated production. Numbers beside phonetic examples indicate that there were multiple instances of that rhythmic form. a22f1 produced mainly imitated productions, but consistent patterns were still evident across different stress patterns.


43

is beginning to produce word-internal unstressed syllables as suggested by her productions of the word CROcoDILE, but apart from this, she realizes very few other unstressed syllables. Thus, there appears to be a development period in which mainly stressed syllables and unstressed syllables at the right edge of the word are preserved. Table 8 presents what appears to be a later developmental state. These two children (28m3 and 34f3) display more consistent production of word-internal unstressed syllables. They are present in the words OCtopus, CROcoDILE, KANgaROO, and some of 34f3’s productions of CINdeRElla. They remain absent from the SWW words Elephant and Animal and the S'WS words TElePHONE and DinoSAUR. At this stage, 28m3 has not started to produce any unstressed syllables at the left edge of the word, but they are beginning to emerge in 34f3’s productions, as suggested by her forms [bEnæ' nE] for baNAna. Thus, there appears to be a developmental period in which some word-internal unstressed syllables (in particular, those with obstruent onsets) are preserved, but left-edge unstressed syllables are not yet consistently preserved. TABLE 8 Productions of Children Who Preserve Mainly Stressed, Right-Edge, and Some Word-Internal Unstressed Syllables Participants Stimulus Words baNAna toMAto Elephant Animal

28m3 [bæ' n8] (S) 3 [bæ' na'] (S) 3 [míjo] (S) 3 [míjo] (S) [la'flIn] (S) 5 [3' f8n] (S) [æ' ma] (S) 5 [æ' ml] (S) [3'bIp*s] (S) [a'dEp*ts] (S) [t3'+fòn] (S) 3 [ta'fón] (I) 3 [d8's#!] (S) 6 [da'*s#! ] (S) [ka'gIda'*] (S) 3 [ka'gIda! *] (I) 2 [kÍgIrú] (S) 2 [k*! gEjú.8] (S) 3 [æ' gè.8] (S) 5 [æ' gèd8] (S) [1ùw3'l8] (S) 3 [-\ìw3' j8] (S) |

OCtopus TÉlePHONE DÍnoSAUR CRÓcoDILE KANgaRÓO ÁlliGAtor CINdeRÉlla

34f3 [hæ' næ'] (S) [bEnæ'n8] (S) 3 [médo] (S) 5 [méd8] (S) [a'fIn] (S) 4 [a'fE-\] (S) [æ'f*s] (S) 5 [æ'm*s] (S) [a'-\tEp*s] (S) 5 [a'dÊp*s] (S) [t3' rfòn] (S) 5 [t3' lfò] (S) [da' Ins$!rz] (S) 5 [da'Is$!wE] (S) [-\3'kEda! I] (S) [ka'kIda! I.8] (I) [k3! garú+] (S) 6 [k3!ng8wú+] (S) [é+gè2E] (S) 2 [æ! gélE] (S) [s#! w8'd8] (S) 3 [sÌndEw8'd8] (S) 3

Note. (S) = spontaneous production; (I) = imitated production. Numbers beside phonetic examples indicate that there were multiple instances of that rhythmic form.

44

KEHOE

Table 9 shows the patterns of two children (28f3 and 34f1) who consistently produce left-edge unstressed syllables (see productions of baNAna and toMAto). Note, however, that some word-internal unstressed syllables have not yet emerged. 28f3 does not realize word-internal unstressed syllables in the words Elephant, Animal, TElePHONE, and DInoSAUR, and in the four-syllable word AlliGAtor. 34f1 realizes most unstressed syllables except in the environment of /l/ as seen in her truncations of Elephant, TElePHONE, and AlliGAtor. She does produce some nontruncated variants of Elephant with /w/ onsets rather than /l/. Thus, the final developmental state is one in which left-edge unstressed syllables are acquired, but some word-internal unstressed syllables remain to be acquired—in particular, those with sonorant onsets. These developmental patterns are now discussed in detail under the section headings “Preservation of stressed syllables and right-edge unstressed syllables only,” “Preservation of word-internal unstressed syllables,” and “Preservation of left-edge unstressed syllables.” TABLE 9 Productions of Children Who Preserve Mainly Stressed, Right-Edge, Left-Edge, and Some Word-Internal Unstressed Syllables Participants Stimulus Words baNAna toMAto Elephant Animal OCtopus TÉlePHONE DÍnoSAUR CRÓcoDILE KANgaRÓO ÁlliGAtor CINdeRÉlla

28f3 [bunæ'n8] (S) 6 [bumæ' n8] (S) [tuméd8] (S) 5 [tunéjo] (S) [a'f3nt] (S) 6 [a'fInt] (S) [3'+ma] (I) [3'm*] (I) [æ' pEpEs] (S) 5 [æ' kIp*s] (S) [ta'*fòn] (S) 6 [t3' fA! n] (S) [da'Is#! ] (S) 6 [da'Inq$!] (S) [kwa'tEda! Ijo] (S) 5 [kwa'gIda! I] (S) [k3! ngEwú] (S) 6 [tÌngEwú] (S) [æ' lgè28] (S) 5 [æ' lgèd8] (S) [sÌnd7w8'd8] (S) 6 [sÌndEw8'l8] (S)

34f1 [b8næ'n8] (S) 6 [mEnæ'nE] (S) [tEmédo] (S) 6 [t8médo] (S) [3'l+fInt] (S) 3 [a'*wEfInt] (S) 2 [æ' nEmlz] (S) |

[a'ktEp*s] (S) 6 [a'ktEpEs] (S) [t3' lfo] (S) 6 [t3'l+fon] (S) [da'InjEs$!r] (S) 6 [da'InEq$!r] (S) [kra'kEda' I.E] (S) 3 [kra'kEda! Il] (S) 3 [kæ! ngErú+] (S) 4 [kæ! ngarú+] (S) [æ'lgè27] (S) 2 [æ'lEgè2E] (S) [sÌnd7r3'lw8] (I) [sÌndEr3'l8] (S)



45

4.2.2. Preservation of stressed syllables and right-edge unstressed syllables only. There is evidence for a stage in prosodic development in which stressed syllables and unstressed syllables at the right word edge are realized only. In the productions of long target words, the preservation of the rightmost stressed syllable and the word-final unstressed syllable produces a well-formed foot in the child’s output, but the preservation of the “other” stressed syllable does not always result in a well-formed, nonfinal foot; I refer to forms such as [æ' gè27] for AlliGAtor or [hÌpa'mIs] for HIppoPOtamus. This type of finding is antithetical to a templatic account of truncation because if the medial unstressed syllable is licensed by the foot template, it should be realized. This type of finding is also inconsistent with a prosodic wellformedness account, because in many cases stress is realized on a monomoraic syllable, producing a degenerate foot in the output—a nonfavorable foot in any theory (see section 5.3 for further discussion). Examples of several children’s productions of these words are listed in (8). (8) a. (X) (X .) m m m æ ge 27 AlliGAtor b. (X) (X .) m m m hÌ pa' mIs HIppoPOtamus

