Social disadvantage and language development—what matters, and how much?

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This is one of the largest studies we’ve seen in a while on factors than impact infant and toddler language—over 1000 babies were followed to see what matters most for language development in the first two years of life.

First, one of the really beautiful things about this study is that they measure social disadvantage, but actually differentiate things parents can control (that is, what they do with their child) from things they can’t (e.g. family income, maternal education). So bravo for that! Then, note that this study is dense. We’re only skimming the surface, here, with the biggest takeaways for SLPs, which are:

 What parents do with their child matters:

  • e.g. “…reading to their child, telling stories, singing and taking the child on errands to public places… having toys… books available in the home… having a safe and supportive home environment.”

  • (In fact, here’s another recent study showing that responsive verbal behaviors in play interactions with a parent at 12 months are predictive of language outcomes at 36 months in a cohort of families experiencing adversity.)

Language at 15 months is highly predictive of language at 2 years.

  • Implication: Are we catching kids early enough?

Now, I think most SLPs pretty much already knew that. But what you may not have a good feel for is how much these things matter. To put it in perspective—the single strongest measured predictor of language was biological sex. Also, most of what predicts language development was not something the researchers were able to measure. Instead, it’s some other thing(s), likely, “… other developmental or genetic mechanisms.” So, basically, what parents do with their children is important not because it matters the most, but because we have control over it (well… we can try to).

 

Law, J., Clegg, J., Rush, R., Roulstone, S., Peters, T.J. (2018) Association of proximal elements of social disadvantage with children's language development at 2 years: an analysis of data from the Children in Focus (CiF) sample from the ALSPAC birth cohort. International Journal of Language and Communication Disorders. Advance online publication. doi: 10.1111/1460-6984.12442.

Preterm birth + social disadvantage = extra at-risk

*Another study on social disadvantage; this time, over 100 infants studied.

We know that babies born pre-term are at a higher risk for developmental delays, including language. We also know that children born into socially disadvantaged environments are at risk for language delay. So what happens when a baby from a socially disadvantaged* background is born early? The most SLP-relevant findings include:

  • full-term infants with fewer social risk factors had the best language scores at age 5

  • but low social risk isn’t enough to make up for prematurity (< 30 week gestation)— that is, preterm infants with low social risk did not experience as much language growth from 2- to 5-years as the full-term children (thus, addressing social risk for preterm kids is good, but may not be enough to close the language gap by 5 years)

  • high social risk was associated with decreasing language scores as developmental demands increased with age (and the authors found this trajectory was associated with maternal affect and maternal intellectual ability, so parent interventions addressing affect and responsiveness may be helpful for these children)

The big picture? Just because everything looks “ok” for a child at 2 years doesn’t mean things will look that way at 5 years when cognitive, linguistic, and motor development gets more demanding. Also, very preterm infants and toddlers, at a social disadvantage or not, need our support. We can start by training parent responsivity, but it looks like some preterm children could need more intensive interventions to close the developmental gap between themselves and their full term peers.

*Their definition of social risk included factors like teen parents, single parents, no high school diploma. Refer back to the previous study, though, that shows how a healthy home environment can reduce the impact of these factors.

 

Lean, R. E., Paul, R. A., Smyser, T. A., Smyser, C. D., & Rogers, C. E. (2019). Social adversity and cognitive, language, and motor development of very preterm children from 2 to 5 years of age. The Journal of Pediatrics. Advance online publication. doi:10.1016/j.jpeds.2018.07.110.

Language delay and behavior problems: How can we help?

It’s not much of a surprise to EI SLPs that language problems and behavior problems can be pretty intertwined (e.g., here), and parenting style can be associated with both behavior and language outcomes. We also know that well-designed parent-implemented interventions can be wonderfully effective (they had better be if entire states are re-vamping their early intervention programs to promote the coaching model). So—can we support these things simultaneously?

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Garcia et al. implemented the Infant Behavior Program (IBP) with a group of mother–child pairs. The Infant Behavior Program was adapted from the Child-Directed Interaction (CDI) component of Parent-Child Interaction Therapy (PCIT). Programs like PCIT and Triple P- Positive Parenting Program have been shown to help children reduce negative behaviors, but no one has really studied what how (or if) those parent implemented behavior interventions affect language development. While PCIT training and certification is geared toward mental health professionals, the components of CDI and IBP will sound familiar to EI SLPs. The intervention guides parents to interact with their children using positive parenting skills, avoiding negative parenting skills, and ignoring unwanted behavior, and consisted of 5–7 weekly visits of 60–90 minutes. Parents were then asked to continue using the taught parenting skills in 5-minute increments throughout the day.

