Bilingualism: Language and 73% of the observed bilingual Cognition (dis)advantageous effects on cognition stem cambridge.org/bil from sociolinguistic factors: A systematic review Camilla Masullo1 , Vittoria Dentella1 and Evelina Leivada2,3 Review Article 1 Department of English and German Studies, Universitat Rovira i Virgili, Tarragona, Spain; 2Department of Catalan Philology, Universitat Autònoma de Barcelona, Barcelona, Spain and 3Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain Cite this article: Masullo, C., Dentella, V., & Leivada, E. (2023). 73% of the observed Abstract bilingual (dis)advantageous effects on cognition stem from sociolinguistic factors: A Being bilingual confers certain behavioral effects. Determining their precise origin is of utmost systematic review. Bilingualism: Language and importance given the need to avoid unjust misattribution of labels such as “bilingual (dis) Cognition, 1–15. https://doi.org/10.1017/ advantage” to people’s bilingual experiences. To this end, this systematic PRISMA-based S1366728923000664 review aims to shed light on the social and sociolinguistic origins of bilingualism-related behavioral effects. Analyzing 368 studies, we find that 73.41% of the 267 studies that report Received: 14 March 2023 Revised: 23 August 2023 such effects attribute them either to sociolinguistic factors alone or to the interaction of socio- Accepted: 24 August 2023 linguistic and cognitive factors. Linking the two fronts, type of effect and origin of effect, we find a previously unreported correlation: Studies that find evidence for bilingual disadvantages Keywords: are more likely to claim a sociolinguistic origin, while studies that report advantages are more bilingualism; cognitive adaptations; sociolinguistic prestige; socio-economic status likely to link their findings to a cognitive origin. We discuss these results and present the key components of a sociolinguistic theory of the origin of bilingual effects. Corresponding author: Camilla Masullo; Email: camilla.masullo@urv.cat 1. Introduction Developing a theory that accounts for the effects of bilingualism on cognition is an endeavor fraught with methodological, interpretative, and expository difficulties, to the extent that it has been described as a challenge of the deepest scientific nature (Mueller Gathercole, 2015). 100 years since the first studies that described bilingualism as causing mental confusion (Saer, 1923), and 50 years since the first studies that reported bilingual advantages (Feldman & Shen, 1971; see Barac & Bialystok, 2011 for a detailed timeline), the topic of bilingual effects on cognition is still riddled with open questions (Blanco-Elorrieta & Caramazza, 2021). Although many studies have provided ample evidence for bilingual effects on cognition (often presented as bilingual advantages and disadvantages), the field still lacks a solid theory that enjoys consensus and covers critical topics such as what the observed effects boil down to and what the driving factors behind them are (Treccani & Mulatti, 2015). In broad terms, it can be claimed that two ongoing discussions surround bilingual adapta- tions on cognition. The first one concerns the type of the effects and recognizes three categor- ies of results: bilingual advantages (i.e., positive findings), bilingual disadvantages (i.e., negative findings), and null effects (i.e., findings that suggest that the differences between monolinguals and bilinguals are indistinguishable from zero). Regarding the terminology we use, while we a priori reject the use of evaluative terms such as “bilingual advantage” and “bilingual disadvan- tage” as simplistic (Leivada et al., 2022), the primary purpose of any systematic review is to take stock. We thus employ these mainstream terms, following a long line of systematic reviews, meta-analyses, and quantitative analyses that adhere to the same practice (Donnelly et al., 2019; Grundy, 2020; Lehtonen et al., 2018; van den Noort et al., 2019; Ware et al., 2020). Specifically, the present work explores the origin of bilingual (dis)advantages across cognitive domains, to present a fine-grained picture of the origin of the conferred bilingual adaptations. In this respect, another terminological specification should be made about the term “bilingual adaptations”, which we use synonymously with the term “bilingual effects”. © The Author(s), 2023. Published by We follow recent literature (e.g., D’Souza & D’Souza, 2021; Ivanova et al., 2023) that borrowed Cambridge University Press. This is an Open the term “adaptation” from research on human evolution to highlight that the act of adapting Access article, distributed under the terms of to the surrounding linguistic environment is on par with other ecological adaptations (Leivada the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/), et al., 2022). Thus, we use the term “bilingual adaptations” to indicate the offset between which permits unrestricted re-use, distribution advantageous and disadvantageous effects that the bilingual experience has across different and reproduction, provided the original article cognitive domains, such as executive functions (Bialystok, 2007; Costa et al., 2008 inter is properly cited. alia), semantic fluency (Gollan et al., 2002; Ivanova & Costa, 2008), syntactic processing (Siu & Ho, 2022), and metalinguistic awareness (Adesope et al., 2010). This article has earned badges for transparent research practices: Open Data and Open Materials. For details see the Data Availability Statement. https://doi.org/10.1017/S1366728923000664 Published online by Cambridge University Press 2 Camilla Masullo et al. Although certain disagreements still exist in relation to the but their bilingual groups are formed based on a positive answer type of effects (e.g., related to what counts as an advantage vs. a to one question: does the participant speak another language disadvantage; see Leivada et al., 2022 for an overview), several other than English? (e.g., Brito & Noble, 2017). Grouping together explanations have been offered for these different sets of results different types of bilinguals, who acquired and, in all likelihood, (van den Noort et al., 2019; Leivada et al., 2021a; Paap et al., use their languages in different contexts and registers, inevitably 2021). For instance, van den Noort et al. (2019) ascribe the het- invests the bilingual group with some degree of sociolinguistic erogeneity of results to differences in studies’ methods. They variation, the impact of which is unclear. point out that cognitive reserve can be shaped by several factors Measuring variables such as degree of language use and profi- (e.g., level of education, linguistic input, lifestyle, profession, ciency is useful –however, it may bring along certain challenges and language typology), which are operationalized differently that contribute to the debate. Degree of use is typically measured among studies – hence, the varied set of results. Similarly, by asking participants whether and to what degree they use two Leivada et al. (2021a) also acknowledge the impact of multiple languages, or a language other than the one used in the commu- factors, such as language proximity, the heterogeneity of the nity, when conversing with friends and family (e.g., Dick et al., term “bilingual”, sample size effects, and task effects. 2019). One challenge that comes from grouping together, in The second discussion, which concerns the origin of the one big bilingual group, people who use another language with observed effects, is trickier to classify in terms of main categories friends and family is that heritage language learners, who fit of results. Succinctly put, this discussion deals with the following this inclusion criterion, receive variable qualitative and quantita- question: where do these advantages and disadvantages stem tive input, facing socio-political and sociolinguistic pressures from? One popular answer refers to cognitive factors such as from the majority language spoken in their community enhanced monitoring abilities, increased switching flexibility, (D’Alessandro et al., 2021; Montrul, 2015). and sharpened executive control, tracing the origin of the effects Consequently, while the degree of use may be controlled for in to cognitive adaptations to constant language monitoring and many studies, the variability that is inherent to the sociolinguistic inhibition in bilinguals (Bialystok & Martin, 2004; Bialystok values attached to the many different languages (often more than et al., 2004, 2012; Abutalebi & Green, 2007; see Blanco-Elorrieta 30), that are included in big and heterogeneous bilingual groups, & Caramazza, 2021 for a recent review). However, it has been is usually neither measured nor acknowledged (Leivada et al., argued that such cognitive enhancements may be substantially 2023). This is relevant to the origin of the bilingual effects debate mitigated when we account for individual differences between because using two languages does not entail viewing them in a monolinguals and bilinguals in terms of social, socio-economic, similar way or, more importantly, being able to reliably reflect and sociolinguistic factors (Dick et al., 2019). Thus, another on their use. Every bilingual person has a preferred language answer is that bilingualism and socio-economic status (SES) (Dodson, 1985), and both the emotional stance bilinguals adopt may both confer adaptive effects, but act independently, such towards their languages as well as the way these languages are that the observed bilingual advantages are not limited by social compartmentalized and used across contexts have strong implica- factors (Calvo & Bialystok, 