The cognate facilitation effect, a classic example of cross-language interaction in the bilingual lexicon, has mostly been studied in adults. We examined the extent to which such effects occurred in simultaneous bilingual children’s word processing, to what extent these were modulated by language dominance, and to what extent this differed between comprehension and production tasks. Simultaneous bilingual Dutch-Greek children, ranging from Dutch-dominant to Greek-dominant, performed auditory lexical decision and picture-naming tasks in an online experiment. Cognate facilitation effects emerged in both tasks but manifested themselves differently. In lexical decision, there was an interaction effect with language dominance in accuracy, while in picture naming there was a main effect in reaction times. These findings suggest that, similar to what has been found for adults, simultaneous bilingual children have an integrated lexicon, in which both languages are interactively connected. Effects may differ as a combined result of factors such as comprehension versus production and individual differences in language dominance. Importantly, despite such differences, our results show that cognate effects emerge across tasks and across a range of individual children’s language dominance, indicating that shared representations within the bilingual lexicon are accessed during both word comprehension and production.

For bilinguals, lexical access in one language may affect, or be affected by, activation of words in another language. Research to date suggests seemingly contradictory effects of such cross-linguistic influence (CLI): in some cases CLI facilitates lexical access while in others it is a hindrance. Here we provide a comprehensive review of CLI effects drawn from multiple disciplines and paradigms. We describe the contexts within which CLI gives rise to facilitation and interference and suggest that these two general effects arise from separate mechanisms that are not mutually exclusive. Moreover, we argue that facilitation is ubiquitous, occurring in virtually all instances of CLI, while interference is not always present and depends on levels of cross-language lexical competition. We discuss three critical factors – language context, direction, and modality of CLI – which appear to modulate facilitation and interference. Overall, we hope to provide a general framework for investigating CLI in future research.

This study investigated the morphosyntax of adjectival concord in case and number and subject-verb person agreement by monolingual and bilingual speakers of Russian. The main focus of the study is on the potential factors that may trigger divergence between Heritage Language (HL) speakers and those speakers who are dominant in that language, be they monolingual or bilingual. We considered the effects of cross-linguistic influence; limited input (as indexed by Age of Onset of Bilingualism, AOB), and working-memory limitations. An auditory offline grammaticality judgment task was performed by 119 adult participants split into four groups: (1) Monolingual Russian-speaking controls (MonoControl), (2) Immigrant Controls, that is, Russian-Hebrew bilinguals with AOB after the age of 13 (IMMControl); (3) bilinguals with AOB between 5–13 (BL-Late); and (4) bilinguals with AOB before the age of 5 (BL-Early). The latter group represents HL speakers. We did not find effects of cross-linguistic influence or extra memory load; at the same time, the effects of AOB were robust. Additionally, HL speakers (BL-Early group) differed from the other groups in poor performance on adjectival concord, but patterned with the others on person agreement, which indicates that the feature [person] is more robust than other agreement/concord features in HL grammars.

In a recent study, Fernandez et al. (2021) investigated parafoveal processing in L1 English and L1 German–L2 English readers using the gaze contingent boundary paradigm (Rayner, 1975). Unexpectedly, L2 readers derived an interference from a non-cognate translation parafoveal mask (arrow vs. pfeil), but derived a benefit from a German orthographic parafoveal mask (arrow vs. pfexk) when reading in English. The authors argued that bilingual readers incurred a switching cost from the complete German word, and derived a benefit by keeping both lexicons active from the partial German word. In this registered report, we further test this finding with L1 German–L2 English participants using improved items, but with the sentences presented in German. We were able to replicate the non-cognate translation interference but not the orthographic facilitation. Follow up comparisons showed that all parafoveal masks evoked similar inhibition, suggesting that bilingual readers do not process non-cognate semantic or orthographic information parafoveally.

This study compared patterns of nonselective cross-language activation in L1 and L2 visual word recognition with different-script bilinguals. The aim was to determine (1) whether lexical processing is nonselective in the L1 (as in L2), and (2) if the same cross-linguistic factors affected processing similarly in each language. To examine the time course of activation, eye movements were tracked during lexical decision. Thirty-two Japanese–English bilinguals responded to 250 target words in Japanese and in English. The same participants and items (i.e., cognate translation equivalents) were used to directly compare L1 and L2 processing. Response latencies as well as eye movements representing early and late processing were analyzed using mixed-effects regression modeling. Similar cross-linguistic effects, namely cognate word frequency, phonological similarity, and semantic similarity, were found in both languages. These factors affected processing to different degrees in each language, however. While cognate frequency was significant as early as the first fixation, effects of cross-linguistic phonological and semantic similarity arose later in time. Increased phonological similarity slowed responses in L2 but speeded them in L1, while greater semantic overlap was facilitatory in both languages. Results are discussed from the perspective of the BIA+ model of visual word recognition.

