A Comparison of Linguistic Profiles in Subgroups of Children With Specific Language Impairment Purpose To compare morphosyntactic skills of preschoolers in different subgroups of language impairment. Method Eighty-three children participated in this study. They represented 4 groups: (a) language impairment-only, (b) speech-language impairment with minimal or no final cluster reduction/consonant deletion, (c) speech-language impairment with frequent final cluster reduction/consonant deletion, and ... Research Article
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Research Article  |   August 01, 2007
A Comparison of Linguistic Profiles in Subgroups of Children With Specific Language Impairment
 
Author Affiliations & Notes
  • Allison M. Haskill
    Augustana College, Rock Island, IL
  • Ann A. Tyler
    University of Nevada, Reno
  • Contact author: Allison M. Haskill, Department of Communication Sciences and Disorders, Brodahl Building, Augustana College, 639 38th Street, Rock Island, IL 61201. E-mail: allisonhaskill@augustana.edu.
  • Ann A. Tyler is now at Western Michigan University.
    Ann A. Tyler is now at Western Michigan University.×
Article Information
Speech, Voice & Prosodic Disorders / Language Disorders / Specific Language Impairment / Speech, Voice & Prosody / Research Articles
Research Article   |   August 01, 2007
A Comparison of Linguistic Profiles in Subgroups of Children With Specific Language Impairment
American Journal of Speech-Language Pathology, August 2007, Vol. 16, 209-221. doi:10.1044/1058-0360(2007/026)
History: Received April 11, 2006 , Revised August 22, 2006 , Accepted January 22, 2007
 
American Journal of Speech-Language Pathology, August 2007, Vol. 16, 209-221. doi:10.1044/1058-0360(2007/026)
History: Received April 11, 2006; Revised August 22, 2006; Accepted January 22, 2007
Web of Science® Times Cited: 6

Purpose To compare morphosyntactic skills of preschoolers in different subgroups of language impairment.

Method Eighty-three children participated in this study. They represented 4 groups: (a) language impairment-only, (b) speech-language impairment with minimal or no final cluster reduction/consonant deletion, (c) speech-language impairment with frequent final cluster reduction/consonant deletion, and (d) a no-impairment control group. Group performance was compared for finite and nonfinite morpheme production and sentence structure.

Results Children in the language impairment-only group had significantly higher performance than children in both speech-language impairment subgroups, even when errors that could be attributed to final consonant deletion/cluster reduction were taken into account. The language impairment-only and control groups' performance was similar for finite and nonfinite morpheme production, and both groups produced nonfinite plurals with significantly higher accuracy than finite third person singular forms. The language impairment-only group had significantly higher accuracy for both plural and third person singular relative to the group with speech-language impairment characterized by infrequent final cluster reduction/consonant deletion.

Conclusions Children with speech-language impairment generally had poorer morphosyntactic skills than peers who had language deficits and age-appropriate speech skills. Final consonant and final cluster production skills alone did not account for group differences. Clinically, the findings suggest that it is important to assess carefully the speech skills, including final cluster production skills, of preschoolers who have language deficits and language skills of preschoolers who have speech sound disorders.

