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Reading and Writing: An Interdisciplinary Journal 15: 389–407, 2002. © 2002 Kluwer Academic Publishers. Printed in the Netherlands.

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Correlates of spelling abilities in children with early speech sound disorders BARBARA A. LEWIS, LISA A. FREEBAIRN & H. GERRY TAYLOR Department of Pediatrics, Rainbow Babies and Childrens Hospital, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA Abstract. The correlates of spelling impairment were examined in children with histories of early speech sound disorders. The spelling errors of 52 children with histories of speech sound disorders were analyzed to predict the association between weaknesses in expressive language skills in early childhood and school-age spelling abilities. Results revealed that children with preschool speech sound and language problems became poorer spellers at school age than did children with preschool speech sound disorders only. However, even children with isolated speech sound disorders demonstrated a weakness in spelling skills relative to their reading and language abilities and Weschler Performance IQ. Measures of phonological awareness were highly correlated with spelling skills, suggesting that phonological processing abilities are related to the ability to spell phonetically predictable words. Analysis of spelling errors based on level of phonological awareness skill revealed that children with preschool speech sound disorders utilize phonetic strategies in spelling phonetically predictable words. Familial aggregation of spelling disorders suggests a possible genetic component that is modified by gender. Key words: Genetics, Language, Phonology, Reading, Speech disorders, Spelling

Introduction The association of early speech and language disorders with later spelling impairments has not been as extensively studied as have relationships between these disorders and reading problems (Clark-Klein 1994; Webster Plante & Couvillion 1997). However, a growing body of research suggests that children with early speech sound disorders1 may be at risk for spelling difficulties since spelling abilities may be even more closely related to phonological processing abilities than reading (Richgels 1995). Co-morbid conditions, such as poor language skills and poor reading abilities, may contribute to spelling difficulties in children with early speech sound disorders. Further, familial aggregation of speech, language, reading, and spelling disorders suggests a possible genetic component to spelling impairment. Genetic factors may thus place children with early speech sound disorders at risk for later academic difficulties including spelling.

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Spelling and phonological processing Spelling relies heavily on phonological processing, including phoneme awareness, sound segmentation, auditory sequencing, phonological memory, and phonological assembly (Ball & Blachman 1991; Snowling 1985). Children with speech sound disorders at preschool may be at risk for later spelling difficulties due to poor phonological awareness skills and a weakness in phonological coding in verbal memory. Clark-Klein & Hodson (1995) report that children with histories of expressive speech sound disorders made more phonologically deviant spelling errors than their normally developing peers. However, speech sound errors do not map directly onto spelling errors (Stackhouse 1996). Rather, difficulty with speech output may result in imprecise phonological representations of the word in the lexicon. If degraded phonological representations lead to spelling problems, these problems may well occur in children with isolated speech sound disorders. Several authors have suggested that children with early expressive speech sound disorders exhibit deficiencies in underlying phonological representations, even after the early expressive speech sound disorders have resolved (Bird, Bishop & Freeman 1995; Fowler 1991; Snowling 1985; Studdert-Kennedy 1987). A study by Bird, Bishop & Freeman (1995) reported that children with phonological impairments performed more poorly than age and nonverbal ability matched control children on spelling measures. They suggest that children with expressive phonological impairment have difficulty with the classification and analysis of speech sounds. An observation by Hoffman & Norris (1989) that phonological simplifications observed in speech development reoccur in misspellings in later childhood supports this hypothesis. Spelling and language Children with speech sound disorders often have difficulties in other areas of language as well. Estimates of the co-morbidity of speech and language disorders range from 9 to 77% (Shriberg, Tomblin & McSweeny 1999). In a large epidemiological sample, the percentages of boys and girls of normal cognitive abilities with concurrent speech and language impairments were 15.2% and 11.1%, respectively (Shriberg et al. 1999). Children with histories of language problems in addition to speech sound disorders may be at an even higher risk for spelling problems than children with isolated speech sound disorders, as spelling also draws on lexical and morphological knowledge, and on verbal memory. Treiman & Cassar (1996) demonstrated that children use morphological relationships among words, as well as phonology, in early spelling.

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Spelling and reading Children with combined speech and language problems are also more likely than those with isolated speech sound disorders to have reading difficulties. Although spelling is a distinct process from reading, acquisition of both skills is dependent on the development of phoneme-grapheme correspondence knowledge (Frith 1980). According to Ehri (1992a, b), letter-sound associations made in reading facilitate the storage of words in memory through associations of spelling patterns and their pronunciation. Children with language problems who demonstrate reading difficulties may not benefit as much as normal readers from the reinforcement of letter-sound associations provided through reading and may thus be at an increased risk for spelling problems. Familial aggregation of spelling impairment Previous studies have demonstrated that speech, language, and reading difficulties aggregate within families of children with expressive phonology disorders (Felsenfeld, McGue & Broen 1995; Gopnik & Crago 1991; Lahey & Edwards 1995; Lewis 1992; Neils & Aram 1986; Rice, Haney & Wexler 1998; Spitz, Tallal, Flax & Benasich 1997; Tallal, Ross & Curtiss 1989; Tomblin 1989). Phonological processing skills have been identified as a heritable component to reading ability (Olson, Wise, Connors & Rack 1989). Spelling abilities that rely strongly on phonological processing may also be heritable. Twin studies have supported the notion that spelling may be heritable and have estimated the heritability (h2 g) of spelling to be 0.62 (DeFries, Stevenson, Gillis & Wadsworth 1991; DeFries, Alarcon & Olson 1997). Genetic influences of spelling skills, however, may differ somewhat from those underlying reading development. Stevenson, Graham, Fredman & McLoughlin (1987), suggested developmental differences in the genetic influence on reading and spelling. These investigators have proposed that whereas genetic influence on reading decreases with age, genetic influence on spelling increases with age. Other data suggest that spelling may be more heritable and less influenced by the environment than reading (DeFries et al. 1991; Stevenson et al. 1987; Wadsworth, Gillis, DeFries & Fulker 1989). Methodological limitations of previous studies Many previous follow-up studies of children with early speech sound disorders have failed to examine spelling outcomes in relation to the type of early speech/language disorder. Another limitation is that past researchers have not employed sensitive methods for scoring spelling errors. Traditional

