Vocabulary interventions for second language (L2) learners up to six years of age.

BACKGROUND: Second language (L2) learners are a heterogeneous group. Their L2 skills are highly varied due to internal factors (e.g. cognitive development) and external factors (e.g. cultural and linguistic contexts). As a group, their L2 vocabulary skills appear to be lower than their monolingual peers. This pattern tends to persist over time and may have negative consequences for social interaction and inclusion, learning, and academic achievement. OBJECTIVES: To examine the immediate and long-term effects of second language (L2) vocabulary interventions targeting L2 learners up to six years of age on vocabulary and social-emotional well-being. To examine the associations between L2 vocabulary interventions and the general characteristics of L2 learners (e.g. age, L2 exposure, and L1 skills). SEARCH METHODS: We used standard, extensive Cochrane search methods. The latest search date was December 2022. SELECTION CRITERIA: We included randomised controlled trials (RCTs) comparing the effects of vocabulary interventions for L2 learners up to six years of age with standard care. DATA COLLECTION AND ANALYSIS: We used standard methodological procedures expected by Cochrane. Our primary outcomes were 1. receptive and 2. expressive L2 vocabulary (both proximal and distal), and 3. mean length of utterance (MLU; which is a measure of potential adverse effects). Our secondary outcomes were 4. L2 narrative skills, 5. L1 receptive vocabulary (both proximal and distal), 6. L1 expressive vocabulary (both proximal and distal), 7. L1 listening comprehension, 8. L2 grammatical knowledge, 9. L2 reading comprehension (long-term), and 10. socio-emotional well-being (measured with Strengths and Difficulties Questionnaire). MAIN RESULTS: We found 12 studies involving 1943 participants. Two studies were conducted in Norway, seven in the USA, and single studies conducted in Canada, China, and the Netherlands. Ten studies were conducted in preschool settings, with a preschool teacher being the most common delivery agent for the intervention. The interventions were mainly organised as small-group sessions, with three or four children per group. The mean dosage per week was 80 minutes and ranged from 24 to 120 minutes. The studies commonly applied shared book reading (reading aloud with the children), with target words embedded in the books. Standard care differed based on the setting and local conditions in each country or (pre)school. In some studies, the comparison groups received vocabulary instruction in preschool groups. Compared to standard care, the effect of L2 vocabulary interventions varied across outcome measures. For vocabulary measures including words that were taught in the intervention (proximal outcome measures), the intervention effects were large for both receptive L2 vocabulary (i.e. understanding of words; standardised mean difference (SMD) 0.97, 95% confidence interval (CI) 0.64 to 1.30; 4 studies, 1973 participants; very low-certainty evidence) and expressive L2 vocabulary (i.e. expressing or producing words; SMD 0.86, 95% CI 0.56 to 1.17; 6 studies, 1121 participants; very low-certainty evidence). However, due to some concerns in the overall risk of bias assessment, substantial heterogeneity, and wide CIs, we have limited confidence in these results. For language measures that did not include taught vocabulary (distal outcome measures), the intervention effects were small for receptive vocabulary (SMD 0.29, 95% CI 0.02 to 0.55; 6 studies, 1074 participants; low-certainty evidence) and probably made little to no difference to expressive vocabulary (SMD 0.10, 95% CI -0.02 to 0.23; 7 studies, 960 participants; moderate-certainty evidence). There was little to no intervention effect on L2 listening comprehension (SMD 0.19, 95% CI -0.31 to 0.68; 2 studies, 294 participants; very low-certainty evidence), but the evidence was uncertain, and the interventions probably increased L2 narrative skills slightly (SMD 0.37, 95% CI 0.14 to 0.59; 2 studies, 487 participants; moderate-certainty evidence). Only one study reported data on MLU, and we were unable to examine the effect of intervention on this outcome. The level of certainty of the evidence was downgraded mainly due to inconsistency and imprecision. We were unable to draw conclusions about socio-emotional well-being, or conduct the planned subgroup analyses to examine the second objective, due to lack of data. AUTHORS' CONCLUSIONS: Findings from this review suggest that, compared to standard care, vocabulary interventions may benefit children's L2 vocabulary learning but have little to no effect on their listening comprehension, though the evidence is uncertain. Vocabulary interventions probably improve the children's storytelling skills slightly. Due to the limited number of studies that met our inclusion criteria and the very low- to moderate-certainty evidence as a result of inconsistency and imprecision, implications for practice should be considered with caution. This review highlights the need for more high-quality trials (e.g. RCTs) of vocabulary interventions for L2 learners, particularly studies of learners outside the USA.

Sentence repetition is a measure of children's language skills rather than working memory limitations.

Sentence repetition tasks are widely used in the diagnosis and assessment of children with language difficulties. This paper seeks to clarify the nature of sentence repetition tasks and their relationship to other language skills. We present the results from a 2-year longitudinal study of 216 children. Children were assessed on measures of sentence repetition, vocabulary knowledge and grammatical skills three times at approximately yearly intervals starting at age 4. Sentence repetition was not a unique longitudinal predictor of the growth of language skills. A unidimensional language latent factor (defined by sentence repetition, vocabulary knowledge and grammatical skills) provided an excellent fit to the data, and language abilities showed a high degree of longitudinal stability. Sentence repetition is best seen as a reflection of an underlying language ability factor rather than as a measure of a separate construct with a specific role in language processing. Sentence repetition appears to be a valuable tool for language assessment because it draws upon a wide range of language processing skills.

Nonword-repetition ability does not appear to be a causal influence on children's vocabulary development.

In the study reported here, we assessed the theory that vocabulary learning in children depends critically on the capacity of a "phonological loop" that is indexed by nonword-repetition ability. A 3-year longitudinal study of 219 children assessed nonword-repetition ability and vocabulary knowledge at yearly intervals between the ages of 4 and 7 years. There was a considerable degree of longitudinal stability in children's vocabulary and nonword-repetition skills, but there was no evidence of any influence of nonword-repetition ability on later vocabulary knowledge. These results seriously call into question the claim that vocabulary learning in children is constrained by nonword-repetition ability, and they cast doubt on the broader theory that the phonological loop functions as a language-learning device.

Screening for Language Delay: Growth Trajectories of Language Ability in Low- and High-Performing Children.

Purpose: This study investigated the stability and growth of preschool language skills and explores latent class analysis as an approach for identifying children at risk of language impairment. Method: The authors present data from a large-scale 2-year longitudinal study, in which 600 children were assessed with a language-screening tool (LANGUAGE4) at age 4 years. A subsample (n = 206) was assessed on measures of sentence repetition, vocabulary, and grammatical knowledge at ages 4, 5, and 6 years. Results: A global latent language factor showed a high degree of longitudinal stability in children between the ages of 4 to 6 years. A low-performing group showing a language deficit compared to their age peers at age 4 was identified on the basis of the LANGUAGE4. The growth-rates during this 2-year time period were parallel for the low-performing and 3 higher performing groups of children. Conclusions: There is strong stability in children's language skills between the ages of 4 and 6 years. The results demonstrate that a simple language screening measure can successfully identify a low-performing group of children who show persistent language weaknesses between the ages of 4 and 6 years.