Children with specific language impairment (SLI) have impaired language skills, despite otherwise normal functioning in hearing, behavior, and nonverbal intelligence (Leonard, 1998; Stark & Tallal, 1981, Tomblin, Records, & Zhang, 1996; Watkins & Rice, 1994). Children with SLI may have a variety of language deficits; however, morphosyntax consistently has been shown to be an area of considerable difficulty. Finite morphemes that reflect tense and agreement have received recent research attention and have been shown to be the area of morphosyntax that is most problematic for many children with SLI (Bedore & Leonard, 1998; Goffman & Leonard, 2000; Leonard, 1998; Rice, 1999; Rice & Wexler, 1996; Rice, Wexler, & Cleave, 1995). Finite morphemes are so challenging for young children with SLI that some researchers have suggested their low accuracy in obligatory contexts may be a sensitive and selective clinical marker for SLI (Bedore & Leonard, 1998; Leonard, Miller, & Gerber, 1999; Rice, 1999; Rice & Wexler, 1996). In English, specific finite forms that have been investigated have included third person singular, past tense, copula and auxiliary be, and auxiliary do forms.
Whereas verb-related finite morphemes have been found to be extremely challenging for young children with SLI, nonfinite morphemes, the majority of which are noun-related, have been found to present less of a problem. There are several nonfinite morphemes, but the forms that have been investigated in studies of SLI include articles, plurals, and possessives (Bedore & Leonard, 1998).
According to Leonard (1998), “during the preschool years, if children experience deficits in morphosyntax and lexical skills, they almost invariably show weakness in phonology as well” (p. 71). Reports indicate that as many as 40% to 60% of clinical samples of preschoolers with speech sound disorders may have co-occurring language impairments (Shriberg & Austin, 1998; Shriberg & Kwiatkowski, 1994). Phonological deficits in SLI have been observed in English as well as in other languages, such as Italian (Bortolini & Leonard, 2000), Catalan-Spanish (Aguilar-Mediavilla, Sanz-Torrent, & Serra-Raventos, 2002), Dutch (Beers, 1992), and Swedish (Nettelbladt, 1992).
Language Impairment Subgroups
As evidence of the heterogeneity in the speech and language impaired population, numerous researchers have suggested the possibility of subtypes of SLI (e.g., Botting & Conti-Ramsden, 2004; Conti-Ramsden & Botting, 1999; Conti-Ramsden, Crutchley, & Botting, 1997; Rapin & Allen, 1983; Snow, 1998; van Daal, Verhoeven, & van Balkom, 2004; Wolfus, Moscovitch, & Kinsbourne, 1980). These investigations typically have employed factor and cluster analyses reflecting participants' performance on a variety of standardized tests. At least two distinct groups with both morphosyntactic and speech deficits have been labeled as either “phonological-syntactic” or “expressive” subgroups, although in some analyses, grammatical comprehension difficulties exist as well. Two specific clusters described in Botting and Conti-Ramsden (2004)  included children with deficits in both expressive language and speech sound production. One cluster (Cluster 3) included children with phonological and expressive language deficits, and another cluster (Cluster 5) included children with phonological, syntactic, and lexical deficits. The difference between these groups appeared to be in overall severity, as well as expressive vocabulary, with Cluster 5 being more severe and performing worse in oral vocabulary than children in Cluster 3. Additional subgroups reflecting pragmatic discourse, auditory sequential memory, and speech-only difficulties have also been identified. The overwhelming majority of studies of subgroups of SLI have included English-speaking participants. However, findings of a recent study of 110 Dutch-speaking children with severe speech and language deficits revealed SLI subgroup types that were similar to those described in English-speaking populations (van Daal et al., 2004).
Children with both phonological and morphosyntactic deficits may represent one of the largest subgroups of children with language impairment. Nearly half of the 229 participants described in Botting and Conti-Ramsden (2004)  had deficits in both speech sound production and morphosyntax (Cluster 5 included 84 children, and Cluster 3 included 29 children).
It is reasonable to predict that the more areas of linguistic deficit a child may have, the greater the overall severity of his or her impairment may be. The “submerged mountains” analogy (Bishop & Edmundson, 1987) illustrates that in SLI, “different aspects of language function are differentially vulnerable so that the pattern of impairment observed depends on the overall severity of the disorder” (p. 157). Specifically, this explanation predicts that children who have deficits in multiple linguistic areas (e.g., phonology, morphosyntax, semantics, and/or receptive language) will have more severe overall impairments. Thus, children who have co-occurring phonological and morphosyntactic deficits may not only constitute a distinct subgroup of SLI, but relative to peers with age-appropriate phonology, the overall severity of their impairment may be greater.
Linguistic Deficits in SLI
The exact underlying nature of the linguistic deficits in SLI has yet to be established, though several hypotheses have been investigated. General processing limitations (Dollaghan, 2004; Hayiou-Thomas, Bishop, & Plunkett, 2004; Leonard, 1998) and phonological working memory deficits (Gathercole & Baddeley, 1990) have been discussed in models of morpheme deficits in SLI. Conti-Ramsden, Botting, and Faragher (2001)  found performance on a nonword repetition task to be a more sensitive, specific, and accurate marker for SLI than tense marking (past tense and third person singular) and sentence repetition. Leonard discussed how the “low phonetic substance” (i.e., decreased acoustic saliency) of several grammatical morphemes may pose perception difficulties, which may contribute to their increased omission rates. Other researchers have suggested that faulty linguistic rule systems and misapplication of language paradigms may account for the deficits (Gopnik & Crago, 1991; Pinker, 1984; Rice & Wexler, 1996).
Several researchers have discussed the apparent relationships that exist between phonology and morphosyntax for children with language impairments by addressing specific contributions of the linguistic domains. Stemberger (2002)  suggested that phonological characteristics may influence the processing of English inflections. The “computational grammatical complexity hypothesis” (Marshall & van der Lely, 2003; van der Lely, 2004, 2005) suggests that children with grammatical SLI (G-SLI) have a core grammatical deficit affecting phonology, as well as syntax and morphology. Chiat (2001)  described a phonological account of SLI based on a mapping theory of developmental language impairment that emphasized deficits in complex phonological processing and related disruptions in mapping, which were reported to influence both lexical and syntactic development. Chiat reported that unlike the phonological theory of SLI, previous grammatical accounts of SLI had not adequately explained how phonological characteristics influence morpheme production in various populations of children.
While it is clear that many children with SLI have significant phonological difficulties, many SLI studies have focused on morphosyntactic skills of participants with less attention devoted to phonology. A child may have phonological constraints that prevent him or her from using certain morphemes (Bernhardt & Stemberger, 2000). Specifically, if a child has constraints that do not allow codas, complex codas, or unstressed syllables, then the deletion of several different morphemes likely will occur (e.g., articles, or affixed past tense or plural forms.) At the sentence level, morphemes occurring in unstressed syllables (such as articles, as in the utterance “I have a cat”) may be subject to omission (Bernhardt & Stemberger, 2000; Gerken, 1991).
Paul and Shriberg (1982)  studied patterns of association between phonology and syntax in their study of 30 children with moderate to severe speech delay. Although four different patterns of association between syntactic skills, morphophoneme production, and speech delay were identified, all patterns were characterized by some level of difficulty in the production of complex morphophonemes that resulted from the addition of nonsyllabic final consonants or final consonant clusters. Similarly, Bortolini and Leonard (2000)  found phonological limitations in their study of English- and Italian-speaking children with SLI, with a significant correlation between final consonant deletion in monomorphemes and omission of consonantal inflections resulting in 80% of clusters being reduced. Rvachew, Gaines, Cloutier, and Blanchet (2005), however, found that the morphological errors of preschool children with speech sound disorder were not a simple reflection of their speech error patterns. For example, plural, possessive, and third person singular regular morphemes were omitted or incorrect more often than were /s, z/ in uninflected (monomorphemic) contexts. More than half of the participants consistently produced /s, z/ in uninflected contexts but frequently omitted the grammatical morphemes examined.
Marshall and van der Lely and colleagues (e.g., Marshall & van der Lely, 2003, 2006; van der Lely, 2004, 2005) and others (e.g., Stemberger, 2002) have discussed various phonological and morphological aspects of English inflections. Marshall and van der Lely investigated past tense inflections in children with G-SLI and found that forms ending in clusters were particularly vulnerable to omission relative to other syllabic sequences. Although their data ultimately were interpreted to suggest a morphological deficit, Marshall and van der Lely (2006)  specifically addressed phonotactics in their study of past tense inflection in school-age children with G-SLI. Participants with G-SLI were found to have significantly more difficulty producing monomorphemically illegal clusters (MICs) than monomorphemically legal clusters (MLCs). MICs were described as final clusters that could be used in affixed past tense forms but not in monomorphemic words (e.g., hummed), whereas MLCs, which are more frequent in the language, may be used bimorphemically, both in affixed past tense forms and monomorphemic words (e.g., filled and gold). Phonotactics did not appear to pose as serious a problem for younger, typically developing participants who did not differ significantly in their production of MICs and MLCs.
Although previous studies have compared finite and nonfinite morpheme usage in children with SLI, one complicating factor is that vastly differing participant selection criteria have been employed with regard to phonological skills. Few, if any, studies have examined finite and nonfinite morpheme usage in subgroups of SLI with consideration of both participants' phonological skills and the phonological characteristics of individual morphemes. The primary purpose of this study was to examine finite and nonfinite morpheme production and syntactic skills of subgroups of children with language impairment. Research questions were aimed at determining whether group differences existed on measures of finite morphemes, nonfinite morphemes, specific morphemes (plural and third person), and sentence structure among children with language-only impairments, two subgroups of children with speech-language impairment, and a no-impairment control group.
Method
Participants
Language-Only Impairment (LI) and Speech (Phonological)-Language Impairment (PLI) Groups
The LI group included 23 children, and the PLI group included 40 children. Participants in both the LI and PLI groups were referred by school speech-language pathologists and were enrolled in speech-language intervention at the time of data collection. LI and PLI participants met the following selection criteria: (a) nonverbal/performance scores of >85 on the Columbia Mental Maturity Scale (Burgemiester, Blum, & Lorge, 1972) or the performance portion of the Kaufman Assessment Battery for Children (Kaufman & Kaufman, 1983); (b) normal hearing acuity; (c) normal neurological function, as well as oral, gross, and fine motor skills, and behavioral, physical, and socio-emotional development; (d) expressive language scores greater than 1 SD below the age mean on the expressive language composite of the Clinical Evaluation of Language Fundamentals—Preschool (CELF–P; Wiig & Semel, 1992) or expressive communication portion of the Preschool Language Scale, Third Edition (PLS–3; Zimmerman, Steiner, & Pond, 1992), or mean lengths of utterance in morphemes (MLUs) greater than 1.5 SD below the age mean; and (e) between the ages of 3;0 (years;months) and 5;11 at the time of data collection. Although receptive language was not included in the study, scores are reported. Receptive scores were from PLS–3 auditory comprehension or CELF–P receptive language composite standard scores, for all but two LI participants, whose receptive scores were from the Peabody Picture Vocabulary Test—III (Dunn & Dunn, 1997). All but 2 participants, one each in the PLI and LI groups, were monolingual English speakers. The 2 participants who were second language learners had documented language deficits in both English and their primary language. Group mean scores for initial selection measures are displayed in Table 1.