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spelling measures have scored spelling words as correct or incorrect without crediting the child for closer approximations of the target word. Developmentally based scoring systems that assess the child’s level of phonological processing are preferred to these traditional methods (Kroese, Hynd & Knight 1998). Developmental stages of spelling acquisition have been well described for normal children (Ehri 1989; Gentry 1982; Henderson & Beers 1980; Lombardino, Bedford, Fortier, Carter & Brandi 1997). Furthermore, normal spellers and individuals with spelling difficulties show a similar developmental pattern. Sawyer, Wade & Kim (1999) suggest that methods that evaluate normal patterns of acquisition would be useful in assessing the degree to which spelling abilities deviate from normal expectations. The goal of this study was to examine correlates of spelling skills in school-age children with histories of early speech sound disorders. Our first hypothesis was that children with early speech sound disorders would exhibit later weaknesses in spelling and that measures of phonological processing skills would be associated with spelling abilities at school age. Second, we predicted that preschool children with combined speech and language disorders would be at higher risk for spelling problems than would preschool children with isolated speech sound disorders. Our final hypothesis was that spelling problems would aggregate within families.

Participants Children were recruited at 4 to 6 years of age from the clinical caseloads of speech/language pathologists working at community speech and hearing centers or in private practice in the greater Cleveland area. Approximately 100 families were invited to participate in the study and 87 families were subsequently recruited. All participants were screened to insure that they met the following criteria: (1) moderate to severe expressive preschool speech sound disorder as defined by a score of 1 SD or greater below the mean on the Goldman–Fristoe Test of Articulation Sounds in Words subtest (GFTA; Goldman & Fristoe 1986) and by commission of at least three phonological error types as identified by the Khan–Lewis Phonological Analysis (Khan & Lewis 1986); (2) normal hearing acuity as defined by passing a pure tone audiometric screening test at 25 dBHL ISO for 500, 1000, 2000, and 4000 Hz bilaterally and fewer than six reported episodes of otitis media prior to age three as reported by the parent; (3) normal peripheral speech mechanism as documented on the Oral Speech and Motor Control Protocol (Robbins & Klee 1987); (4) absence of a history of neurological disorders or developmental delays other than speech and language as reported by the parent; and (5) normal intelligence defined as a Performance Intelligence Quotient (PIQ)

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of 80 or above on the Wechsler Intelligence Test for Children-Third Edition (WISC-III; Wechsler 1991). Fifty-two of the eighty-seven children (60%) were followed to school age (M = 9.29 years; SD = 1.3). The average number of years to follow-up was 4.1 years. Thirty-three children were male and nineteen female. Socioeconomic status (SES) was defined by the Hollingshead Four Factor Index of Social Class (Hollingshead 1975). The children followed did not differ significantly from children not followed in gender ratio (χ 2 = 0.69, P = 0.41), age at initial testing (t = 0.36, P = 0.72), or in SES at the preschool assessment (χ 2 = 4.5, P = 0.34), or performance on the Goldman–Fristoe Test of Articulation (t = 1.73, P = 0.087). Children were assigned to one of two groups based on preschool language status: speech sound disorder in isolation (S group), or speech sound disorder with additional language impairment (SL group). The criteria for language impairment, established by Tomblin, Records, Buckwalter, Zhang, Smith & Obrien (1997), required that the child obtain a scaled score of less than 8 on two or more subtests of the Test of Language Development-Primary, Second Edition (TOLD-P:2; Newcomer & Hammill 1988). Twenty-four children (46%) met this criteria, a percentage considerably higher than the percentage of children with speech delay and speech/language impairment (11–15%) in an epidemiologic sample collected by Shriberg, Tomblin & McSweeny (1999). However, Bird, Bishop & Freeman (1995), who recruited a clinically referred sample similar to ours, reported that 12 of 31 of children with phonology impairment (39%) had additional language problems. Table 1 presents participant demographics. The SL group, although similar in age to the S group at recruitment, was older at follow-up. The S group also had lower SES and higher PIQ than the SL group. The age difference was most likely a result of our decision to follow children to the third or fourth grade, rather than to a specific age. Children in the SL group were older than those in the S group when they entered kindergarten, and a higher proportion of these children had delayed enrollment in kindergarten. Associations of social disadvantage and generalized cognitive dysfunction with language disorders likely accounts for the group differences in SES and PIQ. The groups did not differ in rate of grade retention, which was low for both groups, or in mean grade at follow-up. Comparison of children who dropped out of the study after time 1 to children who remained in follow-up failed to reveal differences in background factors or child characteristics (Lewis, Freebairn & Taylor 2000).

