A Meta-Analysis of Cross Sectional Studies Investigating Language in Maltreated Children Purpose In this review article, meta-analysis was used to summarize research investigating language skills in maltreated children. Method A systematic search of published studies was undertaken. Studies were included in the meta-analysis if they investigated language skills in groups comprising maltreated and nonmaltreated children. Studies were selected if ... Review Article
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Review Article  |   June 01, 2015
A Meta-Analysis of Cross Sectional Studies Investigating Language in Maltreated Children
 
Author Affiliations & Notes
  • Jarrad A. G. Lum
    Deakin University, Melbourne, Australia
  • Martine Powell
    Deakin University, Melbourne, Australia
  • Lydia Timms
    Curtin University, Perth, Australia
  • Pamela Snow
    Monash University, Melbourne, Australia
  • Disclosure: The authors have declared that no competing interests existed at the time of publication.
    Disclosure: The authors have declared that no competing interests existed at the time of publication.×
  • Correspondence to Jarrad A. G. Lum: jarrad.lum@deakin.edu.au
  • Editor: Rhea Paul
    Editor: Rhea Paul×
  • Associate Editor: Elizabeth Kay-Raining Bird
    Associate Editor: Elizabeth Kay-Raining Bird×
Article Information
Development / Research Issues, Methods & Evidence-Based Practice / Attention, Memory & Executive Functions / Language / Review Article
Review Article   |   June 01, 2015
A Meta-Analysis of Cross Sectional Studies Investigating Language in Maltreated Children
Journal of Speech, Language, and Hearing Research, June 2015, Vol. 58, 961-976. doi:10.1044/2015_JSLHR-L-14-0056
History: Received February 18, 2014 , Revised August 9, 2014 , Accepted March 12, 2015
 
Journal of Speech, Language, and Hearing Research, June 2015, Vol. 58, 961-976. doi:10.1044/2015_JSLHR-L-14-0056
History: Received February 18, 2014; Revised August 9, 2014; Accepted March 12, 2015

Purpose In this review article, meta-analysis was used to summarize research investigating language skills in maltreated children.

Method A systematic search of published studies was undertaken. Studies were included in the meta-analysis if they investigated language skills in groups comprising maltreated and nonmaltreated children. Studies were selected if these 2 groups of children were of comparable age and from a similar socioeconomic background.

Results A total of 26 studies were identified that met the inclusion criteria. Results from the meta-analysis showed that maltreated children demonstrated consistently poorer language skills with respect to receptive vocabulary (k = 19; standardized mean difference [SMD] = .463; 95% confidence interval [CI; .293, .634]; p < .001), expressive language (k = 4; SMD =.860; 95% CI [.557, 1.163]; p < .001), and receptive language (k = 9; SMD =.528; 95% CI [.220, .837]; p < .001).

Conclusion Together, these results indicate a reliable association between child maltreatment and poor language skills.

Child maltreatment, which encompasses both abuse (physical, sexual, and emotional) and neglect (physical or emotional), is a significant public health and social welfare problem (Gilbert et al., 2009). Affected individuals have higher risk of mortality (Overpeck, Brenner, Trumble, Trifiletti, & Berendes, 1998; Palusci & Covington, 2014) as well as medical, behavioral, emotional, and mental health problems (Brown, Fang, & Florence, 2011; Éthier, Lemelin, & Lacharité, 2004; Jaffee & Maikovich-Fong, 2011; Keyes et al., 2012; Rhodes et al., 2012). This article reviews research that has investigated language functioning in maltreated children. Using meta-analysis, this literature was summarized and an overall estimate of the association between maltreatment and language functioning was estimated.
There are a number of reasons for suspecting poor language skills in children exposed to maltreatment. First, the stress experienced as a consequence of maltreatment is known to disrupt brain development (De Bellis, 2001; Hart & Rubia, 2012; Twardosz & Lutzker, 2010). Research undertaken with human and nonhuman animals shows that the chronic production of cortisol in response to sustained stress exposure has a neurotoxic effect on the brain (Teicher et al., 2003). This includes the temporal lobes that support learning, memory, and language (Anderson, Teicher, Polcari, & Renshaw, 2002; De Bellis et al., 2002; De Bellis & Kuchibhatla, 2006; De Brito et al., 2013; Teicher, Anderson, & Polcari, 2012; Teicher et al., 1997; Woon & Hedges, 2008). Second, language development may be particularly vulnerable to the effects of maltreatment because development in this domain is contingent on adequate stimulation from the environment. In order for children to learn language, they require direct, child-focused exposure and sustained opportunities to engage in meaningful communicative interactions with caregivers, other adults, and peers (Kuhl, Williams, Lacerda, Stevens, & Lindblom, 1992; Tomasello, 2003; Vihman, 1996). In cases of maltreatment, the necessary engagement and stimulation required for language learning may not be present. For instance, research suggests maltreating caregivers interact less, ignore their children more (Allen & Wasserman, 1985; Eigsti & Cicchetti, 2004; Kavanagh, Youngblade, Reid, & Fagot, 1988; Wasserman, Green, & Allen, 1983), react infrequently when their children talk (Kavanagh et al., 1988), and use a less diverse range of vocabulary and syntactic structures during communication (Allen & Wasserman, 1985; Eigsti & Cicchetti, 2004; Kavanagh et al., 1988; Wasserman et al., 1983).
To date, language functioning in maltreated children has been the subject of several reviews. A systematic review of the child maltreatment literature by Veltman and Browne (2001)  identified a total of 42 studies (published and unpublished) investigating language skills in maltreated children. Of this total, 36 (or 86%) reported poorer language skills in maltreated children. Nonsystematic narrative reviews have also concluded maltreatment negatively impacts language skills (Hwa-Froelich, 2012; Law & Conway, 1992). To our knowledge, a quantitative review of studies investigating language functioning in maltreated children using meta-analysis has yet to be undertaken. In meta-analysis, effect sizes from individual studies are pooled and an average effect size is computed (Hunter, Schmidt, & Jackson, 1982). In the absence of a prior meta-analysis, the magnitude of the association between maltreatment and language functioning is not yet known.
A challenge in quantifying the relationship between language problems and maltreatment is ensuring extraneous variables are controlled. To determine the impact of maltreatment on language skills, it is important that socioeconomic status (SES) is controlled. This is because children's language skills have been shown to covary with socioeconomic level (Hart & Risley, 1995; Hoff & Tian, 2005; Hoff-Ginsberg, 1998). Also, elevated stress levels have been found in children reared in low SES environments (Bradley & Corwyn, 2002; McLoyd, 1998). Because maltreatment is disproportionately associated with low SES (Garbarino & Crouter, 1978; Garbarino & Kostelny, 1992; Trickett, Aber, Carlson, & Cicchetti, 1991), it could be that environmental factors and not maltreatment largely contribute to the language outcomes for this group.
Also missing from the literature at present is a systematic review into the relationship between maltreatment and different aspects of language functioning (for a narrative review of this literature, see Law & Conway, 1992). In the child maltreatment literature, the most widely used method to assess language has been to examine the comprehension or understanding of single words, otherwise known as receptive vocabulary (e.g., Cicchetti & Rogosch, 1997; Noll et al., 2010; Toth, Stronach, Rogosch, Caplan, & Cicchetti, 2011; Trickett, 1993). However, it can be problematic to use this type of assessment as a proxy for general language skills. This is because vocabulary tests measure only one component of linguistic knowledge. Vocabulary tests also have low levels of diagnostic accuracy with respect to identifying children with language problems (Spaulding, Plante, & Farinella, 2006). In contrast, tests that measure how well children can comprehend and produce sentences have higher diagnostic accuracy levels (i.e., sensitivity & specificity levels > 80%, see Spaulding et al., 2006). It is therefore of interest to determine whether the literature indicates maltreated children have difficulties comprehending and producing language.
Although prior reviews suggest language skills are poorer in maltreated children, the magnitude of the relationship between maltreatment and different domains of language functioning has yet to be ascertained. To address this gap in the literature, the current review used meta-analysis to summarize the relationship between maltreatment with respect to vocabulary and the comprehension and production of language.
Method
Study Design
Studies were identified following a systematic search of titles, abstracts, and keywords in four electronic databases. The electronic databases searched were Education Resources Information Center (ERIC), Cumulative Index to Nursing and Allied Health Literature (CINAHL), Medline, and PsycINFO. Only studies (written in any language) that had been published or were in press in a peer-reviewed journal were included. Details of all keywords, fields searched, and search syntax for all databases are presented in the online supplemental file. The search strategy identified studies published between January 1960 and October 2013. An initial search was executed in June 2013 and repeated in October 2013.
Study Inclusion Criteria
Studies were included in the meta-analysis if they met the following criteria. First, the study was required to have examined language in a group of children found to have been maltreated. Studies undertaken exclusively with cases of suspected, but unconfirmed, maltreatment were excluded (e.g., Heath, Colton, & Aldgate, 1994). Second, the study was required to have compared either the expressive or receptive language or vocabulary skills of the maltreated group to a nonmaltreated comparison group. Third, the nonmaltreated/comparison group was required to comprise participants of similar age to the maltreatment group and be of equivalent SES as noted in the study's method section. Fourth, a study was only included if the mean age of the participants was between 2;6 (years;months) and 11;0 years of age.
Study Selection
After the search strategy was executed and duplicates were removed, three reviewers (one of the authors and two research assistants) inspected titles and abstracts of records. Full-text articles were sought for records considered to be potentially relevant. A record was considered to be potentially relevant if the study investigated language or any cognitive ability in maltreated children. Also, a study investigating any aspect of maltreatment that compared a group of maltreated children to a control group on any outcome measure was referred for further screening. Reliability of the reviewers screening was assessed. Ten percent of articles were randomly selected and examined by all reviewers. The agreement between reviewers for this component of the screening was high (κ = .989). There was 100% agreement for the suitability of full-text articles to be included in the meta-analysis.
Our search strategy led to the identification of several studies undertaken at the same laboratory. To ensure these studies did not present data from the same participants, authors were contacted by e-mail and the independence of samples was queried. In cases where data from the same participants were reported in multiple studies, only one study was used in the meta-analysis. The study selected for inclusion in the meta-analysis was the one with the largest sample size. After applying the above criteria, 26 studies were found that were included in the meta-analysis. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA; Moher, Liberati, Tetzlaff, & Altman, 2009) flowchart that summarizes studies removed after application of the aforementioned criteria is presented inFigure 1.
Figure 1.

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flowchart showing process for selecting articles. SES = socioeconomic status.

 Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flowchart showing process for selecting articles. SES = socioeconomic status.
Figure 1.

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flowchart showing process for selecting articles. SES = socioeconomic status.