2014; Engel de Abreu et al., 2012). tions (Duñabeitia, 2017). Regarding the emotional and affective A third answer is that both social and cognitive factors jointly aspects of language learning and use, some recent studies have contribute to enhanced self-regulatory behaviors that may lead operationalized bilingualism considering variables such as accul- to bilingual adaptations (Hartanto et al., 2019). turation, educational context, and parental encouragement to In sum, although many studies acknowledge that the observed learn the languages (Laketa et al., 2021; Studenica et al., 2022). bilingual advantages and disadvantages are amenable to a multi- In some cases, acculturation was found to play an important factorial account that recognizes the presence of both cognitive role in shaping the bilinguals’ language profile and appeared to and socio-demographic/sociolinguistic factors of influence (e.g., have independent effects from bilingualism on cognition Antón et al., 2019; Chen et al., 2013; Garraffa et al., 2015; (Laketa et al., 2021). Mueller Gathercole et al., 2010), in a large part of the literature In sum, it has been argued that many early studies in bilingual- either the interaction of the two sets of factors is not spelled ism research were flawed because they did not control for SES or out or one set of factors, cognitive or sociolinguistic, is not men- other sociocultural differences between the tested groups of tioned at all, depending on the focus of the work. Moreover, con- monolinguals and bilinguals (Mueller Gathercole et al., 2010 trolling for SES is undoubtedly a useful practice, but it does not and references therein). While the considerable progress made fully eliminate the potential confounding effects of social factors, since then is incontestable and very helpful in enabling us to if many uncontrolled and ambiguous variables come into play. To map variation in bilingual experiences (Fricke et al., 2019), we give an example, overall L2 proficiency has been linked to cogni- have not yet resolved all the ambiguities that surround the occur- tive control abilities (Luque & Morgan-Short, 2021), but profi- rence of bilingual effects. Finding bilingual advantages and disad- ciency across registers is tightly connected to language use in vantages is not enough, if we cannot explain what the effects boil different contexts, which may be a proxy for sociolinguistic pres- down to and what factors drive them. Possibly, this is the key rea- tige (Leivada et al., 2021a). From this perspective, proficiency and son that this domain of research has been linked to “insufficiently use are ambiguous factors that can be plausibly read in favor of clear theories and hypotheses that are difficult to falsify” (de both cognitive and sociolinguistic accounts of the origin of bilin- Bruin et al., 2021, p. 433), even after decades of testing. The gual effects. aim of this work is to address this issue through shedding light A second example of the complex nature of this debate can be on the origin of bilingual effects on cognition. More specifically, found in the many studies that test bilingual adaptations without, we seek to determine what percentage of the studies conducted however, considering certain sociolinguistically loaded notions in this field test and control for sociodemographic factors such as type of bilingual trajectory (i.e., simultaneous bilingual, (Research Question 1), what percentage of studies that find bilin- heritage language user, L1 attriter, unbalanced second/foreign gual adaptations attribute them to a cognitive, sociolinguistic, or language learner). For instance, some studies control for SES, mixed origin (Research Question 2), and what social, https://doi.org/10.1017/S1366728923000664 Published online by Cambridge University Press Bilingualism: Language and Cognition 3 sociodemographic, and sociolinguistic factors are typically for inclusion. In all cases, consensus was eventually reached involved in studies that find bilingual adaptations (Research among all authors. Question 3). The selection of relevant studies was conducted based on pre- In relation to these questions, one important challenge refers viously determined inclusion and exclusion criteria. First, studies to the scope of these domains, which remains vague in the litera- had to present original experimental results. Therefore, ture: what counts as a cognitive vs. a social/sociolinguistic deter- meta-analyses, review articles, and theoretical articles were minant of bilingual adaptations? While some proposals are excluded. Second, studies had to be written in English, to enable straightforward (e.g., attributing differences between monolin- all three researchers to clearly understand the content of the stud- guals and bilinguals to cognitive processes related to general ies and make the database easily accessible to as many readers as conflict-monitoring and goal-orienting abilities; Costa et al., possible. Third, studies had to be published after 1960. Fourth, 2009; Hernández et al., 2013), other factors are variably treated studies involving neuroatypical populations were excluded. Fifth, as pertaining to the sociolinguistic or the cognitive component. data from at least one monolingual and one bilingual group had For example, differences in cultural knowledge may be attributed to be reported, to avoid any bias of grouping together fundamen- to the cognitive component (Green et al., 2007) or not (Barac & tally different groups. Last, studies focusing solely on the brain Bialystok, 2012). For the purpose of this systematic review, we without any reference to behavioral measures were excluded. employ one specific criterion (following de Cat, 2020) in classify- The obtained database covers results from 368 studies, 474 experi- ing the origin of bilingual effects as either cognitive or sociolin- ments, and 109.604 participants. Figure 1 presents the screening guistic: if the results of a study suggest that any observed and selection process. differences between monolinguals and bilinguals are due to The pool of data and the complete list of studies that were ana- INDIVIDUAL-INTERNAL cognitive processes (e.g., sharpened monitor- lyzed for this review are available at: https://osf.io/2z4cx/? ing or switching abilities, different use of neural markers, view_only=95009316afe3479aa3249b419551a6b4. In the classifi- enhanced control of attentional resources, weakened retrieval cap- cation of the screened articles, the sociodemographic variables acity), this is classified as cognitive origin. If the differences are of age, gender, and SES, together with the language profile, are amenable to an explanation that relies on COGNITION-EXTERNAL fac- presented, when measured. With reference to SES, studies are tors (e.g., SES, age, education, social prestige, sociocultural knowl- divided into three groups: studies that did not mention it, studies edge, language use in different contexts, typological proximity, that merely acknowledged it in their introduction or discussion script), this is classified as sociolinguistic origin. sections, and studies that either measured it or controlled for it All in all, while these sociolinguistic factors are an inherent by group matching. Articles were subsequently screened by two part of the bilingual experience, we cannot afford to subsume researchers to determine both the reported bilingual effects (i.e., them under the generic label “bilingualism-related factors”. In bilingual advantage, bilingual disadvantage, both effects, or null the current context of replacing dichotomous labels such as “cog- effect) and the origin of the effects (i.e., cognitive origin, sociolin- nitive (dis)advantage” with a more nuanced approach (Leivada guistic origin, or mixed origin). The two researchers were com- et al., 2022), examining the role and magnitude of sociolinguistic pletely aligned in their judgements about the classification of factors of influence will shed light on the characteristics of differ- the bilingual effects reported by the articles (Cohen’s k = 1) and ent trajectories, helping us to avoid unjust misattribution of cer- presented a very high agreement in their judgements about the tain labels and behavioral outcomes to people’s bilingual origin of such effects (Cohen’s k = 0.972). When the origin of experiences (Luk, 2022). the bilingual effect could not be unambiguously established for some studies (n = 5), a third researcher was consulted for reaching agreement. 