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Table 1. Sample characteristics

Age at preschool, M (SD) Age at follow-up*, M (SD) Males/females SES rating*, M (SD) PIQ**, M (SD)

Isolated speech disorder (S) group (n = 28)

Speech/language disorder (SL) group (n = 24)

Total cohort

5.0 (0.9) 8.9 (1.3) 15/9 3.3 (1.3) 115.9 (13.1)

5.1 (1.0) 9.9 (1.4) 18/10 4.0 (1.0) 98.8 (13.0)

5.0 (0.9) 9.3 (1.3) 33/19 3.6 (1.2) 108.2 (15.5)

(n = 52)

∗ Significant difference between S and SL groups, P < 0.05. ∗∗ Significant difference between S and SL group, P < 0.001.

Methods Follow-up measures Phonology. The GFTA was re-administered at follow up to determine the presence of residual articulation errors. Phonological awareness was assessed by the Nonsense Word Repetition Test (Kamhi & Catts 1986), the Elision Task-Experimental Version (Torgesen & Wagner 1994), and the Goldman– Fristoe–Woodcock Sound Symbol Tests, Sound Analysis (GFWSA) and Sound Blending (GFWSB) (Goldman, Fristoe & Woodcock 1974). Spelling. Written spelling was evaluated using the Test of Written Spelling, Third Edition (TWS-3; Larsen & Hammill 1994). The TWS-3 contains both predictable and unpredictable words. Predictable words are those that are spelled as they sound, whereas unpredictable words are exceptions to regular spelling to sound correspondences. Examples of predictable words are ‘stop, forty, visualize, and ambiguous’. Examples of unpredictable words are ‘two, eight, campaign, facsimile, and feign’. Spelling abilities were assessed in two ways. First, spelling attempts were scored as correct or incorrect and standard scores assigned according to the TWS-3 test manual. Second, spelling errors were coded for phonetic accuracy using the 8 point Spelling Rating Scale developed by Kroese, Hynd & Knight (1998). The latter rating scale credits the speller for more phonetically accurate approximations to the correct pronunciation of the word. Points are awarded as follows: 0 = random string of letters, 1 = phonetically related letter, 2 = correct beginning sound, 3 = more than 1 phoneme correct, 4 = correct number of syllables, 5 = correct number of sounds, 6 = all phonemes represented with conventional letters, 7 = correct spelling. Spelling errors were coded for phonetic accuracy according to the eight point Spelling Rating Scale developed by

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Kroese, Hynd & Knight (1998) by two licensed speech language pathologists who were trained in the system. Inter-rater reliability was 94%. In the case of disagreement in scoring, errors were reviewed and consensus achieved. Reading. The Word Attack and Word Identification subtests of the Woodcock Reading Mastery Tests-Revised (WRMT-R; Woodcock 1987) assessed reading decoding skills. The Reading Comprehension Subtest of the Wechsler Individual Achievement Test (WIAT; 1992) was also administered to evaluate the child’s ability to read short passages and answer questions in context. Language. The Clinical Evaluation of Language Fundamentals-Revised (CELF-R; Semel, Wiig & Secord 1987) was used to assess expressive and receptive language skills. A Total standard score, Expressive Language score, and Receptive Language score were utilized in data analysis. Familial aggregation. Familial aggregation of spelling abilities was assessed through direct testing of nuclear family members and completion of a family history questionnaire. Mothers, fathers, and school-age siblings of children with phonology disorders received the TWS-3. Nuclear family members scoring at or below the 10th percentile were considered to be impaired in spelling. All parents also completed a family history interview as described by Lewis & Freebairn (1993). Information regarding enrollment in therapy and remedial classes was requested. Affection status of nuclear family members for speech, language, reading and spelling disorders was determined through these parent interviews and direct testing of siblings. A parent was coded as having a speech or language disorder, if, by history, that individual had ever been enrolled in speech/language therapy, or if he/she was unable to be understood until 5 years of age or older. A sibling was coded as having a speech or language disorder if he/she had ever been enrolled in speech/language therapy, and/or if he/she performed below age standards on tests of speech/language skills (defined by a score falling more than 1 SD below the mean for age). Siblings received the GFTA and either the TOLDP:2 or the CELF-R, depending on which of these oral language measures was age appropriate. A parent or sibling was coded as having a reading disorder if that individual had received tutoring or special classes for reading. Siblings who scored more than 1SD below age norms on WRMT-R Word Attack and Word Identification subtests were also coded as having a reading disorder. Procedures for follow-up assessments The participants were tested individually in two sessions. Testing was carried out in a speech research laboratory at Case Western Reserve University’s Department of Pediatrics or at the parent’s request, in a quiet and adequately lit room in the family’s home. Speech productions were recorded using a Sony Professional Tape Recorder (WM-DC6) and an Audio-Technica Omni-

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directional Microphone (AT-804). Responses were recorded initially on-line using phonetic transcription. Data analysis Correlation analyses were undertaken to determine the relationship of the TWS-3 standard scores and the Spelling Rating Scale scores to measures of phonology, language, reading, and spelling. Analysis of covariance (ANCOVA) was employed to compare the S and SL groups in the domains of phonology, language, reading and spelling. Because of group differences in age at follow-up, SES, and PIQ, these factors were included as covariates in the analysis. An alpha level of 0.05 was used in carrying out the ANCOVAs, with Bonferroni corrections applied in examining univariate differences within multi-measure domains. Paired t-tests were employed to compare participants’ performance on the spelling measure with their performance in other domains. Familial aggregation was evaluated in terms of the percentages of nuclear family members affected for disorders. Parentchild and sib-pair correlation of scores on the TWS-3 were computed to assess within family resemblances.