TABLE 1 Identifying information for the study groups.
Identifying information for the study groups.×
Group N (M/F) Age in months MLU Speech production scores Expressive language scores Receptive language scores Nonverbal scores
    M SD M SD M SD M SD M SD M SD
LI 23 (15/8) 59.62 6.90 3.49 0.62 94.43 6.38 74.91 7.59 86.30 9.21 95.26 7.05
PLI/FCD− 29 (19/10) 51.38 7.32 2.91 0.52 71.28 5.99 80.04 10.53 86.64 14.72 101.62 10.50
PLI/FCD+ 11 (8/3) 48.36 4.76 2.15 0.62 65.36 1.21 71.20 12.70 83.67 17.46 104.18 9.20
Control 20 (8/12) 36.00 0.83 4.01 0.70 97.85 7.82 107.4 14.60
Note. Speech production scores were obtained from the Word Inventory of the Bankson–Bernthal Test of Phonology (BBTOP) for the LI and PLI groups and from the Arizona Articulation Proficiency Scale, Third Revision for the control group; expressive language scores were obtained from the Clinical Evaluation of Language Fundamentals—Preschool (CELF–P) or Preschool Language Scale, Third Edition (PLS–3); receptive language scores were obtained from the CELF–P, PLS–3, or Peabody Picture Vocabulary Test—III; nonverbal scores were obtained from the Kaufman Assessment Battery for Children or the Columbia Mental Maturity Scale. Dashes indicate that scores were not available. MLU = mean length of utterance in morphemes; LI = language-only impairment; PLI/FCD− = speech (phonological)-language impairment with rarely exhibited final consonant deletion and/or final cluster reduction (FCR); PLI/FCD+ = PLI with frequently exhibited FCD/FCR.
Note. Speech production scores were obtained from the Word Inventory of the Bankson–Bernthal Test of Phonology (BBTOP) for the LI and PLI groups and from the Arizona Articulation Proficiency Scale, Third Revision for the control group; expressive language scores were obtained from the Clinical Evaluation of Language Fundamentals—Preschool (CELF–P) or Preschool Language Scale, Third Edition (PLS–3); receptive language scores were obtained from the CELF–P, PLS–3, or Peabody Picture Vocabulary Test—III; nonverbal scores were obtained from the Kaufman Assessment Battery for Children or the Columbia Mental Maturity Scale. Dashes indicate that scores were not available. MLU = mean length of utterance in morphemes; LI = language-only impairment; PLI/FCD− = speech (phonological)-language impairment with rarely exhibited final consonant deletion and/or final cluster reduction (FCR); PLI/FCD+ = PLI with frequently exhibited FCD/FCR.×
TABLE 1 Identifying information for the study groups.
Identifying information for the study groups.×
Group N (M/F) Age in months MLU Speech production scores Expressive language scores Receptive language scores Nonverbal scores
    M SD M SD M SD M SD M SD M SD
LI 23 (15/8) 59.62 6.90 3.49 0.62 94.43 6.38 74.91 7.59 86.30 9.21 95.26 7.05
PLI/FCD− 29 (19/10) 51.38 7.32 2.91 0.52 71.28 5.99 80.04 10.53 86.64 14.72 101.62 10.50
PLI/FCD+ 11 (8/3) 48.36 4.76 2.15 0.62 65.36 1.21 71.20 12.70 83.67 17.46 104.18 9.20
Control 20 (8/12) 36.00 0.83 4.01 0.70 97.85 7.82 107.4 14.60
Note. Speech production scores were obtained from the Word Inventory of the Bankson–Bernthal Test of Phonology (BBTOP) for the LI and PLI groups and from the Arizona Articulation Proficiency Scale, Third Revision for the control group; expressive language scores were obtained from the Clinical Evaluation of Language Fundamentals—Preschool (CELF–P) or Preschool Language Scale, Third Edition (PLS–3); receptive language scores were obtained from the CELF–P, PLS–3, or Peabody Picture Vocabulary Test—III; nonverbal scores were obtained from the Kaufman Assessment Battery for Children or the Columbia Mental Maturity Scale. Dashes indicate that scores were not available. MLU = mean length of utterance in morphemes; LI = language-only impairment; PLI/FCD− = speech (phonological)-language impairment with rarely exhibited final consonant deletion and/or final cluster reduction (FCR); PLI/FCD+ = PLI with frequently exhibited FCD/FCR.
Note. Speech production scores were obtained from the Word Inventory of the Bankson–Bernthal Test of Phonology (BBTOP) for the LI and PLI groups and from the Arizona Articulation Proficiency Scale, Third Revision for the control group; expressive language scores were obtained from the Clinical Evaluation of Language Fundamentals—Preschool (CELF–P) or Preschool Language Scale, Third Edition (PLS–3); receptive language scores were obtained from the CELF–P, PLS–3, or Peabody Picture Vocabulary Test—III; nonverbal scores were obtained from the Kaufman Assessment Battery for Children or the Columbia Mental Maturity Scale. Dashes indicate that scores were not available. MLU = mean length of utterance in morphemes; LI = language-only impairment; PLI/FCD− = speech (phonological)-language impairment with rarely exhibited final consonant deletion and/or final cluster reduction (FCR); PLI/FCD+ = PLI with frequently exhibited FCD/FCR.×
×
Participants in the PLI group had phonology standard scores of <85, and participants in the LI group had phonology standard scores of >85 on the Word Inventory of the Bankson–Bernthal Test of Phonology (BBTOP; Bankson & Bernthal, 1990). Results of a t test for independent means revealed significantly different BBTOP Word Inventory scores for the PLI and LI groups (p < .001). The BBTOP, an 80-item single-word phonology test, was selected in part because relative to other commercially available measures, it contains comparatively numerous opportunities for final cluster production (lamp, milk, hand, elephant, and vest.) To ensure that each child in the PLI group had three opportunities to produce 24 consonants in initial and final word positions, a 14-item single-word probe was used to supplement BBTOP productions. Supplemental stimulus words included knob, juice, chief, zebra, shovel, vacuum, wash, drive, hammer, yes, thank, this/that, thing, and there.
PLI subgroups. Many of the morphological endings of interest included phonologically complex suffixes with final consonants or final consonant clusters (e.g., jumped,jumps). To address more thoroughly the potential influence of participants' final cluster and final consonant production skills, the PLI group was divided into two subgroups. The PLI/FCD− subgroup included 29 children who rarely exhibited final consonant deletion (FCD) and/or final cluster reduction (FCR), and the PLI/FCD+ subgroup included 11 children who frequently exhibited FCD/FCR.
The PLI subgroups were formed based on combined FCR and FCD frequency-of-occurrence percentages from the BBTOP and 14 supplemental single-word stimuli. There were a total of 69–72 possible opportunities in which FCD and FCR could apply. Three stimulus words had two possible productions, not all of which included final consonants or clusters (e.g., jam/jelly). Percentage occurrence scores for FCR and FCD were rank-ordered for the 40 children in the PLI group. The score demarcating the upper quartile was determined to be 13%, and the 29 children whose final cluster reduction/consonant deletion scores fell below the upper quartile (i.e., those with scores below 13%) composed the PLI/FCD− subgroup. The 11 children whose final cluster reduction/consonant deletion scores were above this level composed the PLI/FCD+ subgroup. Table 2 displays the rank-ordering of PLI participants' scores reflecting percentage use of FCD/FCR.
TABLE 2 Rank ordering of PLI participants' percentage use of final cluster reduction and final consonant deletion.
Rank ordering of PLI participants' percentage use of final cluster reduction and final consonant deletion.×
Participant % final cluster reduction/final consonant deletion Participant % final cluster reduction/final consonant deletion
27 0 26 8
25 3 46 8
36 3 28 9
51 3 32 9
52 3 59 10
39 3 54 10
38 3 55 10
31 4 60 10
42 4 43 10
30 4 37 13
47 4 29 13
34 4 57 13
53 4 56 14
40 4 43 17
49 4 48 22
63 4 35 23
44 6 33 33
50 6 41 42
58 7 61 42
62 7 24 43
Note. Median = 7.5; upper quartile = 13.
Note. Median = 7.5; upper quartile = 13.×
TABLE 2 Rank ordering of PLI participants' percentage use of final cluster reduction and final consonant deletion.
Rank ordering of PLI participants' percentage use of final cluster reduction and final consonant deletion.×
Participant % final cluster reduction/final consonant deletion Participant % final cluster reduction/final consonant deletion
27 0 26 8
25 3 46 8
36 3 28 9
51 3 32 9
52 3 59 10
39 3 54 10
38 3 55 10
31 4 60 10
42 4 43 10
30 4 37 13
47 4 29 13
34 4 57 13
53 4 56 14
40 4 43 17
49 4 48 22
63 4 35 23
44 6 33 33
50 6 41 42
58 7 61 42
62 7 24 43
Note. Median = 7.5; upper quartile = 13.
Note. Median = 7.5; upper quartile = 13.×
×
No-Impairment Control Group
The control group consisted of 20 participants, who had a mean age of 3;0. Children in the control group were participants in Tolbert’s (2004)  investigation of final cluster development in 3- and 4-year-old typically developing children. Participants in the control group passed a pure-tone hearing screening and had speech and language skills within normal limits, as indicated through MLU, receptive language testing using the PLS–3, and standardized speech testing using the Arizona Articulation Proficiency Scale, Third Revision (Fudala, 2001).
Procedure
Speech Data
Additional speech data for individual LI and PLI participants, along with group means and standard deviations, are displayed in Tables 3 and 4. Included are consonant inventory size, percentage of consonants correct, and accuracy of production of monomorphemic and bimorphemic final clusters. Monomorphemic final cluster data for the LI and PLI groups were derived from BBTOP productions, which included contexts for five final clusters. PLI participants also produced the word thank on their supplemental word probe. Bimorphemic final cluster data included words that contained final clusters that were used in affixed grammatical morpheme contexts in language sample utterances. Bimorphemic final clusters also could be used in nongrammatical contexts as well—for example, _ks (e.g., /kiks/, /bαks/); _nd (/plænd/ and /wαnd/), _st (/kist/ and /list/), and _kt (/pikt/ and /kənɛkt/. The four specific final cluster types that were reflected in the bimorphemic cluster data were selected because they were used with relatively high frequency in the participants' language samples.
TABLE 3 LI participants' speech data.
LI participants' speech data.×
Participant BBTOP (Word Inventory standard scores) Percentage of consonants correct Number of consonants in phonetic inventorya Monomorphemic final cluster accuracyb Bimorphemic final cluster accuracyc
1 87 93 21 5/5 1/2
2 85 86 18 5/5 1/4
3 84 86 20 4/5 4/5
4 97 96 22 4/5 3/4
5 92 92 20 5/5 0/1
6 91 93 22 5/5 2/3
7 104 95 20 5/5 1/1
8 103 91 20 5/5 6/6
9 90 93 21 5/5 2/3
10 85 89 18 5/5
11 98 95 21 4/5 1/2
12 99 98 22 5/5 7/9
13 102 91 20 5/5 2/3
14 92 95 22 5/5
15 97 95 19 5/5 4/5
16 95 93 20 4/5 1/2
17 89 91 20 5/5 1/5
18 98 95 20 5/5 3/3
19 97 95 20 5/5 4/5
20 86 92 20 5/5
21 102 96 20 4/5 2/3
22 102 96 20 5/5 0/2
23 97 93 20 2/5 1/4
M 94.43 93 20.26 93.04 59.05
SD 6.38 2.98 1.07 14.28 31.02
Note. Dashes indicate no opportunities for production in the participant’s language sample.
Note. Dashes indicate no opportunities for production in the participant’s language sample.×
aConsonants used at least 3 times in initial or final word position, or those used correctly 2 times in initial or final word position.
aConsonants used at least 3 times in initial or final word position, or those used correctly 2 times in initial or final word position.×
bNumber of final clusters for which both consonants were correctly produced/5 BBTOP stimulus items with monomorphemic final clusters.
bNumber of final clusters for which both consonants were correctly produced/5 BBTOP stimulus items with monomorphemic final clusters.×
cNumber of final clusters for which both consonants were correctly produced/total number of bimorphemic final clusters obtained from language sample data.
cNumber of final clusters for which both consonants were correctly produced/total number of bimorphemic final clusters obtained from language sample data.×
TABLE 3 LI participants' speech data.
LI participants' speech data.×
Participant BBTOP (Word Inventory standard scores) Percentage of consonants correct Number of consonants in phonetic inventorya Monomorphemic final cluster accuracyb Bimorphemic final cluster accuracyc
1 87 93 21 5/5 1/2
2 85 86 18 5/5 1/4
3 84 86 20 4/5 4/5
4 97 96 22 4/5 3/4
5 92 92 20 5/5 0/1
6 91 93 22 5/5 2/3
7 104 95 20 5/5 1/1
8 103 91 20 5/5 6/6
9 90 93 21 5/5 2/3
10 85 89 18 5/5
11 98 95 21 4/5 1/2
12 99 98 22 5/5 7/9
13 102 91 20 5/5 2/3
14 92 95 22 5/5
15 97 95 19 5/5 4/5