2. Method We performed a systematic review of the literature on bilingual 3. Results advantages and disadvantages. The review was conducted accord- ing to the PRISMA Statement (Liberati et al., 2009; Page et al., The findings of the analyzed studies are first classified according 2021), which is a reporting guideline designed to assist authors to the bilingual effects they report. Considering the entire pool of of systematic reviews and meta-analyses in describing the purpose data, comprising a total of 368 analyzed articles, 57.34% of them and the methodology of their work in a transparent way. Data report a bilingual advantage, 11.41% report a bilingual disadvan- were plotted and analyzed using R, version 4.2 (R Core Team, tage, 3.80% find both advantageous and disadvantageous effects 2021), and jamovi, version 1.8 (The jamovi project, 2021). and 27.45% find a null effect. These advantages and disadvantages A systematic search of the literature was conducted in the fol- pertain to different cognitive domains (e.g., executive functions, lowing databases: PsycInfo, PsycExtra, PsycBooks, APA Journals, memory, metalinguistic awareness, different types of fluency, syn- and PubMed. The searches were conducted in December 2021. tactic processing, phonological awareness, etc); unlike most previ- The search strategy consisted of the following keywords: “bilin- ous systematic reviews and meta-analyses on bilingual gual” & “advantage” OR “bilingual” & “disadvantage”. As these adaptations, we did not limit our pool of results to one cognitive are popular terms, a total of 1753 articles were obtained from domain (typically, executive functions). Figure 2 presents a sum- this search procedure, which marks the highest number of mary of the distribution of effects. screened studies in a systematic review/meta-analysis in bilingual- The findings of the analyzed studies are subsequently classified ism research. Duplicates were removed through Mendeley into the following three categories: Desktop software, and the remaining abstracts were screened for content. First, two researchers (C.M. & V.D.) independently (i) Effects attributed to social, sociolinguistic, or sociodemo- searched the databases, selected the relevant studies, and extracted graphic factors (category “sociolinguistic origin”) the data, following predefined criteria. In cases of disagreement, a (ii) Effects attributed to a combination of sociolinguistic and third researcher (E.L.) was asked to evaluate the study in question cognitive factors (category “mixed origin”) https://doi.org/10.1017/S1366728923000664 Published online by Cambridge University Press 4 Camilla Masullo et al. Figure 1. PRISMA Flow Chart. Figure 2. Frequencies of effects per category. https://doi.org/10.1017/S1366728923000664 Published online by Cambridge University Press Bilingualism: Language and Cognition 5 Figure 3. Number of studies that reported different origins of bilingual effects. (iii) Effects attributed exclusively to bilingualism and cognitive (χ2 = 14.3, p < .001). The significant difference boils down to the adaptations linked to it (category “cognitive origin”). fact that studies that find bilingual disadvantages are more likely to attribute them to sociolinguistic factors, while those that find Figure 3 presents a summary of the origin of effects. bilingual advantages are more likely to claim that these effects Encompassing a variety of tasks and populations, our results are linked to either a cognitive or a mixed cognitive and sociolin- suggest that 73.41% of the screened studies that find bilingual guistic origin. To provide the full picture, we reran the previous effects can be linked to either a sociolinguistic or a mixed origin. analysis including the previously omitted category “both effects” The overall distribution of these effects in terms of origin is shown (n = 14). Treating effect and origin as multinomial variables, in Figure 4. again we found a significant association between the two variables To find whether there is a significant correlation between the (χ2 = 16.4, p = .003). Table 1 presents the model results and type of effects and their origin, we performed two analyses. First, Table 2 presents the post-hoc comparisons with Bonferroni cor- we ran a χ2 test of association to determine the relationship rection for multiple comparisons. In the “both effects” category, between the two variables. In this analysis, we omitted the cat- results are equally distributed between the sociolinguistic and egory “both effects”, and we focused on the categories “bilingual the cognitive type of origin. advantage” and “bilingual disadvantage”. Results show a sig- Analyzing the role of specific sociodemographic factors in our nificant correlation between the type of effect and its origin pool of data, we find that age is controlled for in 98.91% of studies Figure 4. Frequencies of bilingual effects for type of effect (advantage, disadvantage, both) and origin (sociolinguistic, cognitive, mixed). https://doi.org/10.1017/S1366728923000664 Published online by Cambridge University Press 6 Camilla Masullo et al. Table 1. Model results for the association of the two variables, type of effect, and origin of effect. 95% Exp(B) Confidence Interval Response Contrasts Names Effect Estimate SE exp(B) Lower Upper z p Both - Advantage (Intercept) (Intercept) −2.726 0.281 0.0655 0.0941 0.224 −9.707 < .001 Origin 1 Cognitive - 0.251 0.727 1.2857 0.0593 0.531 0.346 0.729 Sociolinguistic Origin 2 Mixed - Sociolinguistic 0.595 0.666 1.8134 0.1661 0.848 0.893 0.372 Disadvantage - (Intercept) (Intercept) −1.93 0.221 0.1451 0.0378 0.114 −8.743 < .001 Advantage Origin 1 Cognitive - −1.73 0.559 0.1773 0.3094 5.343 −3.093 0.002 Sociolinguistic Origin 2 Mixed - Sociolinguistic −0.98 0.416 0.3752 0.4913 6.693 −2.358 0.018 (n = 364/368), followed by gender which is assessed in 70.92% of 2. Variables related to the sociolinguistic context where bilinguals studies (n = 261/368). With reference to SES, this variable is use their languages. These concern the sociocultural and socio- unmentioned in 35.60% of studies (n = 131/368), whereas linguistic properties of the environment: the societal status of a 11.41% of studies (n = 42/368) mention it in their introduction/ language, the culture and patterns of use associated with it, the discussion sections, without measuring or controlling for it. In learning context of a given language, the subsequent commu- the remaining 52.99% of studies (n = 195/368), SES is controlled nicative and learning demands posed on speakers/signers. for in the matching of the tested samples. With reference to the 3. Variables related to the sociodemographic profile of partici- sociolinguistic factors that come into play in the emergence of pants, that in turn can both affect their bilingual experience bilingual effects, the most frequently encountered variables are and act independently. These include age, gender, and aspects those related to the sociolinguistic status of the languages (e.g., of SES, including education, parental education, and societal status, context of acquisition, and learning trajectory) profession. and to the actual practice of using them in different contexts 4. Variables related to linguistic factors as a category refers to the (e.g., language exposure/use, amount of switching). Overall, the variability and diversification of the linguistic input as well as sociolinguistic factors that come into play can be classified in the typological properties, including script, of the languages at terms of the following four tightly connected categories, which play. only together can outline the complexity of the bilingual nature. 1. Variables related to how bilinguals experience and use their While the classification of variables in the aforementioned cat- languages. These variables amount to factors involved in egories serves organizational purposes, it does not entail the the emergence of bilingual effects, and include age of acqui- absence of grey areas between them. This means that these cat- sition, length of bilingual experience, proficiency measures, egories are not rigidly demarcated, but host variables that occur literacy competence, measures and domains of language on a continuum of influencing factors, as shown in Figure 5. In use, both in relation to the amount of use specific to a relation to the magnitude of contribution, Figure 6 shows the given language – thus including measures of language occurrence of each sociolinguistic factor individually in (i) the switching – and to specific contexts of use, and measures studies that find results that evoke a sociolinguistic/mixed origin of language exposure, including language immersion. and (ii) the overall pool of data (i.e., all studies that find evidence Table 2. Post-hoc comparisons. Effect Origin Difference SE z pbonferroni Advantage Cognitive-Mixed 0.0703 0.0568 1.236 0.788 Sociolinguistic-Cognitive −0.1768 0.0567 −3.119 0.062 Sociolinguistic-Mixed −0.1065 0.0602 −1.769 0.382 Disadvantage Cognitive-Mixed −0.0534 0.044 −1.213 0.812 Sociolinguistic-Cognitive 0.198 0.0491 4.032 0.021 Sociolinguistic-Mixed 0.1446 0.0534 2.707 0.106 Both Cognitive-Mixed −0.0168 0.0397 −0.424 1 Sociolinguistic-Cognitive −0.0213 0.0323 −0.657 1 Sociolinguistic-Mixed −0.0381 0.0335 −1.136 0.898 https://doi.org/10.1017/S1366728923000664 Published online by Cambridge University Press Bilingualism: Language and Cognition 7 Figure 5. Sociolinguistic factors that have been linked to bilingual adaptations. Color warmth indicates the degree of occurrence in the pool of data. for bilingual adaptations, regardless of origin). Table 3 presents Bruin et al., 2015). As Figure 7 shows, while bilingual advan- the overall occurrence of each factor in (i) the studies that find tages are the most frequent category (7a), if we follow the pre- results that evoke a sociolinguistic/mixed origin, (ii) the overall vious practice of grouping null and negative outcomes in one pool of data, and (iii) the context of the entire range of sociolin- category (following the classification system in de Bruin et al., guistics factors. With respect to (iii), a study may find evidence for 2015), the negative/null category (7b) is not the least frequent more than one sociolinguistic factor, so the total instances of one, as we expected based on the literature. At the same time, mentioned sociolinguistic factors and the total number of studies the classification system matters. If bilingual advantages and do not coincide. disadvantages form trade-offs (Leivada et al., 2021b), it is more reasonable to group negative outcomes with positive out- comes (7c) than with null effects (7b). A null result (i.e., failure 4. Discussion to find an effect) is not the same as finding evidence for a nega- Taking stock, our results suggest that bilingual populations can tive outcome – hence, grouping them