Results Correlation of spelling scores to phonology measures As shown in Table 2, standard scores of both predictable and unpredictable words and the total score on the TWS-3 were highly correlated with measures of phonology (i.e. Nonword Repetition, Elision Task, and Sound Analysis Test). Somewhat weaker correlations were found between the TWS-3 and the GFTA. As shown in Table 3, when errors on the TWS-3 were scored using the Spelling Rating Scale, only the total score and predictable words correlated with scores on the Nonword and Elision tasks. The percentages of error types as categorized by the Spelling Rating Scale were as follows: 2% random string (example: ‘ageo’ for ‘uncle’; 0 points), 2% phonetically related letter (example; ‘chag’ for ‘shake’; 1 point), 1% correct beginning sound (example: ‘nat’ for ‘knife’; 2 points), 26% more than one phoneme correct (example: ‘stong’ for ‘strong’; 3 points), 18% correct number of syllables (example: ‘hopitel’ for ‘hospital’; 4 points), 39% correct number of sounds (example: ‘sulut’ for ‘salute’; 5 points), and 12% all phonemes with correct letters (example: ‘opake’ for ‘opaque’; 6 points). Predictable and unpredictable words did not differ significantly in the percentage of each error type.

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Table 2. Correlations of TWS-3 standard scores with phonology, language, and reading measures Measure

TWS-3 total

TWS-3 predictable

TWS-3 unpredictable

Phonology GFTA Nonword Elision Sound analysis Sound blending

0.39** 0.55** 0.73** 0.36* 0.25

0.43** 0.55** 0.76** 0.34* 0.28

0.32* 0.52** 0.64** 0.33* 0.21

Language CELF-R total CELF-R expressive CELF-R receptive

0.49** 0.45** 0.47**

0.51** 0.46** 0.47**

0.49** 0.46** 0.45**

Reading Word ID Word Attack Comprehension

0.68** 0.77** 0.55**

0.70** 0.79** 0.53**

0.64** 0.70** 0.53**

∗ Significant at P < 0.05 level; ∗∗ Significant at P < 0.001 level.

Correlation of spelling scores to language and reading measures The TWS-3 total, predictable, and unpredictable scores were also strongly correlated with the CELF-R Total, Receptive, and Expressive scores and the Word Identification, Word Attack and Reading Comprehension scores. When errors on the TWS-3 were scored using the Spelling Rating Scale, only the total score and predictable words correlated significantly to the CELF total and CELF expressive scores (see Table 3). All scores from the Spelling Rating Scale correlated with Word Identification and Word Attack. Comparisons of speech sound alone (S) and speech with language (SL) groups Mann–Whitney U Tests were used to compare affection status at follow-up of children in the S and SL groups. Children were considered to present with a disorder if they attained a score of 1 SD or greater below the standardized mean. Using this definition, only one child in the S group (4%) compared to 6 children in the SL group (22%) continued to present with an articulation disorder (U = 278; P = 0.054) as measured by the GFTA. Similarly, 4 children in the S group (14%) compared to 12 children in the SL group

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Table 3. Correlation of spelling rating scale to phonology, language, and reading measures Measure

TWS-3 total

TWS-3 predictable

TWS-3 unpredictable

Phonology GFTA Nonword Elision Sound analysis Sound blending

0.18 0.47** 0.53** 0.05 –0.07

0.16 0.56** 0.58** –0.05 –0.09

0.16 0.21 0.31 0.17 0.02

Language CELF-R total CELF-R expressive CELF-R receptive

0.28* 0.29* 0.23

0.31* 0.31* 0.25

0.14 0.15 0.10

Reading Word ID Word attack Comprehension

0.49** 0.63** 0.37*

0.50** 0.64** 0.39*

0.36** 0.48** 0.20

∗ P < 0.05; ∗∗ P < 0.001.

(60%) presented with a language disorder (U = 208; P = 0.007) as measured by the CELF-R. One child in the S group (4%) compared to 11 in the SL group (46%) presented with a reading decoding disorder as measured by the WRMT-R Word Attack and Word Identification subtests (U = 138; P < 0.001). Reading comprehension deficits based on the WIAT were observed for one child in the S group (4%) and 6 children in the SL group (25%) (U = 28; P < 0.001). Eight children in the S group (30%) compared to 14 in the SL group (55%) had a spelling disorder as measured by the TWS-3 (U = 232; P = 0.028). As shown in Table 4, employing ANCOVA with covariates age, PIQ, and SES, group comparisons revealed that children in the SL group scored at lower levels than did children in the S group on the language, reading, and spelling measures. Group comparisons on the phonology measures revealed that children in the SL group scored significantly lower than did children in the S group on the Nonword Repetition Task, the Elision Task, and the Sound Analysis Subtest. The S and SL groups differed on all but two of the measures, the GFTA and the GFWSB.

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Table 4. Group means (standard deviations) for measures of spelling, phonology, language, and reading Isolated speech (S) group

Speech/language (SL) group

F

Spelling measures TWS-3 total TWS-3 predictable words TWS-3 unpredictable words

91.9 (16.0) 96.1 (15.0) 92.0 (13.8)

82.6 (12.6) 85.5 (10.2) 84.2 (13.0)

4.45* 4.99* 3.41*

Phonology measures GFTA percentile Nonword repetition % correct Elision z-score GFWSA GFWSB

74.3 (28.00) 44.9 (14.4) 3.6 (15.5) 52.8 (9.6) 56.8 (8.2)

60.1 (41.5) 24.5 (26.0) –0.3 (1.0) 45.1 (14.6) 52.6 (11.8)

2.25 7.63** 5.22* 3.51* 1.13

Language measures CELF-R total CELF-R receptive CELF-R expressive

99.6 (14.2) 107.3 (16.6) 92.4 (11.4)

81.7 (14.6) 88.2 (14.3) 78.8 (14.4)

16.23** 14.97** 10.60**

Reading measures WRMT-R word attack WRMT-R word identification WIAT reading comprehension

102.5 (13.3) 104.4 (12.8) 108.3 (12.1)

83.7 (17.5) 84.6 (13.5) 87.8 (10.8)

7.72** 9.11** 9.31**

Standard scores are reported unless otherwise indicated. ∗ Significant difference between S and SL groups, P < 0.05. ∗∗ Significant difference between S and SL groups, P < 0.001.