22f 1 22f2 28f3 28m3 27f2 27f5 27f6 30f6

! d7] (I) 4 [æ'gæ [æ' gèjE] (S) 5 [æ'gè.E] (S) 4 [æ'gè.8] (S) 5 [hÌpa'mIs] (S) [hÌpa'mIs] (I) 2 [hÌpa'wIs] (S) 3 [hÌpa'mIs] (S)

In principle, children could avoid such output patterns by truncating to two syllables or by realizing four syllables of the input form, but in a large percentage of cases they do not do so. From the point of view of correspondence, however, these outputs fare well because children maintain correspondence between the syllables containing stress in the input and in their own productions. The correspondence relation between stressed and right-edge syllables is illustrated in (9). Correspondence between syllables and not segments is assumed for convenience. (9) I: A1 lli2 GA3 tor4 I: HI1 ppo2 PO3 ta4 mus5

O: A1 GA3 tor4 O: HI1 PO3 mus5

This pattern may be consistent with a recent modification of the prosodic structure account for Spanish by Demuth (1997) and Gennari and Demuth (1997), who argued that Spanish-speaking children expand beyond the one-foot stage by adding a uniary foot. Note, however, children produce two-syllable forms for the word baNAna but three-syllable forms for four-syllable words.

46

KEHOE

(10) WSW SWS' W WSW SWS'W

baNAna AvoCAdo baNAna AvoCAdo

27m6 28f2

[ba'ni] (S) 4 [a!ka'do] (S) (3) [bæ'+n8] (S) 4 [8! ka'do] (S) 3

If children can produce output shapes of SS'W, we may wonder why we do not see [b8! næ' n8] for baNAna at the same time as [8! ka'do] for AvoCAdo. Given a prosodic structure account in which constraints on word shape determine output, similar patterns for both words could be anticipated. The difference is that in baNAna, children maintain faithfulness with an unstressed syllable in initial position and in AvoCAdo, with a stressed syllable. Faithfulness to stressed syllables obviously takes precedence over unstressed syllables, resulting in the earlier emergence of forms such as [8! ka'do] compared to [b8! næ' n8]. The correspondence relation is shown in (11). (11) I: ba1 NA2 na3 I: A1 vo2 CA3 do4

O: NA2 na3 O: A1 CA3 do4

4.2.3. Preservation of word-internal unstressed syllables. These findings suggest that the emergence of word-internal unstressed syllables depends largely on syllable structure and less obviously on foot structure. The results clearly show that children produce some word-internal unstressed syllables before others. For example, in 28f3’s productions in (12), it matters little whether the unstressed syllable is contained within a foot in the adult target form; she realizes the unstressed syllable in OCtopus and CROcoDILE but not in DInoSAUR, TElePHONE, Elephant, and Animal.12 (12) SWW S' WS SWW S'WS SWW S'WS

OCtopus CROcoDILE Animal DInoSAUR Elephant TElePHONE

28f3

[a'gEfEs] (S) 5 [kwa'gIda! I.8] (S) 5 [3'+ma] (I) 2 [da'Is#!] (S) 6 [a'fInt] (S) 6 [ta'*fò] (S) 6

Unfortunately, the limited nature of the stimulus set does not allow a full understanding of this effect, but it appears to relate to whether the onset of the unstressed syllable is sonorant or obstruent (Kehoe and Stoel-Gammon (1997b)). When the word-internal unstressed syllable in the target form contains an fact that children do not distinguish between S'WS and SWW patterns may arise because of the nature of the English stimulus items. In all cases in which two word-final unstressed syllables occur together (e.g., Elephant, OCtopus, biNOculars, and RHINOceros), the word-final unstressed syllable contains a coda consonant. The importance of foot structure in determining the realization of unstressed syllables may be more evident using different stimulus words controlled for segmental factors (Gerken (1994)). 12 12The


47

obstruent onset, children produce the unstressed syllable at an earlier stage in development than when the unstressed syllable contains a sonorant onset. However, there is no way to determine whether place of articulation also plays a role. The onsets of unstressed syllables in words that were frequently truncated were coronal sonorants (e.g., /n, l/), and it may be this class of sounds, rather than sonorants as a whole, that are responsible for the results. There was some evidence that noncoronal sonorants emerged earlier as onsets, as suggested by forms such as [t3'w8fòn] for TElePHONE in some children’s inventories. Independent findings in the database support a syllable-based account of internal unstressed syllable realization. Often when children realized unstressed syllables in target words that were highly susceptible to truncation (e.g., Elephant, TElePHONE, AlliGAtor), they did so by being segmentally unfaithful to the onset of the unstressed syllable. That is, they realized the unstressed syllable with an obstruent rather than a sonorant onset (or with a noncoronal sonorant), as suggested by the examples in (13). Note that 28f1 and 30f6 alternate between truncated productions of AlliGAtor and nontruncated productions in which the word-internal unstressed syllable is realized with an obstruent onset. (13) SWW S' WS S' WSW

Elephant TElePHONE AlliGAtor

18f8 24f3 18f8 24f4 28f1 30f6

[3! mE-\a'p] (S) [d3' gEgòn] (I) [hídEha! IdE] (S) 3 [æ'ldidè2o] (I) [æ'géd7] (S) [æ'dEgèd7] (S) 5 [æ'gètE] (S) [æ'ldEdèdE] (S)

4.2.4. Preservation of left-edge unstressed syllables. The English results suggest that the nonrealization of left-edge or word-initial unstressed syllables stems from a common underlying constraint. If we examine the realization of left-edge unstressed syllables across a variety of input forms (e.g., WS, WSW, WSWW, and WSWS'W), we observe consistent trends in the data. There are some children who never realize left-edge unstressed syllables across all input forms, as seen in 24m1’s and 30f1’s productions ((14a) and (14b)), and there are some children who display variability in their realizations of initial unstressed syllables, but this variability exists across different input forms as well, as seen in 27f5’s productions ((14c)). At least some time in development there appears to be a single constraint that accounts for children’s nonrealization of left-edge unstressed syllables, and this is different from the constraint that accounts for children’s nonrealization of word-internal unstressed syllables. Again, an optimality account, which appeals to edge alignment and faithfulness, provides a superior analysis of the findings than does a prosodic structure account. A prosodic structure account would suggest that 24m1 and 30f1 are at the one stress-foot stage in their productions of giRAFFE and goRIlla (e.g., [waf] and [gÍlE]) and at the two stress-feet stage in their produc-