together may not do just- indeed be associated with robust adaptations to bilingualism, con- ice to the observed correlations between positive and negative firming the results of van den Noort et al. (2019) and Grundy outcomes. (2020). Analyzing the occurrence of bilingual effects in our sam- Overall, this review addresses three questions: what percentage ple (Figure 3), a χ2 Goodness of Fit suggests a significant differ- of the studies that report bilingual effects control for sociodemo- ence in study outcome, with 72.55% of the studies in our pool graphic factors (Research Question 1); what percentage of the of data finding evidence for bilingual effects (χ2 = 74.9, p< .001). studies reporting such effects attribute them to a cognitive, socio- Recall that 73.41% of these studies attribute them to sociolinguis- linguistic, or mixed origin (Research Question 2); and what are tic factors. the sociolinguistic factors most typically involved in studies that Importantly, the reported bilingual effects include both advan- find bilingual adaptations (Research Question 3). tages and disadvantages. An important matter that arises con- Regarding the first research question, it was found that all 368 cerns the publication biases that have been argued to favor the articles in our pool of data controlled for at least one sociodemo- publication of results that support positive outcomes (de graphic factor: age, gender, and/or SES. While only four studies https://doi.org/10.1017/S1366728923000664 Published online by Cambridge University Press 8 Camilla Masullo et al. Figure 6. The occurrence of individual sociolinguistic factors in the pool of data. Other factors include language dominance, language similarity/typology, length of bilingual experience, biliteracy, vocabulary size, bilingual trajectory, profession, education, gender, minority language status, script, subtractive bilingualism, accul- turation, input variation/diversity, age of literacy acquisition, personal motivation, multicultural identity, and parental education. The complete list is provided in Table 3. The x-axis values show the degree of occurrence in the overall pool of data on a 0-1 scale. did not account for age in their sample, almost 30% of the articles number of variables belonging to different domains. The bilingual did not report their participants’ gender, despite the potential status, in fact, is not enough, raising the question of “how bilin- impact of this variable (Kormi-Nouri et al., 2003; Tarighat & gual one needs to be to benefit from a cognitive advantage” (de Krott, 2021). With reference to SES, more than 60% of studies Cat et al., 2018, p. 125), or more broadly, for advantageous and at least mentioned it, and more than 50% either measured it or disadvantageous effects to be observed? Not only the outcome used it as a matching variable in sample selection. (which is variably described in terms of advantages, disadvan- In relation to the second research question, our results suggest tages, both effects, and null effects; Figure 2), but also the origin that the observed effects are predominantly attributed to sociolin- boils down to a mosaic of intertwined variables (Figure 5): there guistic factors. The relevance of sociolinguistic factors becomes are many, both sociolinguistic and cognitive, factors that work even stronger if we consider the studies that ascribe their findings together or compete in conferring cognitive adaptations (Valian, to both sociolinguistic and cognitive origins (Figure 3). These 2015). For example, profession is one of them: interpreters are findings attest to the need for developing a social-based theory more likely to perform well in certain cognitive tasks that test spe- for explaining the origin of bilingual effects, further suggesting cific abilities which are trained in the course of their work experi- that bilingual adaptations are a mosaic trait that entails a large ence (Henrard & Van Daele, 2017; Yudes et al., 2011). The results https://doi.org/10.1017/S1366728923000664 Published online by Cambridge University Press Bilingualism: Language and Cognition 9 Table 3. Magnitude of contribution for each sociolinguistic factor. Occurrence in studies with a Occurrence in the entire Occurrence in the total range of Sociolinguistic factor sociolinguistic/mixed origin pool of data sociolinguistic factors Proficiency 22.96% 16.85% 15.31% Bilingual/multilingual 17.86% 13.11% 11.90% exposure Language use 16.84% 12.36% 11.22% Age 12.76% 9.36% 8.50% Bilingual (active/native) 11.22% 8.24% 7.48% experience Age of acquisition 5.61% 4.12% 3.74% Sociocultural context/status 5.10% 3.75% 3.40% Immersion schooling 5.61% 4.12% 3.74% Language switching 5.61% 4.12% 3.74% Sociolinguistic context/ 5.10% 3.75% 3.40% status Communicative demands 4.08% 3.00% 2.72% Learning/linguistic context 4.08% 3.00% 2.72% SES 4.08% 3.00% 2.72% Language dominance 3.57% 2.62% 2.38% Language similarity/ 3.57% 2.62% 2.38% typology Length of bilingual 3.57% 2.62% 2.38% experience Biliteracy 3.06% 2.25% 2.04% Vocabulary size 3.06% 2.25% 2.04% Bilingual trajectory 2.55% 1.87% 1.70% Profession 1.02% 0.75% 0.68% Education 1.02% 0.75% 0.68% Gender 1.02% 0.75% 0.68% Minority language status 1.02% 0.75% 0.68% Script 1.02% 0.75% 0.68% Subtractive bilingualism 1.02% 0.75% 0.68% Acculturation 1.02% 0.75% 0.68% Input variation/diversity 0.51% 0.37% 0.34% Age of literacy acquisition 0.51% 0.37% 0.34% Personal motivation 0.51% 0.37% 0.34% Multicultural identity 0.51% 0.37% 0.34% Parental education 0.51% 0.37% 0.34% of the present review seem to suggest that the more bilingualism is be faced with little to no exceptions, the tested samples in the broken down into particular components that define different analyzed studies have surprisingly little in common. Participant types of bilingualism (e.g., use, status, proficiency, etc), the selection and group matching criteria are by no means fixed, more likely it is that the ecologically broad BILINGUAL EFFECT may which means that some variables that have been shown to be ascribed to something more specific, which oftentimes hap- influence results (e.g., SES) are sometimes considered, and some- pens to be of sociolinguistic, rather than cognitive, nature. It times not. Our hypothesis is that the rate at which bilingual seems that the question concerning the origin of bilingual effects advantages and disadvantages are attributed to sociolinguistic is hard to address, most notably because of the variability of the factors can be traced back to how bilingualism itself is con- samples. While the terms “bilingualism” and “bilingual” are ceptualized in study design and sample selection: the more multi- employed in such a way that their ecological validity seems to faceted the bilingual experience is considered, the more likely it is https://doi.org/10.1017/S1366728923000664 Published online by Cambridge University Press 10 Camilla Masullo et al. Figure 7. Different ways of grouping bilingual effects. In 7a, bilingual disadvantages and null effects are kept separate. In 7b, bilingual disadvantages and null effects are merged. In 7c, null effects are kept separate from bilingual (dis)advantages. that the origin of its effects will be traced back to a specific sub- sociolinguistic/cognitive factors play crucial roles, together with component of bilingualism, recognizing some of the many inter-individual variability. Delineating the whole range of the sociolinguistically-informed nuances of the bilingual experience. implicated variables as well as their strength of contribution (as The importance of breaking down the bilingual experience in Figures 5 and 6) can be a successful way of approaching the into all its components is also stressed by the significant correl- bilingual mind. A better conceptualization of bilingualism is ation we found between type of effects and origin. Studies report- also the key to interpreting its effects (Diaz & Farrar, 2018). As ing bilingual advantages often attributed them to a cognitive previously mentioned, controlling different subcomponents of origin, and these studies often focused on the cognitive dimension bilingualism enables a better linking of bilingual effects to specific of the bilingual experience, without specific attention to its social factors of the bilingual experience. The upshot is that bilingualism aspects. Chabal et al. (2015), for example, inquired about how should be perceived as the result of a thick network of sociolin- bilingualism influences attention in an object search task. The guistic factors that influence each other in a chain-reaction superior ability to focus on relevant information for bilinguals fashion. was associated with enhanced executive control. Importantly, The resulting question, then, is about the specific sociolinguis- the main purpose of the study was to observe whether the “bilin- tic factors that give rise to bilingual effects; this was the third guals’ advantage in cognitive control extends to real-world, multi- research question of the present research. Our results show that modal settings” (Chabal et al., 2015, p. 3), suggesting that authors the sociolinguistic origins of bilingual effects can be ascribed to had a pre-set cognitive approach to bilingualism and its outcomes a continuum of social, sociodemographic, sociolinguistic, linguis- in the executive control domain. The executive control domain tic, and language experience/use factors (Figure 5). These vari- was also the focus of Clare et al. (2016), who however additionally ables appear to be intrinsically linked in a thick network, stressed the importance of considering the confounding impact of influencing each other, and defining the