“Do” (Positive parenting skills)

  • Imitating

  • Describing

  • Reflecting

“Don’t” (Negative parenting skills)

  • Negative talk

  • Questions

  • Commands

Researchers found that change in parenting style was associated with an increase in the children’s total number of utterances. (Note: this effect was seen at six months after the intervention ended; the kids didn’t show a difference in total number of utterances at three months, or number of different utterances at either time they were tested). But the authors cautioned that presence of negative parenting skills did not change the toddlers’ number of utterances for better or for worse, so definitely don’t interpret this to mean we should throw out questions and commands.

So if an EI SLP is called in on a case where both language and behavior are concerns, but parent priority is behavior, maybe we start with those “positive” responsive techniques (labeling, imitating, and reflecting) before we jump in with questions and commands, because it looks like these positive behavior strategies can also help with language development!

 

Garcia, D., Hungerford, G. M., Hills, R. M., Barroso, N. E., & Bagner, D. M. (2019). Infant language production and parenting skills: A randomized controlled trial. Behavior Therapy. Advance online publication. doi:10.1016/j.beth.2018.09.003

And more...

  • Dai et al. found that bilingual caregivers of children with ASD and DD can communicate with their children in both languages without adverse effect on their children’s language functioning. (Feel like you already knew that? Well here’s a citation for ya!)

  • Fusaroli et al. found that parents’ language complexity predicted the complexity of their toddler with ASD’s language four months down the road. This finding suggests that modeling grammatically rich and complex language for toddlers with ASD may benefit their language development (as opposed to over-simplified telegraphic speech). While we need an intervention study to tell us if that is truly the case, research has already demonstrated this for toddlers with language delays (which you can read about in a previous review here).

  • To get a better feel for how underserved and under-identified families access health information about development, Gallagher et al. conducted focus groups of parents of typically developing and children with disabilities who lived in an urban area and experienced low income and low literacy skills. The authors found that while these parents knew about a variety of sources of information, they experienced and reported barriers to health literacy resources (e.g., printed materials were too dense, or not literal enough). The parents in the focus groups offered suggestions for making developmental health information accessible to a more diverse audience. This is a good read if you are ever in a position to develop marketing or awareness materials.

  • EI SLPs sometimes encounter (and experience!) mom-guilt when serving families whose mothers work. This study was exploratory but offers us a bit of information we can share when the need arises. Laing and Bergelson found that 17-month-olds’ vocabulary measures of noun type and token did not differ significantly between toddlers of full-time working and stay-at-home mothers. Interestingly, toddlers who experienced mixed care (so their moms worked part time, or stayed home early and went back to work as their children got older), did have more noun types and tokens than kids who experienced one type of care.

  • McLeod et al. examined teacher–child interactions during Enhanced Milieu Teaching (EMT) sessions. All children in the study had DLD and attended Head Start. Two teacher inputs were linked to greater usage of target vocabulary words by children during EMT sessions: (1) following the child’s attentional or communicative lead and (2) providing vocabulary supports to teach or clarify the meanings of target words. We’ve written about parent-implemented EMT for children with DLD before. For more descriptive info about teacher input and child vocabulary go check out the article.

  • Can you screen “everybody” (e.g. via routine pediatricians’ checkups) and reliably catch autism early, between 14–36 months, without over-identification? Yes, probably! This meta-analysis by Sanchez-Garcia provides quantitative data in support of universal toddler screenings for ASD.

  

Dai, Y.G., Burke, J.D., Naigles, L., Eigsti, I.M., & Fein, D.A. (2018). Language abilities in monolingual- and bilingual- exposed children with autism or other developmental disorders. Research in Autism Spectrum Disorders. Advanced online publication. doi: 10.1016/j.rasd.2018.08.001.

Fusaroli, R., Weed, E., Fein, D., & Naigles, L. (2019). Hearing me hearing you: Reciprocal effects between child and parent language in autism and typical development. Cognition183, 1–18.

Gallagher, P. A., Greenberg, D., Campbell, J. M., Stoneman, Z., & Feinberg, I. Z. (2018). Early identification and connection to services among urban parents who have low income and low-literacy skills. Focus on Autism and Other Developmental Disabilities. Advance online publication. doi: 10.1177/1088357618794913.