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tions of oRANGuTAN and reFRIgeRAtor (e.g., [ræ'nEtæ!n] and [tÍdÊwè27]), but this misses the generalization that most of the time children are realizing all syllables of the target with the exception of left-edge unstressed syllables. (14) a. WS WSW WSWW WS'WS b. WS WSW WS'WS WSWS'W c. WS

giRAFFE goRIlla biNOculars oRANGuTAN giRAFFE goRIlla oRANGuTAN reFRIgeRAtor giRAFFE

WSW

baNAna

WSWW

biNOculars

24m1

30f1

27f5

[daf] (S) 7 [gÍl8] (S) [na'kEd#! z] (S) [wæ'nEtæ!n] (I) [waf] (S) 4 [grÍl8] (S) 2 [ræ'nEtæ!n] (I) 2 [tÍdÊwè2E] (S) [waf] (S) [dÎwa'f] (S) 6 [næ'na] (S) 6 [dEnæ'nE] (S) 2 [na'kj#z] (S) 2 [jEna'k#z] (S)

5. FORMAL ACCOUNT OF THE LATTER STAGES OF PROSODIC ACQUISITION 5.1. Optimality Accounts of Child Truncation: Review In recent years, several investigators have proposed optimality accounts of children’s prosodic patterns (Bernhardt and Stemberger (1998), Demuth (1996a; 1996b), Ota (1997), Paradis (1995), Pater (1997), Pater and Paradis (1996)). Most approaches have focused on the stage at which children’s productions conform to a bisyllabic minimum, and to illustrate one of these approaches, I review Pater and Paradis’s account of truncation in the word Elephant. Here and in later analyses of the data, a correspondence framework of optimality is assumed. To derive the size restriction in truncation, Pater and Paradis (1996) employed three structural constraints: AlignLeft, Parse-s, and FtBin, ordered above a faithfulness constraint Max I–O (input–output). AlignLeft aligns the left edge of every foot with the left edge of a prosodic word and, if fully satisfied, limits words to a single foot. FtBin requires all feet to be binary at either the moraic or syllabic level. Parse-s requires all syllables to be parsed within a foot. Max I–O militates against deletion by requiring all input elements to have output correspondents. The combination of these constraints limits the size of children’s productions but does not designate which syllables from the target are retained. To achieve the pattern of stressed and rightmost preservation, Pater and Paradis utilized two faithfulness constraints: StressFaith and RightAnchor. StressFaith requires that a stressed syllable in the input have a stressed correspondent in the output, and


49

RightAnchor requires that an element at the right edge of the input have a correspondent at the right edge of the output. Pater and Paradis’s approach applied to the truncation of selected words is shown in (15). Following Pater (1997), I simplify the analysis by employing the constraint WordSize to achieve the size restriction in truncation. Orthography is employed to indicate retained syllables. (15) Truncation in selected target words according to Pater and Paradis (1996)

This approach accounts nicely for children’s earliest truncation patterns, but the previous analysis showed that the vast majority of children beyond the earliest stages of multisyllabic word production did not produce prosodic patterns of a consistent size and shape.13 In the remainder of this section, I explore optimality accounts of the latter stages of prosodic acquisition. 13 13Recently, Ota (1997) observed that 2-year-old Japanese-speaking children do not always truncate in their productions of multisyllabic words, but when they do their outputs adhere to a one-foot restriction. He proposed a constraint hierarchy in which correspondence constraints between input and output are ranked higher than shape constraints, which in turn are ranked higher than correspondence constraints between the base and truncated form. This hierarchy results in the concurrent presence of truncated and nontruncated forms at any one time. The “unmarked” word shape emerges in truncation but not in the phonology at large. Ota’s analysis will not work for the current data because not all truncations are consistent with shape restrictions, but an analysis of a similar nature may explain the concurrent presence of some forms consistent with input–output and some with “templatic effects.”

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5.2. Optimality Account of the English Data 5.2.1. Overview. To explain the predominant prosodic patterns in the English data, I assume the set of constraints listed in (16). (16) Constraints in child truncation: Latter stages StressFaith A primary stressed syllable in the input has a stressed correspondent in the output (exact prosodic role). RightAnchor(Syl) A syllable at the right edge of the input has a correspondent at the right edge of the output. *Unstress14 Unstressed syllables are not present in the output. AlignPrWd(Head)15 The head of the prosodic word is aligned with the left edge of the prosodic word. AlignPrWd(Foot) The head of a foot is aligned with the left edge of the prosodic word. *Son-Ons Sonorant onsets are not present in the output. FtBin Feet are binary in terms of syllables or moras. Max I–O Every element in the input has a correspondent in the output (correspondence between syllables and not segments is assumed). The constraint StressFaith in this analysis refers specifically to primary stressed syllables. It ensures that a primary stressed syllable in the input is both present in the output and receives the exact prosodic role. The relatively powerful constraint *Unstress, when ranked above Max I–O, accounts for the wholesale deletion of unstressed syllables at the earliest stages of development. This constraint appears to be always dominated by RightAnchor(Syl) (abbreviated as RightAnchor), a faithfulness constraint that demands correspondence between the rightmost syllable of the input and the output, because children’s earliest word attempts (in English) typically contain unstressed syllables in word-final position.16 14 14There

are various ways to derive deletion of an unstressed syllable in optimality theory, including a syllable economy constraint, one of the family of *Structure constraints (Prince and Smolensky (1993)). For simplicity, I employ *Unstress. Here, it refers specifically to unstressed syllables that contain reduced vowels, lax vowels, or syllabic sonorant consonants. Support for such a constraint comes from adult English, in which schwa deletion may occur in fast speech in pre- and posttonic position (e.g., SEparate fi SEprate; poLICE fi PLICE). 15 AlignPrWd(Head) is equivalent to AlignHead (Align15(PrWd, L, Head, L)), which requires all prosodic words to begin with a prosodic head. AlignPrWd(Foot) is equivalent to AlignPrWd (Align (PrWd, L, Ft, L)), which requires all prosodic words to begin at a foot edge (McCarthy and Prince (1993a)). 16 If *Unstress 16 is present in the developmental grammar, one prediction is that outputs containing only stressed syllables should occur. Although this pattern was not common in the English database, isolated examples were attested (e.g., [òìndr3'z] for CINdeRElla); this pattern has also been reported in Dutch (Lohuis-Weber and Zonneveld (1996)).


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*Unstress is dominated at later stages of development allowing more selective realization of unstressed syllables. Two alignment constraints explain left-edge effects in children’s speech. First, there appears to be a time early in development in which primary stress is aligned with the left edge of the child’s prosodic word but in which a size restriction does not apply. This effect can be captured by AlignPrWd(Head) (abbreviated as AlignHead), which requires that the head of the prosodic word begin at the left edge of the prosodic word, as shown in (17a). A candidate that contains an unstressed syllable or a secondary stressed syllable in initial position violates this constraint (17b). (17) a. b.