Within group comparisons of measures According to results from paired t-tests, children in the S group obtained lower standard scores on the TWS-3 than on the CELF-R Total Language (t = 2.3; df = 26; P = 0.031) or WRMT-R Word Attack (t = 5.5; df = 26; P < 0.001). In contrast, the SL group obtained similar scores on the TWS-3 relative to performance on the CELF-R Total Language (t = –1.0; df = 23; P = 0.318) and WRMT-R Word Attack (t = 1.0; df = 23; P = 0.311). Familial aggregation of spelling disorders Nuclear family members scoring at or below the 10th percentile on the TWS3 were considered to be impaired in spelling. According to this criterion, 8% of mothers, 17% of fathers, and 35% of siblings tested had spelling impair-

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Table 5. Correlations of proband and sibling spelling scores

Sisters TWS-3 total TWS-3 predictable TWS-3 unpredictable Brothers TWS-3 total TWS-3 predictable TWS-3 unpredictable

Proband scores TWS-3 total

TWS-3 predictable

TWS-3 unpredictable

–0.147 –0.163 –0.002

–0.212 –0.212 –0.082

–0.091 –0.107 0.049

0.635** 0.585** 0.569**

0.639** 0.616** 0.569**

0.583** 0.564** 0.497**

∗ Significant at P < 0.05 level. ∗∗ Significant at P < 0.001 level.

Table 6. Frequencies (percentages) of nuclear family members reporting spelling, language, speech and reading disorders Disorders

Brothers (n = 56)

Sisters (n = 39)

Fathers (n = 52)

Mothers (n = 52)

Total (n = 199)

Spelling Language Speech Reading

8 (14%) 13 (23%) 26 (46%) 14 (25%)

4 (10%) 4 (10%) 13 (33%) 5 (13%)

9 (17%) 5 (10%) 14 (27%) 10 (19%)

3 (6%) 1 (2%) 7 (13%) 5 (10%)

24 (12%) 23 (12%) 60 (30%) 34 (17%)

ment. Rates of spelling impairment based on test results differed only slightly from those based on historical reports. Three out of the four mothers with spelling impairment and four out of the four fathers with spelling impairment had children who were spelling impaired. Eighteen of twenty-one (86%) of the impaired siblings had a sibling who was a proband with spelling problems. A shown in Table 5, the brothers’ spelling scores correlated significantly and positively to the probands’ spelling scores. The spelling scores of the probands did not correlate significantly with those of other nuclear family members (sisters, mothers, and fathers). Table 6 lists the frequencies of spelling and other disorders found in association with poor spelling in the nuclear family members of the probands. Family members reported high affection rates for speech disorders, followed by reading and language disorders. Brothers were most often affected.

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Discussion The findings of this study support previous research that suggests that children with early speech sound disorders are at risk for later spelling difficulties (Bird, Bishop & Freeman 1995; Clark-Klein & Hodson 1995; Webster, Plante & Couvillion 1997). Further, our results are in agreement with studies that have shown that children with speech sound disorders accompanied by additional language problems have poorer spelling outcomes than children with isolated speech sound disorders (Bishop & Adams 1990; Bishop, Bishop, Bright, James, Delaney & Tallal 1999; Catts 1993; Levi, Capozzi, Fabrizi & Sechi 1982; Hall & Tomblin 1978; Menyuk, Chesnick, Liebergott, Korngold, D’Agostino & Belanger 1991; Shriberg & Kwiatkowski 1988). Previous reports concluded that children with isolated speech sound disorders are not at risk for academic difficulties. However, we found that, relative to their language and reading skills, these children demonstrate a weakness in spelling. These findings are in accord with those of Bird, Bishop & Freeman (1995). Finally, this study demonstrated that spelling disorders, as well as speech, language, and reading disorders, aggregate within families. The relationship of speech sound errors to spelling performance may be mediated by residual articulation errors. The majority of children did not display speech sound errors upon follow up. It is thus unlikely that spelling errors for this group map directly on to speech sound errors as suggested by early investigators (Hoffman & Norris 1989; Marcel 1980; Treiman 1985). Rather, spelling difficulties are suggestive of underlying phonological processing deficits that persist even after the expressive phonology disorder resolves, perhaps as the result of deficient underlying phonological representations (Studdert-Kennedy 1987). Seven children continued to demonstrate articulation errors upon followup, scoring greater than 1 SD below the mean on the GFTA. All but one of these seven children also scored greater than 1 SD below the mean on the TWS-3. This finding supports the ‘critical age hypothesis’ proposed by Bishop & Adam (1990). According to this hypothesis children whose expressive phonological problems have not resolved by the time that they learn to read are at greater risk for reading and spelling problems than children without residual disorders. It is also notable, however, that six of these seven children presented with both speech and language problems, and that they had a mean PIQ of 87, suggesting that this subset of children had more general delays. Inadequate phonemic representations may be responsible for both poor spelling skills and deficiencies in phonological processing tasks, such as those that measure phoneme awareness, sound segmentation, auditory sequencing, phonological memory, and phonological assembly (Fowler 1991; Snowling

