n Empirische Arbeit Dieser Beitrag steht open access online unter https: / / dx.doi.org/ 10.2378/ peu2025.art05d Vocabulary Acquisition of Bilingual Preschoolers in Different Training Conditions: The Role of Children’s First Language Melihan Cinar 1 , Ilonca Hardy 1 , Astrid Jurecka 1 & Nele McElvany 2 1 Goethe University Frankfurt 2 IFS Dortmund Summary: This study investigated bilingual preschoolers’ vocabulary acquisition in German as a second language (L2) using an implicit training approach with auditory language input. Based on the theory of learning from context (Sternberg & Powell, 1983), we implemented an experimental design with four conditions, varying input in children’s family language of Turkish (L1) beyond L2 input (N = 86). An untrained monolingual group served as baseline (N = 54). Controlling for initial vocabulary and cognitive ability, results revealed no significant differences between the intervention groups, with overall small effects from pretest to posttest and delayed posttest. Yet, mean gains of the intervention groups were greater than those of monolingual children. Multiple regressions revealed that prior L2 vocabulary knowledge predicted L2 vocabulary at posttest beyond L1, age and cognitive ability. The results are discussed with respect to early bilingual education practices and research. Keywords: Vocabulary, incidental learning, bilingual, preschool, training Wortschatzerwerb von zweisprachigen Kindergartenkindern in unterschiedlichen Trainingsbedingungen: Die Bedeutung der Erstsprache Zusammenfassung: Die Studie untersucht den Wortschatzerwerb von bilingualen Kindergartenkindern in der Zweitsprache Deutsch (L2) durch eine implizite Fördermethode mit Hörtexten. Auf der Grundlage der Kontexttheorie (Sternberg & Powell, 1983) wurde ein experimentelles Design mit vier Bedingungen umgesetzt, in denen der auditive Input in der Familiensprache Türkisch (L1) neben dem L2-Input variiert wurde (N = 86). Eine untrainierte monolinguale Stichprobe wurde als Baseline erhoben (N = 54). Unter Kontrolle des Zielwortschatzes im Prätest und der kognitiven Grundfähigkeit ergaben sich keine signifikanten Gruppenunterschiede und insgesamt kleine Effektstärken im zeitlichen Verlauf von Prätest, Posttest und verzögertem Posttest. Die mittleren Zugewinne der Interventionsgruppen waren allerdings größer als bei der einsprachigen Vergleichsgruppe. Multiple Regressionen zeigten, dass der initiale L2-Wortschatz den Wortschatz im Posttest über die L1, das Alter und die kognitive Grundfähigkeit vorhersagt. Die Ergebnisse werden bezüglich ihrer Bedeutung für Forschung und Praxis der mehrsprachigen Bildung diskutiert. Schlüsselbegriffe: Wortschatz, implizites Lernen, bilingual, Kindergarten, Förderung Psychologie in Erziehung und Unterricht, 2025, 72, 64 -82 DOI 10.2378/ peu2025.art05d © Ernst Reinhardt Verlag Recent work emphasizes vocabulary knowledge as both a predictor and an outcome of academic achievement (Heppt et al., 2016; Karlsen et al., 2017; Röthlisberger et al., 2020; Storch & Whitehurst, 2002). Yet, it is also known that vocabulary knowledge differs between bilingual and monolingual children already in preschool age and beyond (Bialystok, 2009; Bialystok et al., 2010; Cinar & Hardy, 2017; Dubowy et al., 2008; Karlsen et al., 2017; Röthlisberger et al., 2020; Weinert et al., 2012), with significantly lower vocabulary knowledge in the language of Vocabulary Acquisition of Bilingual Preschoolers 65 schooling (L2) in bilingual children. As according to several studies (Golinkoff et al., 2016; Hart & Risley, 2003; Leseman et al., 2009; Niklas & Schneider, 2013; Schwab & Lew- Williams, 2016), vocabulary development is associated with families’ literary practices and socio-economic background (SES), children with little exposure to literary practices at home, low input in the language of schooling, and a low family SES are especially at risk of delayed language development (Howard et al., 2014; Kelley et al., 2015). Consequently, many early interventions focus on enhancing vocabulary acquisition especially with children of low language competency (Jahreiss et al., 2018; Moore & Schleppegrell, 2014; see Nagy et al., 2012). With respect to the specific situation of bilingual learners, there has been increasing interest in the role of children’s family languages (L1) for vocabulary knowledge in the L2 (Ertanir et al., 2018; Grøver et al., 2018; Leseman et al., 2009; see Larson et al. for a systematic review on language-focused interventions, 2020). The theory of learning from context (Sternberg & Powell, 1983) provides a theoretical framework in which the specific role of L1 in vocabulary acquisition in the L2 may be investigated, focusing on incidental processes of knowledge construction (McElvany et al., 2017; Sander et al., 2018). It assumes that children will construct the meaning of new words in contexts of formal and informal education by using contextual cues that activate prior semantic and linguistic knowledge. Against this background, in the present study 1 , we investigated the effects of a five-week intervention on bilingual preschoolers’ vocabulary acquisition in different experimental conditions of auditory language input in storybook readings. Specifically, we asked whether bilingual children’s vocabulary acquisition in the L2 will be fostered if they are additionally exposed to L1 input. This language input may serve as an additional contextual cue for the construction of L2 word meaning and global text coherence by enhancing children’s semantic connotations and cognitive processing of unknown words. Vocabulary in School-relevant Contexts Generally, language use in school has been conceptualized as the specific register of academic language (Schleppegrell, 2004; Heppt et al., 2021). Compared to everyday language, it is characterized by a low degree of contextual cues, a high degree of abstraction, explicitness, and density of information as well as complex syntax (cf. Heppt et al., 2014; Heppt et al., 2021; Schmölzer-Eibinger et al., 2013). While basic vocabulary draws on highly frequent words in everyday contexts, the academic lexicon consists of composites, domain-specific and domaingeneral expressions, and morphologically complex words of low frequency (Heppt et al., 2014; Schmölzer-Eibinger et al., 2013). Empirical studies have repeatedly shown the predictive value of academic language for students’ academic success in different school subjects (Heppt et al., 2016; Schuth et al., 2017; Uccelli et al., 2015). Therefore, fostering academic language across the curriculum is considered a crucial aspect of schooling (Gogolin & Lange, 2011). With regard to preschool contexts, several authors have distinguished between language that is related to academic language and language of everyday life. Bialystok et al. (2010) differentiate vocabulary used in school-relevant contexts versus home contexts; van Kleeck (2014) considers interactions of academic talk versus casual talk to be prone for vocabulary development of young children. Specifically, academic talk is conceptualized as literary, of greater length, of domain-specificity, and largely novel, infrequent words (van Kleeck, 2014). Building on the work of Bialystok et al. (2010) and van Kleek et al. (2014), this study views vocabulary of low familiarity due to low frequency as a precursor to academic language at school (see also Jurecka et al., 2019). 1 The project InterMut (Potential der Muttersprache zur Verringerung von Bildungsungleichheit - Wortschatzerwerb von Kindern nichtdeutscher Familiensprache vor zentralen Übergängen des Bildungssystems) at TU Dortmund and Goethe-Universität Frankfurt was funded by the German National Ministery for Education and Research (BMBF) [01JC1121B]. 