[s' s] ! s' ], PrWd[s PrWd

'] PrWd[ss

AlignHead *AlignHead

Second, a more pervasive stage in prosodic development is one in which a stressed syllable is always aligned with the left edge of the child’s output. The constraint AlignPrWd(Foot) (abbreviated as AlignFoot) accounts for the nonrealization of unstressed syllables in initial position (18b), but does not prevent the realization of secondary stressed syllables in initial position, as shown in (18a).17 (18) a. b.

[s' s], '] PrWd[ss PrWd

PrWd

[s! s' ]

AlignFoot *AlignFoot

To explain the tendency for unstressed syllables with sonorant onsets to be deleted more frequently than unstressed syllables with obstruent onsets, I employ the constraint *Son-Ons. This constraint ranked higher than Max I–O results in the selective realization of some unstressed syllables—specifically, those that do not have sonorant onsets. This constraint encompasses a set of constraints with degree of sonority correlated to the ranking of the constraint (see Pater (1997)). The English data suggest degree of sonority plays a role because unstressed syllables with nasal onsets emerge earlier than unstressed syllables with liquid onsets. However, for the sake of simplicity, gradients of sonority are not dealt with in this analysis. In addition I deal only with the effect of this constraint on word-internal unstressed syllables. As shown in (19), children often realize sonorant onsets elsewhere in the word. 28m1 realizes a stressed syllable with a nasal onset in baNAna and word-final unstressed syllables with nasal onsets in baNAna and Animal. He does not realize word-internal unstressed syllables with nasal onsets in Animal and DInoSAUR, but does realize word-internal unstressed syllables in other words (e.g., CROcoDILE). 17 17A high-ranking foot form constraint (e.g., Troch) is also assumed, thus preventing right-headed feet from being aligned at the left edge.

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(19) WSW SWW S'WS S' WS

baNAna Animal DInoSAUR CROcoDILE

28m1

[næ' n8] (S) 6 [æ'ml] (I) 2 [da'Is$+] (S) 6 [ka'koda!IjE] (S) 3 |

An alternate account of the sonority effect on syllable preservation is that the medial sonorant is syllabified as a coda resulting in an onsetless medial syllable, which is deleted. This argument is consistent with a proposal by Lohuis-Weber and Zonneveld (1996) that a stress-to-weight principle (i.e., after a stressed syllable, a consonant resyllabifies as a coda) is active in children’s phonologies, with the added proviso that in English stress-to-weight is sensitive to the sonority gradient. In this case, an additional constraint ONSET may be instated to prevent the emergence of output forms with onsetless syllables as in (20). (20) Sonorant effect on syllable preservation ONSET, *Son-Ons >> Max I–O

One final point: The present analysis does not interpret children’s output patterns in terms of foot structure, rather, it displays output patterns in terms of the correspondence relation between syllables. This avoids the additional complication of inferring prosodic structure from children’s outputs. Are children’s two-syllable truncations (initial stress) of S'WS words, such as DInoSAUR, one or two stress-feet? In Fikkert’s (1994) model, these forms exist only as one foot, but in the English data there is evidence that they may exist as two feet. For example, children occasionally epenthesized an extra syllable to their truncated forms ([da' Is$! wE]), suggesting that the final stressed syllable in the input constituted a foot in the child’s outputs, as seen in (21).

(21) (X (X) daI

(X s$

) .) wE


53

In the current analysis, I assume that two syllable forms of S' WS words have the output pattern in (22a) in which the secondary stressed syllable in the input is maintained as stressed in the output. Because StressFaith refers specifically to primary stress, nothing hinges on this interpretation, and the form in (22b) may also be a possible output pattern. (22) a. I: DÍ1no2SAUR3 b. I: DÍ1no2SAUR3

O: DÍ1SAUR3 O: DI1saur3

5.2.2. Optimality developmental account. I now present constraint hierarchies to account for developmental patterns in the data; these patterns are summarized in (23). (23) Developmental patterns in the latter stages of prosodic acquisition 1 Alignment of primary stress with the left edge of the child’s output. 2 Preservation of stressed and right-edge unstressed syllables. 3 Preservation of stressed, right-edge, and some word-internal unstressed syllables (obstruent onsets). 4 Preservation of stressed, right-edge, some word-internal, and left-edge unstressed syllables. At the first stage, primary stress is aligned with the left edge of the child’s output. Stressed syllables, which occur to the left of the primary stressed syllable, are deleted. The constraint ranking in (24) yields one-syllable forms for KANgaROO, two-syllable forms for poTAto, and three-syllable forms for AlliGAtor. AlignHead prevents unstressed syllables at the left edge, as in candidates (a) and (b) for poTAto, and syllables with secondary stress at the left edge, as in candidates (a) and (e) for KANgaROO. StressFaith prevents primary stressed syllables from becoming unstressed as in candidate (c) for poTAto, from assuming secondary stress as in candidate (d) for KANgaROO, or from not being present in the output as in candidate (c) for KANgaROO and (b) for AlliGAtor. RightAnchor ensures that all right-edge syllables are preserved in the output, thus eliminating candidates (c) and (d) for AlliGAtor. *Unstress prevents the nontruncated AlliGAtor from being a possible output form, leaving Max I–O to decide between candidates (e) and (f) for AlliGAtor. AGAtor wins out over Ator because it incurs the fewest violations of Max I–O while satisfying structural and correspondence constraints. In this situation, Max I–O plays an important role in the preservation of secondary stressed syllables. Its ranking below *Unstress prevents it from having an effect on unstressed syllables.

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(24) Alignment of primary stress with the left edge of the child’s output AlignHead, StressFaith, RightAnchor >> *Unstress >> Max I–O

At the next stage, stressed and right-edge unstressed syllables are preserved, but other unstressed syllables are not preserved. The constraint ranking in (25) yields one-syllable forms for giRAFFE, two-syllable forms for Elephant and KANgaROO, and three-syllable forms for AvoCAdo.


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(25) Preservation of stressed and right-edge unstressed syllables StressFaith, RightAnchor >> *Unstress >> Max I–O

AlignHead has now been demoted, allowing the emergence of outputs that do not contain primary stress at the left edge. Several candidates are eliminated due to violations of StressFaith and RightAnchor (candidate (c) for giRAFFE, (b) for Elephant, (c) for KANgaROO, and (c) and (d) for AvoCAdo) and nontruncated forms of giRAFFE, Elephant, KANgaROO, and AvoCAdo (candidates (a) for each word) are eliminated due to *Unstress. Max I–O allows the output forms KANGROO and ACAdo to win out over ROO and CAdo, respectively, playing a part in the preservation of secondary stressed syllables.

