L2 vocabulary learning through interactive book reading and factors that affect learning in emergent bilingual primary school children

Vocabulary acquisition is essential for language development. Numerous studies consistently show that interactive book reading (IBR) effectively stimulates children's vocabulary growth by fostering story-based interaction before, after, and during reading aloud. However, emergent bilingual children often start with lower L2 vocabulary knowledge and show smaller gains from IBR compared to native speakers. Adopting a between-subject design, the present study aims to investigate the impact of three IBR approaches, differing in the presence and use of emergent bilinguals’ L1 during vocabulary instruction. In addition, the influence of learner-related (prior L1 and L2 vocabulary knowledge) and word-related characteristics (age of acquisition – AoA, vocabulary tiers, L1-L2 cognateness) on productive L2 vocabulary gains from IBR are investigated. Seventy-seven Turkish-Dutch emergent bilingual children (M age = 7.4. SD = 0.89) were involved in a five-week IBR intervention containing five picture books. At pretest, posttest and delayed posttest productive L2 target vocabulary was measured using a form recall test. The results indicate that all conditions showed progress in vocabulary acquisition after the intervention, with no significant differences between them. This suggests that all treatments, regardless of L1 use, contributed equally to this improvement. Posttest and delayed posttest scores were influenced by children’s prior receptive L2 vocabulary knowledge, prior productive L2 knowledge of target items, AoA, tier, and target vocabulary cognateness. More particularly, children with larger prior L2 vocabulary knowledge learned more words than children with smaller L2 vocabulary. Words with a lower AoA, tier 2 domain-specific words, and cognates were learned more easily. At the delayed posttest prior L1 receptive vocabulary knowledge significantly impacted L2 vocabulary retention. These findings underscore the effectiveness of IBR for vocabulary learning for emergent bilinguals and suggest that using L2-only approaches yield similar vocabulary gains as using children’s L1 alongside L2 instruction.