66 Melihan Cinar, Ilonca Hardy, Astrid Jurecka, Nele McElvany Mechanisms of Vocabulary Acquisition A person’s mental lexicon is typically differentiated into receptive and productive vocabulary (Rothweiler & Kauschke, 2007). In addition, both the breadth (number of known words) and depth (knowledge about words, Wesche & Paribakht, 1996) of basic vocabulary increase during language development (Beck et al., 2013). Meaning construction of unknown words has been described as incidental vocabulary learning (Penno et al., 2002). In the theory of fast-mapping (Carey & Bartlett, 1978), it is assumed that individuals construct a partial lexical representation when encountering an unknown word. This representation is strongly tied to the context in which the word was encountered. After several encounters in different contexts, lexical connotations are expanded and the representation is successively integrated into preexisting semantic networks (Carey, 2010; Rothweiler & Kauschke, 2007). Lexical acquisition rates of young children correspond to presumptions of fast-mapping in different age groups (vocabulary spurt: Tracy, 2007; preschool: Ritterfeld et al., 2006; elementary school: Apeltauer, 2010). In addition to fast-mapping models of vocabulary acquisition, the theory of learning from context by Sternberg and Powell (1983) proposed specific supporting conditions for meaning construction from texts. Similar to the model of reading comprehension by Kintsch (1998), this theory is based on the assumption of a reciprocal relationship between vocabulary development and text comprehension (see Marx & Roick, 2012; Tsui & Fullilove, 1998, for respective models of listening comprehension). Learners are thought to acquire new vocabulary by differentiating relevant from irrelevant information in a given text, thus combining the meaning of relevant textual cues to construct a (partial) representation of the new word (Sternberg, 1987). Eight contextual cues may be differentiated which refer to information on time, space, valence, description (state and function), causality, class, and equivalence (see figure 1 for an example). The theory postulates that the recognition of contextual cues in a given text will allow learners to successfully construct a mental model of the text by applying basic reading strategies and embedding information into prior knowledge (Sternberg, 1987). A number of studies support the theoretical assumptions of contextual learning for vocabulary growth in monolingual children (Fukkink, 2005; NICHD, 2000; Swanborn & de Glopper, 2002). Further, in experimental studies with bilingual elementary school students in Germany, effects of contextual learning on vocabulary acquisition were detected in different conditions with reading texts (McElvany et al., 2017; Sander et al., 2018). When applying the context theory to vocabulary acquisition of preschool children, language input may be provided in terms of auditory material instead of reading texts, as in a setting of storybook reading. In empirical research, effects of listening to language input on both word recognition and productive language of preschoolers were found (Ritterfeld et al., 2006; Zamuner et al., 2017), with the degree of verbal explanations and frequency of input as factors impacting vocabulary acquisition (Penno et al., 2002). Approaches to Vocabulary Training With regard to language-focused interventions for young children from linguistically and culturally diverse backgrounds, a systematic review by Larson et al. (2020) highlights that interventions that are responsive to children’s backgrounds have positive effects on the vocabulary acquisition of English-speaking dual language learners from birth to age 5. In 41 reviewed studies, the authors differentiated four types of interventions: Explicit instruction on target skills, interactive book reading, classroom curriculum interventions and naturalistic, routinesbased interventions. Specifically, interventions with input-enhancement such as book reading and those with explicit instruction proved to be effective for vocabulary development in English. Some of these interventions explicitly included Vocabulary Acquisition of Bilingual Preschoolers 67 children’s L1, thus pointing to beneficial effect of L1 use for children’s L2 acquisition. The approaches described in this review correspond to distinctions of explicit and implicit methods of vocabulary training (Marulis & Neuman, 2010; NICHD, 2000). A meta-analysis by Marulis and Neuman (2010), drawing on studies with older students showed that combined approaches of explicit and implicit vocabulary training had the highest effect sizes. In explicit approaches, vocabulary items are taught by explicating their meaning either by word definitions or by translating meaning into the students’ L1. In implicit approaches, new vocabulary is provided in rich educational contexts, and learners need to construct meaning from activities of listening, reading, writing, or oral speech without additional support (Hulstijn, 2001). For example, in the context of foreign language instruction, readers are provided with texts which repeatedly use new words in a predefined context and genre, so-called narrow reading (Decarrico, 2001). Overall, implicit approaches best simulate contexts of incidental language acquisition in everyday contexts in which meaning construction is typically driven by contextual cues (Biemiller, 2003; Landauer et al., 2007). However, with regard to children with low language competencies, there is evidence that meaning construction of new words, for example in contexts of storybook reading, is lower than that of children with higher prior knowledge (Kelley et al., 2015; Penno et al., 2002). Against this background, in early education, implicit approaches typically are enriched to draw attention to specific words. Early educators serve as models of language use, they provide rich language input, and they use scaffolding techniques such as questioning, focusing attention on specific language input, or word explanations in contextually rich situations (Kucharz et al., 2022). Empirical research shows that learning environments in which high quality L2 language scaffolding is implemented are effective for bilingual children’s domain-specific and language development, including vocabulary (Hardy et al., 2019; Larson et al., 2020). Children’s Family Language as a Cognitive Resource With regard to the relationship between L1 and L2 competence, several hypotheses have been put forward. In Cummins’ (1979) interdependence hypothesis, for example, positive transfer between L1 and L2 proficiency is assumed. From this theoretical perspective, children with a family language other than the majority language will benefit from L1 proficiency in acquiring the L2, including academic language. In contrast, Carroll's (1989) time-on-task hypothesis suggests that the time spent learning a language has a particular beneficial effect on language proficiency. From this theoretical perspective, it would therefore be especially relevant to invest (instructional) time into the L2 while the inclusion of the L1 may hinder the process of L2 acquisition (see also Uccelli, 2023, for a broader perspective on L1 in education). Empirically, studies with older children and adults (Barac et al., 2014; for an overview see Kempert et al., 2016), but also some studies with young children (Leseman et al., 2009), find positive correlations between children’s L1 and L2 language competencies. Language transfer between the L1 and the L2 may be explained by models of cognitive