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At this point in development we cannot see evidence of AlignFoot (or *Son-Ons) because the constraint *Unstress achieves deletion of all unstressed syllables (except in word-final position). However, at the next stage in development in which *Unstress has been demoted and there is realization of some nonfinal unstressed syllables, we now have evidence that there is a constraint preventing the realization of left-edge (and some word-internal) unstressed syllables. The constraint hierarchy in (26) yields truncated forms for poTAto, TElePHONE, and AlliGAtor and nontruncated forms for CROcoDILE. For simplicity sake, the tableau assumes high-ranking StressFaith and RightAnchor, and hence, a limited set of candidates are displayed. AlignFoot prevents unstressed syllables at the left edge, thus disallowing nontruncated poTAto. The ordering of *Son-Ons above Max I–O prevents the realization of word-internal unstressed syllables with sonorant onsets in the words TElePHONE and AlliGAtor but allows the realization of an unstressed syllable with a nonsonorant onset in CROcoDILE. High-ranking identity constraints, here summarized as Ident, prevent the realization of sonorant onsets as nonsonorant in the output, as in the candidates TEdePHONE and AddiGAtor for TElePHONE and AlliGAtor, respectively. (26) Preservation of stressed, right-edge, and some word-internal unstressed syllables AlignFoot (StressFaith, RightAnchor), *Son-Ons, Ident >> Max I–O >> *Unstress


57

Finally, the last developmental stage attested in the data is one in which unstressed syllables are realized at the left-edge position but not always word internally. This can be accounted for by the demotion of AlignFoot and the maintenance of the *Son-Ons above Max I–O. The constraint hierarchy in (27) yields nontruncated forms for poTAto but truncated forms for TElePHONE.18 (27) Preservation of left-edge but not all word-internal unstressed syllables (StressFaith, RightAnchor), *Son-Ons >> Max I–O

Constraint rankings for the latter stages of prosodic acquisition are summarized in (28). (28) Constraint rankings for the latter stages of prosodic acquisition 1 Alignment of primary stress with the left edge of the child’s output. AlignHead, (AlignFoot), StressFaith, RightAnchor, (*Son-Ons) >> *Unstress >> Max I–O 2 Preservation of stressed and right-edge unstressed syllables. (AlignFoot), StressFaith, RightAnchor, (*Son-Ons) >> *Unstress >> Max I–O 3 Preservation of stressed, right-edge, and some word-internal unstressed syllables. AlignFoot, StressFaith, RightAnchor, *Son-Ons >> Max I–O 4 Preservation of stressed, right-edge, some word-internal, and leftedge unstressed syllables. StressFaith, RightAnchor, *Son-Ons >> Max I–O 18 18One

problem with the current constraint ranking is that an initial unstressed syllable with a sonorant onset would violate *Son-Ons and subsequently would be deleted. There are no target words in the data set to determine whether sonorant onsets in initial position are also vulnerable to omission at this stage of development. Further constraints may be necessary to ensure that this constraint applies specifically to medial unstressed syllables.

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This analysis shows that during the latter stages of prosodic acquisition the constraints StressFaith and RightAnchor are always highly ranked. The main developmental effects can be captured by the demotion of AlignHead, *Unstress, and AlignFoot. Initially, AlignHead ensures that a primary stressed syllable is always aligned with the left edge of the output. At later stages of acquisition, it is dominated by AlignFoot, which ensures that a stressed syllable is always aligned with the left edge of the output. *Unstress, ranked above Max I–O but below RightAnchor, prevents the emergence of all nonfinal unstressed syllables at Stages 1 to 2. Its demotion at Stage 3 allows the realization of some nonfinal unstressed syllables. The demotion of AlignFoot at Stage 4 allows unstressed syllables at the left edge to emerge. *Son-Ons is highly ranked from the earliest stages of development. Its impact on the realization of word-internal unstressed syllables is apparent only once *Unstress has been demoted. It may influence other aspects of the phonology, however. For example, some children prefer nonsonorant over sonorant onsets even in their productions of stressed syllables, as suggested by the frequent truncation pattern [bæ'nE] for baNAna. See Gnanadesikan (1995) and Pater (1996) for optimality analyses of segmental substitutions in truncation using syllable structure constraints similar to *Son-Ons.

5.3. Unresolved Issues Thus far the discussion has not addressed two important concerns that arise from the current analysis. One is the issue of stress errors and how they can be built into a developmental account, which assumes high-ranking prosodic faithfulness; the other is the role of markedness, particularly in relation to nonoptimal feet type that occur in the nonfinal position. I start with a discussion of stress errors. One of the main difficulties with building stress errors into an account of prosodic development is that they do not occur frequently. They were evident in several children’s productions but never characterized all or even the majority of output patterns for a particular child. This in itself is some evidence that StressFaith is highly ranked; otherwise pervasive and frequent stress shift should be expected. Children seem to be highly sensitive to the prosodic role of stressed syllables in the input. There were several types of stress errors, which, although not widespread, occurred frequently enough to suggest systematic effects. One target stress pattern in which stress shift was regularly attested was the pattern SWS' (e.g., KANgaROO). It received two main stress shift variants: truncated forms with initial stress in the youngest children productions (e.g., [kæ' nru] for KANgaROO), and nontruncated forms with initial stress in the older children’s productions (e.g., [kæ' ngErù] for KANgaROO). Because these two types of stress errors were generally seen in different age groups of chil-


59

dren, it is unlikely that a single constraint effect can explain both developmental patterns. The second pattern most likely reflects the influence of the Nonfinality constraint active in English stress. This constraint, when ranked above StressFaith, will produce output forms in which primary stress is shifted away from final position. Several adults in the study also displayed the same tendency to shift stress in their productions of experimental SWS' words, indicating that this constraint may apply to produce stress errors in adult speech. The first pattern appears to be a possible output form occurring at the early stages in development when AlignHead is highly ranked. The problem with deriving this pattern in the current analysis is that it requires demotion of StressFaith below Max I–O. Given the set of constraints listed in (16), the only way to select the bisyllabic form KÁNROO over the monosyllabic form ROO is by ranking Max I–O above StressFaith, as in (29). At later stages of development, however, StressFaith is promoted again to be ranked above Max I–O, creating an unlikely developmental scenario in which StressFaith is highly ranked, lowly ranked, and then highly ranked. (29) Alignment of primary stress resulting in stress shift (AlignHead), Max I–O >> StressFaith

One possible way around this problem is to dissect StressFaith into two separate constraints: one that preserves the segmental content of all stressed syllables but does not evaluate whether these syllables retain their stress, and another that preserves the prosodic role of stressed syllables in the output. For now, I refer to the former constraint as MaxStress (segmental faithfulness to stressed syllables) and the latter as StressFaith (prosodic faithfulness to stressed syllables). Stress errors of the type [kæ' nru] for KANgaROO could be derived by allowing MaxStress to dominate StressFaith while maintaining high-ranking AlignHead. The tableau in (30) shows this pattern. At later stages of development, MaxStress would continue to remain highly ranked in children’s systems with the main developmental burden placed on Max I–O and its effect on unstressed syllables. In its present form, StressFaith is too broad in its scope to explain all aspects of child truncation and stress.