The present study investigates current proposals that priming is a mechanism of cross-linguistic influence (CLI) in bilinguals by aiming to boost CLI through priming. In two cross-linguistic structural priming experiments with less-proficient adolescent (Study 1) and more highly proficient adult German-English learners (Study 2), we assess whether structural priming enhances CLI for well-formed, dispreferred, and ungrammatical structures. L2 learners in both studies showed CLI in their production, in particular for structures with word order overlap. They also exhibited short-term cross-linguistic priming of grammatical L1-L2 word orders in L2 English, which extended to longer-term priming among the more highly proficient learners in Study 2. However, there was no evidence that cross-linguistic priming increased the use of dispreferred or ungrammatical L1-based word orders in L2 English in either study. Rather, the overall production of these word orders decreased. Together, these results suggest that, while cross-linguistic priming leads learners to increase the use of shared, grammatical L1-L2 word orders, it leads to the inhibition of non-shared ungrammatical structures in L2 production. We conclude that priming has asymmetrical effects on CLI of grammatical and ungrammatical L1-based structures in the L2.

Bringing together lines of research from sentence processing and lexical access, this empirical study investigates the interplay between lexical (grammatical gender) and syntactic (word order) cross-linguistic overlap in L2 German. Eighty-six L1 Spanish-L2 German and thirty-six monolingual German adults completed a German self-paced reading task with noun phrases (NPs) manipulated by L1-L2 gender congruency (congruent, incongruent, neuter) and L1-L2 adjective-noun word order (pre- vs. postnominal adjectives). The study examines the effects of gender congruency, the type of L1-L2 gender mapping (i.e., presence vs. absence of each class in L1 and L2), and L2 proficiency level. Results show that the detection of ungrammatical word order in L2 German interacts with gender congruency, in that L2 speakers are only sensitive to word order violations for sentences with gender-congruent nouns. The detection of ungrammaticality for sentences containing gender-incongruent nouns only emerges at higher L2 proficiency levels. These findings underscore the role of cross-linguistic lexical overlap in syntactic processing.

We investigated cross-modal influences between speech and sign in hearing bimodal bilinguals, proficient in a spoken and a sign language, and its consequences on visual attention during message preparation using eye-tracking. We focused on spatial expressions in which sign languages, unlike spoken languages, have a modality-driven preference to mention grounds (big objects) prior to figures (smaller objects). We compared hearing bimodal bilinguals’ spatial expressions and visual attention in Dutch and Dutch Sign Language (N = 18) to those of their hearing non-signing (N = 20) and deaf signing peers (N = 18). In speech, hearing bimodal bilinguals expressed more ground-first descriptions and fixated grounds more than hearing non-signers, showing influence from sign. In sign, they used as many ground-first descriptions as deaf signers and fixated grounds equally often, demonstrating no influence from speech. Cross-linguistic influence of word order preference and visual attention in hearing bimodal bilinguals appears to be one-directional modulated by modality-driven differences.

To assess the presence of cross-linguistic influence, this study compared the processing of Dutch sentences by English–Dutch and German–Dutch bilingual and Dutch monolingual children in a self-paced listening task. We combined insights from studies on child bilingualism and adult second language acquisition. Sentence structures showing partial overlap between languages were investigated (long passives), as well as structures with complete or no overlap (verb second and verb third sentences). We found evidence for syntactic co-activation of overlapping structures in the form of inhibition during listening. Syntactic, and possibly lexical, overlap between languages, and language dominance modulated effects. In particular, online cross-linguistic influence was visible only in the German–Dutch group. Furthermore, effects were most pronounced when structures partially overlapped and were absent in non-overlapping structures. Effects of online cross-linguistic influence became stronger the more German-dominant children were. Our results indicate that syntactic co-activation across languages affects sentence processing in bilingual children.

Although cross-linguistic influence at the level of morphosyntax is one of the most intensively studied topics in child bilingualism, the circumstances under which it occurs remain unclear. In this meta-analysis, we measured the effect size of cross-linguistic influence and systematically assessed its predictors in 750 simultaneous and early sequential bilingual children in 17 unique language combinations across 26 experimental studies. We found a significant small to moderate average effect size of cross-linguistic influence, indicating that cross-linguistic influence is part and parcel of bilingual development. Language dominance, operationalized as societal language, was a significant predictor of cross-linguistic influence, whereas surface overlap, language domain and age were not. Perhaps an even more important finding was that definitions and operationalisations of cross-linguistic influence and its predictors varied considerably between studies. This could explain the absence of a comprehensive theory in the field. To solve this issue, we argue for a more uniform method of studying cross-linguistic influence.

The current study investigates cross-linguistic influence of second language (L2) learning on native language (L1) processing of morphosyntactic variation in proficient L2 learners immersed in their L1. Despite Spanish pre- and postverbal clitic pronoun positions being grammatical in complex verb phrases, preferences of use have been well attested in naturalistic language production. To examine whether those preferences obtain for comprehension in monolinguals, as well as how those preferences might be modulated by learning an L2 with fixed pronoun positions, we administered a self-paced reading experiment to 20 Spanish monolinguals as well as 22 proficient learners English (L1 Spanish). The results of a Bayesian mixed effects regression analysis suggest that preferences in production are echoed in comprehension—but only for the monolingual group. We find support for facilitation in the bilingual group precisely where both languages overlap, as well as evidence that bilinguals may not use clitic position as a reliable cue at all. We interpret the results as evidence that learning an L2 that lacks variation for a particular feature may lead to reduced sensitivity to that feature as a cue in an analogous L1 structure. We situate these results in an experience-based, shared-syntax account of language processing.