Research ArticleSOCIAL SCIENCES

Stability of core language skill from infancy to adolescence in typical and atypical development

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Science Advances  21 Nov 2018:
Vol. 4, no. 11, eaat7422
DOI: 10.1126/sciadv.aat7422
  • Fig. 1 Study 1.

    Standardized solution for stability model (N = 925). Numbers associated with single-headed arrows are standardized path coefficients; numbers associated with dotted single-headed arrows are error variances or disturbances, the amount of variance not accounted for by paths in the model. Indicators of each latent variable are listed below the latent variable with their factor loadings. Marker indicators of the latent factors (loadings set to 1 to scale and identify the factor). Covariances that were in the model, but not shown in the figure, included year 2 MCDI vocabulary and RDLS comprehension, standardized coefficient = 0.22, P < 0.001; year 5 RDLS comprehension and Initial Consonant Detection Test, standardized coefficient = −0.26, P < 0.001; year 5 Bus Story information and Bus Story sentence length, standardized coefficient = 0.78, P < 0.001; and year 9 word and nonreal word reading, standardized coefficient = 0.39, P < 0.001. Correlations of 0.10, 0.30, and 0.50 correspond to small, medium, and large effect sizes, respectively (78).

  • Fig. 2 Study 2.

    Average stabilities and their 95% CIs of language by group. Average stability represents the mean of correlation coefficients between language measures controlled for child age only. Average stability controlled for covariates represents the mean of partial correlations controlled for child age, nonverbal intelligence, sociability, and maternal age and education.

  • Table 1 Study 1: Sample size, child age, and language measures at each data collection wave.

    N represents the number of available observations. Except for wave 1 (child age in months), child ages are in years.

    Data collection waveNChild age, M (SD)MeasuresScalesSource
    18596.24 (0.45)Modified DDST (53)CommunicationCaregiver
    28731.28 (0.06)Modified MCDI Words
    and Gestures (11)
    Understand,
    vocabulary, and social
    (nonverbal)
    communication
    Caregiver
    38941.51 (0.04)Modified DDST (53)CommunicationCaregiver
    48622.01 (0.03)Modified MCDI Words
    and Sentences (11)
    Vocabulary, grammar,
    plurals, and tense
    Caregiver
    58572.07 (0.02)RDLS (54)ComprehensionChild assessment
    68523.19 (0.09)Modified MCDI Words
    and Sentences (11)
    Vocabulary, plurals,
    past tense, and word
    combination
    Caregiver
    77884.07 (0.03)WPPSI (41)Information,
    comprehension,
    vocabulary, and
    similarity
    Child assessment
    87565.15 (0.06)Bus Story Test (55)Information and
    sentence length
    Child assessment
    RDLS (54)ComprehensionChild assessment
    Initial Consonant
    Detection Test (56)
    Number of correct
    responses
    Child assessment
    97207.44 (0.12)WORD (57)Reading and spellingChild assessment
    Phoneme Detection
    Task (58)
    Number of correct
    responses
    Child assessment
    106618.62 (0.18)WISC (59)Information,
    comprehension,
    vocabulary, and
    similarity
    Child assessment
    WOLD (60)Listening
    comprehension and
    oral expression
    Child assessment
    116689.84 (0.17)WORD (57)Number of correct
    responses (real and
    nonreal words)
    Child assessment
    NARA II (62)Accuracy and
    comprehension
    Child assessment
    1250213.77 (0.15)TOWRE (63)Number of correct
    responses (word and
    pseudoword)
    Child assessment
    1347215.34 (0.16)WASI (64)VocabularyChild assessment
  • Table 2 Study 2: Stability of language across age by groups.

    Numbers before the slashes represent correlations controlling for child age only (to control age variation within waves); numbers after the slashes represent correlations controlling for child age, nonverbal intelligence, sociability, and maternal age and education. Correlations of 0.10, 0.30, and 0.50 correspond to small, medium, and large effect sizes, respectively (78).

    6 months →
    year 1
    Year 1 →
    year 2
    Year 2 →
    year 3
    Year 3 →
    year 7
    Year 7 →
    year 8
    Year 8 →
    year 9
    Year 9 →
    year 13
    Year 13 →
    year 15
    Typical (n =
    4111)
    0.36/0.250.68/0.570.55/0.480.23/0.210.60/0.440.62/0.520.79/0.750.48/0.30
    Moderate-late
    preterm
    (n = 435)
    0.33/0.160.69/0.550.59/0.470.34/0.310.64/0.490.65/0.560.83/0.800.48/0.35
    Very preterm
    (n = 51)
    0.48/0.400.81/0.620.66/0.540.27/0.280.55/0.380.66/0.530.64/0.660.50/0.25
    Dyslexia
    (n = 322)
    0.37/0.200.68/0.480.54/0.460.27/0.240.51/0.390.50/0.440.82/0.820.26/0.24
    Autism (n = 89)0.32/0.120.70/0.480.65/0.580.53/0.490.70/0.620.71/0.660.85/0.810.53/0.40
    Hearing
    impairment
    (n = 221)
    0.38/0.260.72/0.550.58/0.500.27/0.270.54/0.420.58/0.540.77/0.800.37/0.25
  • Table 3 Study 2: Average stability of language by groups.

    Average stability represents the mean of correlation coefficients controlled for child age only. Average stability controlled for covariates represents the mean of partial correlations controlled for child age, nonverbal intelligence, sociability, and maternal age and education. The relatively small sample sizes in the very preterm and autism groups contributed to somewhat diminished precision in the point estimates of average correlation and, thus, wider 95% CIs.

    Average stabilityAverage stability controlled for covariates
    Point estimate95% CIPoint estimate95% CI
    Typical (n = 4111)0.560.54–0.580.460.43–0.48
    Moderate-late preterm
    (n = 435)
    0.590.53–0.650.490.41–0.55
    Very preterm (n = 51)0.590.37–0.740.470.22–0.66
    Dyslexia (n = 322)0.520.44–0.600.440.34–0.52
    Autism (n = 89)0.650.50–0.750.540.38–0.68
    Hearing impairment (n = 221)0.550.45–0.630.470.36–0.57

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/4/11/eaat7422/DC1

    Study 1 Supplementary Text

    Study 1 Materials and Methods

    Study 1 Measurement Models

    Study 2 Supplementary Text

    Table S1. Study 1: Child language measures and covariates: Descriptive statistics.

    Table S2. Study 2: Sample size and child age at each data collection wave.

    Table S3. Study 2: Child language measures and covariates: Descriptive statistics.

    Fig. S1. Study 1.

    Fig. S2. Study 2.

    References (83144)

  • Supplementary Materials

    This PDF file includes:

    • Study 1 Supplementary Text
    • Study 1 Materials and Methods
    • Study 1 Measurement Models
    • Study 2 Supplementary Text
    • Table S1. Study 1: Child language measures and covariates: Descriptive statistics.
    • Table S2. Study 2: Sample size and child age at each data collection wave.
    • Table S3. Study 2: Child language measures and covariates: Descriptive statistics.
    • Fig. S1. Study 1.
    • Fig. S2. Study 2.
    • References (83144)

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