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(30) Alignment of primary stress resulting in stress shift AlignHead >> MaxStress >> StressFaith >> *Unstress

A second unresolved issue in the current analysis is the role of foot binarity and markedness in early child truncation. Markedness in optimality theory can be defined in terms of constraint violation; an unmarked form is one that does not violate or minimally violates the highest ranking constraints. Children’s unmarked prosodic forms reflect the satisfaction of a few basic constraints, one of which is FtBin. However, the findings in this study show that, at the latter stages of prosodic acquisition, foot binarity may be violated. The main empirical observation was that the final foot in the child’s system rarely violated FtBin, but the nonfinal foot could. Given that FtBin is considered to be undominated in adult speech, we again have an unlikely developmental scenario in which FtBin is highly ranked in early child speech, lowly ranked in the current analysis, and then highly ranked in the adult grammar. To explain this situation, I offer two possibilities. One is that FtBin is in fact not violated. More precise measurement procedures may show that children produce “apparent” monomoraic syllables as “phonetically” long or with intervocalic consonants that are ambisyllabic, thus, in effect, achieving bimoracity and satisfying FtBin. The second alternative is that FtBin may need to be dissected into two constraints: one that refers to the final foot in the output and the other to the nonfinal foot. FtBinfinal was undominated in the current analysis, but FtBinnonfinal was subject to developmental effects. Closely connected with FtBin is children’s development of syllable structure. Because codas frequently emerge in word-final syllables before they emerge in nonfinal syllables (Bernhardt and Stemberger (1998)), FtBinnonfinal violations may reflect syllable structure development, such as the later acquisition of codas in nonfinal position. Additional information is also needed on children’s syllabification within words (i.e., how do children syllabify intervocalic consonants), as this will have bearing on truncation. Regardless of whether these or other options are considered, the findings suggest that foot binarity in development warrants further attention.


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6. DISCUSSION This study contrasted two different approaches to prosodic acquisition: a prosodic structure approach, which proposes that during development children’s outputs are constrained by prosodic shape constraints, and a correspondence approach, which proposes that alignment and faithfulness effects between input and output play the greatest role in explaining children’s prosodic patterns. The findings yielded support for both prosodic accounts: Shape constraints played the dominant role at the earliest stages of development, and correspondence played the dominant role at later stages in development. It must be noted that shape uniformity was less pervasive than what has generally been claimed as characteristic of early prosodic acquisition. All of the 22-month-old children in Data Set A and four out of six 24-month-old children in Data Set B produced forms greater than a foot, suggesting that by the age of 2, children have largely exceeded size restrictions in development. As for the one child (28m2) whose output patterns were indicative of two stress-feet, his prosodic patterns were strikingly different from the other children’s in many respects, and it remains to be seen how common such “higher level” shape constraints are at the latter stages of development. Within optimality theory, the correspondence account can be viewed simply as an extension of the prosodic structure account. Constraints that yield shape restrictions in early acquisition are demoted and outranked by constraints that yield outputs of varying size and shape. In early child truncation, alignment constraints that refer to the foot play the greatest role initially and are later succeeded by alignment constraints that refer to the prosodic word. Children’s preservation patterns are also subject to developmental effects. The English results in combination with previous literature findings suggest three stages. First, children attend to stressed syllables on the right side of the word, regardless of primary or secondary stress. Second, children attend to the distinction between primary and secondary stress, and this leads them to focus on stressed syllables leftward in the word. Third, children attend to all stressed syllables in the target form regardless of word position or stress prominence. Given this pattern, a single faithfulness constraint (i.e., StressFaith) is insufficient to capture all preservation effects with stressed syllables. StressFaith in this analysis refers to the primary stressed syllable and would thus not select the rightmost stressed syllable at the early stages of prosodic development. Further work is needed to modify existing constraints to form an integrated account of early and later prosodic acquisition. The current consensus in optimality is that structural constraints initially outrank faithfulness constraints leading to unmarked outputs (Demuth (1995; 1996a), Gnanadesikan (1995)) and that development can be characterized as the promotion of faithfulness. Alignment constraints are generally subsumed under the category of structural constraints and likewise are dominated in development, although when minimally violated, they continue to play a role in the adult grammar (Pater (1996)). Recent analyses in prosodic development by Barlow and Dinnsen (1998)

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and Ota (1999) provide strong empirical support for this conceptualization of development. Nevertheless this study shows that certain faithfulness constraints (e.g., StressFaith and RightAnchor) appear to be highly ranked even in early acquisition, thus allowing children to satisfy both faithfulness and markedness. The application of optimality as a framework for understanding development has yet to be fully explained, and the exact constellation of faithfulness and markedness within the child’s developing system is a topic of ongoing research. In the remainder of this article, I explore why the results of English-speaking children differ from those previously reported for Dutch-speaking children (in particular, Fikkert (1994)). I consider differences in the linguistic characteristics of Dutch and English and also differences in the methodology between the two studies. 6.1. Differences Between the English and Dutch Results 6.1.1. Differences in stimuli. Differences in the linguistic characteristics of Dutch and English may explain several of the differences in the Dutch and English data. First, most of the unstressed syllables in the English words (with the exception of word-final unstressed syllables) contained reduced vowels in contrast to the unstressed syllables in the Dutch words, which contained a lesser proportion of reduced vowels. Lohuis-Weber and Zonneveld (1996) showed that the distinction between reduced and nonreduced unstressed syllables plays an important role in their Dutch-speaking child’s productions. Joost acquired unstressed syllables with schwa much later than nonreduced unstressed syllables. The fact that English children often preserve only stressed and word-final unstressed syllables without exhibiting the templatic effects characteristic of the Dutch-speaking children may lie in the nature of the English input (i.e., unstressed syllables are predominantly reduced) in combination with a high-ranking constraint *Unstress that discourages reduced syllables in the output. Second, the Dutch corpora did not contain exceptional stress patterns in which primary stress was retracted from the last three syllables of the word. These forms, as represented by the words AlliGAtor and HEliCOPter, were commonly produced by the English-speaking children. Even the youngest children in the study displayed a strong tendency to produce both stressed syllables and the word-final syllable in their productions of these words, providing crucial evidence for input–output effects over shape constraints. When older children produced occasional primitive forms, consistent with a foot, they did so more frequently when primary stress was situated closest to the end of the word. Thus, the greater presence of truncations consistent with shape constraints in the Dutch data may again result from differences in the corpora of Dutch and English. 6.1.2. Differences in methodology. One obvious methodological difference between the English and Dutch studies is that the English study was based on cross-sectional data, whereas Fikkert’s (1994) study was based on longitudinal


63

data. In the current situation, developmental stages were inferred from consistent patterns across the corpora of several children; however, it is highly possible that transient stages of development were not well represented in the data. This may explain the reduced number of stress shift patterns. Another methodological difference between this study and studies that have reported shape restrictions is that this study was based on the analysis of both spontaneous and imitated productions. In general, the literature suggests that imitated productions are more likely to resemble characteristics of the target input than spontaneous productions. Therefore, it is important to consider whether the results were influenced by the confound of imitation. Although it was true that longer words and words with marked stress pattern showed a greater tendency to be imitated than two- and three-syllable words in the data set, it was not true that longer multisyllabic words were always imitated. Words such as AlliGAtor, HEliCOpter, and KANgaROO were some of the words most frequently produced spontaneously by the youngest children, and these words were not always reduced to one stress-foot. On the other hand, several twoand three-syllable words (caBOOSE, eCHIDna) were frequently produced as imitated productions by the older children, and these were reduced to one stress-foot. In sum, imitation alone was not a good predictor of whether a particular target form was truncated to a single foot.