bilingual experience as social factors. The lack of enhanced executive control for their the sum of each of these variables. The close junction of sociode- bilingual participants compared to monolinguals was traced mographic and sociolinguistic factors is clearly shown by SES, a back to the specific sociolinguistic context of the study. Indeed, social variable frequently addressed in our pool of data, as previ- bilingual participants were speakers of English and Welsh who ously discussed. With respect to SES assessment, the reviewed were used to alternate their languages in “a more automatic and studies show a great variability of measures: some authors assert less effortful process” compared to other bilingual profiles their sample homogeneity through explaining that only partici- (Clare et al., 2016, p. 422). Thus, the weak lexical competition pants of the same neighbourhood or geographical area were they experienced might have brought fewer demands on executive recruited (e.g., Duñabeitia et al., 2014), others calculate SES by control and reduced training in this cognitive domain. Besides the summing up different proxy variables such as educational level, tendency of linking bilingual advantages to cognitive origins and type of occupation, and position in the occupation (e.g., bilingual disadvantages to social origins, these examples suggest Chrysochoou et al., 2020), while in other cases, especially in stud- that considering the subcomponents of specific bilingual experi- ies focussing on children, parental education is measured as an ences could help in clarifying the apparent inconsistencies of approximate value for SES (e.g., Giguere et al., 2022; Goetz, results found in research on bilingualism (Marton et al., 2017). 2003; Lesniak et al., 2014). Overall, the way in which SES and Indeed, factorizing these subcomponents may be the key to bilingual experience interact shows that variables pertaining to finding the origin of bilingual effects. More concretely, we pro- both the core sociodemographic dimension and variables related pose that tracing the effect of bilingualism back to cognitive or to the actual experience of using two languages cannot be per- sociolinguistic factors partially depends on how gradually bilin- ceived as stand-alone factors; they are crucial components of gual experience itself is represented (i.e., as a spectrum vs. a bin- the same thick weft of variables that together give rise to bilingual ary option that is based on the question “Does the participant adaptations. Acknowledging the reality of individual differences know any language other than language X?”, cf. DeLuca et al., entails that employing umbrella terms like “bilingual status”, 2019; Sulpizio et al., 2020). Defining bilingualism through isolated without pinpointing the sociolinguistic characteristics of the bilin- factors/parameters (i.e., L1/L2 proficiency or age of acquisition as gual experience SPECIFIC to the tested sample, may result in a sub- stand-alone elements) may lead to an oversimplified view of this stantially incomplete picture. Similarly, the mainstream practice notion: being bilingual is not a dichotomous condition depending of grouping in one bilingual mega-category a mix of people that on just one factor, rather it is a gradient status where different speak or sign different L1s, acquired through variable https://doi.org/10.1017/S1366728923000664 Published online by Cambridge University Press Bilingualism: Language and Cognition 11 developmental trajectories (e.g., heritage language users, immi- ENVIRONMENT: choosing to use one language instead of another is grants that go through L1 attrition, sequential bilinguals, etc) not a mere linguistic question, rather it entails social conse- raises similar concerns. In such cases, it is almost impossible to quences for the speaker/signer. determine with a reasonable degree of confidence whether the Another interesting sociolinguistic factor linked to the bilin- claimed bilingual advantages and disadvantages are due to hand- gual communicative dimension is language switching. In most ling two or more languages or to some uncontrolled degree of cases, it is drawn from other social components, and it is not sociolinguistic variation. independently operationalized, as are proficiency and language As Figure 5 suggests, variables pertaining to language use play use (Verhagen et al., 2019). Similar to proficiency, the frequency an important role in the origin of bilingual effects. Proficiency is a of language switching is often found to be positively correlated clear example. Most of the reviewed studies find a positive correl- with bilingual advantages (Barbu et al., 2020; Woumans et al., ation between higher degrees of proficiency and bilingual advan- 2019), in line with the code-switching hypothesis of Peal and tages (e.g., K. Antoniou et al., 2016; Bialystok & Majumder, 1998; Lambert (1962). According to this hypothesis, the bilingual Escobar et al., 2018; Segal & Gollan, 2018; Skoe & Karayanidi, experience of switching from one language to another helps in 2019). Higher or lower proficiency may depend on different vari- reinforcing symbolic reorganization, turning into both strength- ables, such as language use, sociolinguistic status, context, and the ened performance in tasks requiring conceptual reorganization consequent linguistic attitudes that speakers/signers have toward and better communication skills. The low frequency of language their language(s). While some studies tend to consider proficiency switching is also brought into play to justify the absence of posi- as a compact variable, and accordingly control for it in their sam- tive effects of bilingualism. For example, Scaltritti et al. (2017) ples, other studies spell out the connection of proficiency with explain the lack of bilingual advantages in their bidialectal other sociolinguistic factors. Woumans et al. (2015), for instance, Italian speakers through suggesting that the latter have fewer explain their results by tracing enhanced cognitive control back to opportunities of language switching than other bilingual popula- balanced language use and degree of language switching, that in tions (e.g., Spanish–Catalan bilinguals). In this case, the import- turn results in higher proficiency. The prominence of proficiency ance of sociolinguistic context is evident, and it shows once as a primary measure to assess bilingualism can also be ascribed again how different bilingual subcomponents are linked in a to the fact that this has often been used as an umbrella-notion chain-reaction fashion: the social prestige of a linguistic variety that includes other aspects of the bilingual experience, such as affects the communicative contexts in which it is used and, in language use, and in some cases, this has led some scholars to turn, the frequency of switching. In Italy, dialects are often per- ascribe bilingual effects to proficiency only. According to ceived as less prestigious than standard Italian, therefore language Verhagen et al. (2019), the impossibility of teasing apart the switching from Italian to dialect is less frequent and occurs under effects of language proficiency and other sociolinguistic variables few communicative dimensions. The more prestigious social sta- stems from the absence of separate measures for each independ- tus of Catalan, on the other hand, enables the use of the ent factor. Catalan language in more contexts, with a consequent higher Among these factors, there are two that merit special mention: opportunity of language switching, which inevitably arises due language exposure and language use (Bedore et al., 2012). The to the need to address different monolingual Spanish-speaking impact of exposure is most evident in research focused on bilin- interlocutors. gual children. Going back to our pool of data, the bilingual disad- This picture suggests that sociolinguistic factors leave a cogni- vantage found by Andreou et al. (2021) is a clear example: the tive imprint, such that the different origins of bilingual effects are lower performance of Albanian–Greek bilingual children is linked intertwined (Blom et al., 2017; Marian & Hayakawa, 2021). This is to the fact that their Albanian-speaking parents chose to use the relevant to the debate about the origins of bilingual effects societal language (i.e., Greek) at home despite their low profi- because the status of some factors may seem ambiguous. For ciency in this language. Interestingly, this study shows once instance, we have classified switching as a sociolinguistic factor. again the close connection between different aspects of the bilin- However, it could be plausibly viewed as a cognitive factor: having gual experience: besides the crucial role of immigrant status and to monitor external cues in order to be able to switch engages parental language attitudes, the quality of language exposure cognitive control regions in the brain (Blanco-Elorrieta & influences bilingual children’s linguistic abilities. This point has Pylkkänen, 2017). We argue that both findings are correct: lan- also been discussed by Rothman (2009), who argues that quanti- guage switching indeed has cognitive implications, but its occur- tative and qualitative variation in the linguistic input that bilin- rence is driven by sociolinguistic happenstance. Recognizing the gual speakers receive can affect their resulting grammar. cognitive repercussions of switching does not mean that this is About language use, terminology matters. The term “language a cognitive factor per se, or that all sociolinguistic factors that use” is usually ascribed to two main concepts of using a language. recruit and affect