representation. The construction of mental categories in the L2 is thought to be connected to the L1 mental lexicon, where semantic, phonological, orthographical, syntactical, and pragmatic forms, including larger linguistic units, are stored (Aitchison, 2003). In recent work, it is particularly the types of bilinguals’ shared and nonshared conceptual representations between L1 and L2 as well as between different language competencies that have been investigated (see Ertanir et al., 2018; Pavlenko, 2009). For example, in the modified hierarchical model, it is assumed that conceptual representations may be fully shared by L1 and L2, fully language-specific (i. e., either L1 or L2), or partially overlapping between L1 and L2 (Pavlenko, 2009). Thus, the process of L2 acquisition will at least partially involve conceptual restructuring, and vocabulary in one language may contribute to language transfer. In several studies, the transfer of early 68 Melihan Cinar, Ilonca Hardy, Astrid Jurecka, Nele McElvany L1 skills to the L2 has been investigated with overall inconsistent results. Leseman et al. (2009) found that L1 oral proficiency predicted L2 listening comprehension and L2 semantic skills (vocabulary and concept knowledge) in preschoolers, controlling initial cognitive ability, short-term memory, and L2 vocabulary knowledge at the age of three. Goodrich et al. (2017) did not find evidence of a unique contribution of L1 vocabulary on L2 acquisition in a longitudinal design after controlling for initial L2 vocabulary. Similarly, a cross-sectional study with young Turkish-German children did not find evidence for a relation between L1 and L2 vocabulary; yet, dual language proficiency was predicted by phonological memory, early daycare entry, and a stimulating home environment (Ertanir et al., 2018). The authors conclude that there may be a competition between L1 and L2 especially for language skills with a high dependency on frequency and quality of input. Yet, they also emphasize that young children’s L1 is a resource in educational settings since there were no hindering effects of bilingualism if the children entered preschools (with L2 input) early on. One of the few studies investigating explicitly to what extent the L1 functions as a cognitive resource for L2 vocabulary acquisition is the study by Goodrich et al. (2017). They asked whether children’s level of proficiency in the L1 and L2 moderated the effect of an intervention on early literacy skills in the L2. They found that the level of L2 proficiency moderated the effect of the intervention for L1 oral language, but not vice versa. However, the study did not include instructional contexts in which both languages were employed, but focused on the contribution of children’s level of bilingualism in L2 settings. In two further studies with elementary school students, the activation of children’s L1 in reading texts was investigated. McElvany et al. (2017) found that the activation of children’s L1 by providing additional language input when reading texts in the L2 did not affect their L2 vocabulary acquisition. Sander et al. (2018) investigated the additional role of auditive input in the L1 and the L2 for vocabulary acquisition. In both studies, reading texts solely in the L2 were found to be most effective. However, to our knowledge, the specific effects of L1 activation as an implicit approach to L2 vocabulary acquisition have not been investigated in the age group of preschool children in Germany. Background of the Study In preschool age and beyond, bilingual children show lower vocabulary breadth in the L2 compared with monolinguals, even though their total breadth of vocabulary in L1 and L2 does not necessarily differ (Bialystok et al., 2010; for an overview on bilingual learners’ language proficiency see also Hoff, 2018). Due to the relation of vocabulary growth with family socio-economic background, literary practices, and L2 input at home, bilinguals’ meaning construction in the L2 in natural contexts is less successful which may have consequences for reduced vocabulary growth over time (Marulis & Neuman, 2010). In interventions with both L1 and L2, the theory of learning from context (Sternberg, 1987) provides a framework for interpreting young children’s meaning construction of new words. Empirically, it has been demonstrated that contextual word learning is applicable to bilinguals instructed in the L2 (e. g., Carlo et al., 2004; McElvany et al., 2017). In bilingual students, the activation of partially shared representations in the L1 (Pavlenko, 2009) may therefore productively be used to support meaning construction in the L2 when dealing with auditory or written texts: In a first step, L2 learners may construct text meaning in their L1, drawing on contextual cues and L1-specific lexical knowledge; in a second step, new word meanings in the L2 may be successfully constructed from global text coherence in L1 and partially shared L1 and L2 lexical representations. In our study, we therefore specifically asked whether young bilingual children will profit from contexts in which auditory texts in the L1 are provided as a conceptual anchor for L2 vocabulary acquisition. In an experimental design, we varied different conditions of auditory text presentation Vocabulary Acquisition of Bilingual Preschoolers 69 in L2 only, L1 and L2, and L2 with a translation of target vocabulary into L1. In prior analyses, overall effects of contextual learning were found to be small (Cinar & Hardy, 2017; McElvany et al., 2017; Sander et al., 2018). The following research questions were investigated: 1) Effects of Contextual Learning Formats 1 a) What are the effects of different forms of intervention based on contextual cues on bilingual children’s learning gains in immediate and delayed posttests of L2 target vocabulary in comparison to a control group without contextual cues? Will effects of an intervention with prior L1 text processing be superior compared to L2 text processing only, and an intervened control group with singular L1 word translation? 1 b) What are the effects of different forms of intervention based on contextual cues on bilingual children’s learning gains in comparison to a monolingual baseline group? Will effects of an intervention with prior L1 text processing be superior compared to L2 text processing only, and an intervened control group with singular L1 word translation? We hypothesized that bilingual preschoolers will be able to construct meaning of L2 target words by using contextual cues, especially by prior activation of their L1, because of shared linguistic representation of vocabulary and text coherence. Therefore, we expected that activating children’s L1 prior to presenting the same text in the L2 will support meaning construction better than L2-only or L1 word-translation conditions. 