16 95 93 20 4/5 1/2
17 89 91 20 5/5 1/5
18 98 95 20 5/5 3/3
19 97 95 20 5/5 4/5
20 86 92 20 5/5
21 102 96 20 4/5 2/3
22 102 96 20 5/5 0/2
23 97 93 20 2/5 1/4
M 94.43 93 20.26 93.04 59.05
SD 6.38 2.98 1.07 14.28 31.02
Note. Dashes indicate no opportunities for production in the participant’s language sample.
Note. Dashes indicate no opportunities for production in the participant’s language sample.×
aConsonants used at least 3 times in initial or final word position, or those used correctly 2 times in initial or final word position.
aConsonants used at least 3 times in initial or final word position, or those used correctly 2 times in initial or final word position.×
bNumber of final clusters for which both consonants were correctly produced/5 BBTOP stimulus items with monomorphemic final clusters.
bNumber of final clusters for which both consonants were correctly produced/5 BBTOP stimulus items with monomorphemic final clusters.×
cNumber of final clusters for which both consonants were correctly produced/total number of bimorphemic final clusters obtained from language sample data.
cNumber of final clusters for which both consonants were correctly produced/total number of bimorphemic final clusters obtained from language sample data.×
×
TABLE 4 PLI participants' speech data.
PLI participants' speech data.×
Participant BBTOP (Word Inventory standard scores) PCC Phonetic inventory sizea Monomorphemic final cluster accuracyb Bimorphemic final cluster accuracyc
PLI/FCD−
25 82 81 21 3/6 0/1
26 79 77 19 3/6 6/6
27 70 76 19 5/6 0/2
28 65 57 16 3/6 0/1
31 78 80 17 4/6 3/3
32 67 56 18 1/6 1/2
34 67 69 17 5/6 2/2
36 65 51 12 3/6 2/3
38 74 71 20 5/6 1/5
39 65 56 17 1/6 3/4
40 75 79 20 4/6 5/6
42 76 71 15 4/6 2/3
44 65 52 15 2/6 0/4
45 65 65 18 2/6 1/1
46 71 69 19 2/6 1/1
47 65 39 12 3/6 0/1
48 65 45 16 1/6 1/2
49 72 79 19 5/6
50 74 66 18 3/6 2/2
51 77 75 19 2/6 0/5
52 75 73 19 3/6 2/6
53 73 65 15 2/6 4/6
54 65 57 15 1/6 0/3
55 65 52 17 1/6 7/10
58 83 81 20 3/6 2/9
59 65 34 15 1/6 0/4
60 65 46 15 0/6 1/1
61 65 27 14 0/6
63 82 84 21 4/6 3/3
M 70.86 63.21 17.17 43.69 52.00
SD 6.21 15.35 2.47 24.88 41.52
PLI/FCD+
24 65 38 14 1/6 0/2
29 69 65 18 1/6 0/2
30 71 62 17 2/6 0/2
33 65 41 12 1/6 1/3
35 65 48 12 2/6 3/7
37 65 49 14 1/6 0/2
41 65 33 12 0/6 2/3
43 65 35 11 0/6 0/1
56 65 38 11 2/6
57 65 54 16 1/6 4/6
62 71 60 15 2/6
M 66.45 47.55 13.82 19.73 29.61
SD 2.54 11.43 2.44 12.33 23.33
Note. Dashes indicate no opportunities for production in the participant’s language sample. PCC = percentage of consonants correct.
Note. Dashes indicate no opportunities for production in the participant’s language sample. PCC = percentage of consonants correct.×
aConsonants used at least 3 times in initial or final word position, or those used correctly 2 times in initial or final word position.
aConsonants used at least 3 times in initial or final word position, or those used correctly 2 times in initial or final word position.×
bNumber of final clusters for which both consonants were correctly produced/6 stimulus words with monomorphemic final clusters.
bNumber of final clusters for which both consonants were correctly produced/6 stimulus words with monomorphemic final clusters.×
cNumber of final clusters for which both consonants were correctly produced/total number of bimorphemic final clusters obtained from language sample data.
cNumber of final clusters for which both consonants were correctly produced/total number of bimorphemic final clusters obtained from language sample data.×
TABLE 4 PLI participants' speech data.
PLI participants' speech data.×
Participant BBTOP (Word Inventory standard scores) PCC Phonetic inventory sizea Monomorphemic final cluster accuracyb Bimorphemic final cluster accuracyc
PLI/FCD−
25 82 81 21 3/6 0/1
26 79 77 19 3/6 6/6
27 70 76 19 5/6 0/2
28 65 57 16 3/6 0/1
31 78 80 17 4/6 3/3
32 67 56 18 1/6 1/2
34 67 69 17 5/6 2/2
36 65 51 12 3/6 2/3
38 74 71 20 5/6 1/5
39 65 56 17 1/6 3/4
40 75 79 20 4/6 5/6
42 76 71 15 4/6 2/3
44 65 52 15 2/6 0/4
45 65 65 18 2/6 1/1
46 71 69 19 2/6 1/1
47 65 39 12 3/6 0/1
48 65 45 16 1/6 1/2
49 72 79 19 5/6
50 74 66 18 3/6 2/2
51 77 75 19 2/6 0/5
52 75 73 19 3/6 2/6
53 73 65 15 2/6 4/6
54 65 57 15 1/6 0/3
55 65 52 17 1/6 7/10
58 83 81 20 3/6 2/9
59 65 34 15 1/6 0/4
60 65 46 15 0/6 1/1
61 65 27 14 0/6
63 82 84 21 4/6 3/3
M 70.86 63.21 17.17 43.69 52.00
SD 6.21 15.35 2.47 24.88 41.52
PLI/FCD+
24 65 38 14 1/6 0/2
29 69 65 18 1/6 0/2
30 71 62 17 2/6 0/2
33 65 41 12 1/6 1/3
35 65 48 12 2/6 3/7
37 65 49 14 1/6 0/2
41 65 33 12 0/6 2/3
43 65 35 11 0/6 0/1
56 65 38 11 2/6
57 65 54 16 1/6 4/6
62 71 60 15 2/6
M 66.45 47.55 13.82 19.73 29.61
SD 2.54 11.43 2.44 12.33 23.33
Note. Dashes indicate no opportunities for production in the participant’s language sample. PCC = percentage of consonants correct.
Note. Dashes indicate no opportunities for production in the participant’s language sample. PCC = percentage of consonants correct.×
aConsonants used at least 3 times in initial or final word position, or those used correctly 2 times in initial or final word position.
aConsonants used at least 3 times in initial or final word position, or those used correctly 2 times in initial or final word position.×
bNumber of final clusters for which both consonants were correctly produced/6 stimulus words with monomorphemic final clusters.
bNumber of final clusters for which both consonants were correctly produced/6 stimulus words with monomorphemic final clusters.×
cNumber of final clusters for which both consonants were correctly produced/total number of bimorphemic final clusters obtained from language sample data.
cNumber of final clusters for which both consonants were correctly produced/total number of bimorphemic final clusters obtained from language sample data.×
×
Groups' final cluster data also are available for morphemic productions in spontaneous language samples. Children in the LI group correctly produced all consonants in final clusters for 72.93% (515/702) of finite and nonfinite morphemes in spontaneous language samples, whereas children in the PLI/FCD− subgroup correctly produced all consonants in final cluster finite and nonfinite forms for only 54.14% (432/798) of opportunities. This difference indicates that even though children in the PLI/FCD− group did not frequently omit final consonants or reduce final clusters based on their BBTOP performance, their impaired phonological skills may have affected their production of morphophonemic final clusters in spontaneous speech.
Language Sample Data
Data were obtained through analysis of spontaneous language samples that included mean sample sizes of 232 (SD = 58), 277 (SD = 95), and 195 (SD = 58) utterances for the LI, PLI, and control groups, respectively. Recording equipment included a Marantz PMD 430 stereo audio-recorder and a Sony EMC-T110 lapel microphone. Language samples were elicited by the first author or speech-language pathology graduate students either in the children’s preschool or at the University of Nevada Speech and Hearing Clinic. Language samples were centered around conversation about a standard toy set and wordless picture book from the Carl the Dog series (Day, 1986). Semi-structured scripts were followed to ensure a minimum of 3 obligatory contexts for Brown’s (1973)  14 grammatical morphemes. Obligatory contexts averaged 13.02 and ranged from 4 to 68 across language samples and individual morphemes.
Language samples were transcribed orthographically using the same equipment that was used for audio-recording. The first and second passes through the language samples were completed by the first author or a trained doctoral student. On the first pass, child utterances were transcribed. On the second pass, examiner utterances were added, child utterances were revised, and grammatical codes were added for child utterances to enable subsequent analysis with Systematic Analysis of Language Transcripts Version 6.1 (SALT; Miller & Chapman, 2000). For the third pass, trained speech-language pathology graduate student research assistants listened to language sample recordings that originally were transcribed and coded by the first author.
The graduate assistants were trained by transcribing and coding two language samples elicited from preschoolers with language impairments who were not participants in the present study. Assistants achieved a minimum of 90% agreement in transcription and 95% accuracy in grammatical coding before they were permitted to perform agreement procedures for the samples in this study. Assistants who met the training criteria noted all transcription disagreements for child utterances. The first author reviewed the assistants' corrections. Transcription discrepancies that persisted after the first author listened to the tape a second time were resolved through consensus. The first author served as expert transcriber in the few instances in which consensus could not be achieved. Mean point-by-point percentage agreement for transcription for the 63 language samples was 97% (range = 93%–99%). This percentage was calculated by dividing the number of matches by the total number of words and reflected the number of transcription agreements prior to consensus. Grammatical coding conventions were followed, as described in the SALT and Kansas Language Transcript Database (Howe, 1992) manuals. In the few instances in which coding discrepancies occurred (n = 18 across samples; the majority of which were omitted codes), coding manuals were consulted if needed and revisions were made as appropriate. The first author, who initially transcribed and coded the language samples, was aware of participants' group classification; however, the research assistants were blind to participants' classification.
Dependent Measures
Finite and nonfinite morpheme composite scores. Percentage correct usage in obligatory contexts was calculated for each morpheme of interest. Contexts for individual morphemes were found by SALT and were calculated by hand. Finite and nonfinite morpheme composites (Bedore & Leonard, 1998; Rice & Wexler, 1996) reflected a child’s combined percentage correct usage of several verbs and inflections, respectively. Following Bedore and Leonard’s conventions, forms included in the finite morpheme composite were third person singular –s (jumps), regular past tense –ed (jumped), and auxiliary and copula be forms (I amhappy; We arejumping). Nonfinite morpheme composites were calculated in the same manner as finite morpheme composites and reflected each child’s combined percentage correct usage of three nonfinite forms: articles (a,an, the), possessive 's (Mom'scar), and regular plural -s (two ducks).
IPSyn Sentence Structure subscale scores. Participants' sentence structure skills were evaluated using the Sentence Structure subscale of the Index of Productive Syntax (IPSyn), following the guidelines established by Scarborough (1990) . Up to two exemplars of 20 different sentence structure elements could be credited if found in a 100-utterance portion of a language sample, resulting in possible sentence structure scores in the range of 0 to 40.
For this measure, the first author completed initial scoring by hand and trained graduate student assistants checked for accuracy. In cases of disagreement, the IPSyn manual was consulted, and disagreed-upon items were corrected based on consensus. Prior to consensus, agreement for sentence structure scores ranged from 86% to 94%.
Statistical Analyses
Statistical analyses for this study included a 4 × 2 mixed-model analysis of variance (ANOVA) with two separate follow-up one-way ANOVAs and corresponding Tukey’s honestly significant difference (HSD) tests for pairwise comparisons, one t test, and a 2 × 2 ANOVA. Effect size for ANOVAs is reported through partial eta squared (ηp2), a measure that reflects the proportion of variance that is explainable between variables (Cohen, 1988). Because few, if any, studies have investigated the same research questions involving the types of subgroups of children in this study, effect sizes were interpreted using conventional ranges (Cohen, 1988, 1992; Kline, 2004). For the d statistic, .2 = small, .5 = medium, and .8 = large; for ηp2, small = .1, medium = .3, and large = .5. An alpha level of .05 was used for all analyses.
Results
To address the broad question of whether group differences existed for morpheme production between the LI, PLI/FCD−, PLI/FCD+, and control groups, a 4 (group) × 2 (morpheme composite) mixed-model ANOVA was applied. Figure 1 displays group means and standard deviations for finite and nonfinite morpheme composite results. Diagnostic group served as the between-subjects variable, and morpheme composite (finite and nonfinite) served as the within-subjects variable. A significant group-related difference, F(3, 79) = 14.40, p < .01, ηp2 = .35, and morpheme composite-related difference, F(1, 79) = 104.19, p < .01, ηp2 = .57, were found. A medium effect size for group and a large effect size for morpheme composite were found. An interaction between group and morpheme composite type was identified, F(3, 79) = 5.97, p = .001, ηp2 = .185.
FIGURE 1