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1985; Studdert-Kennedy 1987). In support of a common underlying deficit spelling scores were highly correlated with tasks such as Nonword Repetition, Elision, and Sound Analysis. Previous studies demonstrating that phoneme segmentation is highly correlated with spelling ability (Marcel 1980; Nation & Hulme 1997) and that segmentation training in kindergarten children improved spelling skills (Ball & Blachman 1991) provide further evidence for this possibility. Our findings are also consistent with the previous research showing association between spelling skills, language, and reading abilities (Ehri 1989; Pennington 1999). Although spelling draws heavily on phonological processing skill, other aspects of language such as morphology make additional contributions to spelling. Children with poor language skills in addition to the phonology deficits may also have deficits in reading decoding (Catts 1986; Kamhi & Catts 1986). Because reading serves to bolster spelling skill by providing exposure to grapheme-phoneme correspondences, children with reading difficulties may not benefit in this regard as much as normal readers. Like other investigators (Scarborough 1990), we found that language disorders were associated with later reading problems. As evidence for this association, the SL group scored more poorly than the S group on measures of reading decoding (WRMT Word Attack and Word Identification) and reading comprehension (WIAT Reading Comprehension). The poor performance of the SL group across all reading and spelling domains may represent the cumulative effect of early weaknesses in phonology, language and reading skills on acquisition processes. Stanovich & Seigel (1994) refer to this as the ‘Mathew Effect’. Although many children with speech sound disorders have deficits in phonological processing that adversely affect their spelling skills, evidence from this study suggests that poor spelling is not due to reliance on visualorthographic strategies. Analysis of the error types on the Spelling Rating Scale demonstrated that only 2% of errors were random strings of letters. The more frequent errors had more than one phoneme correct (26%), the correct number of syllables (18%) and the correct number of sounds (39%). The fact that the errors that these children made on the Spelling Rating Scale correlated with the measures of phonological awareness implies that they utilized phonetic strategies in spelling in spite of their weaknesses in this area. This finding is consistent with other studies showing that poor spellers follow the same developmental sequence as children who are good spellers (Sawyer et al. 1999). Evidence from this study for familial aggregation of speech/language and written language disorders also raises the possibility of a common genetic influence. Familial aggregation for speech, language, reading and

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spelling disorders in these families exceeded expectations based on prevalence estimates for these disorders in the general population. Although the underlying genetic mechanism for these disorders is not known, a gender specific threshold for expression of the disorder is suggested as brothers of probands report significantly more disorders than sisters. Further, brothers’ scores on the TWS-3 correlated significantly and positively to proband scores, while sisters’ scores did not correlate significantly. The lack of a significant parent-child correlation of spelling scores is possibly due to developmental differences as suggested by Stevenson et al. (1987). Further study of the genetic basis of these conditions is needed employing molecular genetic techniques to examine transmission of spelling problems within families. The findings of this study have several clinical implications. First, preschool children with speech sound disorders are at risk for later spelling impairments even after productive speech disorders have resolved. Since the stages of spelling development closely parallel the development of phonological awareness, teaching children to apply phonological strategies to spelling may be one method for improving this skill. A second implication is that preschool children with both speech sound and language disorders are likely to have more severe spelling problems than preschoolers with isolated speech sound disorders. Careful follow-up of children with both disorders would appear to be especially critical even after the speech sound disorder has resolved. Finally, family history of spelling difficulties may be used to identify children at risk for later written language disorders.

Acknowledgments This research was supported by the National Institutes of Health, National Institute on Deafness and Other Communication Disorders, Grant DC00528, awarded to Barbara A. Lewis. We wish to express our appreciation to Anne Birnbaum for her help in the preparation of this manuscript, the speech/language pathologists who assisted us in recruiting subjects, and to the families who generously agreed to participate.

Note 1. Speech sound disorders refer to impairment of the sound system of the language. A distinction is not made between expressive phonology disorders and articulation disorders as both involve speech sounds.