×
Table 1 presents a summary of each study's participants with respect to their age, gender, maltreatment type, SES, and residential status. This table shows variability between studies with respect to the mean age of participants. Substantial differences also exist between studies in relation to the type of maltreatment experienced by the children. It should be noted that only two studies (Alessandri, 1991; Barnett, Vondra, & Shonk, 1996) presented information about the onset and/or duration of maltreatment. A limitation of this meta-analysis was we could not examine how the onset and/or duration of maltreatment might impact children's language skills. Nearly all studies examined language skills in children from low SES backgrounds. This is to be expected given low SES is a risk factor for maltreatment (Brown, Cohen, Johnson, & Salzinger, 1998). Table 1 also presents the residential status of the maltreated children. That is, whether the maltreated children were residing with a biological relative (parent, grandparent) or with a nonbiological relative after adoption or foster care placement. For most studies, children were residing with a biological relative, with three studies examining language functioning in maltreated children who were all in foster care. In three studies, the residential status of the maltreated children was mixed.
Table 1. Summary of studies' maltreatment and control group characteristics.
Summary of studies' maltreatment and control group characteristics.×
Study Sample size
% of female participants
Mean age (years)
Specific types of maltreatment reported in cases (%)c,d
Exposed to multiple types of maltreatment (% of cases) Study group from low SES background? Residential status of study group
Study group Control group Study group Control group Study group Control group Neglect Emotional abuse Physical abuse Sexual abuse
Alessandri (1991)  15 15 46.7 46.7 4.3 4.6 53.0 53.0 33.0 33.0 66.7 Yes Family
Allen & Oliver (1982)  51a 28 33.3 64.0 3.78 4.0 74.5 86.3 60.8 Yes Family
Ayoub et al. (2006)  75 66 Not reported 3.5–6b 3.5–6b 86.7 65.3 36.0 14.7 64.0 Yes Family
Barnett et al. (1996)  50 26 54.0 39.0 8.9 8.5 80.0 44.0 54.0 10.0 70.0 Yes Family
Beers & De Bellis (2002)  14 15 42.9 46.7 11.4 12.2 35.7 14.3 50.0 No Family
Cicchetti et al. (1993)  127 79 39.8 9.6 9.6 44.9 47.2 7.9 Yes Family
Coster et al. (1989)  20 20 45.0 40.0 2.6 75.0 50.0 25.0 5.0 50.0 Yes Family
De Bellis et al. (2009)  61 45 48.7 38.0 7.6 7.8 100.0 0.0 No Mixed: 34% in foster care.
Eigsti & Cicchetti (2004)  19 14 47.4 50.0 4.8 5.0 94.7 84.2 52.6 47.4 Yes Family
Flores et al. (2005)  76 57 26.3 36.8 8.5 8.9 74.6 83.1 66.2 15.5 77.6 Yes Family
Fox et al. (1988)  30 10 43.3 50.0 5.1 5.4 66.7 33.3 Yes Foster care
Gregory & Beveridge (1984)  13 16 46.2 50.0 6.3 6.4 100.0 Yes Family
Hoffman-Plotkin & Twentyman (1984)  28a 14 32.1 35.7 4.2 4.2 50.0 50.0 Yes Family
Nolin & Ethier (2007)  84a 53 41.3 49.0 9.1 8.8 100.0 66.7 0.0 66.7 Yes Family (or temporarily in foster care)
Perry et al. (1983)  21 21 42.9 47.6 4.6 5.5 100.0 Yes Family
Prasad et al. (2005)  19 19 47.4 57.9 2.9 2.5 100.0 0.0 Yes Foster
Rieder & Cicchetti (1989)  72 70 50.0 51.4 6.4 6.3 85.0 81.0 50.0 6.0 Yes Foster
Robinson et al. (2012)  70 70 51.7 55.7 7.4 7.6 80.0 9.0 4.0 Mixed: 34% from low SES Mixed: 54% in foster care.
Smith & Walden (1999)  15 15 60.0 47.0 4.4 4.6 27.0 19.0 27.0 27.0 46.7 Yes Not stated
Stipanicic et al. (2008)  11 11 54.5 54.5 7.3 7.5 100.0 No Mixed: 27% in foster care.
Toth & Cicchetti (1996)  29 32 49.0 49.0 9.8 9.4 41.4 27.6 31.0 55.0 Yes Family
Toth et al. (2000)  56 37 29.0 35.0 3.7 3.9 23.2 48.2 28.6 66.0 Yes Family
Toth et al. (2011)  91 43 62.0 67.0 10.1 10.5 86.0 51.0 41.0 14.0 58.0 Yes Family
Trickett et al. (1991, NIMH Sample) 21 21 33.0 33.0 6.2 6.1 100.0 0.0 Yes Family
Valentino et al. (2008)  96a 128 35.4 48.4 10.0 10.0 88.0 75.0 52.0 27.0 81.2 Yes Family
Vondra et al. (1990)  12 11 42.0 42.0 5.6 4.9 83.0 50.0 33.0 Yes Family
Note. SES = socioeconomic status; NIMH = National Institute of Mental Health.
Note. SES = socioeconomic status; NIMH = National Institute of Mental Health.×
a Combines data from multiple subgroups.
Combines data from multiple subgroups.×
b Study reports age range only.
Study reports age range only.×
c Empty cell value denotes data not reported in study.
Empty cell value denotes data not reported in study.×
d Row totals exceeding 100% indicate participants experienced multiple forms of maltreatment.
Row totals exceeding 100% indicate participants experienced multiple forms of maltreatment.×
Table 1. Summary of studies' maltreatment and control group characteristics.
Summary of studies' maltreatment and control group characteristics.×
Study Sample size
% of female participants
Mean age (years)
Specific types of maltreatment reported in cases (%)c,d
Exposed to multiple types of maltreatment (% of cases) Study group from low SES background? Residential status of study group
Study group Control group Study group Control group Study group Control group Neglect Emotional abuse Physical abuse Sexual abuse
Alessandri (1991)  15 15 46.7 46.7 4.3 4.6 53.0 53.0 33.0 33.0 66.7 Yes Family
Allen & Oliver (1982)  51a 28 33.3 64.0 3.78 4.0 74.5 86.3 60.8 Yes Family
Ayoub et al. (2006)  75 66 Not reported 3.5–6b 3.5–6b 86.7 65.3 36.0 14.7 64.0 Yes Family
Barnett et al. (1996)  50 26 54.0 39.0 8.9 8.5 80.0 44.0 54.0 10.0 70.0 Yes Family
Beers & De Bellis (2002)  14 15 42.9 46.7 11.4 12.2 35.7 14.3 50.0 No Family
Cicchetti et al. (1993)  127 79 39.8 9.6 9.6 44.9 47.2 7.9 Yes Family
Coster et al. (1989)  20 20 45.0 40.0 2.6 75.0 50.0 25.0 5.0 50.0 Yes Family
De Bellis et al. (2009)  61 45 48.7 38.0 7.6 7.8 100.0 0.0 No Mixed: 34% in foster care.
Eigsti & Cicchetti (2004)  19 14 47.4 50.0 4.8 5.0 94.7 84.2 52.6 47.4 Yes Family
Flores et al. (2005)  76 57 26.3 36.8 8.5 8.9 74.6 83.1 66.2 15.5 77.6 Yes Family
Fox et al. (1988)  30 10 43.3 50.0 5.1 5.4 66.7 33.3 Yes Foster care
Gregory & Beveridge (1984)  13 16 46.2 50.0 6.3 6.4 100.0 Yes Family
Hoffman-Plotkin & Twentyman (1984)  28a 14 32.1 35.7 4.2 4.2 50.0 50.0 Yes Family
Nolin & Ethier (2007)  84a 53 41.3 49.0 9.1 8.8 100.0 66.7 0.0 66.7 Yes Family (or temporarily in foster care)
Perry et al. (1983)  21 21 42.9 47.6 4.6 5.5 100.0 Yes Family
Prasad et al. (2005)  19 19 47.4 57.9 2.9 2.5 100.0 0.0 Yes Foster
Rieder & Cicchetti (1989)  72 70 50.0 51.4 6.4 6.3 85.0 81.0 50.0 6.0 Yes Foster
Robinson et al. (2012)  70 70 51.7 55.7 7.4 7.6 80.0 9.0 4.0 Mixed: 34% from low SES Mixed: 54% in foster care.
Smith & Walden (1999)  15 15 60.0 47.0 4.4 4.6 27.0 19.0 27.0 27.0 46.7 Yes Not stated
Stipanicic et al. (2008)  11 11 54.5 54.5 7.3 7.5 100.0 No Mixed: 27% in foster care.
Toth & Cicchetti (1996)  29 32 49.0 49.0 9.8 9.4 41.4 27.6 31.0 55.0 Yes Family
Toth et al. (2000)  56 37 29.0 35.0 3.7 3.9 23.2 48.2 28.6 66.0 Yes Family
Toth et al. (2011)  91 43 62.0 67.0 10.1 10.5 86.0 51.0 41.0 14.0 58.0 Yes Family
Trickett et al. (1991, NIMH Sample) 21 21 33.0 33.0 6.2 6.1 100.0 0.0 Yes Family
Valentino et al. (2008)  96a 128 35.4 48.4 10.0 10.0 88.0 75.0 52.0 27.0 81.2 Yes Family
Vondra et al. (1990)  12 11 42.0 42.0 5.6 4.9 83.0 50.0 33.0 Yes Family
Note. SES = socioeconomic status; NIMH = National Institute of Mental Health.
Note. SES = socioeconomic status; NIMH = National Institute of Mental Health.×
a Combines data from multiple subgroups.
Combines data from multiple subgroups.×
b Study reports age range only.
Study reports age range only.×
c Empty cell value denotes data not reported in study.
Empty cell value denotes data not reported in study.×
d Row totals exceeding 100% indicate participants experienced multiple forms of maltreatment.
Row totals exceeding 100% indicate participants experienced multiple forms of maltreatment.×
×
Table 2 presents the tests used in each study to measure language. The table shows receptive vocabulary received the most empirical attention having been investigated in 19 studies. Only two studies were found that examined expressive vocabulary skills. Receptive language skills were investigated in eight studies. In three of these studies, receptive language was measured by using a composite score that summed performance over multiple subtests. Expressive language skills were assessed in four studies. In two studies, expressive language was measured by using a composite score. In the remaining two studies (Coster, Gersten, Beeghly, & Cicchetti, 1989; Eigsti & Cicchetti, 2004), expressive language was measured by collecting spontaneous speech samples from children playing with an adult. The utterances from the child are later coded for completeness and grammatical complexity.
Table 2. Summary of language tests and language domain assessed in studies included in the meta-analysis.
Summary of language tests and language domain assessed in studies included in the meta-analysis.×
Study Language test/s used Expressive vocabulary Receptive vocabulary Expressive language Receptive language
Alessandri (1991)  Expressive One-Word Picture Vocabulary Test (Gardner, 1979); Test of Auditory Comprehension of Language–Revised (Carrow-Woolfold, 1985)
Allen & Oliver (1982)  Auditory Verbal Ability and Auditory Comprehension Quotients from the Preschool Language Scale (Zimmerman, Steiner, & Pond, 1979)
Ayoub et al. (2006)  Peabody Picture Vocabulary Test–Revised (Dunn, Dunn, & Dunn, 1981)
Barnett et al. (1996)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Cicchetti et al. (1993)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Coster et al. (1989)  Mean Length of Utterance; Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
De Bellis et al. (2009)  Comprehension of Instructions subtest from the NEPSY (Korkman, Kirk, & Kemp, 1998); Peabody Picture Vocabulary Test–III (Dunn, Dunn, & Williams, 1997)
Eigsti & Cicchetti (2004)  Index of Productive Syntax (Scarborough, 1990); Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Flores et al. (2005)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Fox et al. (1988)  Miller-Yoder Language Comprehension Test–Clinical Edition (Miller & Yoder, 1984); Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Gregory & Beveridge (1984)  Naming Vocabulary from the British Ability Scale (National Foundation for Educational Research, 1977); Sentence Comprehension Test (Wheldall, Mittler, & Hobsbaum, 1979)
Hoffman-Plotkin & Twentyman (1984)  Peabody Picture Vocabulary Test (edition not reported)
Nolin & Ethier (2007)  Comprehension of Instructions subtest from the NEPSY (Korkman et al., 1998)
Perry et al. (1983)  Peabody Picture Vocabulary Test (edition not reported)
Prasad et al. (2005)  Expressive and Receptive Language Composite Scores from the Sequenced Inventory of Communication Development (Hendrick, Prather, & Tobin, 1995); Expressive and Receptive Language Composite Scores from the Clinical Evaluation of Language Fundamentals (Semel, Wiig, & Secord, 1995)
Rieder & Cicchetti (1989)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Robinson et al. (2012)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Smith & Walden (1999)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Stipanicic et al. (2008)  Comprehension of Instructions subtest from the NEPSY (Korkman et al., 1998)