Group means and standard deviations (in error bars) for finite morpheme composites (combined mean percentage correct usage of third person singular, regular past tense, and copula and auxiliary to be), nonfinite morpheme composites (combined percentage correct usage of plurals, possessives, and articles), percentage correct usage of plurals, and percentage correct usage of third person singular. Means are reported for the language-only impairment (LI; n = 23), speech (phonological)-language impairment with rarely exhibited final consonant deletion and/or final cluster reduction (PLI/FCD−; n = 29), speech (phonological)-language impairment with frequently exhibited final consonant deletion and/or final cluster reduction (PLI/FCD+; n = 11), and control (n = 20) groups.

 Group means and standard deviations (in error bars) for finite morpheme composites (combined mean percentage correct usage of third person singular, regular past tense, and copula and auxiliary to be), nonfinite morpheme composites (combined percentage correct usage of plurals, possessives, and articles), percentage correct usage of plurals, and percentage correct usage of third person singular. Means are reported for the language-only impairment (LI; n = 23), speech (phonological)-language impairment with rarely exhibited final consonant deletion and/or final cluster reduction (PLI/FCD−; n = 29), speech (phonological)-language impairment with frequently exhibited final consonant deletion and/or final cluster reduction (PLI/FCD+; n = 11), and control (n = 20) groups.
FIGURE 1

Group means and standard deviations (in error bars) for finite morpheme composites (combined mean percentage correct usage of third person singular, regular past tense, and copula and auxiliary to be), nonfinite morpheme composites (combined percentage correct usage of plurals, possessives, and articles), percentage correct usage of plurals, and percentage correct usage of third person singular. Means are reported for the language-only impairment (LI; n = 23), speech (phonological)-language impairment with rarely exhibited final consonant deletion and/or final cluster reduction (PLI/FCD−; n = 29), speech (phonological)-language impairment with frequently exhibited final consonant deletion and/or final cluster reduction (PLI/FCD+; n = 11), and control (n = 20) groups.

