Socio-cognitive research on bilinguals points to a moral foreign-language effect (MFLE), with more utilitarian choices (e.g., sacrificing someone to save more people) for moral dilemmas presented in the second language (L2) relative to the first language. Yet, inconsistent results highlight the influence of subject-level variables, including a critical underexplored factor: L2 proficiency (L2p). Here we provide a systematic review of 57 bilingualism studies on moral dilemmas, showing that L2p rarely modulates responses to impersonal dilemmas, but it does impact personal dilemmas (with MFLEs proving consistent at intermediate L2p levels but unsystematic at high L2p levels). We propose an empirico-theoretical framework to conceptualize such patterns, highlighting the impact of L2p on four affective mediating factors: mental imagery, inhibitory control, prosocial behavior and numerical processing. Finally, we outline core challenges for the field. These insights open new avenues at the crossing of bilingualism and social cognition research.

Bilinguals may choose to speak a language either at their own will or in response to an external demand, but the underlying neural mechanisms in the two contexts is poorly understood. In the present study, Chinese–English bilinguals named pairs of pictures in three conditions: during forced-switch, the naming language altered between pictures 1 and 2. During non-switch, the naming language used was the same. During free-naming, either the same or different languages were used at participants' own will. While behavioural switching costs were observed during free-naming and forced-switching, neuroimaging results showed that forced language selection (i.e., forced-switch and non-switch) is associated with left-lateralized frontal activations, which have been implicated in inhibitory control. Free language selection (i.e., free-naming), however, was associated with fronto-parietal activations, which have been implicated in self-initiated behaviours. These findings offer new insights into the neural differentiation of language control in forced and free language selection contexts.

The Adaptive Control Hypothesis and the Control Process Model propose that bilingual language use in different interactional contexts requires control processes that can adapt in different ways to linguistic demands. This study explored the effects of language experience on cognitive flexibility and inhibition among 41 Chinese–English bilingual adults. In particular, it aimed to investigate the relationship between spontaneous language production (i.e., bilingual conversation and narration tasks) and cognitive control. Participants’ inhibitory control and cognitive flexibility efficiency was measured through verbal and spatial Stroop tasks, and a colour-shape switching task. Overall, it showed that frequent practices of intersentential switching in speech production resulted in significant facilitatory effects in both verbal and nonverbal inhibitory control. This study provides new evidence for the importance of bilingual language experience in adaptive cognitive control in naturalistic speech production and furthers our theoretical knowledge of the relationship between the language system and crucial domain-general cognitive processes.

To examine the combined effects of ageing and bilingualism in language processing, we tested young and older mono- and bilingual speakers in L1 comprehension and production. In Experiment 1, bilinguals were slower to detect words than monolinguals in sentences with a low-constraint context, but not when a high-constraint context was provided. Older adults tended to outperform younger adults in high-constraint sentences. In Experiment 2, older speakers were slower than younger speakers to produce small-scope prepositional phrases (e.g., ‘the cone above the grape), suggesting more extensive planning. Bilingual disadvantages were observed in larger-scope complex phrases (e.g., ‘the cone and the pink grape’). Individual differences in language proficiency did not modulate the effects. The results support bilingual disadvantages in syntactic processing and age-preserved syntax, alongside semantic processing unaffected by either bilingualism or age. We found no interactions between age and bilingualism, suggesting that these two factors independently impact language processing.

Using a priming paradigm, we investigated the processing of overtly identical verb forms with different sets of morphosyntactic features in L1 and L2 German. We found that more specific functions of a verb (inflected verbs) were better primes for less specific verb functions (past participles) than vice versa. For L1 speakers, these priming asymmetries were observed regardless of whether the lexical verb was repeated in prime and target or not (i.e., priming also for abstract configurations). For L2 learners, a similar but not native-like asymmetric priming pattern was seen only with repetition of the lexical verb. It was absent when the verb was not repeated. We conclude that in L2, morphosyntactic information is processed more on a lexical, item-based level compared to L1. We discuss our results in the context of several accounts, e.g., Shallow Structure Hypothesis, Declarative Procedural Model and the Ontogenesis Model of the L2 Lexical Representation.

This study investigated how second language (L2) learners process the Korean numeral quantifier construction by using transferable and nontransferable information. For Chinese-speaking learners of Korean (Chinese group), agreement between an honorific numeral quantifier and a noun in Korean constitutes transferable information in the canonical structure and nontransferable L2-specific information in the scrambled structure. For Japanese-speaking learners of Korean (Japanese group), this information gives rise to crosslinguistic conflicts in both structures. The results from a self-paced reading task showed that the Japanese group did not exhibit sensitivity to grammatical errors in both structures, whereas the Chinese group detected the agreement violation in the canonical but not in the scrambled structure. When a context sentence was provided to license scrambling in the test sentence, however, another group of Chinese-speaking learners of Korean showed sensitivity to the violation. These findings suggest varying degrees of crosslinguistic influence in L2 sentence processing.