Toth & Cicchetti (1996)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Toth et al. (2000)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Toth et al. (2011)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Trickett et al. (1991, NIMH Sample) Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Valentino et al. (2008)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Vondra et al. (1990)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Note. NEPSY = A Developmental Neuropsychological Assessment; NIMH = National Institute of Mental Health.
Note. NEPSY = A Developmental Neuropsychological Assessment; NIMH = National Institute of Mental Health.×
Table 2. Summary of language tests and language domain assessed in studies included in the meta-analysis.
Summary of language tests and language domain assessed in studies included in the meta-analysis.×
Study Language test/s used Expressive vocabulary Receptive vocabulary Expressive language Receptive language
Alessandri (1991)  Expressive One-Word Picture Vocabulary Test (Gardner, 1979); Test of Auditory Comprehension of Language–Revised (Carrow-Woolfold, 1985)
Allen & Oliver (1982)  Auditory Verbal Ability and Auditory Comprehension Quotients from the Preschool Language Scale (Zimmerman, Steiner, & Pond, 1979)
Ayoub et al. (2006)  Peabody Picture Vocabulary Test–Revised (Dunn, Dunn, & Dunn, 1981)
Barnett et al. (1996)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Cicchetti et al. (1993)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Coster et al. (1989)  Mean Length of Utterance; Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
De Bellis et al. (2009)  Comprehension of Instructions subtest from the NEPSY (Korkman, Kirk, & Kemp, 1998); Peabody Picture Vocabulary Test–III (Dunn, Dunn, & Williams, 1997)
Eigsti & Cicchetti (2004)  Index of Productive Syntax (Scarborough, 1990); Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Flores et al. (2005)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Fox et al. (1988)  Miller-Yoder Language Comprehension Test–Clinical Edition (Miller & Yoder, 1984); Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Gregory & Beveridge (1984)  Naming Vocabulary from the British Ability Scale (National Foundation for Educational Research, 1977); Sentence Comprehension Test (Wheldall, Mittler, & Hobsbaum, 1979)
Hoffman-Plotkin & Twentyman (1984)  Peabody Picture Vocabulary Test (edition not reported)
Nolin & Ethier (2007)  Comprehension of Instructions subtest from the NEPSY (Korkman et al., 1998)
Perry et al. (1983)  Peabody Picture Vocabulary Test (edition not reported)
Prasad et al. (2005)  Expressive and Receptive Language Composite Scores from the Sequenced Inventory of Communication Development (Hendrick, Prather, & Tobin, 1995); Expressive and Receptive Language Composite Scores from the Clinical Evaluation of Language Fundamentals (Semel, Wiig, & Secord, 1995)
Rieder & Cicchetti (1989)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Robinson et al. (2012)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Smith & Walden (1999)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Stipanicic et al. (2008)  Comprehension of Instructions subtest from the NEPSY (Korkman et al., 1998)
Toth & Cicchetti (1996)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Toth et al. (2000)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Toth et al. (2011)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Trickett et al. (1991, NIMH Sample) Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Valentino et al. (2008)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Vondra et al. (1990)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Note. NEPSY = A Developmental Neuropsychological Assessment; NIMH = National Institute of Mental Health.
Note. NEPSY = A Developmental Neuropsychological Assessment; NIMH = National Institute of Mental Health.×
×
Study Quality
The methodological quality of the studies included in the meta-analysis was assessed by using a modified version of the Newcastle–Ottawa Scale (Wells et al., 2000) for cohort studies. This scale evaluates the extent studies reduce bias with respect to participant selection and comparability of control and study groups.
Following the guidelines of the Newcastle–Ottawa Scale (Wells et al., 2000), bias in participant selection is reduced if a study indicates participants in the study and control groups were recruited from the same communities, and government/official legal records were used to determine the presence/absence of exposure. Comparability of the study and control groups was also evaluated in relation to how similar the groups were with respect to SES, age, and gender. A study was considered to have met this criterion if the difference between groups was found to be less than a medium effect size on one of the above variables. At this level, there is 67% or more overlap in a distribution of scores or cases (Cohen, 1988). The Newcastle–Ottawa Scale does not credit a study for demonstrating groups are comparable when only a statement is provided in the publication that groups did not differ on a matching variable. For this criterion to be met, results from statistical tests and/or summary data must be reported. A study was considered to have reduced bias during data collection if it was reported that the individual/s undertaking the language assessment were blind to the maltreatment status of the child. We also coded whether studies excluded children with developmental problems. This was important to examine whether there might be other reasons a study observed poorer language skills in maltreated children.
Table 3 summarizes the methodological quality of the studies in relation to selection, comparability, outcome, and whether the study excluded children with developmental disabilities. Cells with black circles indicate a criterion was met, and empty cells indicate the study did not meet the criterion or did not provide sufficient information to determine whether a criterion had been met.
Table 3. Study quality assessment using a modified version of the Newcastle–Ottawa Scale (Wells et al., 2000).
Study quality assessment using a modified version of the Newcastle–Ottawa Scale (Wells et al., 2000).×
Study Selection
Comparability
Outcome
Exclusion criteria for developmental problems Method used to measure SES
Both groups recruited from same community Exposure determined by using government records Nonexposure determined by using government records SES Age Gender Assessor blind to maltreatment status
Alessandri (1991)  Autism; intellectual disability (mean FSIQa: maltreated group = 84, control group = 88.13); neurological impairments Household income;
maternal education
Allen & Oliver (1982)  Neurological impairments Household income;
maternal education
Ayoub et al. (2006)  Developmental delay Household Income
Barnett et al. (1996)  Hollingshead Four Factor Index
Beers & De Bellis (2002)  Developmental delay; head injury; intellectual impairments (mean FSIQb: maltreated group = 105.71; control group = 113.20); psychiatric problems Hollingshead Four Factor Index
Cicchetti et al. (1993)  Household income;
maternal education
Coster et al. (1989)  Neurological impairments Household prestige;
maternal education
De Bellis et al. (2009)  Autism; intellectual impairments (mean FSIQc: maltreated group = 99.73, control group = 101.96); medical illness; head injury; low birth weight; neurological impairment Hollingshead Four Factor Index
Eigsti & Cicchetti (2004)  Household income;
maternal education
Flores et al. (2005)  Hollingshead Two Factor Index
Fox et al. (1988)  Developmental delay; hearing impairments; neurological impairments Recipients of government income assistance
Gregory & Beveridge (1984)  Not stated
Hoffman-Plotkin & Twentyman (1984)  Intellectual impairment (mean FSIQa: maltreated group = 81, control group = 102) Household income;
maternal education
Nolin & Ethier (2007)  Birth problems; intellectual impairments (mean nonverbal IQe: maltreated group = 103.35; control group = 106.35); neurological impairment Household income
Perry et al. (1983)  Hollingshead Two Factor Index;
maternal education
Prasad et al. (2005)  Developmental delay; gestational age <32 weeks; neurological impairment Hollingshead Four Factor Index
Rieder & Cicchetti (1989)  Neurological impairment; physical impairment Household income;
maternal education
Robinson et al. (2012)  Intellectual impairments (mean nonverbal IQd: maltreated group = 96.47, control group = 104.09) Household income;
maternal education
Smith & Walden (1999)  Household income;
maternal education
Stipanicic et al. (2008)  Hearing impairments; intellectual impairments (mean FSIQa = maltreated group = 86.36, control group = 104.09); visual impairments Household income
Toth & Cicchetti (1996)  Hollingshead Four Factor Index
Toth et al. (2000)  Hollingshead Four Factor Index;
maternal education
Toth et al. (2011)  Hollingshead Four Factor Index
Trickett et al. (1991, NIMH Sample) Hollingshead Four Factor Index
Valentino et al. (2008)  Hollingshead Four Factor Index
Vondra et al. (1990)  Hollingshead Four Factor Index
Note. SES = socioeconomic status; FSIQ = Full Scale Intelligence Quotient; NIMH = National Institute of Mental health.
Note. SES = socioeconomic status; FSIQ = Full Scale Intelligence Quotient; NIMH = National Institute of Mental health.×
a Estimated using the Stanford-Binet Intelligence Scale (Thorndike, Hagen, & Sattler, 1986);
Estimated using the Stanford-Binet Intelligence Scale (Thorndike, Hagen, & Sattler, 1986);×
b Estimated using the Wechsler Intelligence Scale for Children (Wechsler, 1991);
Estimated using the Wechsler Intelligence Scale for Children (Wechsler, 1991);×
c Estimated using the Wechsler Abbreviated Scale of Intelligence (Wechsler, 1999);
Estimated using the Wechsler Abbreviated Scale of Intelligence (Wechsler, 1999);×
d Estimated using the Kaufman Brief Intelligence Test (Kaufman & Kaufman, 1990);
Estimated using the Kaufman Brief Intelligence Test (Kaufman & Kaufman, 1990);×
e Average of Picture Completion and Block Design subtests from the Wechsler Intelligence Scale for Children (scaled scored transformed to standard score to permit comparison with other test results).
Average of Picture Completion and Block Design subtests from the Wechsler Intelligence Scale for Children (scaled scored transformed to standard score to permit comparison with other test results).×
Table 3. Study quality assessment using a modified version of the Newcastle–Ottawa Scale (Wells et al., 2000).
Study quality assessment using a modified version of the Newcastle–Ottawa Scale (Wells et al., 2000).×
Study Selection
Comparability
Outcome
Exclusion criteria for developmental problems Method used to measure SES
Both groups recruited from same community Exposure determined by using government records Nonexposure determined by using government records SES Age Gender Assessor blind to maltreatment status
Alessandri (1991)  Autism; intellectual disability (mean FSIQa: maltreated group = 84, control group = 88.13); neurological impairments Household income;
maternal education
Allen & Oliver (1982)  Neurological impairments Household income;
maternal education
Ayoub et al. (2006)  Developmental delay Household Income
Barnett et al. (1996)  Hollingshead Four Factor Index