×
Finite Morpheme Composite
Participants in the LI group had a mean finite morpheme composite of 67.69 (SD = 20.57), whereas participants in the PLI/FCD− and PLI/FCD+ subgroups had mean scores of 46.71 (SD = 21.68) and 24.88 (SD = 24.82), respectively (see Figure 1). Control group participants had a mean score of 69.39 (SD = 21.52). Follow-up testing was completed for the finite morpheme composite measure by applying a one-way Group × Finite Morpheme composite ANOVA, which revealed a significant difference between the four groups, F(3, 79) = 13.98, p < .001, ηp2 = .347, with a medium effect size. Tukey’s HSD pairwise analyses were used to determine contrasts between participant groups for finite morpheme composite. Results revealed that participants in the LI group had significantly higher scores than children in both the PLI/FCD− (p = .005) and PLI/FCD+ (p < .001) subgroups. The PLI/FCD+ group had finite morpheme composite scores that were significantly lower than those achieved by PLI/FCD− (p = .029), LI (p = .005), and control (p < .001) peers. The PLI/FCD− group, like its PLI/FCD+ counterpart, had significantly lower finite morpheme composite scores than the control group (p = .003). The LI and no-impairment control participants did not have significantly different finite morpheme composite scores (p = .995).
Nonfinite Morpheme Composite
Group differences for nonfinite morpheme composites were examined using the same procedures described for finite morpheme composites. The LI, PLI/FCD−, PLI/FCD+, and no-impairment control groups had mean nonfinite morpheme composite scores of 85.20 (SD = 13.06), 85.35 (SD = 9.25), 62.31 (SD = 26.70), and 83.58 (SD = 15.99), respectively. A follow-up one-way Group × Nonfinite Morpheme composite ANOVA revealed significant group differences, F(3, 79) = 6.439, p = .001, ηp2 = .197, with a small effect size. Subsequent Tukey’s HSD pairwise comparisons revealed that nonfinite morpheme composite scores were not significantly different between the LI and PLI/FCD− (p = .91) or control (p = .985) groups. The PLI/FCD+ group had significantly lower scores than the other three groups: LI (p = .001), PLI/FCD− (p = .002), and control (p = .002). The PLI/FCD− and control groups did not have significantly different nonfinite morpheme composite scores (p = .992).
Syntactic Complexity
Children in the LI group achieved higher levels of accuracy than peers in the PLI group (combined PLI/FCD− and PLI/FCD+ groups) on the IPSyn (Scarborough, 1990) Sentence Structures subscale, a measure of syntactic complexity. Children in the LI group had a mean score of 21.96 on this measure, whereas children in the PLI group had a mean score of 15.28. The LI group’s mean score was significantly higher than the PLI group’s, t(61) = 5.80, p < .001, d = 1.54, with a large effect size.
To identify specific areas of difficulty that may have contributed to this group difference, a descriptive analysis was completed. As revealed in the Appendix, children in the PLI group received scores of 2 (i.e., full credit for the item category) on only the first four items. These items were the least syntactically challenging of the 20 items and involved basic subject-verb-(object) construction. Children in the LI group consistently had a greater proportion of participants who received scores of 2 and 1 relative to the PLI group for IPSyn Sentence Structures Items 5–18. Most of these syntactic items required the inclusion of function words or morphemes (e.g., conjunctions, infinitival to, relative pronouns) in addition to verb phrase elaboration. Chi-square analyses were completed for subscale Items S5–S18 and S20 to determine items for which the groups' performance differed. Results indicated significant group differences for the following Sentence Structure subscale items: S5/conjuctions χ2(2, n = 63) = 11.66, p < .01; S6/use two verb phrases χ2(2, n = 63) = 11.90, p < .01; S7/conjoined phrase χ2(2, n = 63) = 6.19, p = .05; S8/infinitive χ2(2, n = 63) = 9.57, p < .01; S10/adverbial conjunction χ2(2, n = 63) = 25.68, p < .01; S11/propositional complement χ2(2, n = 63) = 6.40, p = .05; S12/subject-conjunction-subject χ2(2, n = 63) = 6.03, p = .05; S13/wh-clause χ2(2, n = 63) = 8.16, p = .025; and S20/other sentence structures χ2(2, n = 63) = 9.52, p < .01. Group differences were not significant for the following subscale items: S9/introducers χ2(2, n = 63) = 2.32, p = 1.0; S14/bitransitive sentence χ2(2, n = 63) = 4.66, p = .10; S15/three verb phrase sentence χ2(2, n = 63) = .52; p = 1.0; S16/relative clause χ2(2, n = 63) = 3.54, p = .20; and S17/infinitive clause with new subject χ2(2, n = 63) = 4.19, p = .20. Chi-square analyses could not be completed for Items S1–S4 and S19 because participants in both groups did not have scores in one or more score columns.
Production of Specific Morphemes
Third person singular (verb-related) and plural forms (noun-related) are phonologically similar in the addition of /s/ or /z/ resulting in final clusters. These two morphemes showed a large discrepancy in their percentage of correct usage. Comparing their accuracy for the LI and PLI/FCD− groups enabled further examination of participants' finite and nonfinite morpheme skills, through analysis of forms ending in similar final consonant clusters. The LI group produced plurals with a mean percentage accuracy of 93.00 (SD = 11.15) and third person singular with a mean of 58.81 (SD = 24.47), while the PLI/FCD− group produced these forms with 71.88 (SD = 25.53) and 25.24% (SD = 24.27), respectively. Figure 1 displays LI and PLI/FCD− groups' mean percentage correct use and standard deviations for plural and third person singular forms. Results of a mixed-design 2 (group) × 2 (grammatical form) ANOVA, with group (LI and PLI/FCD−) as the between-subjects factor and grammatical form as the within-subjects factor, revealed significant main effects for group, F(1, 50) = 23.94, p < .001, ηp2 = .324, with a medium effect size, and form, F(1, 50) = 88.88, p < .001, ηp2 = .640, with a large effect size. The LI group had significantly higher mean accuracy for production of both forms than the PLI/FCD− group. Plural forms were produced with significantly higher accuracy than were third person singular forms. An interaction between group and form was not found, F(1, 50) = 3.86, p = .055, ηp2 = .072.
There was a concern that perhaps the specific types of final clusters resulting in the affixation of third person and plural forms might vary considerably, and thus comparison of the two forms would not be easily interpretable. Therefore, specific final clusters for each form were examined. Appraisal of cluster types revealed a surprisingly high degree of similarity in both numbers and types of plural and third person singular final cluster forms. Eighty percent (12/15) of final clusters were used in both plural and third person singular contexts. The twelve clusters that were used in both plural and third person singular contexts were _ps (chips,stops); _bz (tubes,grabs); _mps (lamps,jumps); _mz (times,bombs); _vz (gloves,drives); _ts (pets,sits); _dz (kids,rides); _nts (elephants,wants); _nz (ones,opens); _ŋz (things,hangs); _lz (animals,pulls); and _ks (snakes,likes). Three clusters that were used only in plural or third person singular contexts were _ŋks (thinks), _gz (dogs), and _sts (dentists).
Summary of Results
The LI group consistently outperformed both PLI subgroups, those with and without frequent final cluster reduction/consonant deletion, on finite morpheme and sentence structure measures. However, the LI group performed similarly to younger participants in a no-impairment control group on both finite and nonfinite composite measures. Finite morphemes were produced with higher accuracy than nonfinite forms for all groups. Phonologically similar yet grammatically different plural and third person singular forms were both produced with significantly higher levels by the LI group than the PLI/FCD− group. Both these groups, however, produced plurals with greater accuracy than third person singular forms.
Discussion
Finite and Nonfinite Morphemes
The finding that finite morphemes were more challenging than nonfinite morphemes for children in this study to produce is similar to reports from previous studies (Bedore & Leonard, 1998). It is important to consider that two of the three forms in the nonfinite morpheme composite, plural and possessive, are phonologically complex. If phonological characteristics alone were to be responsible for production accuracy rates, one would assume that nonfinite forms may be equally vulnerable to omission as finite forms that also primarily are phonologically complex. Importantly, even the PLI group with infrequent FCD/FCR was no different from the LI group in nonfinite morpheme production.
Production of Third Person Versus Plural Forms
When phonologically similar plurals and third person singular forms were examined, however, the PLI group with infrequent FCD/FCR performed worse than the LI group. Evidence from the present study and others (e.g., Rvachew et al., 2005) indicates that morphological production may not be related solely to children’s ability to produce final consonants or clusters. It may be the case that for children with a speech component to their impairment, deficits may be compounded in multiple, interacting domains, resulting in their poorer performance relative to peers with LI only.
Differences observed between the plural and third person singular forms for both the LI and PLI/FCD− groups highlight the apparent difficulty posed by finite morphemes. This was true even though the majority of final cluster types were the same for both plural and third person singular forms. These results are similar to those of Hayiou-Thomas et al. (2004)  in their study for which linguistic patterns frequently reported in children with SLI were simulated in a group of linguistically normal school-age children. The particular susceptibility for omission for third person singular may stem from its relatively low frequency of occurrence in the language and also from problems that occur in verb affixation. Such problems may stem from linguistic (i.e., morphological rule) deficits or from phonological factors, such as legality of resulting final clusters (Bernhardt & Stemberger, 2000) or acoustic saliency of the forms. Hayiou-Thomas and colleagues suggested that the pattern of performance favoring plurals over third person singular forms may be due not only to phonetic saliency and linguistic features of the forms but also to input frequency. It has been shown that not only is the plural more frequent than third person singular in speech directed to young language learners, it also occurs more often in sentence-final position, where it is longer in duration and thus more salient (Hsieh, Leonard, & Swanson, 1999).
Syntactic Complexity
On the sentence structure measure, children in the PLI group, including both PLI/FCD− and PLI/FCD+ participants, once again performed significantly worse than peers in the LI group. The “morphosyntax perspective” (Rice & Wexler, 1996, 2001) suggests that sentence structure rules and finite morphology are closely related in complex ways. Because of the interconnectedness of finite verbs and sentence structure, it is not surprising that children in the PLI group, who performed significantly worse than their LI counterparts on the finite morpheme measure, also performed worse than the LI group on the sentence structures measure. Many of the items on the IPSyn (Scarborough, 1990) Sentence Structures subscale not only required the use of challenging inflections and syntactic construction (e.g., use of multiple verb phrases, embedding) but also included weakly stressed words or syllables that have low perceptual salience (e.g., infinitival to, conjunctions, prepositions). Such items may be particularly challenging to produce at the sentence level for children who have a speech deficit in addition to language impairment.
Subgroups of Language Impairment
An important clinical implication of this study’s findings is that medium and large effect sizes were found for group performance on several morphological and syntactic measures. Such findings may indicate that different subgroups of children with language impairment may exist. Investigations of subgroups within the SLI population have revealed at least two groups with both morphosyntactic and speech deficits (Botting & Conti-Ramsden, 2004; Conti-Ramsden et al., 1997; Rapin & Allen, 1983). Although a comprehensive battery of measures was not administered to the participants in the present study, their deficits in both speech and language allow rough comparison to subgroups previously identified. Conti-Ramsden and colleagues' phonological-syntactic and expressive cluster subgroup descriptions best describe the children in the PLI group in the present study; however, the variable differentiating these two clusters, expressive vocabulary, was not available for the current participants. Conti-Ramsden and colleagues' lexical-syntactic cluster subgroup may best fit the children in the LI group in the present study. Children in the lexical-syntactic cluster reportedly had difficulties with grammatical comprehension, word reading, and story retelling, but age-appropriate phonology. Although comprehension was not a selection criterion for participants in the current study, it is noteworthy that the PLI groups' average receptive language standard score was 86, indicative of borderline, low-average performance and similar to grammatical comprehension percentiles of comparative subgroups.
Children who have both morphosyntactic and speech sound production deficits initially may be identified as having either a “primary” speech deficit or a language deficit. For example, Rvachew and her colleagues (2005)  and Paul and Shriberg (1982)  described the morphological skills of children they referred to as speech delayed, and other researchers have described speech/phonological deficits in populations of children identified as primarily language impaired. Previous findings from studies of subgroups along with the present group performances suggest that at least one distinct subgroup is characterized by deficits in both speech production and morphosyntax. One reason why preschool-age children may be identified first as being speech delayed is that syntactic measures such as the IPSyn or other language sample-based syntactic analyses may not be completed. The large effect size found between the LI and PLI groups on the IPSyn sentence structure subscale measure suggests that considerable group differences may exist between subgroups of children in the language impaired population. Standardized tests that frequently are used in clinical practice and in research studies may not reveal syntactic deficits as explicitly as measures based on language sample data. Incorporating such measures, therefore, may lead to improved determination of subgroups of children who have deficits in both domains.
Differences in morpheme production between the LI and PLI groups but similarities in morpheme production between the LI and control group suggest a greater confound when phonology is impaired. These findings may fit, in part, a domain-specific linguistic interpretation of SLI. The “computational grammatical complexity hypothesis” (Marshall & van der Lely, 2003; van der Lely, 2004, 2005) accounts for the cumulative effects of deficits in syntax, morphology, and phonology by suggesting these cause difficulty in building complex linguistic representations. Children in the present study, like the children described by Marshall and van der Lely, have characteristics of a core deficit that affects various components of grammar, as expressed not only by their finite and nonfinite morpheme composites and IPSyn (Scarborough, 1990) performance, but also their phonological performance. Marshall and van der Lely argue that the computational grammatical deficit account differs from the linguistic interpretations of SLI (e.g., the Extended Optional Infinitive account) because it describes where the deficit occurs within the linguistic system and how a cumulative effect in different levels of language may influence language skills.
However, what remains to be determined or explained by the results of this study or existing models of SLI is how, specifically, phonological complexity may contribute to morphosyntactic deficits. As numerous researchers, including Stemberger (2002), have pointed out, morpheme production for both children with typical and atypical language development may be influenced by combinations of multiple factors, such as frequency of the forms in the language and the phonotactic legality of resultant final clusters. Results of the present study are not completely explained by existing accounts of SLI; however, they do appear to support the observation that perhaps the cumulative effect of interacting phonological and perceptual factors involved in morpheme production may be compounded for children who have a deficit involving both speech and language.
Clinical Implications
Clinically, the findings from this investigation suggest that it is important to assess carefully the speech skills of preschoolers who have language deficits and vice versa, the language skills of preschoolers who have speech sound disorders. Morphosyntax, particularly finite morphology, is a known area of deficit that is likely to affect the language production skills of young children with SLI. Because many finite morphemes contain final clusters, it would be ideal for screenings used for participant selection to include final clusters reflective of the types resulting from morpheme affixation (e.g., __ts, __ks, __nz, __gz, and __dz). Frequently used monomorphemic screenings tend to be primarily composed of stimuli with final /s, z, t, d/ singletons such as hose. The ability to produce final consonants in nonmorphemic probes may not be an adequate indicator of a child’s speech “sufficiency” for producing morphophonemes. The solution to this problem is very complicated, however, because as Bernhardt and Stemberger (2000)  pointed out, many inflected verb forms result in phonotactically illegal clusters that are found only in monomorphemic grammatical contexts. The types of final clusters that frequently result from morpheme affixation are not able to be simulated through a monomorphemic consonant probe. Clearly, including such clusters (e.g., _gd) in inflectional contexts in phonological probes would further confound the already complicated interpretation of the interaction of phonology and morphosyntax.
The heterogeneous nature of subgroups of children with SLI may warrant the application of different intervention techniques and careful prioritization of intervention goals. For example, one may consider the finding that children in the LI group performed similarly to younger control participants on the finite morpheme measure, but children in both PLI subgroups performed significantly worse than the control group. This may suggest that prioritizing goals to include finite morphemes may be particularly important for children who have a phonological component to their language impairment (Haskill, Tyler, & Tolbert, 2001). Further, the findings of this study suggest that particular morpheme-specific final consonant clusters may be important to include as intervention stimuli. Specifically, the final clusters with which the children in the PLI/FCD− group had the most difficulty, in comparison to children in the SLI group, included the following: __ts, __mpt, __mz, __nts, __nz, __ks, and __gz.
Conclusion
In conclusion, finite morphemes are challenging for both typically developing children and children with SLI to perceive and produce. Children with co-occurring speech sound deficits repeatedly were outperformed by children with LI only. Children with LI only, however, had similar performance as younger, typically developing children for finite and nonfinite morpheme measures. These findings allude to the complexity of the relationship between speech sound production and morphosyntactic skills. Final consonant and final cluster production ability appeared to be necessary, but not sufficient, for successful morphosyntactic production. Through future research, improved understanding of the relationship between speech sound production and morphosyntax may result in more effective assessment tools and interventions for the relatively large number of children in the subgroup who have deficits in both areas.
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Appendix
LI and PLI Participants' Performance on Index of Productive Syntax (Scarborough, 1990) Sentence Structures Subscale Items
Item: subscale LI participants receiving each score PLI participants receiving each score
2 1 0 2 1 0
% n % n % n % n % n % n
S1: Any 2 words 100 23 0 0 0 0 100 40 0 0 0 0
S2: Subject-verb 100 23 0 0 0 0 100 40 0 0 0 0
S3: Verb-direct object 100 23 0 0 0 0 100 40 0 0 0 0
S4: Subject-verb-object 100 23 0 0 0 0 100 40 0 0 0 0
S5: Uses any conjunction 96 22 4 1 0 0 55 22 23 9 23 9
S6: Uses any 2 verb phrases 91 21 9 2 0 0 50 20 20 8 30 12
S7: Conjoined phrase 57 13 30 7 13 3 33 13 25 10 42 17
S8: Infinitive 61 14 13 3 26 6 23 9 35 13 42 17
S9: Introducers (e.g., let’s) 26 6 39 9 35 8 13 5 38 15 49 20
S10: Adverbial conjunction 78 18 22 5 0 0 18 7 32 13 50 20
S11: Propositional comp. 17 4 26 6 57 13 8 3 8 3 84 34
S12: S-conjunction-S 13 3 26 6 61 14 13 5 5 2 82 33
S13: Wh- clause 31 7 39 9 31 7 13 5 20 8 67 27
S14: Bitransitive sentence 4 1 22 5 74 17 0 0 8 3 92 37
S15: Sentence with 3 verb phrases 4 1 9 2 87 20 3 1 5 2 92 37
S16: Relative clause 13 3 22 5 65 15 8 3 8 3 84 34
S17: Infinitive (2) 9 2 13 3 78 18 3 1 3 1 94 38
S18: Gerund 30 7 26 6 44 10 3 1 13 5 84 34
S19: Move subject 4 1 0 0 96 22 4 2 0 0 96 38
S20: Other sentence structures 13 3 30 7 57 13 0 0 13 5 87 35
Note. For SLI group, n = 23; for PLI group, n = 40; boldface type indicates items for which the children in the LI group received a significantly higher proportion of scores of 2 or 1 than the children in the PLI group, based on chi-square testing. Chi-square analyses were not possible for Items S1–S4 and S19.
Note. For SLI group, n = 23; for PLI group, n = 40; boldface type indicates items for which the children in the LI group received a significantly higher proportion of scores of 2 or 1 than the children in the PLI group, based on chi-square testing. Chi-square analyses were not possible for Items S1–S4 and S19.×
Item: subscale LI participants receiving each score PLI participants receiving each score
2 1 0 2 1 0
% n % n % n % n % n % n
S1: Any 2 words 100 23 0 0 0 0 100 40 0 0 0 0
S2: Subject-verb 100 23 0 0 0 0 100 40 0 0 0 0
S3: Verb-direct object 100 23 0 0 0 0 100 40 0 0 0 0
S4: Subject-verb-object 100 23 0 0 0 0 100 40 0 0 0 0
S5: Uses any conjunction 96 22 4 1 0 0 55 22 23 9 23 9
S6: Uses any 2 verb phrases 91 21 9 2 0 0 50 20 20 8 30 12
S7: Conjoined phrase 57 13 30 7 13 3 33 13 25 10 42 17
S8: Infinitive 61 14 13 3 26 6 23 9 35 13 42 17
S9: Introducers (e.g., let’s) 26 6 39 9 35 8 13 5 38 15 49 20
S10: Adverbial conjunction 78 18 22 5 0 0 18 7 32 13 50 20
S11: Propositional comp. 17 4 26 6 57 13 8 3 8 3 84 34
S12: S-conjunction-S 13 3 26 6 61 14 13 5 5 2 82 33
S13: Wh- clause 31 7 39 9 31 7 13 5 20 8 67 27
S14: Bitransitive sentence 4 1 22 5 74 17 0 0 8 3 92 37
S15: Sentence with 3 verb phrases 4 1 9 2 87 20 3 1 5 2 92 37
S16: Relative clause 13 3 22 5 65 15 8 3 8 3 84 34
S17: Infinitive (2) 9 2 13 3 78 18 3 1 3 1 94 38
S18: Gerund 30 7 26 6 44 10 3 1 13 5 84 34
S19: Move subject 4 1 0 0 96 22 4 2 0 0 96 38
S20: Other sentence structures 13 3 30 7 57 13 0 0 13 5 87 35
Note. For SLI group, n = 23; for PLI group, n = 40; boldface type indicates items for which the children in the LI group received a significantly higher proportion of scores of 2 or 1 than the children in the PLI group, based on chi-square testing. Chi-square analyses were not possible for Items S1–S4 and S19.
Note. For SLI group, n = 23; for PLI group, n = 40; boldface type indicates items for which the children in the LI group received a significantly higher proportion of scores of 2 or 1 than the children in the PLI group, based on chi-square testing. Chi-square analyses were not possible for Items S1–S4 and S19.×
×
FIGURE 1