7. CONCLUSION In conclusion, this study, based on cross-sectional data in English-speaking children, finds little support for a two stress-feet stage of acquisition. Instead, the findings reveal a different prosodic account for English with salience of stress (prosodic heads) and word edges playing a stronger role in accounting for output size and shape. In this analysis, the inclusion of unstressed syllables is not explained by the single prosodic effect of footedness but depending on position receives alternate explanations. The realization of unstressed syllables at the right edge of the word is accounted for by the high-ranking faithfulness constraint RightAnchor. The selective realization of some internal unstressed syllables is explained by the interaction of syllable structure constraints such as *Son-Ons with the faithfulness constraint Max I–O. The realization of unstressed syllables at the left edge of the word is accounted for by alignment effects. Results suggest children are first able to realize only primary stress at the left edge, then secondary stress, and then finally reduced unstressed syllables. This pattern can be accounted for by the constraints AlignHead and AlignFoot; AlignHead is initially highly ranked and then later dominated by AlignFoot. Some of the differences between findings in English and those previously reported for Dutch (Fikkert (1994)) may lie in the nature of unstressed syllables, which are very weak (predominantly reduced) in English.

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ACKNOWLEDGMENTS Margaret Kehoe is now at the Center for Multilingualism, University of Hamburg. This study is based on data collected while I was a doctoral student at the University of Washington. This research was conducted in Professor Carol StoelGammon’s Child Speech Laboratory and was supported by a Hall-Ammerer Interdisciplinary Fellowship. I am grateful to the parents and children who took part in the study and to students who assisted in data collection and transcription reliability. I also thank the anonymous reviewers of this journal whose comments greatly contributed to this article.

REFERENCES Archibald, J. (1995) “The Acquisition of Stress,” in J. Archibald, ed., Phonological Acquisition and Phonological Theory, Lawrence Erlbaum Associates, Inc., Hillsdale, New Jersey. Barlow, J. and D. Dinnsen (1998) “Asymmetrical Cluster Development in a Disordered System,” Language Acquisition 7, 1–49. Bernhardt, B. and J. Stemberger (1998) Handbook of Phonological Development From the Perspective of Constraint-Based Nonlinear Phonology, Academic, San Diego. Blasdell, R. and P. Jensen (1970) “Stress and Word Position as Determinants of Imitation in First-Language Learners,” Journal of Speech and Hearing Research 13, 193–202. Borer, H. and K. Wexler (1987) “The Maturation of Syntax,” in T. Roeper and E. Williams, eds., Parameter Setting, Reidel, Dordrecht, The Netherlands. Demuth, K. (1995) “Markedness and the Development of Prosodic Structure,” in J. Beckman, ed., Proceedings of the NorthEastern Linguistic Society 25, 13–25. Demuth, K. (1996a) “Alignment, Stress, and Parsing in the Construction of Early Prosodic Words,” in B. Bernhardt, J. Gilbert, and D. Ingram, eds., Proceedings of the UBC International Conference on Phonological Acquisition, Cascadilla Press, Somerville, Massachusetts. Demuth, K. (1996b) “The Prosodic Structure of Early Words,” in J. Morgan and K. Demuth, eds., From Signal to Syntax: Bootstrapping from Speech to Grammar in Early Acquisition, Lawrence Erlbaum Associates, Inc., Hillsdale, New Jersey. Demuth, K. (1996c) “Stages in the Development of Prosodic Words,” in E. Clark, ed., Proceedings from the 27th Child Language Research Forum, Stanford University, Center for the Study of Language and Information, California. Demuth, K. (1997) “Prosodic Constraints and Morphological Development,” in J. Weissenborn and B. Höhle, eds., Phonological, Syntactic and Neurophysiological Aspects of Early Language Acquisition, John Benjamins, Amsterdam, The Netherlands. Demuth, K. and E. J. Fee (1995) “Minimal Words in Early Phonological Development,” ms., Brown University, Providence, Rhode Island, and Dalhousie University, Halifax, Nova Scotia. Dobrich, W. and H. Scarborough (1992) “Phonological Characteristics of Words Young Children Try to Say,” Journal of Child Language 19, 597–616. Echols, C. and E. Newport (1992) “The Role of Stress and Position in Determining First Words,” Language Acquisition 2, 189–220. Fee, E. J. (1995) “Segments and Syllables in Early Language Acquisition,” in J. Archibald, ed., Phonological Acquisition and Phonological Theory, Lawrence Erlbaum Associates, Inc., Hillsdale, New Jersey.