2) Impact of L1 Proficiency on L2 Vocabulary Acquisition What is the contribution of L1 proficiency measures to L2 vocabulary knowledge at posttest, taking into account relevant control variables? We expected to find an impact of L1 proficiency measures (L1 text comprehension, L1 receptive vocabulary) beyond initial L2 vocabulary, cognitive ability, socio-economic status, parent-child reading frequency on L2 posttest scores. Method Data collection took place within the project InterMut 1 implementing an experimental design with three points of measurement. The procedure employed for recruitment and data collection conformed to ethical standards of the German Association of Educational Research (DGfE). Sample Bilingual Sample A total of n = 93 of Turkish (L1) - German (L2) bilingual Kindergarten children participated in the study, with a mean age of 5.6 years (SD = 0.63). Of the sample, 55.9 % were female. The children were recruited from 15 early education institutions of a large city in Germany which were contacted via the respective head organisations. They were targeted because they included a large percentage of children with German as L2 due to demographic factors in the surrounding neighborhoods. None of the preschools offered programs of bilingual education. All of the participating children had been identified by their educators as learners of German as L2 with a Turkish family background. Turkish was chosen because it is one of the large immigrant communities in Germany. Upon contact, the languages spoken at home were confirmed by the parents in a questionnaire. Data collection took place in two waves. The children were assigned to four experimental conditions according to the procedure described in the design section, ascertaining that in each wave and within each wave in each early education institution, all of the experimental conditions were realized. Results for the two subsamples are reported together in the following section. Information on the socio-economic status (SES) of the participating families was obtained for 63 % of the sample in wave 1 and 2. It showed a mean status of 40.89 (SD = 15.01) according to HISEI (Highest International Socio-Economic Index of Occupational Status; Ganzeboom et al., 1992). The partial sample with information on the highest professional degree achieved by the mother or the father was distributed evenly across the participating institutions; the pretest results of children whose parents provided information on their SES and the children without respective information did not differ significantly with respect to the highest professional degree achieved 70 Melihan Cinar, Ilonca Hardy, Astrid Jurecka, Nele McElvany by the mother or the father. Of the final sample, 32 % of parents reported their family language to be Turkish, 53 % Turkish and German, and 15 % German. The inclusion of children into the final sample was determined by the following criteria: 1) attendance of more than 50 % of 20 training sessions; 2) basic comprehension of content presented in the respective individual training sessions with a content comprehension score of at least 30 % of all attended training sessions; 3) basic L1 language competence, consisting of text comprehension (cut-off lower than 25 %) and L1 basic receptive vocabulary (cut-off lower than 50 %); 4) participation in pretest, the immediate posttest, and the delayed posttest. The cut-off values for L1 competence (criterion 3) were derived from values used in the CITO test (Konak & Duindam, 2008) to determine children at risk. Using these four criteria, 7 of 93 children were excluded from the final sample. Comparison of the experimental groups of the final sample showed no significant group differences between the four intervention groups with regard to cognitive ability, L1 receptive vocabulary, L1 text comprehension, L2 receptive vocabulary, L2 target vocabulary, age, and SES 2 . The final sample with complete measures considered in the following analyses consisted of 86 children. The respective descriptive statistics are provided in tables 1 and 3. Monolingual Sample The monolingual sample with complete measures was comprised of n = 54 children with a mean age of 5.7 years (SD = 0.52), 44 % of which were male. 40,7 % of the children were recruited from the same early education institutions in which the intervention took place. 59.3 % of children came from early education institutions in comparable local areas. Information on the SES of the participating families could be obtained for 87 % of the monolingual sample via an additional parental questionnaire. It showed a mean status of 64.70 (SD = 12.50) according to HISEI (Ganzeboom et al., 1992), see table 2. Group comparisons between the monolingual and the bilingual sample showed that they differed significantly in their L1/ L2 (German) receptive vocabulary (F [1,142] = 109.08, p < .001, η p ² = .44), pretest L1/ L2 (German) target vocabulary (F [1,143] = 256.87, p < .001, η p ² = .65), cognitive ability(F [1,122] = 15.59, p < .001, η p ² = .11), and SES (F [1,102] = 75.21, p < .001, η p ² = .42), but not in their age (F [1,141] = 0.04, p > .05, η p ² = .00), with significantly higher means in the group of monolingual children. Design Within a longitudinal design with five intervention weeks and four intervention days per week we implemented an experimental repeated measures design with four conditions, varying the auditory texts presented to the sample of bilingual children. In group L2 - L2 (n = 19), the auditory texts were presented twice in the L2. In group L1 - L2 (n = 22), the auditory texts were presented in the L1 first and then in the L2. In group L2 - L1tran (n = 23), the auditory text was presented first in the L2 with an additional translation of the target vocabulary in L1 and then again in the L2 (intervened control group). In group CG (control group) (n = 22), the auditory texts did not include the target vocabulary but consisted of age-appropriate commercial audioplays in the L2. Additionally, group BG (baseline group) (n = 54) consisted of a monolingual group without intervention. The pretests were administered in individual sessions of 30 to 45 minutes (distributed over two or three days) in the week before the intervention started. Using pretest scores in L2 target vocabulary, age, and gender as matching variables, the bilingual children were then randomly assigned to the four intervention conditions both in data collection waves 1 and 2. In the assignment of children to the intervention groups it was additionally secured that the four intervention groups were implemented at each site. The immediate posttest took place on the day after the intervention; additionally, a delayed posttest was administered approximately six weeks after the end of the intervention. In the monolingual baseline sample, the pretests were administered simultaneously with the posttests of the intervened bilingual sample in wave 2. The posttests for the monolingual sample were administered approximately five weeks after the pretests, thus corresponding to the time span of the intervention in the bilingual samples. T-tests showed that there were no significant differences in the number of days between pretest and posttest of the monolingual and bilingual sample. 2 Note that for the group of bilingual children, we use the term L2 for all intervention and testing material in German. We use the term L1 for all intervention and testing material in Turkish despite the fact that some bilingual children may have acquired German and Turkish simultaneously. Vocabulary Acquisition of Bilingual Preschoolers 71 Intervention Material and Procedure All interventions took place in groups of a minimum of 5 and a maximum of 10 children. The vocabulary training consisted of auditory texts, which were presented via individualized digital recordings on MP3 players with head phones for each child. This way, the four different experimental conditions could be realized simultaneously in the intervention groups. Each session lasted between 45 and 60 minutes, with a range of 7 to 11 minutes of listening time for each single text. To allow the comparability of the intervention material across the conditions, all texts were first translated by a certified German-Turkish translation office and then read by the same professional speaker and produced in a recording studio. A wide variety of topics such as animals, nature, and everyday life were included in the material; stories were selected