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References Ball, E.W. & Blachman, B.A. (1991). Does phoneme awareness training in kindergarten make a difference in early word recognition and developmental spelling?, Reading Research Quarterly 26: 49–69. Bird, J., Bishop, D.V.M. & Freeman, N.H. (1995). Phonological awareness and literacy development in children with expressive phonological impairments, Journal of Speech and Hearing Research 38: 446–462. Bishop, D.V.M. & Adams, C. (1990). A prospective study of the relationship between specific language impairment, phonological disorders, and reading retardation, Journal of Child Psychology and Psychiatry 31: 1027–1057. Bishop, D.V.M., Bishop, S.J., Bright, P., James, C., Delaney, T. & Tallal, P. (1999). Different origin of auditory and phonological processing problems in children with language impairment- evidence from a twin study, Journal of Speech and Hearing Research 42: 155–168. Catts, H.W. (1986). Speech production/phonological deficits in reading disordered children, Journal of Learning Disabilities 19: 504–508. Catts, H.W. (1993). The relationship between speech-language impairments and reading disabilities, Journal of Speech and Hearing Research 36: 948–958. Clarke-Klein, S.M. (1994). Expressive phonological deficiencies: Impact on spelling development, Topics in Language Disorders 14(2): 40–55. Clarke-Klein, S. & Hodson, B.W. (1995). A phonologically based analysis of misspellings by third graders with disordered-phonology histories, Journal of Speech and Hearing Research 38: 839–849. DeFries, J.C., Stevenson, J., Gillis, J.J. & Wadsworth, S.J. (1991). Genetic aetiology of spelling deficits in the Colorado and London twin studies of reading disability, Reading and Writing: An Interdisciplinary Journal 3: 271–283. DeFries, J.C., Alarcon, M. & Olson, R.K. (1997). Genetic aetiologies of reading and spelling deficits: Developmental differences. In: C. Hulme & M. Snowling (eds.), Dyslexia: biology, cognition, and intervention (pp. 20–37). San Diego, California: Singular Publishing Group, Inc. Ehri, L. (1989). The development of spelling skill and its role in reading acquisition and reading disability, Journal of Learning Disability 22: 356–365. Ehri, L. (1992a). Reconceptualizing the development of sight word reading and its relationship to recoding. In: P.B. Gough, L.C. Ehri & R. Treiman (eds.), Reading acquisition (pp. 145– 174). Hillsdale, New Jersey: Erlbaum. Ehri, L. (1992b). Review and commentary: Stages of spelling development. In: S. Templeton & D.R. Bear (eds.), Development of orthographic knowledge and foundation of literacy (pp. 307–332). Hillsdale, New Jersey: Erlbaum. Felsenfeld, S., McGue, M. & Broen, P.A. (1995). Familial aggregation of phonological disorders: Results from a 28 year follow-up, Journal of Speech and Hearing Research 38: 1091–1107. Fowler, A. (1991). How early phonological development might set the stage for phoneme awareness. In: S.A. Brady & D.P. Shankweiler (eds.), Phonological processes in literacy: A tribute to Isabelle Lieberman (pp. 97–117). Hillsdale, New Jersey: Erlbaum. Frith, U. (1980). Unexpected spelling problems. In: U. Frith (ed.), Cognitive processes in spelling (pp. 495–515). New York/London: Academic Press. Gentry, J.R. (1982). An analysis of developmental spelling in GYNS AT WRK, The Reading Teacher 36: 192–200.

SPELLING IMPAIRMENT

405

Goldman, R. & Fristoe, M. (1986). The Goldman-Fristoe test of articulation. Circle Pines, Minnesota: American Guidance Service. Goldman, R., Fristoe, M. & Woodcock, R.W. (1974). Goldman-Fristoe-Woodcock auditory skills test battery. Circle Pines, Minnesota: American Guidance Service. Gopnik, M. & Crago, M.B. (1991). Familial aggregation of a developmental language disorder, Cognition 39: 1–50. Hall, P.K. & Tomblin, J.B. (1978). A follow-up study of children with articulation and language disorders, Journal of Speech and Hearing Disorders 43: 227–241. Henderson, E.H. & Beers, J.W. (1980). Developmental and cognitive aspects of learning to spell: A reflection of word knowledge. Newark, Delaware: International Reading Association. Hoffman, P.R. & Norris, J.A. (1989). On the nature of phonological development: Evidence from normal children’s spelling errors, Journal of Speech and Hearing Research 32: 787– 794. Hollingshead, A.B. (1975). Four factor index of social class. Unpublished manuscript (available from A.B. Hollingshead, Department of Sociology, Yale University, New Haven, CT 06520, USA). Kamhi, A. & Catts, H.W. (1986). Toward an understanding of developmental language disorders and reading disorders, Journal of Speech and Hearing Disorders 51: 337–347. Khan, L. & Lewis, N. (1986). Khan-Lewis phonological analysis. Circle Pines, Minnesota: American Guidance Service. Kroese, J.M., Hynd, G.W. & Knight, D. (1998). Impact of phonological processing on spelling abilities. Paper presented at the American Speech-Language-Hearing Association Annual Convention, San Antonio, Texas. Lahey, M. & Edwards, J. (1995). Specific language impairment: Preliminary investigation of factors associated with family history and patterns of language performance, Journal of Speech and Hearing Research 38: 643–657. Larsen, S.C. & Hammill, D.D. (1994). Test of written spelling third edition examiner’s manual. Austin, Texas: Pro-Ed. Levi, G., Capozzi, F., Fabrizi, A. & Sechi, E. (1982). Language disorders and prognosis for reading disabilities in developmental age, Perceptual and Motor Skills 54: 1119–1122. Lewis, B.A. (1992). Pedigree analysis of children with phonology disorders, Journal of Learning Disabilities 25: 586–597. Lewis, B.A. & Freebairn, L. (1993). A clinical tool for evaluating the familial basis of speech and language disorders, American Journal of Speech-Language Pathology 2: 38–43. Lewis, B.A., Freebairn, L. & Taylor, H.G. (2000). Follow-up of children with early expressive phonology disorders, Journal of Learning Disabilities 33: 433–444. Lombardino, L.J., Bedford, T., Fortier, C., Carter, J. & Brandi, J. (1997). Invented spellings: developmental patterns in kindergarten children and guidelines for early literacy intervention, Language, Speech, and Hearing Services in Schools 28: 333–343. Marcel, T. (1980). Phonological awareness and phonological representation: Investigation of a spelling problem. In: U. Frith (ed.), Cognitive processes in spelling (pp. 373–403). New York/London: Academic Press. Menyuk, P., Chesnick, M., Liebergott, J.W., Korngold, B., D’Agostino, R. & Belanger, A. (1991). Predicting reading problems in at-risk children, Journal of Speech and Hearing Research 34: 893–903. Nation, K & Hulme, C. (1997). Phonemic segmentation, not onset-rime segmentation, predicts early reading and spelling skills, Reading Research Quarterly 32: 154–167.