cognitive resources should be classified as cog- The first one concerns the amount of time spent speaking/signing nitive in origin. Even SES (i.e., the classic textbook example of a a language, while the second one is strictly connected to the socio- social factor) has an impact on neurocognitive resources communicative environment in which the language is used. In (Migeot et al., 2022), but this does not prevent us from recogniz- this second meaning, the interdependent network of sociolinguis- ing its status as a social factor. In sum, given that all social experi- tic factors becomes once again clear. Referring to the factor “lan- ences may leave an imprint on cognition, it is uninformative to guage use” entails considering the social context of use, which in think of all the sociolinguistic factors as cognitive factors or turn can affect the percentage of time the language is spoken. Our lump them together under the label “cognitive”. Instead, the results suggest that among the sociolinguistic factors linked to the emphasis should be on appreciating the individual characteristics emergence of bilingual adaptations, sociolinguistic context and of different SOCIOLINGUISTIC ECOLOGIES of speakers/signers communicative environment have a strong impact. The important (Rodríguez-Ordóñez et al., 2022). As Luk (2022, p. 5–6) puts it, role of sociolinguistic context in shaping bilinguals’ language use “when shifting the research focus to people and the way that is discussed in Lambert (1973) through the concept of SUBTRACTIVE they become multilingual, it is clear that any investigation of https://doi.org/10.1017/S1366728923000664 Published online by Cambridge University Press 12 Camilla Masullo et al. bilingual (dis)advantage needs to consider the social contexts Supplementary Material. The supplementary material for this article can where language experiences occur”. be found at https://doi.org/10.1017/S1366728923000664 Overall, our proposal about the social imprint on the cognitive Acknowledgements. This work was supported by the European Union’s impact of bilingualism does not mean to delineate a causal rela- Horizon 2020 research and innovation programme under the Marie tion between social factors and their outcomes. Rather, the cogni- Skłodowska-Curie grant agreement n° 945413 and from the Universitat tive mechanisms leading to the emergence of bilingual effects Rovira i Virgili (URV) through 2 Martí i Franquès COFUND Doctoral should be perceived as mediating between the outcomes them- Fellowships to CM and VD. EL acknowledges funding from the Spanish selves and the environmental conditions that shape them. In Ministry of Science and Innovation (MCIN/AEI/10.13039/501100011033) this respect, potential cognitive mediators have been identified under the research project No. PID2021-124399NA-I00. in the domain of attentional control (Bialystok & Craik, 2022) or in language selection (Calabria et al., 2012; cf. Blanco-Elorrieta & Caramazza, 2021 for a review). To offer a con- References crete example, Polinsky and Scontras (2020) propose that process- ing pressures experienced by heritage bilinguals are determined Abutalebi, J., & Green, D. (2007). Bilingual language production: The neuro- by social factors: in most communicative settings, the supremacy cognition of language representation and control. Journal of of the societal language entails less dominance in the heritage lan- Neurolinguistics, 20(3), 242–275. Adesope, O. O., Lavin, T., Thompson, T., & Ungerleider, C. (2010). A guage, which affects both how online resources are handled in Systematic Review and Meta-Analysis of the Cognitive Correlates of processing mechanisms, but also induces linguistic changes in Bilingualism. Review of Educational Research, 80(2), 207–245. https://doi. the heritage language grammar (Polinsky & Scontras, 2020). org/10.3102/0034654310368803 Last, an interesting observation that emerges from our analysis Andreou, M., Tsimpli, I. M., Masoura, E., & Agathopoulou, E. (2021). concerns the “null effect” group of studies. While some studies Cognitive Mechanisms of Monolingual and Bilingual Children in did not find any effect of bilingualism, others stressed the use Monoliterate Educational Settings: Evidence From Sentence Repetition. of different cognitive strategies by monolingual and bilingual par- Frontiers in Psychology, 11(613992). doi: 10.3389/fpsyg.2020.613992 ticipants. Regardless of finding or not finding statistically signifi- Antón, E., Carreiras, M., & Duñabeitia, J. A. (2019). The impact of bilingual- cant differences in terms of task performance, it is important to ism on executive functions and working memory in young adults. PLoS highlight that bilingual experience can impact the use of specific One. 14(2). http://dx.doi.org/10.1371/journal.pone.0206770 Antoniou, K., Grohmann, K. K., Kambanaros, M., & Katsos, N. (2016). The cognitive strategies instead of others (cf. Bialystok et al., 2005; effect of childhood bilectalism and multilingualism on executive con- M. Antoniou et al., 2013; Vaughn et al., 2018). The failure to trol. Cognition, 149, 18–30. https://doi.org/10.1016/j.cognition.2015.12. find significant differences between monolinguals and bilinguals 002 may be ascribed to factors other than sociolinguistic or cognitive Antoniou, M., Best, C. T., & Tyler, M. D. (2013). Focusing the lens of language variables, such as task structure and/or stimulus demands (e.g., experience: Perception of Ma’di stops by Greek and English bilinguals and Lee et al., 2000). What can be drawn from these results is that monolinguals. The Journal of the Acoustical Society of America, 133(4), being bilingual, with all the sociolinguistic variables that bilingual- 2397–2411. https://doi.org/10.1121/1.4792358 ism entails, may affect the way in which a person interacts with Barac, R., & Bialystok, E. (2011). Cognitive development of bilingual children. linguistic and non-linguistic input, and this in turn may inform Language Teaching, 44, 36–54. doi:10.1017/S0261444810000339 processing strategies that may be differently employed by mono- Barac, R., & Bialystok, E. (2012). Bilingual effects on cognitive and linguistic development: role of language, cultural background, and education. Child lingual and bilingual speakers/signers. development, 83(2), 413–422. https://doi.org/10.1111/j.1467-8624.2011. 01707.x Barbu, C. A., Gillet, S., & Poncelet, M. (2020). Investigating the Effects of 5. Outlook Language-Switching Frequency on Attentional and Executive Functioning in Proficient Bilinguals. Frontiers in Psychology, 11. https://doi.org/10. The main findings of the present review support the relevance of a 3389/fpsyg.2020.01078 sociolinguistic theory of bilingual effects. Through the analysis of Bedore, L. M., Peňa, E. D., Summers, C. L., Boerger, K. M., Resendiz, M. D., 368 studies, we have determined the occurrence of different socio- Greene, K., & Gillam, R. B. (2012). The measure matters: Language domin- linguistic variables responsible for bilingual effects in more than ance profiles across measures in Spanish-English bilingual children. Bilingualism: Language and Cognition, 15, 616–629. https://doi.org/10. 73% of the studies in our pool of data. Proficiency, language 1017/S1366728912000090 exposure, language use, communicative context, and sociolinguis- Bialystok, E. (2007). Cognitive Effects of Bilingualism: How Linguistic tic environment are the key factors behind bilingual effects, Experience Leads to Cognitive Change. International Journal of Bilingual together with sociodemographic factors such as age, gender, Education and Bilingualism, 10(3), 210-223. https://doi.org/10.2167/ and SES. Through adopting a sociolinguistic perspective, future beb441.0 studies on bilingual effects may strengthen their explanatory Bialystok, E., & Craik, F. I. M. (2022). How does bilingualism modify cognitive power by taking into account the dense network of sociolinguistic function? Attention to the mechanism. Psychonomic Bulletin & Review, 29 and environmental factors that characterize the bilingual experi- (4), 1246–1269. https://doi.org/10.3758/s13423-022-02057-5 ence and make bilingualism a gradient phenomenon. The take- Bialystok, E., Craik, F. I., Klein, R., & Viswanathan, M. (2004). Bilingualism, home message is that sociolinguistic variables cannot impersonate aging, and cognitive control: Evidence from the Simon task. Psychology secondary roles; their influence on results from tasks that are and Aging, 19(2), 290–303. https://doi.org/10.1037/0882-7974.19.2.290 Bialystok, E., Craik, F. I. M., Grady, C., Chau, W., Ishii, R., Gunji, A., & Pantev, deemed as measuring primarily cognitive outcomes should be C. (2005). Effect of bilingualism on cognitive control in the Simon task: acknowledged. This conclusion advances our understanding of Evidence from MEG. NeuroImage, 24(1), 40–49. https://doi.org/10.1016/j. the bilingual experience, by showing that bilingualism, as a spec- neuroimage.2004.09.044 trum of dynamic experiences, cannot be isolated, neither from the Bialystok, E., & Majumder, S. (1998). The relationship between bilingualism cognitive mediators that sustain it nor from the social environ- and the development of cognitive processes in problem solving. Applied ment that shapes and nourishes it. Psycholinguistics, 19(1), 69–85. https://doi.org/10.1017/s0142716400010584 https://doi.org/10.1017/S1366728923000664 Published online by Cambridge University Press Bilingualism: Language and Cognition 13 Bialystok, E., & Martin, M. M. (2004). Attention and inhibition in bilingual and function. Proceedings of the National Academy of Science, 116, 7565– children: Evidence from the dimensional change