based on considerations of age appropriateness, content domains covered in early education guidelines, and contexts with the potential for use of academic language (see criteria for test construction in the following section). Published children’s literature with a variety of literary genres (fairy tales, stories, and factual texts) was adapted by including three selected target vocabulary items and additional contextual cues based on the theoretical background of contextual learning (Sternberg & Powell, 1983) into each of the texts. Figure 1 presents a sample text including contextual cues. The final 20 auditory texts included a total of 60 vocabulary items identified as the target vocabulary (see Jurecka et al., 2019). For the CG, the chosen commercial texts of the same genres and total listening time did not include the target vocabulary. In the sessions, additionally one to two pictures of the story line and/ or main characters were presented with each text to secure the children’s attention and motivation to process the presented material. Trained students of early education conducted the sessions. After having listened individually to the first text, all children participated in a physical activity game with the student teacher. Following the game, the texts were listened to a second time individually. Each of the twenty sessions ended with an implementation check on children’s listening comprehension and an immediate partial posttest of the three presented target vocabulary items. This test is not included in the following analyses. Tests L2 Target Vocabulary A vocabulary test with 60 target vocabulary items was constructed for this study with a total of 60 points to be scored in the test (min = 7; max = 50). The test is described in detail in Cinar & Hardy (2017) and Jurecka et al. (2019). The scale shows sufficient reliability, with Cronbach’s alpha of .61/ .75 (pretest/ posttest). Similarly to the PPVT (Peabody Picture Vocabulary Test, Roßbach et al., 2005), the children had to select one picture out of four which corresponded to the target vocabulary item read out loud by the teacher. The distractor items were chosen to be similar to the target item in phonology, semantics, or visual characteristics. Figure 2 presents a sample test item (“flowerbed”). The test included different semantic fields and laid a focus on nouns (n = 49), with some additional adjectives (n = 3), and verbs (n = 8). Target vocabulary was chosen according to item difficulties in the age group of 4to 6-year-olds and considerations of academic language in preschool age (van Kleeck, 2014). A sample item is included in figure 2. The test of L2 target vocabulary was administered in individual sessions as pre-, post-, and follow-up measure and took approximately 20 - 25 minutes each. A setter has got puppies 1 . The six tiny 2 dog 3 babies 4 are lying in the dog basket 5 with their mother 6 . They are only one day old 7 and their eyes are still closed. 1 unknown word 2 descriptive cue 3 class membership cue 4 equivalence cue 5 spatial cue 6 descriptive cue 7 temporal cue Figure 1: Sample Text including Contextual Cues 72 Melihan Cinar, Ilonca Hardy, Astrid Jurecka, Nele McElvany Control Variables We assessed proficiency in L2 (subscale German receptive vocabulary; min = 18; max = 60) and L1 subscales Turkish receptive vocabulary (min = 25; max = 55) and text comprehension (min = 2; max = 20) by the computer-based program CITO (Konak & Duindam, 2008). The manual reports sufficient to good reliabilities with regard to the subscales of receptive vocabulary ( α = .91 for German α = .85 for Turkish), and text comprehension ( α = .69; Heppt & Jungmann, 2020). As a measure of cognitive ability, we employed the language-free subscales of the K-ABC (Melchers & Preuß, 2009) for children between the age of 4 and 6 years in the pretest, with sufficient to good measures of reliability and validity according to the manual (Rollett & Preckel, 2011), min = 53; max = 133. Further, we employed a parental questionnaire to obtain information on children’s family background (SES, family language) and parent-child reading activity on a four-point Likert-type scale from daily reading activity to infrequent reading activity. Implementation Checks During the sessions, an observation protocol was used to record the procedure and deviations from it by the student teacher. Results showed that the procedure was correctly implemented in 100 % of the sessions despite of interruptions with individual children which were resolved by immediate and adaptive reactions of the student teachers such as drawing the children’s attention to the instructional material. Moreover, the standardization of the procedure was supported by the presentation of the intervention material via MP3 and headphones. In order to assess children’s listening comprehension of the presented stories, the children also took part in a picture story test after the end of each session. In the picture story test, the children had to sort four pictures into the correct order, thus representing the story plot. One correct sequence of two consecutive pictures was scored as criterion for basic understanding with 0 (incorrect) or 1 (correct) of the respective story. The mean percent correct of sessions 1 to 20 showed a range of 35.3 % to 76.9 %, with a mean of 53.2 % across all the attended intervention sessions, with no significant differences between the intervention groups. Results Tables 1 and 2 provide the descriptive results for the bilingual sample and the monolingual sample separately, with means, standard deviations, and intercorrelations of all tests. Table 3 additionally provides means and standard deviations of all measures per group. A priori group comparisons of the four experimental groups showed that there were no significant differences on the measures of L2 receptive vocabulary (F [3,85] = .62, η p ² = .02), pretest target vocabulary (F [3,85] = .28, η p ² = .01), cognitive ability (F [3,69] = 1.91, η p ² = .07), socio-economic status (F [3,53] = 1.91, η p ² = .10), and parent-child reading frequency (F [3,56] = .73, η p ² = .04). Separate post-hoc comparisons of the four groups turned out insignificant (p > .05). a) b) c) d) Note: Distractor with similar context (a); correct answer (b); visual distractor (c); phonological distractor (d). Figure 2: Sample Item of Target Vocabulary Vocabulary Acquisition of Bilingual Preschoolers 73 Effects of Different Formats of Contextual Learning To investigate research question 1 a, we performed a repeated measures analysis with the within-group factor of time (pretest L2 target vocabulary, immediate posttest L2 target vocabulary, delayed posttest L2 target vocabulary) and the between-group factor of intervention group (L2 - L2, L1 - L2, L2 - L1tran, CG), using pretest scores of L2 receptive vocabulary as a covariate. There was a marginally significant effect of time (F [2,81] = 2.55, p < .10, η p ² = .03), and no effect of group (F [3,81] = 0.94, p > .01, η p ² = .03), or time x group (F [3,83] = .82, p > .01, η p ² = .02), with a significant contribution of the covariate of L2 receptive vocabulary (F [1,81] = 23.71, p < .01, η p ² = .23), and a significant interaction of L2 receptive vocabulary X time (F [2,81] = 4.80, p < .01, η p ² = .06). In performing the same analyses using cognitive ability as an additional covariate and a reduced sample size of 67, the contribution of cognitive ability was found to be nonsignificant (F [1,66] = .78, p > .01, η p ² = .01); time X cognitive ability (F [2,66] = .44, p > .01, η p ² = .007). According to our hypotheses, the gains in the intervention groups (L2 - L2, L1 - L2, L2 - L1tran) from pretest to the immediate posttest were analyzed with planned contrasts in relation to CG, using the covariate of L2 receptive vocabulary. There was a mean difference between the groups of L2 - L2 and CG of 3.02 (1.60), p < .10, d = 0.17 in training gains; however, this effect was not significant when additionally controlling for cognitive ability in the reduced sample, with a mean difference of L2 - L2 and CG of 2.14 (1.55), n. s. The other contrasts did not reveal significant differences between the groups in all tested contrasts, for means and standard deviations see table 3. We further performed t-tests for dependent samples to pinpoint the short-term training effects for each group, revealing significant gains from pretest to posttest in the groups Variables M SD 1 2 3 4 5 6 7 8 1 Target Vocabulary Pretest 14.58 5.17 - 2 Target Vocabulary Immediate Posttest 16.99 6.66 .57** - 3 Target Vocabulary Delayed Posttest 16.61 6.02 .53** .59** - 4 L2 Basic Receptive Vocabulary 40.53 8.45 .25* .37* .51** - 5 L1 Basic Receptive Vocabulary 41.39 7.14 .09 .08 .19 + .44** - 6 L1 Text Comprehension 11.43 3.86 .10 .03 .11 .16 .40** - 7 Nonverbal Cognitive Ability 98.12 16.37 .10 .21 .16 .31** .31** .26* - 8 Socio-Economic Status 40.89 15.01 .17 .32* .26 .34** .26 .14 .36** - 9 Parent-Child Reading Frequency 2.50 0.95 .11 .04 .12 .19 .12 .09 .10 .21 Tab. 1: Means (M ), Standard Deviations (SD), and Intercorrelations of Tests for Bilingual Sample Note: N variable1 = 89; N variable2 = 89; N variable3 = 87; N variable4 = 88; N variable5 = 89; N variable6 = 89; N variable7 = 73; N variable8 = 57; N variable9 = 60. + p < .10; * p < .05; ** p < .01 74 Melihan Cinar, Ilonca Hardy, Astrid Jurecka, Nele McElvany L2 - L2, t (18) = -4.01, p < .01, d = .86, L1 - L2, t (21) = -1.74, p < .10, d = 0.42, L2 - L1tran, t (23) = -1.80, p < .05, d = 0.35, but not in CG, t (21) = -.91, p > .10, d = 0.19. Therefore, controlling for differences in basic L2 vocabulary, an effect of contextual cues could only be observed in tendency for one of the intervention groups with language input twice in German, but not for the groups with additional L1 input in comparison to the control group. We performed additional planned contrasts with the intervention groups of L1 - L2 versus groups L2 - L2 and L2 - L1tran to test for differences with regard to the activation of L1. There were no significant differences between the contrasted groups L1 - L2 versus L2 - L2 with a mean difference of 1.74 (1.74), p > .05, d = 0.40, and L1 - L2 versus L2 - L1tran with a mean difference of 0.44 (1.63), p > .05, d = 0.11 for short-term vocabulary gains from pretest to posttest. To investigate long-term effects, we used planned contrasts with gain scores from the pretest to the delayed posttest in the intervention groups (L2 - L2, L1 - L2, L2 - L1tran) in relation to the CG. The respective contrasts did not reveal significant differences between the groups and only small effect sizes. There was a mean difference of 1.95 (1.65), p > .05, d = 0.31 between group L2 - L2 versus CG, a difference of 0.79 (1.60), p > .05, d = .04, between group L1 - L2 versus CG and a difference of 0.75 (1.57), p > .05, d = 0.07, between L2 - L1tran versus CG in training gains from pretest to delayed posttest. In the reduced sample using cognitive ability a as an additional covariate, these results were confirmed. In separate t-tests, effects of time were found for the groups of L2 - L2, t (18) = -2.98, p < .01, d = .65, L1 - L2, t (21) = -1.28, p = .10, d = .26, L2 - L1tran, t (23) = 1.92, p < .05, d = .38, but not the CG, t (21) = -0.98, p > .10, d = .20. Considering the effects of group comparisons, the hypothesis that the activation of L1 linguistic context will facilitate acquisition of L2 target vocabulary beyond the presentation of L2 input is rejected. To investigate research question 1 b, we compared the gains of each intervention group with gains of the monolingual baseline group without intervention (BG) in a repeated measures analysis with the within-group factor of time (pretest L2 target vocabulary, posttest L2 target vocabulary) and the between-group factor of group (L2 - L2, L1 - L2, L2 - L1tran, BG), using pretest scores of L2 receptive vocabulary and cognitive ability as covariates. Based on the low response rate in questionnaires, SES was not considered as a covariate. There was a significant effect of time, F [1,99] = 11.88, p < .01, η p ² = .11, time X group, F [3,99] = 2.60, p = .05, η p ² = .07, and group, F [3,99] = 14.99, p < .001, η p ² = .31, with a significant contribution of the covariate of L2 receptive vocabulary, F [3, 99] = 20.46, p < .001, η p ² = .17, and time X L2 receptive vocabulary, F [3,99] = 12.31, p < .01, η p ² = .11. The additional covariate of cognitive ability did not contribute significantly to variance in vocabulary gains, F [1,99] = 1.41, p > .05, η p ² = .01. In planned contrasts, the gains of each intervention group were compared to the monolingual group. Results revealed significant differences in the gains of L2 target vocabulary of Variables M SD 1 2 3 4 5 1 Target Vocabulary Pretest 2 Target Vocabulary Immediate Posttest 3 L2 Basic Receptive Vocabulary 4 Nonverbal Cognitive Ability 5 Socio-Economic Status 6 Parent-Child Reading Frequency 33.35 35.76 53.57 109.02 64.70 3.33 8.85 10.39 4.54 13.17 10.39 0.86 - .88** .69** .22 .26 .08 - .76** .29* .27 .10 - .30* .14 .30 - .37* .17 - .15 Tab. 2: Means (M ), Standard Deviations (SD), and Intercorrelations of Tests for Monolingual Sample Note: N variable1 = 54; N variable2 = 54; N variable3 = 54; N variable4 = 51; N variable5 = 47; N variable6 = 48. + p < .10; * p < .05; ** p < .01 Vocabulary Acquisition of Bilingual Preschoolers 75 L2 - L2 and BG with a mean difference of 3.80 (1.44), p < .01, d = .17, L1 - L2 and BG with a mean difference of 3.21 (1.60), p < .05, d = .25, and L2 - L1tran and BG with a mean difference of 2.38 (1.43), p = .10, d = .22. There was a significant gain from pretest to posttest in BG, with 2.41(4.92) words on average, t (53) = -3.60, p < .001, d = 0.27; the respective results for the bilingual groups are reported within research question 1 a. Tests L2 - L2 L1 - L2 L2 - L1 tran CG BG M (SD) M (SD) M (SD) M (SD) M (SD) Target Vocabulary Pretest 13.84 (4.18) 14.73 (4.81) 15.24 (5.77) 14.35 (5.76) 33.64 (8.82) N 19 22 25 23 56 Target Vocabulary Immediate Posttest 18.00 (6.23) 16.73 (7.11) 17.92 (7.55) 15.41 (5.63) 35.87 (10.32) N 19 22 25 23 55 Target Vocabulary Delayed Posttest 17.11 (4.79) 16.27 (6.36) 17.46 (6.61) 15.59 (6.19) - N 19 22 24 22 L2 Basic Receptive Vocabulary 41.58 (6.49) 38.91 (9.90) 39.83 (9.90) 41.96 (6.75) 53.82 (4.55) N 19 22 24 23 57 L1 Basic Receptive Vocabulary 42.26 (7.39) 39.32 (6.57) 41.20 (7.83) 42.87 (6.60) - N 19 22 24 23 L1 Text Comprehension 11.21 (4.24) 10.09 (3.41) 11.88 (3.68) 12.39 (3.99) - N 19 22 24 23 Nonverbal Cognitive Ability 103.12 (11.46) 90.47 (16.79) 98.75 (15.28) 99.84 (19.37) 109.30 (12.80) N 17 17 20 19 54 Socio-Economic Status 44.79 (12.18) 34.93 (12.10) 37.31 (14.70) 45.63 (18.16) 64.70 (12.50) N 14 14 13 16 48 Parent-Child Reading Frequency 2.67 (.97) 2.20 (.97) 2.43 (.85) 2.65 (.99) 3.33 (.85) N 15 14 14 17 48 Family Language Use German .14 .21 .14 .13 - N 14 14 14 15 - Family Language Use Turkish .36 .43 .36 .20 - N 14 14 14 15 - Family Language Use Turkish and German .57 .36 .50 .67 - N 14 14 14 15 - Tab. 3: Means (M ) and Standard Deviations (SD) of Measures by Group Note: L2 - L2: Presentation of texts in German; L1 - L2: Presentation of texts in Turkish followed by German; L2 - L1tran: Presentation of texts in German with translation of target vocabulary; CG: intervened control group; BG: monolingual baseline group. Measures for BG that were not tested are marked with -. Measures for Family Language Use are relative frequencies. 