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Fee, E. J. (1996a) “Syllable Structure and Minimal Words,” in B. Bernhardt, J. Gilbert, and D. Ingram, eds., Proceedings of the UBC International Conference on Phonological Acquisition, Cascadilla Press, Somerville, Massachusetts. Fee, E. J. (1996b) “Two Strategies in the Acquisition of Syllable and Word Structure,” in E. Clark, ed., Proceedings from the 27th Child Language Research Forum, Stanford University, Center for the Study of Language and Information, California. Fenson, L., P. Dale, S. Reznick, D. Thal, E. Bates, J. Hartung, S. Pethick, and J. Reilly (1991) MacArthur Communicative Development Inventories, San Diego State University, California. Fikkert, P. (1994) On the Acquisition of Prosodic Structure, Institute of Generative Linguistics, Dordrecht, The Netherlands. Gennari, S. and K. Demuth (1997) “Syllable Omission in the Acquisition of Spanish,” in A. Stringfellow, D. Cahana-Amitay, E. Hughes, and A. Zukowski, eds., Proceedings of the 21st Annual Boston University Conference on Language Development, Cascadilla Press, Somerville, Massachusetts. Gerken, L. (1994) “A Metrical Template Account of Children’s Weak Syllable Omissions From Multisyllabic Words,” Journal of Child Language 21, 565–584. Gnanadesikan, A. (1995) “Markedness and Faithfulness Constraints in Child Phonology,” ms., University of Massachusetts, Amherst, and Rutgers University, New Brunswick, New Jersey. Halle, M. and J. Vergnaud (1987) An Essay on Stress, MIT Press, Cambridge, Massachusetts. Hayes, B. (1985) A Metrical Theory of Stress Rules, Garland Publishing, New York. Hayes, B. (1995) Metrical Stress Theory: Principles and Case Studies, University of Chicago Press. Holmes, U. (1927) “The Phonology of an English-Speaking Child,” American Speech 2, 219–225. Jusczyk, P., A. Cutler, and N. Redanz (1993) “Infant’s Preference for the Predominant Stress Patterns of English,” Child Development 64, 675–687. Kager, R. (1989) A Theory of Stress and Destressing in English and Dutch, Foris, Dordrecht, The Netherlands. Kehoe, M. (1994) “Beyond the Trochaic Constraint: An Examination of Rhythmic Processes in English Children’s Productions of Multisyllabic Words,” paper presented at the Child Phonology Conference, Sun Valley, Idaho. Kehoe, M. (1995) An Investigation of Rhythmic Processes in English-Speaking Children’s Word Productions, Doctoral dissertation, University of Washington, Seattle, Washington. Kehoe, M. (1996) “Prosodic Strategies in Development: A Case Study,” paper presented at the Child Phonology Conference, Iowa City, University of Iowa. Kehoe, M. and C. Stoel-Gammon (1997a) “The Acquisition of Prosodic Structure: An Investigation of Current Accounts of Children’s Prosodic Development,” Language 73, 113–144. Kehoe, M. and C. Stoel-Gammon (1997b) “Truncation Patterns in English-Speaking Children’s Word Productions,” Journal of Speech and Hearing Research 40, 526–541. Kehoe, M., C. Stoel-Gammon, and E. Buder (1995) “Acoustic Correlates of Stress in Children’s Speech,” Journal of Speech and Hearing Research 38, 338–350. Klein, H. (1981) “Production Strategies for the Pronunciation of Early Polysyllabic Lexical Items,” Journal of Speech and Hearing Research 24, 389–405. Lohuis-Weber, H. and W. Zonneveld (1996) “Phonological Acquisition and Dutch Word Prosody,” Language Acquisition 5, 245–283. McCarthy, J. (1979) “On Stress and Syllabification,” Linguistic Inquiry 8, 249–336. McCarthy, J. (1995) “Extensions of Faithfulness: Rotumen Revisited,” ms., University of Massachusetts, Amherst. McCarthy, J. and A. Prince (1986) “Prosodic Morphology,” ms., University of Massachusetts, Amherst, and Brandeis University, Waltham, Massachusetts. McCarthy, J. and A. Prince (1993a) “Generalized Alignment,” ms., University of Massachusetts, Amherst, and Rutgers University, New Brunswick, New Jersey. McCarthy, J. and A. Prince (1993b) “Prosodic Morphology I: Constraint Interaction and Satisfaction,” ms., University of Massachusetts, Amherst and Rutgers University, New Brunswick, New Jersey.

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McCarthy, J. and A. Prince (1995) “Faithfulness and Reduplicative Identity,” in J. Beckman, L. Walsh, and S. Urbanczyk, eds., “Papers in Optimality Theory,” University of Massachusetts Occasional Papers in Linguistics 18, 249–384. Nespor, M. and I. Vogel (1986) Prosodic Phonology, Foris, Dordrecht, The Netherlands. Ota, M. (1997) “Phonological Constraints and Word Truncation in Early Language Acquisition,” paper presented at the 22nd Annual Boston University Conference on Language Development, Boston. Ota, M. (1999) Phonological Theory and the Acquisition of Prosodic Structure: Evidence From Child Japanese, Doctoral dissertation, Georgetown University, Washington, DC. Paradis, J. (1995) “Prosodic Development and Differentiation in Bilingual First Language Acquisition,” ms., McGill University, Montreal, Canada. Pater, J. (1995) “On the Nonuniformity of Weight-to-Stress and Stress Preservation Effects in English,” ms., McGill University, Montreal, Canada. Pater, J. (1997) “Minimal Violation and Phonological Development,” Language Acquisition 6, 201–253. Pater, J. and J. Paradis (1996) “Truncation Without Templates in Child Phonology,” in A. Stringfellow, D. Cahana-Amitay, E. Hughes, and A. Zukowski, eds., Proceedings of the 20th Annual Boston University Conference on Language Development, Vol. 2, Cascadilla Press, Somerville, Massachusetts. Prince, A. S. and P. Smolensky (1993) “Optimality Theory: Constraint Interaction in Generative Grammar,” ms., Rutgers University, New Brunswick, New Jersey, and University of Colorado, Boulder. Salidis, J. and J. Johnson (1997) “The Production of Minimal Words: A Longitudinal Case Study of Phonological Development,” Language Acquisition 6, 1–36. Schwartz, R. and L. Leonard (1982) “Do Children Pick and Choose: An Examination of Phonological Selection and Avoidance in Early Lexical Acquisition,” Journal of Child Language 9, 319–336. Selkirk, E. (1982) “The Syllable,” in H. van der Hulst and N. Smith, eds., The Structure of Phonological Representations, Vol. 2, Foris, Dordrecht, The Netherlands. Selkirk, E. (1984) Phonology and Syntax: The Relation Between Sound and Structure, MIT Press, Cambridge, Massachusetts. Smith, N. (1973) Acquisition of Phonology, Cambridge University Press, Cambridge, Massachusetts. Wijnen, F., E. Krikhaar, and E. den Os (1994) “The (Non)realization of Unstressed Elements in Children’s Utterances: Evidence for a Rhythmic Constraint,” Journal of Child Language 21, 59–83.


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APPENDIX Numbers of Productions Across Participants in Data Sets A and B Data Set A

Data Set B

Participant

S

I

Participant

S

I

22f1a 22f2 22f3 22m1 22m2 22m3

10 42 33 17 19 35

64 19 48 52 48 21

18f4 18f8 18m4

12 5 20

2 5 5

28f1 28f2 28f3 28m1 28m2 28m3

68 60 66 58 44 52

21 32 20 22 44 40

24f1 24f3 24f4 24f6 24m1 24m6

11 10 15 6 18 12

12 9 8 4 10 3

34f1 34f2 34f3 34m1 34m2 34m3

66 54 75 59 89 60

7 26 17 29 6 35

27f1 27f2 27f3 27f4 27f5 27f6 27m2 27m3 27m4 27m5 27m6

42 86 46 18 54 53 5 37 53 139 42

34 43 27 64 92 41 21 44 8 22 39

30f1 30f4 30f5 30f6 30m2 30m3 30m4 30m5 30m6 30m7

22 24 25 20 30 25 10 16 25 30 911

6 11 11 3 11 8 18 19 12 14 606

Total

907

551

Note. S = spontaneous; I = imitated production. a22f1 is a 22-month-old female participant.

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