Beers & De Bellis (2002)  Developmental delay; head injury; intellectual impairments (mean FSIQb: maltreated group = 105.71; control group = 113.20); psychiatric problems Hollingshead Four Factor Index
Cicchetti et al. (1993)  Household income;
maternal education
Coster et al. (1989)  Neurological impairments Household prestige;
maternal education
De Bellis et al. (2009)  Autism; intellectual impairments (mean FSIQc: maltreated group = 99.73, control group = 101.96); medical illness; head injury; low birth weight; neurological impairment Hollingshead Four Factor Index
Eigsti & Cicchetti (2004)  Household income;
maternal education
Flores et al. (2005)  Hollingshead Two Factor Index
Fox et al. (1988)  Developmental delay; hearing impairments; neurological impairments Recipients of government income assistance
Gregory & Beveridge (1984)  Not stated
Hoffman-Plotkin & Twentyman (1984)  Intellectual impairment (mean FSIQa: maltreated group = 81, control group = 102) Household income;
maternal education
Nolin & Ethier (2007)  Birth problems; intellectual impairments (mean nonverbal IQe: maltreated group = 103.35; control group = 106.35); neurological impairment Household income
Perry et al. (1983)  Hollingshead Two Factor Index;
maternal education
Prasad et al. (2005)  Developmental delay; gestational age <32 weeks; neurological impairment Hollingshead Four Factor Index
Rieder & Cicchetti (1989)  Neurological impairment; physical impairment Household income;
maternal education
Robinson et al. (2012)  Intellectual impairments (mean nonverbal IQd: maltreated group = 96.47, control group = 104.09) Household income;
maternal education
Smith & Walden (1999)  Household income;
maternal education
Stipanicic et al. (2008)  Hearing impairments; intellectual impairments (mean FSIQa = maltreated group = 86.36, control group = 104.09); visual impairments Household income
Toth & Cicchetti (1996)  Hollingshead Four Factor Index
Toth et al. (2000)  Hollingshead Four Factor Index;
maternal education
Toth et al. (2011)  Hollingshead Four Factor Index
Trickett et al. (1991, NIMH Sample) Hollingshead Four Factor Index
Valentino et al. (2008)  Hollingshead Four Factor Index
Vondra et al. (1990)  Hollingshead Four Factor Index
Note. SES = socioeconomic status; FSIQ = Full Scale Intelligence Quotient; NIMH = National Institute of Mental health.
Note. SES = socioeconomic status; FSIQ = Full Scale Intelligence Quotient; NIMH = National Institute of Mental health.×
a Estimated using the Stanford-Binet Intelligence Scale (Thorndike, Hagen, & Sattler, 1986);
Estimated using the Stanford-Binet Intelligence Scale (Thorndike, Hagen, & Sattler, 1986);×
b Estimated using the Wechsler Intelligence Scale for Children (Wechsler, 1991);
Estimated using the Wechsler Intelligence Scale for Children (Wechsler, 1991);×
c Estimated using the Wechsler Abbreviated Scale of Intelligence (Wechsler, 1999);
Estimated using the Wechsler Abbreviated Scale of Intelligence (Wechsler, 1999);×
d Estimated using the Kaufman Brief Intelligence Test (Kaufman & Kaufman, 1990);
Estimated using the Kaufman Brief Intelligence Test (Kaufman & Kaufman, 1990);×
e Average of Picture Completion and Block Design subtests from the Wechsler Intelligence Scale for Children (scaled scored transformed to standard score to permit comparison with other test results).
Average of Picture Completion and Block Design subtests from the Wechsler Intelligence Scale for Children (scaled scored transformed to standard score to permit comparison with other test results).×
×
Table 3 shows nearly all of the 26 studies used government records to determine the presence of maltreatment. Also, nearly all studies matched participants with respect to age and gender. However, there is variability in other aspects of study methodological quality. For instance, 12 of 26 studies indicated that participants were recruited from the same community. Fourteen studies used government records to determine maltreatment was not present in the control group. Eleven studies used assessors who were blind to the maltreatment status of the children. It is interesting to note that eight studies did not meet the criteria for matching on SES according to the Newcastle–Ottawa guidelines. For seven studies, this was because insufficient SES data were reported. In one study, the difference between the maltreatment and control groups exceeded a medium effect size, even though the difference between groups on a SES indicator was not found to be statistically significant.
Table 3 also presents the specific developmental problems that were ruled out in the children. Empty cells indicate this information was not reported. Thirteen of the studies indicated participants were excluded from the research if one or more developmental problem/s was present. The most common developmental problems excluded were neurological and intellectual impairments. Seven studies reported mean IQ scores for the maltreated and control groups. In five of these studies, the mean IQ difference was 10 points or less. In two studies, the difference was 20 points or more.
Data Extraction Procedures and Effect Size Calculations
From each study included in the meta-analysis, data were extracted to compute an effect size and its variance. The effect size computed for this meta-analysis was a standardized mean difference (SMD). This describes the difference between the maltreated and control group on a language measure in standard deviation units. SMD was calculated so that positive values indicated the control group performed better than the maltreated group on the measure. That is, the maltreated group performed poorer on the language measure relative to the control group. Negative SMD values indicate that the maltreated group performed better on the language measure relative to the control group. SMD values approaching zero indicate a smaller difference between groups. The general formula to compute SMD and its variance are presented in (1) and (2), respectively. Display Formula
SMD=X¯ControlX¯MaltreatednControl1SDControl2+nMaltreated1SDMaltreated2nControl+nMaltreated2
(1)
Display Formula
VarSMD=nControl+nMaltreatednControl×nMaltreated+SMD22(nControl+nMaltreated)
(2)
Summary data or results from statistical tests were extracted from each study so that separate values for SMD and Var(SMD) could be computed. For most studies, these values were computed by using mean and standard deviations from the language tests that were reported in the results section (e.g., Alessandri, 1991). For three studies, these data were not available (Barnett et al., 1996; Cicchetti & Rogosch, 1997; Cicchetti, Rogosch, Lynch, & Holt, 1993), and results from statistical tests comparing the maltreated and control group on the language measure of interest were used to compute the effect size and variance. The conversion of extracted data to SMD and Var(SMD) was undertaken by using Comprehensive Meta-Analysis software (Borenstein, Hedges, Higgins, & Rothstein, 2005). For five studies (Allen & Oliver, 1982; De Bellis, Hooper, Spratt, & Woolley, 2009; Hoffman-Plotkin & Twentyman, 1984; Nolin & Ethier, 2007; Valentino, Cicchetti, Rogosch, & Toth, 2008), separate data were reported for two or more maltreated groups. For these studies, data from separate groups were combined to create a single maltreatment group. This was achieved by computing a weighted average and standard deviation for the language scores for the groups (Higgins & Green, 2008).
Meta-Analytic Procedures
A weighted average effect size was computed that summarized the differences between maltreated and control groups with respect to receptive vocabulary, receptive language, and expressive language skills. An average effect size for expressive vocabulary was not computed because only two studies were found that investigated this aspect of language. We tested whether the average effect size value was significantly different from zero. For these and other significance tests, an α level of 0.05 (two-tails) was used. Comprehensive Meta-Analysis software was used to compute average effect sizes (Borenstein et al., 2005).
A random-effects model was used to weight individual studies to compute each average effect size (Hedges, 1983). By using this model, it is assumed that differences between study level effect sizes reflect the contribution of within-study error/sampling error and between-study error/systematic influences. This can be contrasted with a fixed-effects model, which assumes differences between study effect sizes reflect sampling error only (Borenstein, Hedges, Higgins, & Rothstein, 2011). A random-effects model was chosen because both systematic influences and sampling error are likely to lead to differences between study effect sizes. Potential systematic influences might be differences in study's participant characteristics (e.g., Table 1) or methodological quality (e.g., Table 3).
The I2 statistic was also computed for each meta-analysis. This measures the amount of differences between study level effect sizes due to systematic influences or nonrandom error. Thus an I2 value of 80% indicates 80% of the heterogeneity (or differences in study level effect sizes) is attributable to systematic or nonrandom error and 20% to sampling error. As a guideline, Higgins, Thompson, Deeks, and Altman (2003)  suggest that values of 25%, 50%, and 75% correspond to low, moderate, and high levels of heterogeneity, respectively. In cases where moderate to high levels of heterogeneity were found, random effects meta-regression (Thompson & Higgins, 2002) was used to investigate whether the participant or methodological characteristics of a study that were presented in Tables 1 or 3 predicted effect sizes.
Results
Receptive Vocabulary
A summary of each study's effect size examining receptive vocabulary in maltreated children and the weighted average effect size are presented as a forest plot inFigure 2. Also shown in Figure 2 (and Figures 3 & 4) is the weight assigned to each study by the random-effects model expressed as a percentage. Studies with a higher percentage made a larger contribution to the average. The average effect size computed for receptive vocabulary is .463 and significant (p < .001). Calculation of the I2 statistic yielded a value of 62.33% indicating moderate to high levels of heterogeneity. It is noted that the difference in average IQ between maltreated and nonmaltreated groups for one study included in this meta-analysis was greater than 20 points (Hoffman-Plotkin & Twentyman, 1984). To examine whether group differences in IQ were influencing results, the average effect size was recomputed after removing this study. After recomputing the average effect size, a significant result was still observed (SMD = 0.400; 95% confidence interval [0.258, 0.541]; p < .001). According to Cohen's (1988)  taxonomy, this value approximates a medium effect size (i.e., d = .5). The positive value of the effect size indicates that, on average, studies are finding poorer performance by maltreated children compared with control groups. To examine potential publication bias, the fail-safe N (Orwin, 1983) was computed. This value indicates the number of missing studies required to return p to .05. This analysis indicated that 345 nonsignificant studies would be required to return a nonsignificant effect size.
Figure 2.