card sort task. 7574. Developmental Science, 7(3), 325–339. https://doi.org/10.1111/j.1467-7687. Diaz, V., & Farrar, M. J. (2018). The missing explanation of the false-belief 2004.00351.x advantage in bilingual children: a longitudinal study. Developmental Bialystok, E., Craik, F. I., & Luk, G. (2012) Bilingualism: Consequences for Science, 21(4). https://doi.org/10.1111/desc.12594 mind and brain. Trends in Cognitive Sciences 16(4), 240–250. Dick, A. S., Garcia, N. L., Pruden, S. M., Thompson, W. K., Hawes, S. W., Blanco-Elorrieta, E., & Caramazza, A. (2021). On the need for theoretically Sutherland, M. T., Riedel, M. C., Laird, A. R., & Gonzalez, R. (2019). No guided approaches to possible bilingual advantages: An evaluation of the evidence for a bilingual executive function advantage in the nationally rep- potential loci in the language and executive control systems. Neurobiology resentative ABCD study. Nature Human Behaviour, 3(7), 692–701. https:// of Language, 2(4), 452–463. https://doi.org/10.1162/nol_a_00041 doi.org/10.1038/s41562-019-0609-3 Blanco-Elorrieta, E., & Pylkkänen, L. (2017). Bilingual language switching in Dodson, C. J. (1985). Second language acquisition and bilingual development: the lab vs. in the wild: The spatio-temporal dynamics of adaptive language A theoretical framework. Journal of Multilingual and Multicultural control. The Journal of Neuroscience: the official journal of the Society for Development 6, 325–346. DOI: 10.1080/01434632.1985.9994210. Neuroscience. 37,9022–36. Donnelly, S., Brooks, P. J., & Homer, B. D. (2019). Is there a bilingual advan- Blom, E., Boerma, T., Bosma, E., Cornips, L., & Everaert, E. (2017). Cognitive tage on interference-control tasks? A multiverse meta-analysis of global advantages of bilingual children in different sociolinguistic contexts. reaction time and interference cost. Psychonomic bulletin & review, 26(4), Frontiers in Psychology, 8. https://doi.org/10.3389/fpsyg.2017.00552 1122–1147. https://doi.org/10.3758/s13423-019-01567-z Brito, N. H., & Noble, K. G. (2017). The independent and interacting effects of D’Souza, D., & D’Souza, H. (2021). Bilingual adaptations in early develop- socioeconomic status and dual-language use on brain structure and cogni- ment. Trends in cognitive sciences, 25(9), 727–729. https://doi.org/10.1016/ tion. Developmental Science, e12688. j.tics.2021.06.002 Calabria, M., Hernández, M., Branzi, F. M., & Costa, A. (2012). Qualitative dif- Duñabeitia, J. A. (2017). Emotional diglossia in multilingual classroom envir- ferences between bilingual language control and executive control: Evidence onments: A proposal. Psychology and Cognitive Sciences Open Journal, 3(3), from task-switching. Frontiers in Psychology, 2. https://doi.org/10.3389/ 74-78. http://hdl.handle.net/10810/23747 fpsyg.2011.00399 Duñabeitia, J. A., Hernández, J. A., Antón, E., Macizo, P., Estévez, A., Fuentes, Calvo, A., & Bialystok, E. (2014). Independent effects of bilingualism and L. J., & Carreiras, M. (2014). The inhibitory advantage in bilingual children socioeconomic status on language ability and executive functioning. revisited: myth or reality?. Experimental psychology, 61(3), 234–251. https:// Cognition, 130(3), 278–288. doi.org/10.1027/1618-3169/a000243 Chabal, S., Schroeder, S. R., & Marian, V. (2015). Audio-visual object search is Engel de Abreu, P. M., Cruz-Santos, A., Tourinho, C. J., Martin, R., & changed by bilingual experience. Attention, Perception, & Psychophysics, 77, Bialystok, E. (2012). Bilingualism enriches the poor: enhanced cognitive 2684–2693. https://doi.org/10.3758/s13414-015-0973-7 control in low-income minority children. Psychological Science, 23(11), Chen, S., Li, R., Li, G., Wang, Y., & Wu, L. (2013). The effect of dialect experi- 1364–1371. https://doi.org/10.1177/0956797612443836 ence on Chinese children’s Mandarin phonological awareness. Reading and Escobar, G. P., Kalashnikova, M., & Escudero, P. (2018). Vocabulary matters! Writing, 26(8), 1317-1335. https://doi.org/10.1007/s11145-012-9420-5 The relationship between verbal fluency and measures of inhibitory control Chrysochoou, E., Kanaki, S., & Vivas, A. B. (2020). Executive functions in in monolingual and bilingual children. Journal of Experimental Child French-Greek early bilinguals: In search of the suggested bilingual advan- Psychology, 170, 177-189. https://doi.org/10.1016/j.jecp.2018.01.012. tage. Psychology: The Journal of the Hellenic Psychological Society, 25(2), Feldman, C., & Shen, M. (1971). Some language-related cognitive advantages 76–92. https://doi.org/10.12681/psy_hps.25588 of bilingual five-year-olds. Journal of Genetic Psychology, 118, 235–244. Clare, L., Whitaker, C. J., Martyr, A., Martin-Forbes, P. A., Bastable, A. J. M., https://psycnet.apa.org/doi/10.1080/00221325.1971.10532612 Pye, K. L., Quinn, C., Thomas, E. M., Mueller Gathercole, V. C., & Hindle, J. Fricke, M., Zirnstein, M., Navarro-Torres, C., & Kroll, J. F. (2019). Bilingualism V. (2016). Executive control in older Welsh monolinguals and bilinguals. reveals fundamental variation in language processing. Bilingualism Journal of Cognitive Psychology, 28(4), 412-426. https://doi.org/10.1080/ (Cambridge, England), 22(1), 200–207. https://doi.org/10.1017/ 20445911.2016.1148041 S1366728918000482 Costa, A., Hernández, M., Costa-Faidella, J., & Sebastián-Gallés, N. (2009). On Garraffa, M., Beveridge, M., & Sorace, A. (2015). Linguistic and Cognitive the bilingual advantage in conflict processing: Now you see it, now you Skills in Sardinian-Italian Bilingual Children. Frontiers in psychology, 6, don’t. Cognition, 113(2), 135-149. https://doi.org/10.1016/j.cognition.2009. 1898. https://doi.org/10.3389/fpsyg.2015.01898 08.001. Giguere, D., Dickson, D. J., Tulloch, M. K., & Hoff, E. (2022). Majority lan- Costa, A., Hernández, M., & Sebastián-Gallés, N. (2008). Bilingualism aids guage skill, not measures of bilingualism, predicts executive attention in conflict resolution: evidence from the ANT task. Cognition, 106(1), 59– bilingual children. Journal of Experimental Child Psychology, 213. https:// 86. https://doi.org/10.1016/j.cognition.2006.12.013 doi.org/10.1016/j.jecp.2021.105256. D’Alessandro, R., Natvig, D., & Putnam, M. T. (2021). Addressing Challenges Goetz, P. (2003). The effects of bilingualism on theory of mind development. in Formal Research on Moribund Heritage Languages: A Path Forward. Bilingualism: Language and Cognition, 6(1), 1–15. Cambridge University Frontiers in psychology, 12, 700126. https://doi.org/10.3389/fpsyg.2021. Press. 700126 Gollan, T. H., Montoya, R. I., & Werner, G. (2002). Semantic and letter fluency de Bruin, A., Dick, A. S., & Carreiras, M. (2021). Clear theories are needed to in Spanish English bilinguals. Neuropsychology. 16, 562-576. https://doi.org/ interpret differences: Perspectives on the bilingual advantage debate. 10.1037/08944105.16.4.562 Neurobiology of Language, 2(4), 433–451. https://doi.org/10.1162/ Green, D. W., Crinion, J., & Price, C. J. (2007). Exploring cross-linguistic nol_a_00038 vocabulary effects on brain structures using voxel-based morphometry. de Bruin, A., Treccani, B., & Della Sala, S. (2015). Cognitive advantage in bilin- Bilingualism (Cambridge, England), 10(2), 189–199. https://doi.org/10. gualism: an example of publication bias? Psychological science, 26(1), 99– 1017/s1366728907002933 107. https://doi.org/10.1177/0956797614557866 Grundy, J. G. (2020). The effects of bilingualism on executive functions: An de Cat, C. (2020). Predicting language proficiency in bilingual children. Studies updated quantitative analysis. Journal of Cultural Cognitive Science, 4(2), in Second Language Acquisition, 42(2), 279–325. http://dx.doi.org/10.1017/ 177-199. s0272263119000597 Hartanto, A., Toh, W. X., & Yang, H. (2019). Bilingualism narrows socio- de Cat, C., Gusnanto, A., & Serratrice, L. (2018). Identifying a threshold for the economic disparities in executive functions and self-regulatory behaviors dur- executive function advantage in bilingual children. Studies in Second ing early childhood: Evidence from the early childhood longitudinal study. Language Acquisition, 40(1), 119-151. doi:10.1017/S0272263116000486 Child Development, 90(4), 1215–1235. https://doi.org/10.1111/cdev.13032 DeLuca, V., Rothman, J., Bialystok, E., & Pliatsikas, C. (2019). Redefining bilin- Henrard, S., & Van Daele, A. (2017). Different Bilingual Experiences Might gualism: A spectrum of experience that differentially affect brain structure Modulate Executive Tasks Advantages: Comparative Analysis between https://doi.org/10.1017/S1366728923000664 Published online by Cambridge University Press 14 Camilla Masullo et al. Monolinguals, Translators, and Interpreters. Frontiers in psychology, 8, Montrul, S. (2015). The acquisition of heritage languages. Cambridge: 1870. https://doi.org/10.3389/fpsyg.2017.01870 Cambridge University Press. Hernández, M., Martin, C. D., Barceló, F., & Costa, A. (2013). Where is the Mueller Gathercole, V. C. (2015). Are we at a socio-political and scientific cri- bilingual advantage in task-switching? Journal of Memory and Language, sis? Cortex, 73, 345–346. https://doi.org/10.1016/j.cortex.2015.07.022 69(3), 257-276. https://doi.org/10.1016/j.jml.2013.06.004. Mueller Gathercole, V. C., Thomas, E. M., Jones, L., Viñas Guasch, N., Young, Ivanova, I., & Costa, A. (2008). Does bilingualism hamper lexical access in M., & Hughes, E. K. (2010). Cognitive effects of bilingualism: digging dee- speech production? Acta Psychologica. 