406

BARBARA A. LEWIS, LISA A. FREEBAIRN & H. GERRY TAYLOR

Neils, J. & Aram, D.M. (1986). Family history of children with developmental language disorders, Perceptual and Motor Skills 63: 655–658. Newcomer, P.L. & Hammill, D.D. (1988). Test of language development-primary, 2nd edn. Austin, Texas: Pro-Ed. Olson, R., Wise, B., Connors, F. & Rack, J. (1989). Specific deficits in component reading and language skills: Genetic and environmental influences, Journal of Learning Disabilities 22: 339–348. Pennington, B.F. (1999). Toward an integrated understanding of dyslexia: Genetic, neurological, and cognitive mechanisms, Developmental and Psychopathology 11: 629–654. Rice, M.L., Haney, K.R. & Wexler, K. (1998). Family histories of children with SLI who show extended optional infinitives, Journal of Speech, Language, and Hearing Research 41: 419–432. Richgels, D. (1995). Invented spelling ability and printed word learning in kindergarten., Reading Research Quarterly 30: 96–109. Robbins, J. & Klee, T. (1987). Clinical assessment of oropharyngeal motor development in young children, Journal of Speech and Hearing Research 52: 271–277. Sawyer, D.J., Wade, S. & Kim, J.K. (1999). Spelling errors as a window on variations in phonological deficits among students with dyslexia, Annals of Dyslexia 49: 137–159. Scarborough, H.S. (1990). Very early language deficits in dyslexic children, Child Development 61: 1728–1743. Semel, E., Wiig, E.H. & Secord, W. (1987). Clinical evaluation of language fundamentals – revised. San Antonio, Texas: The Psychological Corporation. Shriberg, L.D. & Kwiatkowski, J. (1988). A follow-up of children of phonological disorders of unknown origin, Journal of Speech and Hearing Research 53: 144–155. Shriberg, L.D., Tomblin, J.B. & McSweeny, J.L. (1999). Prevalence of speech delay in 6-yearold children and comorbidity with language impairment, Journal of Speech, Language, and Hearing Research 42: 1461–1481. Snowling, M.J. (1985). Children’s written language difficulties. Windsor, UK: NFER-Nelson. Spitz, R.V., Tallal, P., Flax, J. & Benasich, A.A. (1997). Look who’s talking: A prospective study of familial transmission of language impairments, Journal of Speech and Hearing Research 40: 990–1001. Stackhouse, J. (1996). Speech, spelling, and reading: who is at risk and why? In: M. Snowling & J. Stackhouse (eds.), Dyslexia, speech, and language: A practitioner’s handbook (pp. 12–30). San Diego, California: Singular Publishing Group. Stanovich, K.E. & Seigel, L.S. (1994). The phenotypic performance profile of reading disabled children: A regression-based test of the phonological-core variable difference model, Journal of Educational Psychology 86: 24–53. Stevenson, J., Graham, P., Fredman, G. & McLoughlin, V. (1987). A twin study of genetic influence on reading and spelling ability and disability, Journal of Child Psychology 28: 229–247. Studdert-Kennedy, M. (1987). The phoneme as a perceptumotor structure. In: A. Allport, D. Mackay, W. Prinz & E. Scheerer (eds.), Language perception and production (pp. 67– 84). New York: Academic Press. Tallal, P., Ross, P. & Curtiss, S. (1989). Familial aggregation in specific language impairment, Journal of Speech and Hearing Research 54: 167–173. Tomblin, J.B. (1989). Familial concentration of developmental language impairment, Journal of Speech and Hearing Disorders 54: 287–295.

SPELLING IMPAIRMENT

407

Tomblin, J.B., Records, N.L., Buckwalter, P., Zhang, X., Smith, E. & O’Brien, M. (1997). Prevalence of specific language impairment in kindergarten children, Journal of Speech and Hearing Research 40: 1245–1260. Torgesen, J.K. & Wagner, R.K. (1994). Comprehensive tests of phonological processingexperimental version. Unpublished tests, Florida State University. Treiman, R. (1985). Phonemic awareness and spelling: Children’s judgements do not always agree with adults, Journal of Experimental Child Psychology 39: 161–181. Treiman, R. & Cassar, M. (1996). Effects of morphology on children’s spelling of final consonant clusters, Journal of Experimental Child Psychology 63: 141–170. Wadsworth, S.J., Gillis, J.J., DeFries, J.C. & Fulker, D.W. (1989). Differential genetic aetiology of reading disability as a function of age, Irish Journal of Psychology 10: 509–520. Webster, P.E., Plante, A.S. & Couvillion, L.M. (1997). Phonological impairment and prereading: update on a longitudinal study, Journal of Learning Disabilities 30: 365–375. Wechsler, D. (1991). Wechsler intelligence scale for children- third edition. San Antonio, Texas: The Psychological Corporation. Wechsler individual achievement test (1992). San Antonio, Texas: The Psychological Corporation. Woodcock, R.W. (1987). Woodcock reading mastery tests-revised. Circle Pines, Minnesota: American Guidance Service. Address for correspondence: Barbara Lewis, Ph.D., Behavioral Pediatrics and Psychology 6038, Rainbow Babies and Children’s Hospital, Case Western Reserve University, 11100 Euclid Ave, Cleveland, OH 44106-6038, USA Phone: +1-216-368-3594; Fax: +1-216-844-7601; E-mail: [email protected]