Study and average effect sizes from studies investigating receptive vocabulary. SMD = standardized mean difference; CI, confidence interval; NIMH = National Institute of Mental Health.

 Study and average effect sizes from studies investigating receptive vocabulary. SMD = standardized mean difference; CI, confidence interval; NIMH = National Institute of Mental Health.
Figure 2.

Study and average effect sizes from studies investigating receptive vocabulary. SMD = standardized mean difference; CI, confidence interval; NIMH = National Institute of Mental Health.

×
Figure 3.

Study and average effect sizes from studies investigating expressive language. SMD = standardized mean difference; CI, confidence interval.

 Study and average effect sizes from studies investigating expressive language. SMD = standardized mean difference; CI, confidence interval.
Figure 3.

Study and average effect sizes from studies investigating expressive language. SMD = standardized mean difference; CI, confidence interval.

×
Figure 4.

Study and average effect sizes from studies investigating receptive language. SMD = standardized mean difference; CI, confidence interval.

 Study and average effect sizes from studies investigating receptive language. SMD = standardized mean difference; CI, confidence interval.
Figure 4.

Study and average effect sizes from studies investigating receptive language. SMD = standardized mean difference; CI, confidence interval.

×
Random effects meta-regression was used to investigate potential sources of heterogeneity. In these analyses, we tested whether a study's participant characteristics (presented in Table 1) or methodological quality (presented in Table 3) predicted individual effect sizes (presented in Figure 2). There were an insufficient number of studies to test all predictor variables in a single model (Borenstein et al., 2011). The influence of each predictor variable on effect sizes was tested in separate models. The predictor variables tested were mean age of participants, percentage of female participants, whether participants were from a low SES background (dummy coded where 1 = participants from low SES, 0 = participants from nonlow SES), and the residential status of the maltreatment group (dummy coded where 1 = participants residing with family, 0 = foster care). Studies with more than 50% of participants reported to be residing with a biological relative were coded as 1 (1 = participants residing with family). An additional analysis examined whether the percentage of maltreated children who had been neglected predicted effect sizes. It was not possible to examine whether other types of maltreatment predicted effect sizes. This was because maltreatment data were not reported in a sufficient number of studies that examined receptive vocabulary.
The influence of study quality (presented in Table 3) on effect sizes was also examined in the meta-regression analyses. The predictor variables tested were whether groups were recruited from the same community, matched on age, gender, or SES, and if government records were used to determine the presence and absence of maltreatment. Also tested was whether the use of blinding procedures and excluding participants with developmental disabilities predicted effect sizes. Each of the aforementioned variables was dummy coded for the analyses. A value of 1 was used if the study met the criterion and 0 if the criterion was not met. The results of the meta-regression analyses are presented in Table 4.
Table 4. Results from meta-regression examining predictors of receptive vocabulary effect sizes.
Results from meta-regression examining predictors of receptive vocabulary effect sizes.×
Model No. Predictor Variable k df R2 QModel QResidual β p
1 Mean age of participants 19 1,17 0.079 1.8153 21.1703 −0.281 .178
2 Percentage of female participants 18a 1,16 0.0237 0.5093 20.9578 −0.154 .476
3 Percentage of participants exposed to neglect 17b 1,15 0.0199 0.4098 20.1933 0.141 .522
4 Participants from low SES background 19 1,17 0.1245 2.8624 20.1233 −0.3529 .091
5 Residential status of study group 18c 1,16 0.0125 0.277 21.798 −0.112 .599
6 Maltreated and control groups recruited from same community 19 1,17 0.1288 2.9599 20.0257 0.3588 .085
7 Maltreatment and nonmaltreatment determined by government records 19 1,17 0.0028 0.0634 22.9222 0.0525 .801
8 Maltreatment and control groups matched on maternal education 19 1,17 0.0727 1.6702 21.3154 −0.2696 .196
9 Groups matched on age 19 1,17 0.1525 3.5051 19.4805 0.3905 .061
10 Groups matched on gender 19 1,17 0.1337 3.0735 19.9122 0.3657 .080
11 Groups matched on SES 19 1,17 0.0561 1.2898 21.6959 0.2369 .256
12 Blinding procedure used during data collection 19 1,17 0.0088 0.2017 22.7839 0.0937 .653
13 Study excludes children with developmental disabilities 19 1,17 0.0317 0.7294 22.2562 0.1781 .393
Note. SES = socioeconomic status.
Note. SES = socioeconomic status.×
a One study did not report the number of female participants and was included in this analysis.
One study did not report the number of female participants and was included in this analysis.×
b Two studies did not report the percentage of children who had been neglected and were excluded from this analysis.
Two studies did not report the percentage of children who had been neglected and were excluded from this analysis.×
c One study was not included in this analysis because residential status of the children was not reported.
One study was not included in this analysis because residential status of the children was not reported.×
Table 4. Results from meta-regression examining predictors of receptive vocabulary effect sizes.
Results from meta-regression examining predictors of receptive vocabulary effect sizes.×
Model No. Predictor Variable k df R2 QModel QResidual β p
1 Mean age of participants 19 1,17 0.079 1.8153 21.1703 −0.281 .178
2 Percentage of female participants 18a 1,16 0.0237 0.5093 20.9578 −0.154 .476
3 Percentage of participants exposed to neglect 17b 1,15 0.0199 0.4098 20.1933 0.141 .522
4 Participants from low SES background 19 1,17 0.1245 2.8624 20.1233 −0.3529 .091
5 Residential status of study group 18c 1,16 0.0125 0.277 21.798 −0.112 .599
6 Maltreated and control groups recruited from same community 19 1,17 0.1288 2.9599 20.0257 0.3588 .085
7 Maltreatment and nonmaltreatment determined by government records 19 1,17 0.0028 0.0634 22.9222 0.0525 .801
8 Maltreatment and control groups matched on maternal education 19 1,17 0.0727 1.6702 21.3154 −0.2696 .196
9 Groups matched on age 19 1,17 0.1525 3.5051 19.4805 0.3905 .061
10 Groups matched on gender 19 1,17 0.1337 3.0735 19.9122 0.3657 .080
11 Groups matched on SES 19 1,17 0.0561 1.2898 21.6959 0.2369 .256
12 Blinding procedure used during data collection 19 1,17 0.0088 0.2017 22.7839 0.0937 .653
13 Study excludes children with developmental disabilities 19 1,17 0.0317 0.7294 22.2562 0.1781 .393
Note. SES = socioeconomic status.
Note. SES = socioeconomic status.×
a One study did not report the number of female participants and was included in this analysis.
One study did not report the number of female participants and was included in this analysis.×
b Two studies did not report the percentage of children who had been neglected and were excluded from this analysis.
Two studies did not report the percentage of children who had been neglected and were excluded from this analysis.×
c One study was not included in this analysis because residential status of the children was not reported.
One study was not included in this analysis because residential status of the children was not reported.×
×
Overall, no significant predictors of effect sizes were found. However, we note that four models approached statistical significance (ps < .100). First, Model 4 indicates studies observed a larger difference between maltreated children and controls when participants were not from low SES backgrounds (p = .091). Models 6 (p = .085), 9 (p = .061), and 10 (p = .080) indicate that a larger difference was observed when participants were recruited from the same community and groups were matched on age and gender.
Expressive Vocabulary
The systematic search of the literature only found two studies (Alessandri, 1991; Gregory & Beveridge, 1984) that examined expressive vocabulary in maltreated children. Both studies reported poorer expressive vocabulary skills in maltreated children. However, the difference was not significant, and the observed effect sizes were small to medium (Alessandri [1991]  SMD = .327, p = .373; Gregory & Beveridge [1984]  SMD = .278, p = .458). Because there were only two studies examining expressive vocabulary, it was not feasible to submit their results to a meta-analysis.
Expressive Language
A forest plot showing effect sizes for studies that investigated expressive language in maltreated children is presented in Figure 3. The average effect size was .860 and significant (p < .001). That is, on average, studies are reporting that maltreated children are performing around .9 SD lower on expressive language tests compared with nonmaltreated children from similar SES backgrounds. Calculation of the fail-safe N indicated that 27 unpublished studies with nonsignificant results would be required to return α to .05. The magnitude of the effect size is large according to Cohen's (1988)  guidelines. There was little variability in study level effect sizes. The I2 statistic for this set of effect sizes was found to be less than 1%. Thus all of the heterogeneity between effect sizes for these studies can be attributable to random error.
Receptive Language
Effect sizes for studies examining receptive language in maltreated children are presented in a forest plot in Figure 4. The average weighted effect size for studies examining receptive language in maltreated children and controls was found to be .528 (p < .001). The mean Full Scale Intelligence Quotient difference between maltreated and nonmaltreated children for one of the studies in this meta-analysis differed more than 20 points (Stipanicic, Nolin, Fortin, & Gobeil, 2008). When this study was removed and the average effect size recalculated, a significant positive average effect size that approached a medium effect size was still observed (SMD = .467; 95% confidence interval [.161, .774]; p = .003). Calculation of the fail-safe N indicated that 24 unpublished studies with nonsignificant results would return α to .05. Figure 4 does indicate variability in study level effect sizes. Two observed very large effect sizes between maltreated and control groups (SMD > 1) and two studies found that the control group performed poorer on the comprehension test compared with the maltreated group. Calculation of the I2 indicated that 62.5% of the heterogeneity between studies could be attributed to systematic influences or nonrandom error.
Meta-regression analyses examined whether participant or methodological factors might account for the heterogeneity in receptive language effect sizes. Most of the predictor variables used to examine influences on receptive vocabulary effect sizes were also used in these analyses (see Table 4). However, it was not possible to test the influence of recruiting children from the same community and whether participants were matched on gender. This was because there was no variability in these predictor variables; all studies examining receptive language recruited children from the same community and matched on the basis of gender. Also, it was not possible to test the influence of specific types of maltreatment, including neglect, because this information was reported in less than half of the studies examining receptive language.
Results from the meta-regression analyses are presented in Table 5. None of the models were found to be significant. However, one model approached statistical significance (p < .100). This was the model testing the influence of matching groups by using SES (Model 8; p = .079). The direction of the beta value (which was positive) indicates studies that matched groups on SES observed larger effect sizes.
Discussion
This review article used meta-analysis to summarize the literature investigating language skills in maltreated children. The analyses consistently showed language skills are poorer in maltreated children when compared with nonmaltreated children from similar SES backgrounds. In particular, statistically significant average effect sizes, indicating poorer language skills in maltreated children, were observed when combining studies that measured expressive language, receptive language, and receptive vocabulary skills. An insufficient number of studies were identified to permit meaningful meta-analysis of expressive vocabulary.
The overall findings from this meta-analysis showing poorer language skills in maltreated children is in line with conclusions from a previous systematic review (Veltman & Browne, 2001) and narrative reviews of the literature (Hwa-Froelich, 2012; Law & Conway, 1992). This review article builds on past work by providing an estimate of the effect size that measures the association between maltreatment and poor language skills. Stated in standardized scores (i.e., a distribution that has a mean of 100 and standard deviation of 15), the average finding is that for receptive vocabulary, maltreated children are scoring seven points lower than controls of comparable SES. For expressive language skills, the average finding is that maltreated children are 13 points lower and eight points lower for receptive language.
Another finding to emerge from this meta-analysis concerns the heterogeneity or differences between individual study effect sizes. Around 60% of the differences between effect sizes derived from studies investigating receptive vocabulary and receptive language were not attributable to sampling or random error. This suggests there are one or more systematic influences impacting study findings. Using meta-regression, we tested whether the characteristics of a study's participants or methodology might be influencing results. Although statistically significant predictors of effect sizes were not found, five meta-regression models were close to statistical significance (ps < .100) and reveal potentially informative trends in the literature.
First, one model (Table 4, Model 4, p = .091) potentially indicates the difference between maltreated and nonmaltreated groups on a measure of receptive vocabulary is larger when children were not from a low SES background. In explaining this trend, one possibility is that maltreatment has an equally detrimental impact on children's language skills, irrespective of socioeconomic background. However, in nonmaltreated samples, lower language skills tend to be observed when children are only from disadvantaged socioeconomic backgrounds (Hart & Risley, 1995; Hoff & Tian, 2005; Hoff-Ginsberg, 1998). Thus, in studies where children were from nondisadvantaged SES backgrounds, it appears that only maltreated children obtained lower language scores leading to a large effect size (or difference between groups). It is interesting to note that the corresponding model examining this same variable for receptive language (Table 5, Model 3), whilst not statistically significant, was comparable with respect to the R2 value and direction, as well as the magnitude of the beta-value. From this perspective, low SES might be masking the impact of maltreatment on children's language skills. This proposal will need to be examined in future research.
Table 5. Results from meta-regression examining predictors of receptive language effect sizes.
Results from meta-regression examining predictors of receptive language effect sizes.×
Model No. Predictor Variable k df R2 QModel QResidual β p
1 Mean age of participants 9 1,7 0.0639 0.5946 8.7069 −0.2528 .441
2 Proportion of female participants 9 1,7 0.0153 0.1428 9.1587 0.1239 .706
3 Participants from low SES background 9 1,7 0.0987 0.9182 8.3833 −0.3142 .338
4 Residential status of study group 9 1,7 0.2413 2.2449 7.0566 −0.4913 .134
5 Maltreatment and nonmaltreatment determined by government records 9 1,7 0.0164 0.1527 9.1488 −0.1281 .696
6 Maltreatment and control groups matched on maternal education 9 1,7 0.2324 2.1619 7.1396 0.4821 .142
7 Groups matched on age 9 1,7 0.2703 2.5142 6.7873 0.5199 .113
8 Groups matched on SES 9 1,7 0.3316 3.0844 6.2171 0.5759 .079
9 Blinding procedure used during data collection 9 1,7 0.1269 1.1801 8.1214 −0.3562 .277
10 Study excludes children with developmental disabilities 9 1,7 0.2429 2.2593 7.0422 0.4928 .133
Note. SES = socioeconomic status.
Note. SES = socioeconomic status.×
Table 5. Results from meta-regression examining predictors of receptive language effect sizes.
Results from meta-regression examining predictors of receptive language effect sizes.×
Model No. Predictor Variable k df R2 QModel QResidual β p
1 Mean age of participants 9 1,7 0.0639 0.5946 8.7069 −0.2528 .441
2 Proportion of female participants 9 1,7 0.0153 0.1428 9.1587 0.1239 .706
3 Participants from low SES background 9 1,7 0.0987 0.9182 8.3833 −0.3142 .338
4 Residential status of study group 9 1,7 0.2413 2.2449 7.0566 −0.4913 .134
5 Maltreatment and nonmaltreatment determined by government records 9 1,7 0.0164 0.1527 9.1488 −0.1281 .696
6 Maltreatment and control groups matched on maternal education 9 1,7 0.2324 2.1619 7.1396 0.4821 .142
7 Groups matched on age 9 1,7 0.2703 2.5142 6.7873 0.5199 .113
8 Groups matched on SES 9 1,7 0.3316 3.0844 6.2171 0.5759 .079
9 Blinding procedure used during data collection 9 1,7 0.1269 1.1801 8.1214 −0.3562 .277
10 Study excludes children with developmental disabilities 9 1,7 0.2429 2.2593 7.0422 0.4928 .133
Note. SES = socioeconomic status.
Note. SES = socioeconomic status.×
×
Second, models testing whether maltreated and nonmaltreated groups were matched on age (Table 4, Model 9), gender (Table 4, Model 10), SES background (Table 5, Model 8), and recruited from the same community (Table 4, Model 6) approached statistical significance. Each of these models indicated studies matching on these variables observed a larger effect size or difference between maltreated and control groups. This might arise because studies that controlled for nuisance variables might be able to measure the association between maltreatment and language with smaller levels of interference. Thus the meta-regression analyses presented in this review article reiterate the need for future studies to control for confounding participant characteristics where possible.
Failure to find significant meta-regression models also indicates that reliable predictor/s of language outcomes in maltreated samples have yet to be identified. As noted earlier, chronic stress experienced as a consequence of maltreatment is known to disrupt brain development (De Bellis et al., 2002; De Bellis & Kuchibhatla, 2006). Also, there is evidence to suggest that maltreated children do not receive sufficient linguistic stimulation, or experience sufficient meaningful, child-focused interactions with caregivers (Allen & Wasserman, 1985; Eigsti & Cicchetti, 2004; Kavanagh et al., 1988; Wasserman et al., 1983). Given this, maltreatment type and history may be key predictors of language outcomes. A limitation of this review article was these variables could not be quantitatively examined because insufficient data were reported in primary studies. Thus one avenue for future research would be to examine in detail how maltreatment history and type impacts children's language skills.
The results of this meta-analysis have implications for applied settings. This review article provides strong evidence that children exposed to maltreatment may have difficulties understanding and producing language. Thus, for professionals working with maltreated children, this review highlights communicative difficulties that will most likely be present in this group. It is not clear from this meta-analysis whether language skills are disproportionally affected compared with other cognitive abilities in maltreated children. In this review article, we provide some evidence that the language problems in maltreated children may not be related to other developmental problems or explained by IQ. The meta-regression analyses indicated that whether a study excluded children with a developmental problem did not predict effect sizes (Table 4, Model 13; Table 5, Model 10). Also, removing studies from the meta-analysis that had a large discrepancy in IQ between maltreated and control groups had a negligible impact on the average effect size. However, the influence of co-occurring developmental disabilities on maltreated children's language skills will need to be clarified in future research. A limitation with the analyses undertaken in this review article was that information about children's IQ was only reported in seven of the 26 studies. It is also possible that maltreated children presented with cognitive deficits outside of IQ. Research has found that maltreated children perform poorer on neuropsychological tests that assess attention, learning, and memory (De Bellis et al., 2009). Thus it could be that poor language skills might be only one of a number of abilities vulnerable to the effects of maltreatment.
A strength of meta-analysis and meta-regression is data from multiple studies are pooled producing more reliable and precise effect estimates compared with results from an individual study (Borenstein et al., 2011; Hunter, Schmidt, & Jackson, 1982). However, it is important to note limitations with this approach as well. First, this meta-analysis is unable to determine how maltreatment negatively impacts language development. For instance, all studies analyzed were cross-sectional in design. The developmental trajectory of expressive and receptive language skills following maltreatment will need to be investigated in longitudinal research. Second, caution is required when interpreting meta-regression results. This is because other study characteristics may be highly correlated with one or more predictor variables (Thompson & Higgins, 2002). As a consequence, associations between a predictor variable and effect size might reflect the influence of another variable. Given this, it is important that results from meta-regression are investigated by additional primary research.
Conclusions
This meta-analysis summarized results from research investigating language skills in maltreated children. Based on the findings from 26 studies that represent data from 1,176 maltreated children and 936 controls, the analyses showed poorer language skills in maltreated children, compared with matched SES controls. Additional research is warranted to better understand how maltreatment disrupts language development and to determine the best methods for improving language skills and developmental outcomes in this group.
Acknowledgments
This research was supported by the Australian Research Council (Grant DP1095509). We thank Gillian Clark and Bronwen Manger for their assistance with collecting and reviewing articles for this article.
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Figure 1.