A key question in the study of language representation in bilinguals is whether knowledge is shared across languages. Crosslinguistic syntactic priming has been widely used to test bilingual adults’ shared representations, but studies with child bilinguals are few and have several limitations.

We addressed these limitations in two studies with Polish–English bilingual children aged 5–11 years (N=96). We investigated bidirectional priming across languages and within each language for a structural alternation with syntactic overlap (attributive constructions) and one without structural overlap (possessive constructions).

Bidirectional crosslinguistic priming was found for possessives but not for attributives. Within-languages, there was priming for possessives and attributives in both languages. Priming was not related to children's age, vocabulary, or language dominance scores.

We show that representations can be selectively shared between languages at the construction level. The extent to which young bilinguals have shared representations depends on the frequency and complexity of structures in each language.

Adults often encounter difficulty perceiving and processing sounds of a second language (L2). In order to acquire word-meaning mappings, learners need to determine what the language-relevant phonological contrasts are in the language. In this study, we examined the influence of phonology on non-native word learning, determining whether the language-relevant phonological contrasts could be acquired by abstracting over multiple experiences, and whether awareness of these contrasts could be related to learning. We trained English- and Mandarin-native speakers with pseudowords via a cross-situational statistical learning task (CSL). Learners were able to acquire the phonological contrasts across multiple situations, but similar-sounding words (i.e., minimal pairs) were harder to acquire, and words that contrast in a non-native suprasegmental feature (i.e., Mandarin lexical tone) were even harder for English-speakers, even with extended exposure. Furthermore, awareness of the non-native phonology was not found to relate to learning.

Demonstratives are cross-linguistically widespread deictic expressions. Demonstrative systems exhibit variation in number of terms, and parameters affecting their usage. The present paper assesses the relationship between spatial deixis and bilingualism: how language dominance affects speakers of two languages with different demonstrative systems. Here, we compare the use of demonstratives by 72 European Spanish-Catalan simultaneous bilinguals in Mallorca to 30 European Spanish monolinguals. Our results confirmed a significant effect of physical distance between speaker and referent on demonstrative choice in both languages, and differences between languages in the use of the middle term. We did not find the expected effect of language dominance in simultaneous bilinguals. Moreover, we found no influence of the hearer's position on demonstrative choice in monolinguals or bilinguals in European Spanish or Majorcan Catalan. In view of our results, the present study contributes to the debate on how bilingual speakers employ different deictic expressions.

Evidence from various empirical study types have converged to show bilingualism's potential for serving as a cognitive and brain reserves contributor. In this article, I contextualize, frame the need for and offer some expanding questions in this endeavor, inclusive of empirical pathways to address them. While the set of variables and questions discussed herein are definitively incomplete, they embody a good starting point for shaping future directions in research that considers the role bilingual language engagement can have for the developing mind and brain, inclusive of how various, non-linear factors impact the descent bilinguals of various types take down the proverbial mountain of life.

Bilinguals experience diminished emotion when using their foreign compared with their native language. The diminished emotion has been shown to lead to more lenient moral evaluations in a foreign language. Here we show that non-native speakers of English are less sensitive to emotional mitigating circumstances of a crime than native speakers, presumably because of the diminished experience emotion. This can lead non-native speakers to provide harsher, rather than more lenient, evaluations. Native and non-native speakers of English recommended sentence duration for crimes committed because of mitigating emotional circumstances (e.g., fraud to pay spouse's medical treatment) or for selfish reasons (e.g., buying luxury goods). Native English speakers differentiated more between the two types of scenarios than non-native speakers did. The study thus provides preliminary evidence that processing information in a foreign language can influence decisions, and that the directionality of the effect depends on the role of emotion in the context.

We investigated three aspects of paired associate learning of vocabulary in an unfamiliar language: monolingual-bilingual differences, effects of dominance and language proficiency, and the possible role of associative strategies. Spanish–English bilinguals (48 English-dominant and 48 Spanish-dominant) and English-speaking monolinguals (n = 48) learned Swahili–English and Swahili-Spanish word pairs. Learning was assessed using cued recall (Swahili cue or Swahili response) and associative recognition tests. English-dominant bilinguals did not outperform English monolinguals on any learning measure. Cued recall accuracy was higher when learning through the dominant language than through the non-dominant language, whether the Swahili words were cues or responses. Proficiency scores in the known language were positively correlated with cued recall accuracy, whether the cue or the response was in Swahili, indicating that proficiency effects occurred not in retrievability of known words but in learning of associations. Bilingual and monolingual participants did not differ in their reported use of associative strategies.

Foreign language can either enhance decision-making by triggering more deliberation or worsen it due to cognitive overload. We tested these two hypotheses in one response bias: acquiescence. In three experiments, 413 participants made dichotomous decisions about whether 100 personality traits described them or not. Participants showed more acquiescence in a foreign language (vs. native), giving more certifying responses when deciding on known traits. Reaction time results suggest that a foreign language particularly impacts rejection more than certification of their comprehension. These findings support the cognitive overload hypothesis and provide valuable insights for the influence of language on response bias.