127(2), 277–288. https://doi.org/10. per for the contributions of language dominance, linguistic knowledge, 1016/j.actpsy.2007.06.003 socio-economic status and cognitive abilities. International Journal of Ivanova, I., Seanez, A., Cochran, M., & Kleinman, D. (2023). The temporal Bilingual Education and Bilingualism, 13(5), 617–664. https://doi.org/10. dynamics of bilingual language control. Psychonomic Bulletin & Review, 1080/13670050.2010.48828 30, 774–791. https://doi.org/10.3758/s13423-022-02168-z Paap, K. R., Mason, L., & Anders-Jefferson, R. (2021). Predictions about the Kormi-Nouri, R., Moniri, S., & Nilsson, L. (2003). Episodic and semantic cognitive consequences of language switching on executive functioning memory in bilingual and monolingual children. Scandinavian Journal of inspired by the adaptive control hypothesis fail more often than not. Psychology, 44(1), 47-54. https://doi.org/10.1111/1467-9450.00320 Brain Sciences 11(9), 1217. Laketa, A., Studenica, A., Chrysochoou, E., Blakey, E., & Vivas, A. B. (2021). Page, M. J., McKenzie, J. E., Bossuyt, P. M., Boutron, I., Hoffmann, T. C., Biculturalism, Linguistic Distance, and Bilingual Profile Effects on the Mulrow, C. D., Shamseer, L., Tetzlaff, J. M., Akl, E. A., Brennan, S. E., Bilingual Influence on Cognition: A Comprehensive Multipopulation Chou, R., Glanville, J., Grimshaw, J. M., Hróbjartsson, A., Lalu, M. M., Approach. Journal of Experimental Psychology: General, 150(11), 2273– Li, T., Loder, E. W., Mayo-Wilson, E., McDonald, S., McGuinness, L. A., 2292. https://doi.org/10.1037/xge0000794 Stewart, L. A., Thomas, J., Tricco, A. C., Welch, V. A., Whiting, P., & Lambert, W. E. (1973). Culture and Language as Factors in Learning and Moher, D. (2021). The PRISMA 2020 statement: an updated guideline for Education. ERIC Clearinghouse. https://eric.ed.gov/?id=ED096820 reporting systematic reviews. BMJ, 372 (71). https://doi.org/10.1136/bmj. Lee, T. M. C., Cheung, C. C. Y., Chan, J. K. P., & Chan, C. C. H. (2000). Trail n71 making across languages. Journal of Clinical and Experimental Peal, E., & Lambert, W. E. (1962). The relation of bilingualism to intelligence. Neuropsychology, 22(6), 772–778. https://doi.org/10.1076/jcen.22.6.772.954 Psychological Monographs: General and Applied, 76(27), 1–23. https://doi. Lehtonen, M., Soveri, A., Laine, A., Järvenpää, J., de Bruin, A., & Antfolk, J. org/10.1037/h0093840 (2018). Is bilingualism associated with enhanced executive functioning in Polinsky, M., & Scontras, G. (2020). Understanding heritage languages. adults? A meta-analytic review. Psychological bulletin. 144(4), 394–425. Bilingualism: Language and Cognition, 23(1), 4-20. https://doi.org/10. https://doi.org/10.1037/bul0000142 1017/S1366728919000245 Leivada, E., Westergaard, M., Duñabeitia, J. A., & Rothman, J. (2021a). On the R Core Team (2021). R: A language and environment for statistical computing. phantom-like appearance of bilingualism effects on neurocognition: (How) R Foundation for Statistical Computing, Vienna, Austria. https://www.R- should we proceed?. Bilingualism: Language & Cognition, 24, 197-210. project.org/. https://doi.org/10.1017/S1366728920000358 Rodríguez-Ordóñez, I., Kasstan, J., & O’Rourke, B. (2022). Responding to Leivada, E., Mitrofanova, N., & Westergaard, M. (2021b). Bilinguals are better sociolinguistic change: New speakers and variationist sociolinguistics. than monolinguals in detecting manipulative discourse. PLoS ONE, 16(9), International Jorunal of Bilingualism. 26(5):529–41. http://dx.doi.org/10. e0256173. 1177/13670069221110381 Leivada, E., Dentella, V., Masullo, C., & Rothman, J. (2022). On trade-offs in Rothman, J. (2009). Understanding the nature and outcomes of early bilin- bilingualism and moving beyond the Stacking the Deck fallacy. gualism: Romance languages as heritage languages. International Journal Bilingualism: Language and Cognition 26(3), 550-555. of Bilingualism, 13(2), 155–163. https://doi.org/10.1177/1367006909339814 Leivada, E., Rodríguez-Ordóñez, I., Parafita Couto, M. C., & Perpiñán, S. Saer, D. J. (1923). The effect of bilingualism on intelligence. British Journal of (2023). Bilingualism with minority languages: Why searching for unicorn Psychology: General Section, 14, 25–38. language users does not move us forward. Applied Psycholinguistics 44(3), Scaltritti, M., Peressotti, F., & Miozzo, M. (2017). Bilingual advantage and lan- 384-399. guage switch: What’s the linkage? Bilingualism, 20(1), 80–97. https://doi. Lesniak, A., Myers, L., & Dodd, B. (2014). The English phonological awareness org/10.1017/S1366728915000565 skills of 5;0–6;0-year-old Polish–English, Portuguese–English bilingual Segal, D., & Gollan, T. H. (2018). What’s left for balanced bilinguals? Language speakers and English monolingual children. Speech, Language and proficiency and item familiarity affect left-hemisphere specialization in Hearing. 17(1), 37-48. https://psycnet.apa.org/doi/10.1179/2050572813Y. metaphor processing. Neuropsychology, 32(7), 866–879. https://doi.org/10. 0000000029 1037/neu0000467 Liberati, A., Altman, D. G., Tetzlaff, J., Murlow, C., Gøtzsche, P. C., Ioannidis, Siu, T. S. C., & Ho, S. H. C. (2022). Investigating Effects of Bilingualism on J. P. A., Clarke, M., Devereaux, P. J., Kleijnen, J., & Moher, D. (2009). The Syntactic Processing: Testing Structural Sensitivity Theory. Language PRISMA statement for reporting systematic reviews and meta-analyses of Learning, 72, 534-575. https://doi.org/10.1111/lang.12494 studies that evaluate health care interventions: explanation and elaboration. Skoe, E., & Karayanidi, K. (2019). Bilingualism and speech understanding in PLoS Medicine, 6(7). https://doi.org/10.1371/journal.pmed.1000100 noise: Auditory and linguistic factors. Journal of the American Academy Luk, G. (2022). Justice and equity for whom? Reframing research on the “bilin- of Audiology, 30(2), 115–130. https://doi.org/10.3766/jaaa.17082 gual (dis)advantage.” Applied Psycholinguistics. 1–15. http://dx.doi.org/10. Studenica, A., Laketa, A., Chrysochoou, E., Blakey, E., & Vivas, A. B. (2022). 1017/S0142716422000339 The influence of bilingualism on adolescent cognition: The roles of bicul- Luque, A., & Morgan-Short, K. (2021). The relationship between cognitive turalism, the bilingual profile, and linguistic similarity, Cognitive control and second language proficiency. Journal of Neurolinguistics, 57. Development. 63. https://doi.org/10.1016/j.cogdev.2022.101203. https://doi.org/10.1016/j.jneuroling.2020.100956 Sulpizio, S., Del Maschio, N., Del Mauro, G., Fedeli, D., & Abutalebi, J. (2020). Marian, V., & Hayakawa, S. (2021). Measuring bilingualism: The quest for a Bilingualism as a gradient measure modulates functional connectivity of “Bilingualism Quotient.” Applied Psycholinguistics 42(Suppl 2):527–48. language and control networks. NeuroImage, 205, 116306. https://doi.org/ http://dx.doi.org/10.1017/s0142716420000533 10.1016/j.neuroimage.2019.116306 Marton, K., Goral, M., Campanelli, L., Yoon, J., & Obler, L. K. (2017). Tarighat, S., & Krott, A. (2021). Bilingualism Enhances Reported Perspective Executive control mechanisms in bilingualism: Beyond speed of processing. Taking in Men, but Not in Women. Frontiers in Psychology, 12. https:// Bilingualism, 20(3), 613–631. https://doi.org/10.1017/S1366728915000930 doi.org/10.3389/fpsyg.2021.679524 Migeot, J., Calivar, M., Granchetti, H., Ibáñez, A., & Fittipaldi, S. (2022). The jamovi project (2021). jamovi. (Version 1.8). https://www.jamovi.org. Socioeconomic status impacts cognitive and socioemotional processes in Treccani, B., & Mulatti, C. (2015). No matter who, no matter how… and no healthy ageing. Scientific reports, 12(1), 6048. https://doi.org/10.1038/ matter whether the white matter matters. Why theories of bilingual advan- s41598-022-09580-4 tage in executive functioning are so difficult to falsify. Cortex, 73, 349-351. https://doi.org/10.1017/S1366728923000664 Published online by Cambridge University Press Bilingualism: Language and Cognition 15 Valian, V. (2015). Bilingualism and cognition. Bilingualism: Language and Ware, A. T., Kirkovski, M., & Lum, J. A. G. (2020). Meta-analysis reveals a Cognition, 18, 3–24. bilingual advantage that is dependent on task and age. Frontiers in van den Noort, M., Vermeire, K., Bosch, P., Staudte, H., Krajenbrink, T., Psychology. 11, 1458. Jaswetz, L., Struys, E., Yeo, S., Barisch, P., Perriard, B., Lee, S. H., & Lim, Woumans, E., Ceuleers, E., Van Der Linden, L., Szmalec, A., & Duyck, W. S. (2019). A systematic review on the possible relationship between bilin- (2015). Verbal and nonverbal cognitive control in bilinguals and inter- gualism, cognitive decline, and the onset of dementia. Behavioral Sciences, preters. Journal of Experimental Psychology: Learning Memory and 9(7). https://doi.org/10.3390/bs9070081 Cognition, 41(5), 1579–1586. https://doi.org/10.1037/xlm0000107 Vaughn, K. A., Archila-Suerte, P., & Hernandez, A. E. (2018). Parietal lobe vol- Woumans, E., Van Herck, S., & Struys, E. (2019). Shifting gear in the study of ume distinguishes attentional control in bilinguals and monolinguals: A the bilingual advantage: Language switching examined as a possible moder- structural MRI study. Brain and Cognition, 134, 103–109. https://doi.org/ ator. Behavioral Sciences, 9(8). https://doi.org/10.3390/bs9080086 10.1016/j.bandc.2018.12.001 Yudes, C., Macizo, P., & Bajo, T. (2011). The influence of expertise in sim- Verhagen, J., de Bree, E., & Unsworth, S. (2019). Effects of bilingual language ultaneous interpreting on non-verbal executive processes. Frontiers in use and Language Proficiency on 24-month-olds’ cognitive control. Journal Psychology, 2(309). https://psycnet.apa.org/doi/10.3389/fpsyg.2011. of Cognition and Development 21(1), 46–71. 00309 https://doi.org/10.1017/S1366728923000664 Published online by Cambridge University Press