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flowchart showing process for selecting articles. SES = socioeconomic status.

 Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flowchart showing process for selecting articles. SES = socioeconomic status.
Figure 1.

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flowchart showing process for selecting articles. SES = socioeconomic status.

×
Figure 2.

Study and average effect sizes from studies investigating receptive vocabulary. SMD = standardized mean difference; CI, confidence interval; NIMH = National Institute of Mental Health.

 Study and average effect sizes from studies investigating receptive vocabulary. SMD = standardized mean difference; CI, confidence interval; NIMH = National Institute of Mental Health.
Figure 2.

Study and average effect sizes from studies investigating receptive vocabulary. SMD = standardized mean difference; CI, confidence interval; NIMH = National Institute of Mental Health.

×
Figure 3.

Study and average effect sizes from studies investigating expressive language. SMD = standardized mean difference; CI, confidence interval.

 Study and average effect sizes from studies investigating expressive language. SMD = standardized mean difference; CI, confidence interval.
Figure 3.

Study and average effect sizes from studies investigating expressive language. SMD = standardized mean difference; CI, confidence interval.

×
Figure 4.

Study and average effect sizes from studies investigating receptive language. SMD = standardized mean difference; CI, confidence interval.

 Study and average effect sizes from studies investigating receptive language. SMD = standardized mean difference; CI, confidence interval.
Figure 4.

Study and average effect sizes from studies investigating receptive language. SMD = standardized mean difference; CI, confidence interval.