Prosody refers to stress and intonation patterns in a language. Previous studies have found that prosodic sensitivity (PS) and executive functions can affect reading comprehension in first (L1) and second languages (L2). The current study examined these factors among a group of L1 Mandarin speakers learning L2 English who participated in a series of tasks measuring phonological awareness, Mandarin tone sensitivity, English PS, along with three specific executive functions – namely, cognitive flexibility, inhibitory control, and working memory. The results demonstrated that Mandarin tone sensitivity and cognitive flexibility mediated English PS and reading. A simple slope analysis showed that PS positively predicted word reading for readers with higher but not lower cognitive flexibility. These results imply that PS in L2 reading is affected by both prosodic transfer of L1 tone sensitivity and cognitive flexibility.

Studies suggest that bilingualism may be associated with better cognition, but the role of active bilingualism, the daily use of two languages, on cognitive trajectories remains unclear. One hypothesis is that frequent language switching may protect cognitive trajectories against effects of brain atrophy. Here, we examined interaction effects between language and brain variables on cognition among Hispanic participants at baseline (N = 153) and longitudinally (N = 84). Linguistic measures included self-reported active Spanish–English bilingualism or Spanish monolingualism. Brain measures included, at baseline, regions of gray matter (GM) thickness strongly correlated with cross-sectional episodic memory and executive function and longitudinally, tissue atrophy rates correlated with episodic memory and executive function change. Active Spanish–English bilinguals showed reduced association strength between cognition and gray matter thickness cross-sectionally, β=0.303, p < .01 but not longitudinally, β=0.024, p = 0.105. Thus, active bilingualism may support episodic memory and executive function despite GM atrophy cross-sectionally, but not longitudinally.

Prior research suggests that bilinguals show reduced sensitivity to negative content when operating in the second language (L2). The available evidence, however, is limited to language comprehension. We tested the production of emotional words in Polish (L1)–English (L2) bilinguals in two EEG studies that manipulated emotional cueing. In Experiment 1 (neutral context), white or black circles indicated whether participants should read aloud (shadow) or translate a subsequently presented word. N400 amplitudes were selectively reduced for negative L2 words regardless of the task. In Experiment 2 (emotional context), we used black or white emojis, either sad or neutral, as cues. The previous interaction between word valence and language of operation vanished, but late positive potential amplitudes elicited by negative words were larger for translation from L2 to L1 (i.e., production in Polish) than L1 to L2. These results validate and extend to production previous findings of attenuated emotional response in L2 comprehension.

Both ageing and bilingualism can have positive as well as adverse cognitive effects. We investigated their combined impact on subcomponents of attention. We used the Attention Network Task to examine alerting, orienting, executive control and task-switching costs. Group comparisons revealed age-related declines for alerting alongside benefits for executive control, for mono- and bilinguals alike. For orienting, age-related decline was more pronounced for bilinguals than monolinguals. Task-switching was unaffected by age or language group. Within bilinguals, we found limited impact of individual differences in L2 proficiency, language switching or mixing: proficiency improves orienting and decreases switch costs, for young and older bilinguals alike; but no other individual differences effects were found. Thus, attention is a multi-faceted network, with clear adverse (alerting) and protective (executive control) ageing effects. We found these to be largely similar for mono- and bilinguals, with variability within bilinguals having only limited impact.

L1 lexical attrition is the decline of L1 lexical-semantic abilities due to reduced L1 exposure and/or L2 interference. Semantic fluency tasks are central in this research, but traditional analyses are often inconclusive.

To address this, we employed an innovative network science approach to investigate the bilingual lexicon's structural properties. Semantic fluency data were collected from immersed/non-immersed late bilinguals with comparable L2 proficiencies.

Our results indicate that L2 immersion led to more integrated and efficient L2 networks. Crucially, immersion also resulted in L1 attrition (only evident in the network analysis). Immersed participants exhibited less densely connected and sparser L1 networks. Furthermore, network measures suggest that L1 lexical attrition occurs gradually, initially impacting network interconnectivity, while information flow and community structure remain more stable.

Drawing from these insights, we introduce the Lexical Attrition Foundation (LeAF) framework, offering a network-based perspective on lexical attrition development and laying the groundwork for future research.

Rhetorical questions (RhQs) are a complex phenomenon at the interface of pragmatics, prosody and syntax, which requires reasoning on intentions and goals, and which involves a mismatch between literal and intended meaning. In Italian, RhQs can be marked by optional particles and verbal morphology. We investigated when children aged 6-9 acquire the relevant patterns of optional modification and exploit them in the appropriate pragmatic context. In an elicited production study with 84 monolingual and 88 Italian–German bilingual children, we found that development in monolinguals was determined by age with a progression between 6 and 9 years, while bilingual development was influenced by proficiency in the heritage language and dominance more generally. These results are in line with Tsimpli's (2014) proposal that “very-late-acquired phenomena”, especially interface domains, depend on their timing in acquisition. Unlike for other pragmatic phenomena, such as irony and conversational competence, there was no evidence for a bilingual advantage.