Laing, C. & Bergelson, E. (2019). Mothers’ work status and 17-month olds’ productive vocabulary. Infancy, 24(1), 101–109.

McLeod, R.H., Kaiser, A.P., & Hardy, J.K. (2018). The relation between teacher vocabulary use in play and child vocabulary outcomes. Topics in Early Childhood Special Education. Advance online publication. doi: 10.1177/0271121418812675

Sánchez-García, A.B., Galindo-Villardón, P., Nieto-Librero, A.B. et al. (2019). Toddler Screening for Autism Spectrum Disorder: A Meta-Analysis of Diagnostic Accuracy. Journal of Autism and Developmental Disorders. Advance online publication. doi: 10.1007/s10803-018-03865-2.

Supporting toddlers in foster care

This review is a mash-up of a few different articles, because we have a mini-theme going on this month! Many of us have served children who are in foster care. It’s already known that children who have experienced some sort of abuse or neglect are at a higher risk for having language, social, and behavior difficulties (e.g., Chow & Wehby, 2018; Hoff, 2006; Stock & Fisher, 2006; also, see our discussion on trauma here). So not only are these kids in foster care battling a history of instability (whether in location, security, basic needs, family members, name it), but that history puts them at risk for difficulties in early development that have implications for social, behavioral, and academic impact later on in life. That doesn’t sound like a great start for a toddler, does it? Hopefully, we can do something to help. The following studies looked at children’s receptive language development in relation to foster placement and intervention options.  

Zajac et al. studied a group of children involved with Child Protective Services to see if receptive language scores on the PPVT-3 were related to whether children were placed in foster care or remained with their parents. PPVT-3 scores significantly correlated with things like marital status, income, and level of caregiver education, and foster parents were significantly more likely to have those things going for them than the birth parents in this study. There were differences in receptive language scores between groups (children placed in foster care vs those with biological parents), with children in foster care having better scores on average. Once Zajac and friends controlled for factors such as parent level of education and income, differences between groups were not significant. The takeaway is that the ‘whole picture’ is important: not just placement, but the factors associated with the characteristics of the caregivers in the placement. We need more information to really delve into the “why” here. But a prediction is that when parents feel more secure in their basic and emotional needs, they may be more likely to have energy to spend on addressing kids’ development (and the authors comment on making support available to families whose financial, emotional, and educational resources are stressed).

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At the same time, Raby et al. (some of the same authors were involved in both of these studies) looked at how the intervention Attachment and Behavioral Catch-up for Toddlers (ABC-T) affected foster parents’ sensitivity and responsiveness to their toddlers and whether the intervention affected receptive language development. Compared to families who received the Developmental Education for Families (DEF) intervention, which focused on motor and cognitive skills, families who received the ABC-T intervention were more sensitive and responsive to their toddlers, and toddlers whose foster families received the ABC-T training had better receptive language skills when tested with the PPVT-3. Not bad for 10 weeks’ worth of one-hour sessions!

If you’re not ready to add a new intervention training like the ABC-T to your workload but are thinking, “Wow, this is in line with what I’m seeing clinically, so how do I get and keep these kids on my caseload?” check out the Adrihan et al. review on a collaborative effort between a county’s EI and child welfare departments. They highlight systemic changes to screening, evaluation, and teaming processes that could increase access to EI services for these children who are at risk for social–emotional delays.

Adrihan, S. A., Winchell, B. N., & Greene, S. J. (2018). Transforming early intervention screening, evaluation, assessment, and collaboration practices: Increasing eligibility for children impacted by trauma. Topics In Early Childhood Special Education. Advance online publication. doi: 10.1177/0271121418791288

Raby, K. L., Freedman, E., Yarger, H. A., Lind, T., & Dozier, M. (2018). Enhancing the language development of toddlers in foster care by promoting foster parents’ sensitivity: Results from a randomized controlled trial. Developmental Science. Advance online publication. doi:  10.1111/desc.12753.

Zajac, L., Raby, K. L., & Dozier, M. (2018). Receptive vocabulary development of children placed in foster care and children who remained with birth parents after involvement with child protective services. Child Maltreatment. Advance online publication. doi: 10.1177/1077559518808224

Cultural proficiency 101: Reconsidering the 30 million word gap

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Back in the 1980s, Hart & Risley conducted a hallmark study documenting that children from poor communities hear 30 million fewer words than middle class children. This finding has been often cited to document why so many low SES children perform poorly when they enter school and score lower on measures of language and vocabulary.