×
Table 1. Summary of studies' maltreatment and control group characteristics.
Summary of studies' maltreatment and control group characteristics.×
Study Sample size
% of female participants
Mean age (years)
Specific types of maltreatment reported in cases (%)c,d
Exposed to multiple types of maltreatment (% of cases) Study group from low SES background? Residential status of study group
Study group Control group Study group Control group Study group Control group Neglect Emotional abuse Physical abuse Sexual abuse
Alessandri (1991)  15 15 46.7 46.7 4.3 4.6 53.0 53.0 33.0 33.0 66.7 Yes Family
Allen & Oliver (1982)  51a 28 33.3 64.0 3.78 4.0 74.5 86.3 60.8 Yes Family
Ayoub et al. (2006)  75 66 Not reported 3.5–6b 3.5–6b 86.7 65.3 36.0 14.7 64.0 Yes Family
Barnett et al. (1996)  50 26 54.0 39.0 8.9 8.5 80.0 44.0 54.0 10.0 70.0 Yes Family
Beers & De Bellis (2002)  14 15 42.9 46.7 11.4 12.2 35.7 14.3 50.0 No Family
Cicchetti et al. (1993)  127 79 39.8 9.6 9.6 44.9 47.2 7.9 Yes Family
Coster et al. (1989)  20 20 45.0 40.0 2.6 75.0 50.0 25.0 5.0 50.0 Yes Family
De Bellis et al. (2009)  61 45 48.7 38.0 7.6 7.8 100.0 0.0 No Mixed: 34% in foster care.
Eigsti & Cicchetti (2004)  19 14 47.4 50.0 4.8 5.0 94.7 84.2 52.6 47.4 Yes Family
Flores et al. (2005)  76 57 26.3 36.8 8.5 8.9 74.6 83.1 66.2 15.5 77.6 Yes Family
Fox et al. (1988)  30 10 43.3 50.0 5.1 5.4 66.7 33.3 Yes Foster care
Gregory & Beveridge (1984)  13 16 46.2 50.0 6.3 6.4 100.0 Yes Family
Hoffman-Plotkin & Twentyman (1984)  28a 14 32.1 35.7 4.2 4.2 50.0 50.0 Yes Family
Nolin & Ethier (2007)  84a 53 41.3 49.0 9.1 8.8 100.0 66.7 0.0 66.7 Yes Family (or temporarily in foster care)
Perry et al. (1983)  21 21 42.9 47.6 4.6 5.5 100.0 Yes Family
Prasad et al. (2005)  19 19 47.4 57.9 2.9 2.5 100.0 0.0 Yes Foster
Rieder & Cicchetti (1989)  72 70 50.0 51.4 6.4 6.3 85.0 81.0 50.0 6.0 Yes Foster
Robinson et al. (2012)  70 70 51.7 55.7 7.4 7.6 80.0 9.0 4.0 Mixed: 34% from low SES Mixed: 54% in foster care.
Smith & Walden (1999)  15 15 60.0 47.0 4.4 4.6 27.0 19.0 27.0 27.0 46.7 Yes Not stated
Stipanicic et al. (2008)  11 11 54.5 54.5 7.3 7.5 100.0 No Mixed: 27% in foster care.
Toth & Cicchetti (1996)  29 32 49.0 49.0 9.8 9.4 41.4 27.6 31.0 55.0 Yes Family
Toth et al. (2000)  56 37 29.0 35.0 3.7 3.9 23.2 48.2 28.6 66.0 Yes Family
Toth et al. (2011)  91 43 62.0 67.0 10.1 10.5 86.0 51.0 41.0 14.0 58.0 Yes Family
Trickett et al. (1991, NIMH Sample) 21 21 33.0 33.0 6.2 6.1 100.0 0.0 Yes Family
Valentino et al. (2008)  96a 128 35.4 48.4 10.0 10.0 88.0 75.0 52.0 27.0 81.2 Yes Family
Vondra et al. (1990)  12 11 42.0 42.0 5.6 4.9 83.0 50.0 33.0 Yes Family
Note. SES = socioeconomic status; NIMH = National Institute of Mental Health.
Note. SES = socioeconomic status; NIMH = National Institute of Mental Health.×
a Combines data from multiple subgroups.
Combines data from multiple subgroups.×
b Study reports age range only.
Study reports age range only.×
c Empty cell value denotes data not reported in study.
Empty cell value denotes data not reported in study.×
d Row totals exceeding 100% indicate participants experienced multiple forms of maltreatment.
Row totals exceeding 100% indicate participants experienced multiple forms of maltreatment.×
Table 1. Summary of studies' maltreatment and control group characteristics.
Summary of studies' maltreatment and control group characteristics.×
Study Sample size
% of female participants
Mean age (years)
Specific types of maltreatment reported in cases (%)c,d
Exposed to multiple types of maltreatment (% of cases) Study group from low SES background? Residential status of study group
Study group Control group Study group Control group Study group Control group Neglect Emotional abuse Physical abuse Sexual abuse
Alessandri (1991)  15 15 46.7 46.7 4.3 4.6 53.0 53.0 33.0 33.0 66.7 Yes Family
Allen & Oliver (1982)  51a 28 33.3 64.0 3.78 4.0 74.5 86.3 60.8 Yes Family
Ayoub et al. (2006)  75 66 Not reported 3.5–6b 3.5–6b 86.7 65.3 36.0 14.7 64.0 Yes Family
Barnett et al. (1996)  50 26 54.0 39.0 8.9 8.5 80.0 44.0 54.0 10.0 70.0 Yes Family
Beers & De Bellis (2002)  14 15 42.9 46.7 11.4 12.2 35.7 14.3 50.0 No Family
Cicchetti et al. (1993)  127 79 39.8 9.6 9.6 44.9 47.2 7.9 Yes Family
Coster et al. (1989)  20 20 45.0 40.0 2.6 75.0 50.0 25.0 5.0 50.0 Yes Family
De Bellis et al. (2009)  61 45 48.7 38.0 7.6 7.8 100.0 0.0 No Mixed: 34% in foster care.
Eigsti & Cicchetti (2004)  19 14 47.4 50.0 4.8 5.0 94.7 84.2 52.6 47.4 Yes Family
Flores et al. (2005)  76 57 26.3 36.8 8.5 8.9 74.6 83.1 66.2 15.5 77.6 Yes Family
Fox et al. (1988)  30 10 43.3 50.0 5.1 5.4 66.7 33.3 Yes Foster care
Gregory & Beveridge (1984)  13 16 46.2 50.0 6.3 6.4 100.0 Yes Family
Hoffman-Plotkin & Twentyman (1984)  28a 14 32.1 35.7 4.2 4.2 50.0 50.0 Yes Family
Nolin & Ethier (2007)  84a 53 41.3 49.0 9.1 8.8 100.0 66.7 0.0 66.7 Yes Family (or temporarily in foster care)
Perry et al. (1983)  21 21 42.9 47.6 4.6 5.5 100.0 Yes Family
Prasad et al. (2005)  19 19 47.4 57.9 2.9 2.5 100.0 0.0 Yes Foster
Rieder & Cicchetti (1989)  72 70 50.0 51.4 6.4 6.3 85.0 81.0 50.0 6.0 Yes Foster
Robinson et al. (2012)  70 70 51.7 55.7 7.4 7.6 80.0 9.0 4.0 Mixed: 34% from low SES Mixed: 54% in foster care.
Smith & Walden (1999)  15 15 60.0 47.0 4.4 4.6 27.0 19.0 27.0 27.0 46.7 Yes Not stated
Stipanicic et al. (2008)  11 11 54.5 54.5 7.3 7.5 100.0 No Mixed: 27% in foster care.
Toth & Cicchetti (1996)  29 32 49.0 49.0 9.8 9.4 41.4 27.6 31.0 55.0 Yes Family
Toth et al. (2000)  56 37 29.0 35.0 3.7 3.9 23.2 48.2 28.6 66.0 Yes Family
Toth et al. (2011)  91 43 62.0 67.0 10.1 10.5 86.0 51.0 41.0 14.0 58.0 Yes Family
Trickett et al. (1991, NIMH Sample) 21 21 33.0 33.0 6.2 6.1 100.0 0.0 Yes Family
Valentino et al. (2008)  96a 128 35.4 48.4 10.0 10.0 88.0 75.0 52.0 27.0 81.2 Yes Family
Vondra et al. (1990)  12 11 42.0 42.0 5.6 4.9 83.0 50.0 33.0 Yes Family
Note. SES = socioeconomic status; NIMH = National Institute of Mental Health.
Note. SES = socioeconomic status; NIMH = National Institute of Mental Health.×
a Combines data from multiple subgroups.
Combines data from multiple subgroups.×
b Study reports age range only.
Study reports age range only.×
c Empty cell value denotes data not reported in study.
Empty cell value denotes data not reported in study.×
d Row totals exceeding 100% indicate participants experienced multiple forms of maltreatment.
Row totals exceeding 100% indicate participants experienced multiple forms of maltreatment.×
×
Table 2. Summary of language tests and language domain assessed in studies included in the meta-analysis.
Summary of language tests and language domain assessed in studies included in the meta-analysis.×
Study Language test/s used Expressive vocabulary Receptive vocabulary Expressive language Receptive language
Alessandri (1991)  Expressive One-Word Picture Vocabulary Test (Gardner, 1979); Test of Auditory Comprehension of Language–Revised (Carrow-Woolfold, 1985)
Allen & Oliver (1982)  Auditory Verbal Ability and Auditory Comprehension Quotients from the Preschool Language Scale (Zimmerman, Steiner, & Pond, 1979)
Ayoub et al. (2006)  Peabody Picture Vocabulary Test–Revised (Dunn, Dunn, & Dunn, 1981)
Barnett et al. (1996)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Cicchetti et al. (1993)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Coster et al. (1989)  Mean Length of Utterance; Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
De Bellis et al. (2009)  Comprehension of Instructions subtest from the NEPSY (Korkman, Kirk, & Kemp, 1998); Peabody Picture Vocabulary Test–III (Dunn, Dunn, & Williams, 1997)
Eigsti & Cicchetti (2004)  Index of Productive Syntax (Scarborough, 1990); Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Flores et al. (2005)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Fox et al. (1988)  Miller-Yoder Language Comprehension Test–Clinical Edition (Miller & Yoder, 1984); Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Gregory & Beveridge (1984)  Naming Vocabulary from the British Ability Scale (National Foundation for Educational Research, 1977); Sentence Comprehension Test (Wheldall, Mittler, & Hobsbaum, 1979)
Hoffman-Plotkin & Twentyman (1984)  Peabody Picture Vocabulary Test (edition not reported)
Nolin & Ethier (2007)  Comprehension of Instructions subtest from the NEPSY (Korkman et al., 1998)
Perry et al. (1983)  Peabody Picture Vocabulary Test (edition not reported)
Prasad et al. (2005)  Expressive and Receptive Language Composite Scores from the Sequenced Inventory of Communication Development (Hendrick, Prather, & Tobin, 1995); Expressive and Receptive Language Composite Scores from the Clinical Evaluation of Language Fundamentals (Semel, Wiig, & Secord, 1995)
Rieder & Cicchetti (1989)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Robinson et al. (2012)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Smith & Walden (1999)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Stipanicic et al. (2008)  Comprehension of Instructions subtest from the NEPSY (Korkman et al., 1998)
Toth & Cicchetti (1996)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Toth et al. (2000)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Toth et al. (2011)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Trickett et al. (1991, NIMH Sample) Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Valentino et al. (2008)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Vondra et al. (1990)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Note. NEPSY = A Developmental Neuropsychological Assessment; NIMH = National Institute of Mental Health.
Note. NEPSY = A Developmental Neuropsychological Assessment; NIMH = National Institute of Mental Health.×
Table 2. Summary of language tests and language domain assessed in studies included in the meta-analysis.
Summary of language tests and language domain assessed in studies included in the meta-analysis.×
Study Language test/s used Expressive vocabulary Receptive vocabulary Expressive language Receptive language
Alessandri (1991)  Expressive One-Word Picture Vocabulary Test (Gardner, 1979); Test of Auditory Comprehension of Language–Revised (Carrow-Woolfold, 1985)
Allen & Oliver (1982)  Auditory Verbal Ability and Auditory Comprehension Quotients from the Preschool Language Scale (Zimmerman, Steiner, & Pond, 1979)
Ayoub et al. (2006)  Peabody Picture Vocabulary Test–Revised (Dunn, Dunn, & Dunn, 1981)
Barnett et al. (1996)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Cicchetti et al. (1993)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Coster et al. (1989)  Mean Length of Utterance; Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
De Bellis et al. (2009)  Comprehension of Instructions subtest from the NEPSY (Korkman, Kirk, & Kemp, 1998); Peabody Picture Vocabulary Test–III (Dunn, Dunn, & Williams, 1997)
Eigsti & Cicchetti (2004)  Index of Productive Syntax (Scarborough, 1990); Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Flores et al. (2005)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Fox et al. (1988)  Miller-Yoder Language Comprehension Test–Clinical Edition (Miller & Yoder, 1984); Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Gregory & Beveridge (1984)  Naming Vocabulary from the British Ability Scale (National Foundation for Educational Research, 1977); Sentence Comprehension Test (Wheldall, Mittler, & Hobsbaum, 1979)
Hoffman-Plotkin & Twentyman (1984)  Peabody Picture Vocabulary Test (edition not reported)
Nolin & Ethier (2007)  Comprehension of Instructions subtest from the NEPSY (Korkman et al., 1998)
Perry et al. (1983)  Peabody Picture Vocabulary Test (edition not reported)
Prasad et al. (2005)  Expressive and Receptive Language Composite Scores from the Sequenced Inventory of Communication Development (Hendrick, Prather, & Tobin, 1995); Expressive and Receptive Language Composite Scores from the Clinical Evaluation of Language Fundamentals (Semel, Wiig, & Secord, 1995)
Rieder & Cicchetti (1989)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Robinson et al. (2012)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Smith & Walden (1999)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Stipanicic et al. (2008)  Comprehension of Instructions subtest from the NEPSY (Korkman et al., 1998)
Toth & Cicchetti (1996)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Toth et al. (2000)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Toth et al. (2011)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Trickett et al. (1991, NIMH Sample) Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Valentino et al. (2008)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Vondra et al. (1990)  Peabody Picture Vocabulary Test–Revised (Dunn et al., 1981)
Note. NEPSY = A Developmental Neuropsychological Assessment; NIMH = National Institute of Mental Health.
Note. NEPSY = A Developmental Neuropsychological Assessment; NIMH = National Institute of Mental Health.×
×
Table 3. Study quality assessment using a modified version of the Newcastle–Ottawa Scale (Wells et al., 2000).
Study quality assessment using a modified version of the Newcastle–Ottawa Scale (Wells et al., 2000).×
Study Selection
Comparability
Outcome
Exclusion criteria for developmental problems Method used to measure SES
Both groups recruited from same community Exposure determined by using government records Nonexposure determined by using government records SES Age Gender Assessor blind to maltreatment status
Alessandri (1991)  Autism; intellectual disability (mean FSIQa: maltreated group = 84, control group = 88.13); neurological impairments Household income;
maternal education
Allen & Oliver (1982)  Neurological impairments Household income;
maternal education
Ayoub et al. (2006)  Developmental delay Household Income
Barnett et al. (1996)  Hollingshead Four Factor Index
Beers & De Bellis (2002)  Developmental delay; head injury; intellectual impairments (mean FSIQb: maltreated group = 105.71; control group = 113.20); psychiatric problems Hollingshead Four Factor Index
Cicchetti et al. (1993)  Household income;
maternal education
Coster et al. (1989)  Neurological impairments Household prestige;