Group means and standard deviations (in error bars) for finite morpheme composites (combined mean percentage correct usage of third person singular, regular past tense, and copula and auxiliary to be), nonfinite morpheme composites (combined percentage correct usage of plurals, possessives, and articles), percentage correct usage of plurals, and percentage correct usage of third person singular. Means are reported for the language-only impairment (LI; n = 23), speech (phonological)-language impairment with rarely exhibited final consonant deletion and/or final cluster reduction (PLI/FCD−; n = 29), speech (phonological)-language impairment with frequently exhibited final consonant deletion and/or final cluster reduction (PLI/FCD+; n = 11), and control (n = 20) groups.

 Group means and standard deviations (in error bars) for finite morpheme composites (combined mean percentage correct usage of third person singular, regular past tense, and copula and auxiliary to be), nonfinite morpheme composites (combined percentage correct usage of plurals, possessives, and articles), percentage correct usage of plurals, and percentage correct usage of third person singular. Means are reported for the language-only impairment (LI; n = 23), speech (phonological)-language impairment with rarely exhibited final consonant deletion and/or final cluster reduction (PLI/FCD−; n = 29), speech (phonological)-language impairment with frequently exhibited final consonant deletion and/or final cluster reduction (PLI/FCD+; n = 11), and control (n = 20) groups.
FIGURE 1

Group means and standard deviations (in error bars) for finite morpheme composites (combined mean percentage correct usage of third person singular, regular past tense, and copula and auxiliary to be), nonfinite morpheme composites (combined percentage correct usage of plurals, possessives, and articles), percentage correct usage of plurals, and percentage correct usage of third person singular. Means are reported for the language-only impairment (LI; n = 23), speech (phonological)-language impairment with rarely exhibited final consonant deletion and/or final cluster reduction (PLI/FCD−; n = 29), speech (phonological)-language impairment with frequently exhibited final consonant deletion and/or final cluster reduction (PLI/FCD+; n = 11), and control (n = 20) groups.