Sperry et al. brought the results of this study into question, with the idea that the original methodology of the study may have been culturally biased and not applicable to real-life environments. In particular, the original study looked only at directed speech from the primary caregiver (usually the mother) to the child. They did not measure the number of words spoken by other members of the household, speech that the child may have overheard, and they encouraged the family members not to talk to each other so that they could focus on just the mother/child interaction.

While interaction between the primary caregiver is certainly important, Sperry et al. attempted to expand our knowledge of children’s verbal environments by measuring all speech directed to the child and all bystander or “overheard” speech. The findings were quite interesting. There was no significant gap between number of words heard among any social or economic class. Additionally, some working class and poor communities showed an advantage in the number of words the children heard. Additionally, there was significant variation within classes, rather than between classes. For instance, in this study, poor African American families in the south addressed far more words to their children compared to primary caregivers from other low SES communities (e.g. rural, working class).

These results are important to consider as EI therapists working with diverse families. Often times minority families are viewed in a “one size fits all” context, viewing the majority group (middle class American families) as the model. In fact, in many cultures, children are not spoken to directly during the first few years of life, but still reach developmental language milestones similarly to American children. In sum, different cultures have different preferred ways of interacting with their children, which may all have different benefits. As culturally proficient therapists, we need to look at the whole family.

P.S. This article sparked a bit of a debate:

For a response to this article from another group of researchers, click here.

For Sperry et al.’s reply, click here.

And for even more on different qualities of child-directed speech, see Tal & Arnon’s study, where they found the number of variation sets differed between high-SES and low-SES groups. Variation sets happen when an adult focuses on a theme, and then talks a lot about that theme in a series of comments and questions. The authors suggest more information is needed on the different qualities of child-directed speech in order to make predictions about language outcomes.

 

Sperry, D. E., Sperry, L. L., Miller, P.J., (2018). Reexamining the verbal environments of children from different socioeconomic backgrounds. Child Development. Advance online publication. doi: 10.1111/cdev.13072 

And more...

Normally we try to keep this section fairly brief for you all, but holy moly there was so much research this month!

  • Bradshaw, et al. examined differences in communication and play in groups of infants at high- and low-risk for ASD. High-risk 12-month-olds who were considered “prewalkers” (who didn’t stand or walk) showed significantly lower scores on the CSBS in terms of play skills, gesture use, word use, and behavior measures such as protesting. Even though both high-risk and low-risk groups had similar numbers of prewalkers, standers, and walkers, the authors suggest their results “confirm that the lower social communication scores observed in high-risk infant prewalkers are clinically significant and suggests that these infants may be at higher risk for social communication delays.” SLPs working in the PSP model could keep this information in mind while discussing intake and evaluation plans or while reviewing quarterly updates during teaming meetings. Note: the authors caution that the participants in their study were mostly white, highly educated families, and that results may not generalize to all populations.

  • In a study of over 1200 families in poor rural regions, Burchinal et al. confirmed the presence of a large gap in school readiness skills that emerges during the first five years of life. Specifically, children who experienced poverty before the age of two had more significant delays on their language, cognitive, social, and executive functioning. Self-regulation and executive functioning skills played an important role in school readiness at age five. Check out the original article for a more in-depth analysis of the relationship between poverty & school readiness.

  • If you’re an EI therapist, you’ve most likely evaluated a child who was born premature at one time or another, so you’re also most likely familiar with the idea of age correction. You may have corrected for age on one or more assessments, but you may have also wondered if that’s best practice. And, if it is, when should we stop correcting for age? Harel-Gardassi et al. used the Mullen Scales of Early Learning (MSEL) test to see how age correction impacted the scores of preterm infants at 1, 4, 8, 12, 18, 24, and 36 months of age. Not surprisingly, corrected age scores were found to be significantly higher than chronological scores at all ages, with factors such as gestational age and birth weight affecting the level of difference between the two scores. These findings also suggest that if you use the MSEL, you should be using age correction until the adjusted age of three, not the currently recommended age of two.

  • In terms of input, the large majority of what children, including infants, are exposed to on a day-to-day basis is connected speech, while isolated words are heard infrequently and inconsistently. So, do the single words that infants are exposed to have any kind of impact on their language development? This recent study by Keren-Portnoy et al. of 12-month-olds showed that isolated words, instead of words presented at the end of an utterance, were easier for the children to recognize and remember.

