This study examines how word characteristics like frequency, concreteness, part of speech and length predict Dutch vocabulary knowledge in 763 adult migrant L2 learners who vary widely in their educational levels in their L1, from minimal to extensive formal education. While the impact of these features on vocabulary learning is well-documented among tertiary-educated adult and adolescent L2 learners in the academic track of secondary education, its effect on low-educated adult L2 learners has hardly been explored. Findings confirm that word frequency, concreteness and length significantly predict receptive vocabulary knowledge, aligning with prior research. However, the study also reveals variations in the predictive power of word frequency and length among adults with different educational backgrounds. These results highlight the necessity to reassess the applicability of findings from current research on L2 receptive vocabulary, particularly concerning adult learners with reduced educational backgrounds.

Infants’ language is often measured indirectly via parent reports, but mothers may underestimate or overestimate their infants’ word comprehension. The current study examined estimations of mothers from diverse educational backgrounds regarding their infants’ word comprehension and how these estimations are associated with their verbal input and infants’ receptive vocabulary at 14 months. We compared 34 infants’ looking-while-listening (LWL) performances with the mothers’ Turkish Communicative Development Inventory (TCDI) reports to calculate the mothers’ overestimation and underestimation. During free-play sessions, we assessed the mothers’ number of words, number of clauses, lexical diversity, and linguistic complexity. We found that mothers have overestimations and underestimations regardless of their educational background. Crucially, mothers’ only overestimations were positively associated with their number of words and lexical diversity. Mothers’ verbal input was not related to infants’ receptive vocabulary scores. The findings suggest that mothers’ input might be aligned with their estimations of their infants’ language capabilities, which might not reflect the infants’ true performance.

In this study, monolingual (English) and bilingual (English/Spanish, English/Urdu) five- and six-year-old children completed a grammaticality judgment test in order to assess their awareness of the grammaticality of two types of syntactic constructions in English: word order and gender representation. All children were better at detecting grammatically correct and incorrect word order constructions than gender constructions, regardless of language group. In fact, bilingualism per se did not impact the results as much as receptive vocabulary range. For example, children with the highest receptive vocabulary scores were more accurate in detecting incorrect word order constructions (i.e., word order violations, semantic anomalies) and incorrect gender agreement than children in the lower receptive vocabulary ranges. However, no differences were found between the ranges for ambiguous gender constructions. These results highlight the importance of receptive vocabulary ability on syntactic awareness performance, regardless of language group.

In this research, 5- and 6-year-old monolingual (English) and heritage language (English–Spanish, English–Urdu) children completed a grammaticality judgment test to assess their awareness of grammatically correct and incorrect morphosyntactic structures in English. Results demonstrated that language group differences were minimized when heritage language children exhibited average receptive vocabulary proficiency for the sample, and when more difficult morphosyntactic structures were assessed. In this middle range, only two group differences were found. Our findings highlight the need to consider factors such as receptive vocabulary when assessing morphosyntactic awareness and language group differences.

English receptive vocabulary scores from 797 monolingual and 808 bilingual participants between the ages of 17 and 89 years old were aggregated from 20 studies to compare standard scores across language groups. The distribution of scores was unimodal for both groups but the mean score was significantly different, with monolinguals obtaining higher standard scores than bilinguals. Consistent with previous research, older adults had higher vocabulary scores than younger adults. The results are discussed in terms of the implications for theoretical conceptions of linguistic processing and clinical diagnosis in bilingual populations.