×
TABLE 1 Identifying information for the study groups.
Identifying information for the study groups.×
Group N (M/F) Age in months MLU Speech production scores Expressive language scores Receptive language scores Nonverbal scores
    M SD M SD M SD M SD M SD M SD
LI 23 (15/8) 59.62 6.90 3.49 0.62 94.43 6.38 74.91 7.59 86.30 9.21 95.26 7.05
PLI/FCD− 29 (19/10) 51.38 7.32 2.91 0.52 71.28 5.99 80.04 10.53 86.64 14.72 101.62 10.50
PLI/FCD+ 11 (8/3) 48.36 4.76 2.15 0.62 65.36 1.21 71.20 12.70 83.67 17.46 104.18 9.20
Control 20 (8/12) 36.00 0.83 4.01 0.70 97.85 7.82 107.4 14.60
Note. Speech production scores were obtained from the Word Inventory of the Bankson–Bernthal Test of Phonology (BBTOP) for the LI and PLI groups and from the Arizona Articulation Proficiency Scale, Third Revision for the control group; expressive language scores were obtained from the Clinical Evaluation of Language Fundamentals—Preschool (CELF–P) or Preschool Language Scale, Third Edition (PLS–3); receptive language scores were obtained from the CELF–P, PLS–3, or Peabody Picture Vocabulary Test—III; nonverbal scores were obtained from the Kaufman Assessment Battery for Children or the Columbia Mental Maturity Scale. Dashes indicate that scores were not available. MLU = mean length of utterance in morphemes; LI = language-only impairment; PLI/FCD− = speech (phonological)-language impairment with rarely exhibited final consonant deletion and/or final cluster reduction (FCR); PLI/FCD+ = PLI with frequently exhibited FCD/FCR.
Note. Speech production scores were obtained from the Word Inventory of the Bankson–Bernthal Test of Phonology (BBTOP) for the LI and PLI groups and from the Arizona Articulation Proficiency Scale, Third Revision for the control group; expressive language scores were obtained from the Clinical Evaluation of Language Fundamentals—Preschool (CELF–P) or Preschool Language Scale, Third Edition (PLS–3); receptive language scores were obtained from the CELF–P, PLS–3, or Peabody Picture Vocabulary Test—III; nonverbal scores were obtained from the Kaufman Assessment Battery for Children or the Columbia Mental Maturity Scale. Dashes indicate that scores were not available. MLU = mean length of utterance in morphemes; LI = language-only impairment; PLI/FCD− = speech (phonological)-language impairment with rarely exhibited final consonant deletion and/or final cluster reduction (FCR); PLI/FCD+ = PLI with frequently exhibited FCD/FCR.×
TABLE 1 Identifying information for the study groups.
Identifying information for the study groups.×
Group N (M/F) Age in months MLU Speech production scores Expressive language scores Receptive language scores Nonverbal scores
    M SD M SD M SD M SD M SD M SD
LI 23 (15/8) 59.62 6.90 3.49 0.62 94.43 6.38 74.91 7.59 86.30 9.21 95.26 7.05
PLI/FCD− 29 (19/10) 51.38 7.32 2.91 0.52 71.28 5.99 80.04 10.53 86.64 14.72 101.62 10.50
PLI/FCD+ 11 (8/3) 48.36 4.76 2.15 0.62 65.36 1.21 71.20 12.70 83.67 17.46 104.18 9.20
Control 20 (8/12) 36.00 0.83 4.01 0.70 97.85 7.82 107.4 14.60
Note. Speech production scores were obtained from the Word Inventory of the Bankson–Bernthal Test of Phonology (BBTOP) for the LI and PLI groups and from the Arizona Articulation Proficiency Scale, Third Revision for the control group; expressive language scores were obtained from the Clinical Evaluation of Language Fundamentals—Preschool (CELF–P) or Preschool Language Scale, Third Edition (PLS–3); receptive language scores were obtained from the CELF–P, PLS–3, or Peabody Picture Vocabulary Test—III; nonverbal scores were obtained from the Kaufman Assessment Battery for Children or the Columbia Mental Maturity Scale. Dashes indicate that scores were not available. MLU = mean length of utterance in morphemes; LI = language-only impairment; PLI/FCD− = speech (phonological)-language impairment with rarely exhibited final consonant deletion and/or final cluster reduction (FCR); PLI/FCD+ = PLI with frequently exhibited FCD/FCR.
Note. Speech production scores were obtained from the Word Inventory of the Bankson–Bernthal Test of Phonology (BBTOP) for the LI and PLI groups and from the Arizona Articulation Proficiency Scale, Third Revision for the control group; expressive language scores were obtained from the Clinical Evaluation of Language Fundamentals—Preschool (CELF–P) or Preschool Language Scale, Third Edition (PLS–3); receptive language scores were obtained from the CELF–P, PLS–3, or Peabody Picture Vocabulary Test—III; nonverbal scores were obtained from the Kaufman Assessment Battery for Children or the Columbia Mental Maturity Scale. Dashes indicate that scores were not available. MLU = mean length of utterance in morphemes; LI = language-only impairment; PLI/FCD− = speech (phonological)-language impairment with rarely exhibited final consonant deletion and/or final cluster reduction (FCR); PLI/FCD+ = PLI with frequently exhibited FCD/FCR.×
×
TABLE 2 Rank ordering of PLI participants' percentage use of final cluster reduction and final consonant deletion.
Rank ordering of PLI participants' percentage use of final cluster reduction and final consonant deletion.×
Participant % final cluster reduction/final consonant deletion Participant % final cluster reduction/final consonant deletion
27 0 26 8
25 3 46 8
36 3 28 9
51 3 32 9
52 3 59 10
39 3 54 10
38 3 55 10
31 4 60 10
42 4 43 10
30 4 37 13
47 4 29 13
34 4 57 13
53 4 56 14
40 4 43 17
49 4 48 22
63 4 35 23
44 6 33 33
50 6 41 42
58 7 61 42
62 7 24 43
Note. Median = 7.5; upper quartile = 13.
Note. Median = 7.5; upper quartile = 13.×
TABLE 2 Rank ordering of PLI participants' percentage use of final cluster reduction and final consonant deletion.
Rank ordering of PLI participants' percentage use of final cluster reduction and final consonant deletion.×
Participant % final cluster reduction/final consonant deletion Participant % final cluster reduction/final consonant deletion
27 0 26 8
25 3 46 8
36 3 28 9
51 3 32 9
52 3 59 10
39 3 54 10
38 3 55 10
31 4 60 10
42 4 43 10
30 4 37 13
47 4 29 13
34 4 57 13
53 4 56 14
40 4 43 17
49 4 48 22
63 4 35 23
44 6 33 33
50 6 41 42
58 7 61 42
62 7 24 43
Note. Median = 7.5; upper quartile = 13.
Note. Median = 7.5; upper quartile = 13.×
×
TABLE 3 LI participants' speech data.
LI participants' speech data.×
Participant BBTOP (Word Inventory standard scores) Percentage of consonants correct Number of consonants in phonetic inventorya Monomorphemic final cluster accuracyb Bimorphemic final cluster accuracyc
1 87 93 21 5/5 1/2
2 85 86 18 5/5 1/4
3 84 86 20 4/5 4/5
4 97 96 22 4/5 3/4
5 92 92 20 5/5 0/1
6 91 93 22 5/5 2/3
7 104 95 20 5/5 1/1
8 103 91 20 5/5 6/6
9 90 93 21 5/5 2/3
10 85 89 18 5/5
11 98 95 21 4/5 1/2
12 99 98 22 5/5 7/9
13 102 91 20 5/5 2/3
14 92 95 22 5/5
15 97 95 19 5/5 4/5
16 95 93 20 4/5 1/2
17 89 91 20 5/5 1/5
18 98 95 20 5/5 3/3
19 97 95 20 5/5 4/5
20 86 92 20 5/5
21 102 96 20 4/5 2/3
22 102 96 20 5/5 0/2
23 97 93 20 2/5 1/4
M 94.43 93 20.26 93.04 59.05
SD 6.38 2.98 1.07 14.28 31.02
Note. Dashes indicate no opportunities for production in the participant’s language sample.
Note. Dashes indicate no opportunities for production in the participant’s language sample.×
aConsonants used at least 3 times in initial or final word position, or those used correctly 2 times in initial or final word position.
aConsonants used at least 3 times in initial or final word position, or those used correctly 2 times in initial or final word position.×
bNumber of final clusters for which both consonants were correctly produced/5 BBTOP stimulus items with monomorphemic final clusters.
bNumber of final clusters for which both consonants were correctly produced/5 BBTOP stimulus items with monomorphemic final clusters.×
cNumber of final clusters for which both consonants were correctly produced/total number of bimorphemic final clusters obtained from language sample data.
cNumber of final clusters for which both consonants were correctly produced/total number of bimorphemic final clusters obtained from language sample data.×
TABLE 3 LI participants' speech data.
LI participants' speech data.×
Participant BBTOP (Word Inventory standard scores) Percentage of consonants correct Number of consonants in phonetic inventorya Monomorphemic final cluster accuracyb Bimorphemic final cluster accuracyc
1 87 93 21 5/5 1/2
2 85 86 18 5/5 1/4
3 84 86 20 4/5 4/5
4 97 96 22 4/5 3/4
5 92 92 20 5/5 0/1
6 91 93 22 5/5 2/3
7 104 95 20 5/5 1/1
8 103 91 20 5/5 6/6
9 90 93 21 5/5 2/3
10 85 89 18 5/5
11 98 95 21 4/5 1/2
12 99 98 22 5/5 7/9
13 102 91 20 5/5 2/3
14 92 95 22 5/5
15 97 95 19 5/5 4/5
16 95 93 20 4/5 1/2
17 89 91 20 5/5 1/5
18 98 95 20 5/5 3/3
19 97 95 20 5/5 4/5
20 86 92 20 5/5
21 102 96 20 4/5 2/3
22 102 96 20 5/5 0/2
23 97 93 20 2/5 1/4
M 94.43 93 20.26 93.04 59.05
SD 6.38 2.98 1.07 14.28 31.02
Note. Dashes indicate no opportunities for production in the participant’s language sample.
Note. Dashes indicate no opportunities for production in the participant’s language sample.×
aConsonants used at least 3 times in initial or final word position, or those used correctly 2 times in initial or final word position.
aConsonants used at least 3 times in initial or final word position, or those used correctly 2 times in initial or final word position.×
bNumber of final clusters for which both consonants were correctly produced/5 BBTOP stimulus items with monomorphemic final clusters.
bNumber of final clusters for which both consonants were correctly produced/5 BBTOP stimulus items with monomorphemic final clusters.×
cNumber of final clusters for which both consonants were correctly produced/total number of bimorphemic final clusters obtained from language sample data.
cNumber of final clusters for which both consonants were correctly produced/total number of bimorphemic final clusters obtained from language sample data.×
×
TABLE 4 PLI participants' speech data.
PLI participants' speech data.×
Participant BBTOP (Word Inventory standard scores) PCC Phonetic inventory sizea Monomorphemic final cluster accuracyb Bimorphemic final cluster accuracyc
PLI/FCD−
25 82 81 21 3/6 0/1
26 79 77 19 3/6 6/6
27 70 76 19 5/6 0/2
28 65 57 16 3/6 0/1
31 78 80 17 4/6 3/3
32 67 56 18 1/6 1/2
34 67 69 17 5/6 2/2
36 65 51 12 3/6 2/3
38 74 71 20 5/6 1/5
39 65 56 17 1/6 3/4
40 75 79 20 4/6 5/6
42 76 71 15 4/6 2/3
44 65 52 15 2/6 0/4
45 65 65 18 2/6 1/1
46 71 69 19 2/6 1/1
47 65 39 12 3/6 0/1
48 65 45 16 1/6 1/2
49 72 79 19 5/6
50 74 66 18 3/6 2/2
51 77 75 19 2/6 0/5
52 75 73 19 3/6 2/6
53 73 65 15 2/6 4/6
54 65 57 15 1/6 0/3
55 65 52 17 1/6 7/10
58 83 81 20 3/6 2/9
59 65 34 15 1/6 0/4
60 65 46 15 0/6 1/1
61 65 27 14 0/6
63 82 84 21 4/6 3/3
M 70.86 63.21 17.17 43.69 52.00
SD 6.21 15.35 2.47 24.88 41.52
PLI/FCD+
24 65 38 14 1/6 0/2
29 69 65 18 1/6 0/2
30 71 62 17 2/6 0/2
33 65 41 12 1/6 1/3
35 65 48 12 2/6 3/7
37 65 49 14 1/6 0/2
41 65 33 12 0/6 2/3
43 65 35 11 0/6 0/1
56 65 38 11 2/6
57 65 54 16 1/6 4/6
62 71 60 15 2/6
M 66.45 47.55 13.82 19.73 29.61
SD 2.54 11.43 2.44 12.33 23.33
Note. Dashes indicate no opportunities for production in the participant’s language sample. PCC = percentage of consonants correct.
Note. Dashes indicate no opportunities for production in the participant’s language sample. PCC = percentage of consonants correct.×
aConsonants used at least 3 times in initial or final word position, or those used correctly 2 times in initial or final word position.
aConsonants used at least 3 times in initial or final word position, or those used correctly 2 times in initial or final word position.×
bNumber of final clusters for which both consonants were correctly produced/6 stimulus words with monomorphemic final clusters.
bNumber of final clusters for which both consonants were correctly produced/6 stimulus words with monomorphemic final clusters.×
cNumber of final clusters for which both consonants were correctly produced/total number of bimorphemic final clusters obtained from language sample data.
cNumber of final clusters for which both consonants were correctly produced/total number of bimorphemic final clusters obtained from language sample data.×
TABLE 4 PLI participants' speech data.
PLI participants' speech data.×
Participant BBTOP (Word Inventory standard scores) PCC Phonetic inventory sizea Monomorphemic final cluster accuracyb Bimorphemic final cluster accuracyc
PLI/FCD−
25 82 81 21 3/6 0/1
26 79 77 19 3/6 6/6
27 70 76 19 5/6 0/2
28 65 57 16 3/6 0/1
31 78 80 17 4/6 3/3
32 67 56 18 1/6 1/2
34 67 69 17 5/6 2/2
36 65 51 12 3/6 2/3
38 74 71 20 5/6 1/5
39 65 56 17 1/6 3/4
40 75 79 20 4/6 5/6
42 76 71 15 4/6 2/3
44 65 52 15 2/6 0/4
45 65 65 18 2/6 1/1
46 71 69 19 2/6 1/1
47 65 39 12 3/6 0/1
48 65 45 16 1/6 1/2
49 72 79 19 5/6
50 74 66 18 3/6 2/2
51 77 75 19 2/6 0/5
52 75 73 19 3/6 2/6
53 73 65 15 2/6 4/6
54 65 57 15 1/6 0/3
55 65 52 17 1/6 7/10
58 83 81 20 3/6 2/9
59 65 34 15 1/6 0/4
60 65 46 15 0/6 1/1
61 65 27 14 0/6
63 82 84 21 4/6 3/3
M 70.86 63.21 17.17 43.69 52.00
SD 6.21 15.35 2.47 24.88 41.52
PLI/FCD+
24 65 38 14 1/6 0/2
29 69 65 18 1/6 0/2
30 71 62 17 2/6 0/2
33 65 41 12 1/6 1/3
35 65 48 12 2/6 3/7
37 65 49 14 1/6 0/2
41 65 33 12 0/6 2/3
43 65 35 11 0/6 0/1
56 65 38 11 2/6
57 65 54 16 1/6 4/6
62 71 60 15 2/6
M 66.45 47.55 13.82 19.73 29.61
SD 2.54 11.43 2.44 12.33 23.33
Note. Dashes indicate no opportunities for production in the participant’s language sample. PCC = percentage of consonants correct.
Note. Dashes indicate no opportunities for production in the participant’s language sample. PCC = percentage of consonants correct.×
aConsonants used at least 3 times in initial or final word position, or those used correctly 2 times in initial or final word position.
aConsonants used at least 3 times in initial or final word position, or those used correctly 2 times in initial or final word position.×
bNumber of final clusters for which both consonants were correctly produced/6 stimulus words with monomorphemic final clusters.
bNumber of final clusters for which both consonants were correctly produced/6 stimulus words with monomorphemic final clusters.×
cNumber of final clusters for which both consonants were correctly produced/total number of bimorphemic final clusters obtained from language sample data.
cNumber of final clusters for which both consonants were correctly produced/total number of bimorphemic final clusters obtained from language sample data.×
×
Item: subscale LI participants receiving each score PLI participants receiving each score
2 1 0 2 1 0
% n % n % n % n % n % n
S1: Any 2 words 100 23 0 0 0 0 100 40 0 0 0 0
S2: Subject-verb 100 23 0 0 0 0 100 40 0 0 0 0
S3: Verb-direct object 100 23 0 0 0 0 100 40 0 0 0 0
S4: Subject-verb-object 100 23 0 0 0 0 100 40 0 0 0 0
S5: Uses any conjunction 96 22 4 1 0 0 55 22 23 9 23 9
S6: Uses any 2 verb phrases 91 21 9 2 0 0 50 20 20 8 30 12
S7: Conjoined phrase 57 13 30 7 13 3 33 13 25 10 42 17
S8: Infinitive 61 14 13 3 26 6 23 9 35 13 42 17
S9: Introducers (e.g., let’s) 26 6 39 9 35 8 13 5 38 15 49 20
S10: Adverbial conjunction 78 18 22 5 0 0 18 7 32 13 50 20
S11: Propositional comp. 17 4 26 6 57 13 8 3 8 3 84 34
S12: S-conjunction-S 13 3 26 6 61 14 13 5 5 2 82 33
S13: Wh- clause 31 7 39 9 31 7 13 5 20 8 67 27
S14: Bitransitive sentence 4 1 22 5 74 17 0 0 8 3 92 37
S15: Sentence with 3 verb phrases 4 1 9 2 87 20 3 1 5 2 92 37
S16: Relative clause 13 3 22 5 65 15 8 3 8 3 84 34
S17: Infinitive (2) 9 2 13 3 78 18 3 1 3 1 94 38
S18: Gerund 30 7 26 6 44 10 3 1 13 5 84 34
S19: Move subject 4 1 0 0 96 22 4 2 0 0 96 38
S20: Other sentence structures 13 3 30 7 57 13 0 0 13 5 87 35
Note. For SLI group, n = 23; for PLI group, n = 40; boldface type indicates items for which the children in the LI group received a significantly higher proportion of scores of 2 or 1 than the children in the PLI group, based on chi-square testing. Chi-square analyses were not possible for Items S1–S4 and S19.
Note. For SLI group, n = 23; for PLI group, n = 40; boldface type indicates items for which the children in the LI group received a significantly higher proportion of scores of 2 or 1 than the children in the PLI group, based on chi-square testing. Chi-square analyses were not possible for Items S1–S4 and S19.×
Item: subscale LI participants receiving each score PLI participants receiving each score
2 1 0 2 1 0
% n % n % n % n % n % n
S1: Any 2 words 100 23 0 0 0 0 100 40 0 0 0 0
S2: Subject-verb 100 23 0 0 0 0 100 40 0 0 0 0
S3: Verb-direct object 100 23 0 0 0 0 100 40 0 0 0 0
S4: Subject-verb-object 100 23 0 0 0 0 100 40 0 0 0 0
S5: Uses any conjunction 96 22 4 1 0 0 55 22 23 9 23 9
S6: Uses any 2 verb phrases 91 21 9 2 0 0 50 20 20 8 30 12
S7: Conjoined phrase 57 13 30 7 13 3 33 13 25 10 42 17
S8: Infinitive 61 14 13 3 26 6 23 9 35 13 42 17
S9: Introducers (e.g., let’s) 26 6 39 9 35 8 13 5 38 15 49 20
S10: Adverbial conjunction 78 18 22 5 0 0 18 7 32 13 50 20
S11: Propositional comp. 17 4 26 6 57 13 8 3 8 3 84 34
S12: S-conjunction-S 13 3 26 6 61 14 13 5 5 2 82 33
S13: Wh- clause 31 7 39 9 31 7 13 5 20 8 67 27
S14: Bitransitive sentence 4 1 22 5 74 17 0 0 8 3 92 37
S15: Sentence with 3 verb phrases 4 1 9 2 87 20 3 1 5 2 92 37
S16: Relative clause 13 3 22 5 65 15 8 3 8 3 84 34
S17: Infinitive (2) 9 2 13 3 78 18 3 1 3 1 94 38
S18: Gerund 30 7 26 6 44 10 3 1 13 5 84 34
S19: Move subject 4 1 0 0 96 22 4 2 0 0 96 38
S20: Other sentence structures 13 3 30 7 57 13 0 0 13 5 87 35
Note. For SLI group, n = 23; for PLI group, n = 40; boldface type indicates items for which the children in the LI group received a significantly higher proportion of scores of 2 or 1 than the children in the PLI group, based on chi-square testing. Chi-square analyses were not possible for Items S1–S4 and S19.
Note. For SLI group, n = 23; for PLI group, n = 40; boldface type indicates items for which the children in the LI group received a significantly higher proportion of scores of 2 or 1 than the children in the PLI group, based on chi-square testing. Chi-square analyses were not possible for Items S1–S4 and S19.×
×