  • Lim and Charlop found that speaking a child’s heritage language during play-based intervention sessions seemed to help four bilingual children with ASD play in more functional and interactive ways. The experimenters followed scripts for giving play instructions, verbal praise, and making comments related to play in both English and each child’s heritage language (in this study, Korean or Spanish). None of the children played functionally or interactively before the intervention, but all of the children showed an increase in play during and after intervention sessions in both English and the heritage language, with more impressive gains seen in heritage language sessions. More research is needed, but SLPs should keep this in mind when working with bilingual children with ASD (note: study done on older children).

  • In a qualitative study by Núñez & Hughes, Latina mothers reported higher satisfaction with early intervention services when they had bilingual support through an interpreter or bilingual SLP, received clear explanations about services and paperwork, felt the SLP respected their wishes, and were provided with strategies to work on with their children outside of SLP sessions.

  • Rague et al. found that infants with Fragile X syndrome use fewer gestures than infants at both high and low risk for ASD. Children with Fragile X who used fewer gestures tended to have lower nonverbal abilities. A lack of early gesture use in infants with Fragile X may be an indicator of the child’s broad cognitive ability.  

  • Thrum et al. found that toddlers between 18 and 24 months with language delay had significantly more socioemotional and behavioral problems compared to toddlers without language delay. At 18 months, more than half of children with language delays had scores within the range of clinical concern! These results underscore the importance of early detection & treatment for children with language delays.

  • Torrisi et al. found that toddlers’ communication scores on the Ages and Stages Questionnaire (ASQCS) were not directly associated with mothers’ diagnoses of PTSD related interpersonal violence, but communication development was affected when mothers showed more controlling behavior and were less sensitive to their toddlers. Both of these qualities of maternal behavior were also correlated with severity of PTSD symptoms. This is important information to keep in mind when providing services to families at risk for experiencing or with a history of interpersonal violence.

  • Yu, et al measured 9-month-old typically-developing infants’ attention to objects and joint attention with their parents, to tease out what exactly contributes to vocabulary growth in the first year of life. They found that sustained attention with and without joint attention predicted vocabulary size at 12 and 15 months, but joint attention alone did not predict vocabulary growth. We need more research to figure out exactly how to use this information clinically, but in the meantime, we can always continue to help caregivers make the best use of their children’s interest and attention during play to support vocabulary growth.

 

Bradshaw, J., Klaiman, C., Gillespie, S., Brane, N., Lewis, M., & Saulnier, C. (2018). Walking ability is associated with social communication skills in infants at high risk for autism spectrum disorder. Infancy. Advance online publication. doi: 10.1111/infa.12242.

Burchinal, M., Carr, R.C., Vernon-Feagans, L.V., Blair, C., Cox, M. (2018). Depth, persistence, and timing of poverty and the development of school readiness skills in rural low-income regions: Results from the family life project. Early Childhood Research Quarterly, 45, 115–130.

Harel-Gadassi, A., Friedlander, E., Yaari, M., Bar-Oz, B., Eventov-Friedman, S., Mankuta, D., & Yirmiya, N. (2018). Development assessment of preterm infants: Chronological or corrected age? Research in Developmental Disabilities, 80, 35–43.

Keren-Portnoy, T., Vihman, M., & Lindop Fisher R. (2018). Do infants learn from isolated words? An ecological study. Language Learning and Development. Advance online publication. doi: 10.1080/15475441.2018.1503542.

Lim, N. & Charlop, M. H. (2018). Effects of English versus heritage language on play in bilingually exposed children with autism spectrum disorder. Behavioral Interventions. Advance online publication. doi: 10.1002/bin.1644.

Núñez, G., & Hughes, M. T. (2018). Latina mothers’ perceptions and experiences of home-based speech and language therapy. Perspectives of the ASHA Special Interest Groups, 14(3), 40–56.

Rague, L., Caravella, K., Tonnsen, B., Klusek, J., & Roberts, J. (2018). Early gesture use in fragile X syndrome. Journal of Intellectual Disability Research, 62(7), 625–636.

Thurm, A., Manwaring, S.S., Jimenez, C.C., Swineford, L., Farmer, C., Gallo, R., Maeda, M. (2018). Socioemotional and behavioral problems in toddlers with language delay. Infant Mental Health Journal, 38(5), 569–580. 