76 Melihan Cinar, Ilonca Hardy, Astrid Jurecka, Nele McElvany Contribution of Children’s L1 Proficiency to L2 Vocabulary Acquisition To investigate research question 2, we performed several multiple regression analyses (method: enter). In model 1 a, we entered age, cognitive ability, SES, and parent-child reading frequency. Results showed a significant contribution of SES to posttest scores of L2 target vocabulary, but no significant contribution of the measures of cognitive ability, age, and parent-child reading frequency, see table 4. In model 2 a, we additionally included the L2 vocabulary scores (pretest target vocabulary; L2 receptive vocabulary), with a significant contribution of pretest L2 vocabulary, no further contribution of the other variables, and a high amount of explained variance with R ² = .60; p < .001. In model 3 a, the variables of L1 receptive vocabulary and L1 text comprehension were included. Results revealed no significant change in explained variance with the inclusion of L1 receptive vocabulary and L1 text comprehension to the model. We performed the same regression analyses without SES and parent-child reading frequency, and a resulting sample size of N = 73 in models 1 b, 2 b, and 3 b, with highly similar results, see table 5. Both regression analyses therefore reveal that children’s proficiency in the L1 is not a relevant predictor of their vocabulary gains in the L2. In order to test eventual suppression effects, we performed separate regression analyses (method forward) solely with L1-variables (model 4 a) and L2-variables (model 4 b). In model 4 a, we found R ² = .22, and age ( β = .28, p = .06), SES ( β = .31, p = .045), cognitive ability ( β = .11, p = .48), parent-child reading frequency ( β = -.01, p = .96) as control variables and L1 receptive vocabulary ( β = -.09, p = .58) and L1 text comprehension ( β = .001, p = .99) as variables of interest. In model 4 b, we found R² = .60, with age ( β = .14, p = .22), SES ( β = .21, p = .05), cognitive ability ( β = .03, p = .80), parent-child reading frequency ( β = -.01, p = .31) as control variables and L2 receptive vocabulary ( β = .21, p = .13) and L2 target vocabulary ( β = .60, p < .001) as variables of interest. Model N Variables β R² ΔR² Model 1 a 49 Age NCA SES Parent-Child RF .36 .08 .30* -.01 .217 .217* Model 2 a 49 Age NCA SES L2 target vocabulary (pretest) L2 basic receptive vocabulary Parent-Child RF .14 .03 .22 .59*** .21 -.10 .603 .386*** Model 3 a 49 Age NCA SES L2 target vocabulary (pretest) L2 basic receptive vocabulary Parent-Child RF L1 basic vocabulary L1 listening comprehension .14 .03 .22 .60*** .21 -.10 .00 .07 .603 .000 Tab. 4: Multiple Regression Analyses on Posttest Target Vocabulary in Bilingual Sample (including family measures) Note: NCA = Nonverbal cognitive ability; SES = Socio-economic status; Parent-Child RF = Parent-Child Reading Frequency. * p < .05, ** p < .01, *** p < .001 Vocabulary Acquisition of Bilingual Preschoolers 77 Discussion With this intervention study, we intended to shed light on the role of children’s L1 in processes of incidental vocabulary acquisition in a sample of young L2 learners. In line with the theory of learning from context (Sternberg, 1987) as well as models of bilingual vocabulary representation (Pavlenko, 2009), we presumed that the use of children’s L1 would serve as a contextual cue, aiding L2 vocabulary acquisition without any additional instructional support. Similar to an intervention by Penno et al. (2002), we implemented a design with auditive stories to assess vocabulary gains in different training sessions focusing on incidental learning. Our results show that incidental learning occurred to a small degree in all of the groups. Yet, the mean gains did not differ between the three intervention groups after controlling for initial differences in L2 receptive vocabulary and cognitive ability, with a high variance on the target measure of vocabulary knowledge within the entire sample. Short-term gains due to the training were detected with individual paired samples t-tests for the intervention groups of extended German input (L2 - L2), the group of German with translated Turkish vocabulary (L2 - L1tran), and in tendency for the group of Turkish and German input (L1 - L2). No such gains were found in the control group. In conclusion, employing the children’s L1 in auditory texts additionally to the L2 did not show the expected facilitating contextual effect in comparison to the control group and the intervened control group with translated target vocabulary only. It was only in comparison to mean gains of the monolingual baseline group within the period of five weeks that we found significant effects for all of the intervention groups. Interpreting these results, it seems to have been the repeated L2 input in all of the conditions that was helpful for bilingual children’s vocabulary acquisition. Outcomes of a similar intervention based on written texts in the age group of nineto ten-year-olds in German elementary schools revealed a superiority of the group of extended L2 input in comparison to a group of L1 - L2 (McElvany et al., 2017). In our study, this effect was only found in tendency. Similar to Ertanir et al. (2018), our results may be interpreted in line with the “time-ontask” hypothesis of dual language acquisition (Hopf, 2005), proposing a potential competition between the processing of L1 and L2 input. Yet, so-called cognitive costs in bilingual learners, when knowledge acquired in one language context is transferred to the learner’s other language (e. g., Bialystok, 2009; Saalbach et al., Model N Variables β R² ΔR² Model 1 b 73 Age NCA .26* .18 .111 .111* Model 2 b 73 Age NCA L2 target vocabulary (pretest) L2 basic receptive vocabulary .07 .08 .58*** .23* .483 .372*** Model 3 b 73 Age NCA L2 target vocabulary (pretest) L2 basic receptive vocabulary L1 target vocabulary L1 listening comprehension .08 .09 .57*** .24* -.03 -.02 .484 .002 Tab. 5: Multiple Regression Analyses on Posttest Target Vocabulary in Bilingual Sample (without family measures) Note: NCA = Nonverbal cognitive ability. * p < .05; ** p < .01; *** p < .001 78 Melihan Cinar, Ilonca Hardy, Astrid Jurecka, Nele McElvany 2013 for mathematics) were not observed. While children in the intervention groups with L1 as presented text or translation of target vocabulary were required to mentally process L1 input, the group with L2 texts did not have to invest additional cognitive resources. Unfortunately, in this study, a measure of executive functioning or phonological working memory was not included to pinpoint possible effects. Cognitive load theory (Sweller et al., 1998) predicts that individuals will be hindered in successful knowledge construction if the processing of a task demands additional, task-external cognitive resources. A plausible theoretical extension may be the transfer to conditions of vocabulary acquisition during which cognitive resources are needed for learners to profit from contextual cues. This also implies that presenting texts in the L1 may rely on complex cognitive processing, requiring the translation between different representational formats rather than accessing shared linguistic representations (cf. Pavlenko, 2009). However, even with the target vocabulary chosen in this study which intended to represent academic rather than everyday contexts, specific hindering effects were not detected. Which factors contributed to bilingual children’s L2 vocabulary acquisition? Our