maternal education
De Bellis et al. (2009)  Autism; intellectual impairments (mean FSIQc: maltreated group = 99.73, control group = 101.96); medical illness; head injury; low birth weight; neurological impairment Hollingshead Four Factor Index
Eigsti & Cicchetti (2004)  Household income;
maternal education
Flores et al. (2005)  Hollingshead Two Factor Index
Fox et al. (1988)  Developmental delay; hearing impairments; neurological impairments Recipients of government income assistance
Gregory & Beveridge (1984)  Not stated
Hoffman-Plotkin & Twentyman (1984)  Intellectual impairment (mean FSIQa: maltreated group = 81, control group = 102) Household income;
maternal education
Nolin & Ethier (2007)  Birth problems; intellectual impairments (mean nonverbal IQe: maltreated group = 103.35; control group = 106.35); neurological impairment Household income
Perry et al. (1983)  Hollingshead Two Factor Index;
maternal education
Prasad et al. (2005)  Developmental delay; gestational age <32 weeks; neurological impairment Hollingshead Four Factor Index
Rieder & Cicchetti (1989)  Neurological impairment; physical impairment Household income;
maternal education
Robinson et al. (2012)  Intellectual impairments (mean nonverbal IQd: maltreated group = 96.47, control group = 104.09) Household income;
maternal education
Smith & Walden (1999)  Household income;
maternal education
Stipanicic et al. (2008)  Hearing impairments; intellectual impairments (mean FSIQa = maltreated group = 86.36, control group = 104.09); visual impairments Household income
Toth & Cicchetti (1996)  Hollingshead Four Factor Index
Toth et al. (2000)  Hollingshead Four Factor Index;
maternal education
Toth et al. (2011)  Hollingshead Four Factor Index
Trickett et al. (1991, NIMH Sample) Hollingshead Four Factor Index
Valentino et al. (2008)  Hollingshead Four Factor Index
Vondra et al. (1990)  Hollingshead Four Factor Index
Note. SES = socioeconomic status; FSIQ = Full Scale Intelligence Quotient; NIMH = National Institute of Mental health.
Note. SES = socioeconomic status; FSIQ = Full Scale Intelligence Quotient; NIMH = National Institute of Mental health.×
a Estimated using the Stanford-Binet Intelligence Scale (Thorndike, Hagen, & Sattler, 1986);
Estimated using the Stanford-Binet Intelligence Scale (Thorndike, Hagen, & Sattler, 1986);×
b Estimated using the Wechsler Intelligence Scale for Children (Wechsler, 1991);
Estimated using the Wechsler Intelligence Scale for Children (Wechsler, 1991);×
c Estimated using the Wechsler Abbreviated Scale of Intelligence (Wechsler, 1999);
Estimated using the Wechsler Abbreviated Scale of Intelligence (Wechsler, 1999);×
d Estimated using the Kaufman Brief Intelligence Test (Kaufman & Kaufman, 1990);
Estimated using the Kaufman Brief Intelligence Test (Kaufman & Kaufman, 1990);×
e Average of Picture Completion and Block Design subtests from the Wechsler Intelligence Scale for Children (scaled scored transformed to standard score to permit comparison with other test results).
Average of Picture Completion and Block Design subtests from the Wechsler Intelligence Scale for Children (scaled scored transformed to standard score to permit comparison with other test results).×
Table 3. Study quality assessment using a modified version of the Newcastle–Ottawa Scale (Wells et al., 2000).
Study quality assessment using a modified version of the Newcastle–Ottawa Scale (Wells et al., 2000).×
Study Selection
Comparability
Outcome
Exclusion criteria for developmental problems Method used to measure SES
Both groups recruited from same community Exposure determined by using government records Nonexposure determined by using government records SES Age Gender Assessor blind to maltreatment status
Alessandri (1991)  Autism; intellectual disability (mean FSIQa: maltreated group = 84, control group = 88.13); neurological impairments Household income;
maternal education
Allen & Oliver (1982)  Neurological impairments Household income;
maternal education
Ayoub et al. (2006)  Developmental delay Household Income
Barnett et al. (1996)  Hollingshead Four Factor Index
Beers & De Bellis (2002)  Developmental delay; head injury; intellectual impairments (mean FSIQb: maltreated group = 105.71; control group = 113.20); psychiatric problems Hollingshead Four Factor Index
Cicchetti et al. (1993)  Household income;
maternal education
Coster et al. (1989)  Neurological impairments Household prestige;
maternal education
De Bellis et al. (2009)  Autism; intellectual impairments (mean FSIQc: maltreated group = 99.73, control group = 101.96); medical illness; head injury; low birth weight; neurological impairment Hollingshead Four Factor Index
Eigsti & Cicchetti (2004)  Household income;
maternal education
Flores et al. (2005)  Hollingshead Two Factor Index
Fox et al. (1988)  Developmental delay; hearing impairments; neurological impairments Recipients of government income assistance
Gregory & Beveridge (1984)  Not stated
Hoffman-Plotkin & Twentyman (1984)  Intellectual impairment (mean FSIQa: maltreated group = 81, control group = 102) Household income;
maternal education
Nolin & Ethier (2007)  Birth problems; intellectual impairments (mean nonverbal IQe: maltreated group = 103.35; control group = 106.35); neurological impairment Household income
Perry et al. (1983)  Hollingshead Two Factor Index;
maternal education
Prasad et al. (2005)  Developmental delay; gestational age <32 weeks; neurological impairment Hollingshead Four Factor Index
Rieder & Cicchetti (1989)  Neurological impairment; physical impairment Household income;
maternal education
Robinson et al. (2012)  Intellectual impairments (mean nonverbal IQd: maltreated group = 96.47, control group = 104.09) Household income;
maternal education
Smith & Walden (1999)  Household income;
maternal education
Stipanicic et al. (2008)  Hearing impairments; intellectual impairments (mean FSIQa = maltreated group = 86.36, control group = 104.09); visual impairments Household income
Toth & Cicchetti (1996)  Hollingshead Four Factor Index
Toth et al. (2000)  Hollingshead Four Factor Index;
maternal education
Toth et al. (2011)  Hollingshead Four Factor Index
Trickett et al. (1991, NIMH Sample) Hollingshead Four Factor Index
Valentino et al. (2008)  Hollingshead Four Factor Index
Vondra et al. (1990)  Hollingshead Four Factor Index
Note. SES = socioeconomic status; FSIQ = Full Scale Intelligence Quotient; NIMH = National Institute of Mental health.
Note. SES = socioeconomic status; FSIQ = Full Scale Intelligence Quotient; NIMH = National Institute of Mental health.×
a Estimated using the Stanford-Binet Intelligence Scale (Thorndike, Hagen, & Sattler, 1986);
Estimated using the Stanford-Binet Intelligence Scale (Thorndike, Hagen, & Sattler, 1986);×
b Estimated using the Wechsler Intelligence Scale for Children (Wechsler, 1991);
Estimated using the Wechsler Intelligence Scale for Children (Wechsler, 1991);×
c Estimated using the Wechsler Abbreviated Scale of Intelligence (Wechsler, 1999);
Estimated using the Wechsler Abbreviated Scale of Intelligence (Wechsler, 1999);×
d Estimated using the Kaufman Brief Intelligence Test (Kaufman & Kaufman, 1990);
Estimated using the Kaufman Brief Intelligence Test (Kaufman & Kaufman, 1990);×
e Average of Picture Completion and Block Design subtests from the Wechsler Intelligence Scale for Children (scaled scored transformed to standard score to permit comparison with other test results).
Average of Picture Completion and Block Design subtests from the Wechsler Intelligence Scale for Children (scaled scored transformed to standard score to permit comparison with other test results).×
×
Table 4. Results from meta-regression examining predictors of receptive vocabulary effect sizes.
Results from meta-regression examining predictors of receptive vocabulary effect sizes.×
Model No. Predictor Variable k df R2 QModel QResidual β p
1 Mean age of participants 19 1,17 0.079 1.8153 21.1703 −0.281 .178
2 Percentage of female participants 18a 1,16 0.0237 0.5093 20.9578 −0.154 .476
3 Percentage of participants exposed to neglect 17b 1,15 0.0199 0.4098 20.1933 0.141 .522
4 Participants from low SES background 19 1,17 0.1245 2.8624 20.1233 −0.3529 .091
5 Residential status of study group 18c 1,16 0.0125 0.277 21.798 −0.112 .599
6 Maltreated and control groups recruited from same community 19 1,17 0.1288 2.9599 20.0257 0.3588 .085
7 Maltreatment and nonmaltreatment determined by government records 19 1,17 0.0028 0.0634 22.9222 0.0525 .801
8 Maltreatment and control groups matched on maternal education 19 1,17 0.0727 1.6702 21.3154 −0.2696 .196
9 Groups matched on age 19 1,17 0.1525 3.5051 19.4805 0.3905 .061
10 Groups matched on gender 19 1,17 0.1337 3.0735 19.9122 0.3657 .080
11 Groups matched on SES 19 1,17 0.0561 1.2898 21.6959 0.2369 .256
12 Blinding procedure used during data collection 19 1,17 0.0088 0.2017 22.7839 0.0937 .653
13 Study excludes children with developmental disabilities 19 1,17 0.0317 0.7294 22.2562 0.1781 .393
Note. SES = socioeconomic status.
Note. SES = socioeconomic status.×
a One study did not report the number of female participants and was included in this analysis.
One study did not report the number of female participants and was included in this analysis.×
b Two studies did not report the percentage of children who had been neglected and were excluded from this analysis.
Two studies did not report the percentage of children who had been neglected and were excluded from this analysis.×
c One study was not included in this analysis because residential status of the children was not reported.
One study was not included in this analysis because residential status of the children was not reported.×
Table 4. Results from meta-regression examining predictors of receptive vocabulary effect sizes.
Results from meta-regression examining predictors of receptive vocabulary effect sizes.×
Model No. Predictor Variable k df R2 QModel QResidual β p
1 Mean age of participants 19 1,17 0.079 1.8153 21.1703 −0.281 .178
2 Percentage of female participants 18a 1,16 0.0237 0.5093 20.9578 −0.154 .476
3 Percentage of participants exposed to neglect 17b 1,15 0.0199 0.4098 20.1933 0.141 .522
4 Participants from low SES background 19 1,17 0.1245 2.8624 20.1233 −0.3529 .091
5 Residential status of study group 18c 1,16 0.0125 0.277 21.798 −0.112 .599
6 Maltreated and control groups recruited from same community 19 1,17 0.1288 2.9599 20.0257 0.3588 .085
7 Maltreatment and nonmaltreatment determined by government records 19 1,17 0.0028 0.0634 22.9222 0.0525 .801
8 Maltreatment and control groups matched on maternal education 19 1,17 0.0727 1.6702 21.3154 −0.2696 .196
9 Groups matched on age 19 1,17 0.1525 3.5051 19.4805 0.3905 .061
10 Groups matched on gender 19 1,17 0.1337 3.0735 19.9122 0.3657 .080
11 Groups matched on SES 19 1,17 0.0561 1.2898 21.6959 0.2369 .256
12 Blinding procedure used during data collection 19 1,17 0.0088 0.2017 22.7839 0.0937 .653
13 Study excludes children with developmental disabilities 19 1,17 0.0317 0.7294 22.2562 0.1781 .393
Note. SES = socioeconomic status.
Note. SES = socioeconomic status.×
a One study did not report the number of female participants and was included in this analysis.
One study did not report the number of female participants and was included in this analysis.×
b Two studies did not report the percentage of children who had been neglected and were excluded from this analysis.
Two studies did not report the percentage of children who had been neglected and were excluded from this analysis.×
c One study was not included in this analysis because residential status of the children was not reported.
One study was not included in this analysis because residential status of the children was not reported.×
×
Table 5. Results from meta-regression examining predictors of receptive language effect sizes.
Results from meta-regression examining predictors of receptive language effect sizes.×
Model No. Predictor Variable k df R2 QModel QResidual β p
1 Mean age of participants 9 1,7 0.0639 0.5946 8.7069 −0.2528 .441
2 Proportion of female participants 9 1,7 0.0153 0.1428 9.1587 0.1239 .706
3 Participants from low SES background 9 1,7 0.0987 0.9182 8.3833 −0.3142 .338
4 Residential status of study group 9 1,7 0.2413 2.2449 7.0566 −0.4913 .134
5 Maltreatment and nonmaltreatment determined by government records 9 1,7 0.0164 0.1527 9.1488 −0.1281 .696
6 Maltreatment and control groups matched on maternal education 9 1,7 0.2324 2.1619 7.1396 0.4821 .142
7 Groups matched on age 9 1,7 0.2703 2.5142 6.7873 0.5199 .113
8 Groups matched on SES 9 1,7 0.3316 3.0844 6.2171 0.5759 .079
9 Blinding procedure used during data collection 9 1,7 0.1269 1.1801 8.1214 −0.3562 .277
10 Study excludes children with developmental disabilities 9 1,7 0.2429 2.2593 7.0422 0.4928 .133
Note. SES = socioeconomic status.
Note. SES = socioeconomic status.×
Table 5. Results from meta-regression examining predictors of receptive language effect sizes.
Results from meta-regression examining predictors of receptive language effect sizes.×
Model No. Predictor Variable k df R2 QModel QResidual β p
1 Mean age of participants 9 1,7 0.0639 0.5946 8.7069 −0.2528 .441
2 Proportion of female participants 9 1,7 0.0153 0.1428 9.1587 0.1239 .706
3 Participants from low SES background 9 1,7 0.0987 0.9182 8.3833 −0.3142 .338
4 Residential status of study group 9 1,7 0.2413 2.2449 7.0566 −0.4913 .134
5 Maltreatment and nonmaltreatment determined by government records 9 1,7 0.0164 0.1527 9.1488 −0.1281 .696
6 Maltreatment and control groups matched on maternal education 9 1,7 0.2324 2.1619 7.1396 0.4821 .142
7 Groups matched on age 9 1,7 0.2703 2.5142 6.7873 0.5199 .113
8 Groups matched on SES 9 1,7 0.3316 3.0844 6.2171 0.5759 .079
9 Blinding procedure used during data collection 9 1,7 0.1269 1.1801 8.1214 −0.3562 .277
10 Study excludes children with developmental disabilities 9 1,7 0.2429 2.2593 7.0422 0.4928 .133
Note. SES = socioeconomic status.
Note. SES = socioeconomic status.×
×
Supplemental Material.Description of search strategy and search syntax