Torrisi, R., Arnautovic, E., Pointet Perizzolo, V. C., Vital, M., Manini, A., Suardi, F., …, & Schechter, D. S. (2018). Developmental delay in communication among toddlers and its relationship to caregiving behavior among violence-exposed, posttraumatically stressed mothers. Research in Developmental Disabilities. Advance online publication. doi: 10.1016/j.ridd.2018.04.008.

Yu, C., Suanda, S. H., & Smith, L. B. (2018). Infant sustained attention but not joint attention to objects at 9 months predicts vocabulary at 12 and 15 months. Developmental Science. Advance online publication. doi: 10.1111/desc.12735.

And more

  • Remember the Index of Productive Syntax (IPSyn) from grad school? Altenberg et al. modified the instructions to make them a little clearer and reminded us that IPSyn is great for describing toddlers’ and preschoolers’ grammatical development. See their updated instructions in the article Appendix and consider giving IPSyn another shot. (NOTE: If you’ve never heard of this thing before, it’s a way to measure syntax production in young children.)

 

  • It seems that we’re always looking for a quicker, easier way to quantify our young clients’ language skills and progress in therapy. This study looked at whether the automated language analysis system, LENA (Language Environment Analysis), a device that’s worn around the child’s neck, could provide a reliable measure of rate of vocalizations during short recording sessions. Results suggested that human transcribers were able to capture more reliable rates of child vocalizations when the recording was 25 minutes or less. So, although the LENA seems to be a useful tool for longer recordings, findings from this study suggest that when transcribing and analyzing short language samples, it’s best to stick to doing it the old-fashioned way—by hand.

 

  • Sharabi et al. found that mothers of children with ASD tend to be more involved in their child’s care, especially when they felt they had informal support from family and friends. Fathers with higher education levels tended to be more involved with their child’s care, especially single fathers.

 

Altenberg, E. P., Roberts, J. A., & Scarborough, H. S. (2018). Young children's structure production: A revision of the Index of Productive Syntax. Language, Speech, and Hearing Services in Schools. Advance online publication. doi: 10.1044/2018_LSHSS-17-0092.

Bredin-Oja, H., Fleming, K., & Warren, S. (2018). Clinician vs. machine: Estimating vocalization rates in young children with developmental disorders. American Journal of Speech-Language Pathology, 27, 1066–1072.

Sharabi, A., & Marom-Golan, D. (2018). Social support, education level, and parent’s involvement: A comparison between mothers and fathers of children with autism spectrum disorder. Topics in Early Childhood Special Education. Advance online publication. doi: 10.1177/0271121418762511

Throwback Pub (2008): Early gestures to predict vocabulary

Note: This study was part of a larger longitudinal study, information available here.

Wouldn’t it be fantastic if we could screen infants at 8 months and predict later development? This study looked at gesture and object use at 8 months, then followed up at ages 1;0 and 2;0 to determine whether later vocabulary can be predicted by early gesture and object use. The authors mailed out questionnaire packages to 1,477 families when their children were ages 0;8, 1;0, and 2;0. The Macarthur-Bates Communicative Development Inventories (CDI) were included in the packet, the CDI Words and Gestures (CDI:W&G) was completed for the first two data collections, and the CDI Words and Sentences (CDI:W&S) was completed at the 2-year mark.

In addition to measuring gestures to predict vocabulary use, the authors also examined the effects of SES and gender on vocabulary. Here’s what they found:

  • Gestures at 0;8 didn’t predict vocabulary (at 2;0) all that well. But gestures at 1;0 year did. Also, gestures predicted 2;0 vocabulary comprehension better than production.
  • Girls produced more words than boys at 1;0 and 2;0, but there were no differences between boys and girls in comprehension
  • Children in the two higher SES groups (there were 5 groups total) reportedly understood fewer words than the children in the lower SES groups. And children in the second lowest SES group were reported to produce more words than children in the higher SES groups

Remember that these fun facts were all based on the CDI, which relies on parent report. So how can we use this information? The authors suggest that parent estimation of their children’s skills may differ by SES; that is, families in lower SES backgrounds may overestimate their children’s abilities, or families from higher SES backgrounds may underestimate their children’s knowledge. This is something to keep in mind when many of our assessments in EI are based, in some capacity, on parent report.

 

Bavin, E. L., Prior, M., Reilly, S., Bretherton, L., Williams, J., Eadie, P., ... & Ukoumunne, O. C. (2008). The early language in Victoria study: Predicting vocabulary at age one and two years from gesture and object use. Journal of Child Language35(3), 687-701.