analyses revealed that neither L1 vocabulary knowledge nor L1 text comprehension showed significant predictive power beyond the L2 variables and the control variables in different regressions attempting to disentangle the contribution of L1 with potentially shared variance in L2. In other studies investigating the contribution of L1 proficiency to L2 language acquisition, results vary depending on the outcomes involved. According to results of Goodrich et al. (2016), it is only the vocabulary items already acquired in the L1 that may result in a positive transfer to L2 vocabulary. In contrast to the contribution of L1 measures, in our study prior knowledge of L2 vocabulary was shown to be the most potent predictor of posttest target vocabulary, controlling for individual variation in cognitive ability and age as well as family SES and parent-child reading frequency. This means that within contexts of largely incidental vocabulary acquisition, it is children’s prior knowledge of vocabulary in the target language, including their respective habitual use of contextual cues in that language that will support meaning construction. This result is in line with findings by Penno et al. (2002) who interpreted their results of an experimental study on the effects of storybook reading with L1 English-speaking children as successful, yet not effective enough in overcoming the Mathew-effect. In comparison to gains of the experimental groups, the sample of monolingual children acquired overall less target vocabulary in the respective time period, thus pointing to the benefit of our intervention for the target group of bilingual children. Nevertheless, the initial difference of L2 vocabulary between the monolingual and the bilingual sample is not overcome by this intervention, indicating that in order to close the vocabulary gap, L2 language acquisition contexts need to be enriched with a higher frequency and quality of L2 input (Hoff, 2018; Penno et al., 2002). Also, the results of Larson et al. (2020) point to the importance of combining implicit approaches with explicit language support strategies for enhancing L2 vocabulary acquisition. Beyond language programs pursued in institutional settings, Hoff (2018) points to the complex interplay of language development in bilingual children on the basis of quantity and quality of language input and language output. Methodological Considerations In this study, experimental control was realized by using a strategy of random assignment of participants after their parallelization on the central variables of L2 target vocabulary, age, and gender. However, some initial group differences in cognitive ability and family SES remained which may have contributed to a disadvantage of the group of L1 - L2 which we attempted to address by the inclusion of control variables in the experimental group comparisons. Vocabulary Acquisition of Bilingual Preschoolers 79 In addition, an implementation check and standardized implementation conditions with protocols, the use of individual head phones for the presentation of the auditory stories, and an intensive pilot study were used to achieve a high degree of comparability. Since the sample size did not allow for the computation of hierarchical models, we were not able to perform respective analyses considering institutional variation; however, on average, the children’s vocabulary gains did not differ significantly between institutions. The pursued high degree of internal validity in this study may bring with it costs with regard to external validity. Thus, although the training sessions were conducted in a childappropriate manner, the setting of storybook listening via headphones was most likely unfamiliar to the participating children. In addition, children’s L1 was not commonly used by early education personal in the setting of preschool. Although the children in the experimental group with audio books in the L1 enjoyed this implementation, the lack of a habitual use of L1 in an institutional context may have hindered positive effects of L1 activation. Finally, as we were interested in the incidental processes of vocabulary acquisition in implicit training approaches, there was no further interaction supporting the children’s comprehension with scaffolded discourse or contextual supports during the listening activity besides a visualization of the story plot with one or two pictures. Regarding the sample it needs to be mentioned that not all of the analyses reached statistical significance, likely due to restricted power. The inclusion of SES in all analyses proved difficult due to the low response rate to the parent questionnaire in our sample. Another limitation is that not all characteristics that could potentially explain language competence and possible intercorrelations were taken into account. Thus, quantity and quality of language input in the home environment were not assessed in our questionnaires (see Hoff, 2018, for the interplay of language variables with SES). In addition, training effects may have been more pronounced had the intervention been implemented for a prolonged time period and with higher intensity (see Biemiller, 2003; Hagenauer, 2010). Further, it may be argued that with a sample of highly proficient bilinguals the effects of the trainings, and especially the effects of L1 story contexts, may have been different (see Cummins, 1991). Similarly, we cannot rule out that effects may have been different with an L1 and L2 of greater linguistic proximity than in Turkish-German bilinguals of our study. Implications for Early Bilingual Education Our results suggest that in incidental vocabulary acquisition may be slightly enhanced based on contextual cues in L2 auditory input. As our target vocabulary was more difficult than words of everyday contexts and it tapped into academic language, children of low language proficiency typically are not familiar with these items (cf. Jurecka et al., 2019; van Kleeck, 2014). Thus, also the role of L1 may be a different one if a) more active support of children’s comprehension processes and use of contextual cues is offered and b) different target vocabulary that is closer to everyday contexts was chosen. These two aspects may also interact with each other: Active support of children’s comprehension processes by scaffolded interaction may make explicit children’s use of prior knowledge in L1 and L2. That is, if the active use of the L1 in text comprehension and the strategies to benefit from L1 in general are made explicit, this may also lead to more efficient usage of previously acquired vocabulary. This way, partially shared representations between L1 and L2 may be activated in contexts of storybook reading. Therefore, our results imply that practices of simply exposing children to their L1 in contexts of listening activities do not lead to beneficial effects in L2 vocabulary acquisition. This is in line with findings by Larson et al. 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Developmental Science, (21), e12636. https: / / doi. org/ 10.1111/ desc.12636 Dr. Melihan Cinar AWO Perspektiven gGmbH Jugendmigrationsdienst - Respekt Coaches Mainzer Landstr. 158 60327 Frankfurt Prof. Dr. Ilonca Hardy (corresponding author) Dr. Astrid Jurecka Goethe-Universität Frankfurt Institut für Pädagogik der Elementar- und Primarstufe Fachbereich Erziehungswissenschaften Theodor-W.-Adorno-Platz 6 60323 Frankfurt am Main Telefon +49 (0) 69 7 98 3 62 77 E-Mail: hardy@em.uni-frankfurt.de jurecka@em.uni-frankfurt.de Prof. Dr. Nele McElvany Institut für Schulentwicklungsforschung (IFS) TU Dortmund Vogelpothsweg 78 44227 Dortmund E-Mail: nele.mcelvany@tu-dortmund.de