Does bilingualism come with linguistic costs? A meta-analytic review of the bilingual lexical deficit

Abstract

A series of recent studies have shown that the once-assumed cognitive advantage of bilingualism finds little support in the evidence available to date. Surprisingly, however, the view that bilingualism incurs linguistic costs (the so-called lexical deficit) has not yet been subjected to the same degree of scrutiny, despite its centrality for our understanding of the human capacity for language. The current study implemented a comprehensive meta-analysis to address this gap. By analyzing 478 effect sizes from 130 studies on expressive vocabulary, we found that observed lexical deficits could not be attributed to bilingualism: Simultaneous bilinguals (who acquired both languages from birth) did not exhibit any lexical deficit, nor did sequential bilinguals (who acquired one language from birth and a second language after that) when tested in their mother tongue. Instead, systematic evidence for a lexical deficit was found among sequential bilinguals when tested in their second language, and more so for late than for early second language learners. This result suggests that a lexical deficit may be a phenomenon of second language acquisition rather than bilingualism per se.

Modeling lexical abilities of heritage language and L2 speakers of Hebrew and English in Israel and the United States: a network approach

“…Additionally, we found that at the group level, HL speakers outperformed L2 speakers of each respective language in the same country, supporting findings across linguistic domains that found an advantage for HL speakers over L2 learners in oral production ( Montrul et al, 2008 ; Saadah, 2011 ; Albirini and Benmamoun, 2014 ; Rakhilina et al, 2016 ). Likewise, this finding seems to support the results of the meta-analysis by Bylund et al (2023) , who found an advantage for simultaneous bilinguals (in this case HL speakers, although several of them were, in fact, sequential, although not by a significant number of years) over sequential bilinguals in the L2/HL, but not in the L1/SL. Notably, however, the HL-HEB-US group matched the L2-HEB-IL group on the Hebrew MINT, suggesting that the HL advantage over the L2 learner disappears in an immersive environment.…”

“…A recent meta-analysis of 130 studies found evidence for the bilingual “lexical deficit” ( Bylund et al, 2023 , p. 898) only among sequential bilinguals who learned their L2 later in life, and only in the L2, and not for simultaneous bilinguals or for sequential bilinguals in their L1 ( Bylund et al, 2023 ). Meanwhile, while HL speakers (who can be either simultaneous or early sequential bilinguals) score fairly consistently higher on vocabulary assessments in their dominant SL, usually their L2, than in their HL, their lexical proficiency has been shown to be highly variable (see, for example, Fridman and Meir, 2023a , findings that HL-Hebrew speakers in the US ranged from 15 to 82% accuracy on an HL vocabulary assessment).…”

The Influence of Bilingualism on Statistical Word Learning: A Registered Report

“…Word learning may be more complex for bilinguals than monolinguals: Consistent with this, some studies reported bilingual children to have a smaller vocabulary than monolingual ones (e.g., De Houwer et al, 2014;Montanari et al, 2018). Nevertheless, more recently, some authors did not find a lexical deficit (i.e., smaller vocabulary and slower word retrieval compared to monolinguals) in balanced bilingual children (e.g., Bylund et al, 2022); others have argued that vocabulary tests were created for testing monolinguals and that they, therefore, do not accurately represent bilinguals' word knowledge (Ehl et al, 2020).…”

An examination of the independent and interactive effects of autistic traits, bidialectalism and multilingualism in a general-population, adult sample

“…First, multilinguals show lower performance in some aspects of language processing (e.g., Bialystok et al, 2009). For example, multilingual children and adults are often found to exhibit smaller vocabularies than monolinguals in each of their languages separately; and especially in their second language (e.g., Bialystok & Luk, 2012;Bylund et al, 2023).…”

“…Overall, investigating the interplay between autistic traits, bidialectalism, and multilingualism is important because some research suggests that such experiences have overlapping cognitive domains of impact. On the one hand, some evidencethough currently controversial-suggests that bidialectals and multilinguals exhibit, under certain conditions, better non-verbal cognitive processing (e.g., Bialystok & Craik, 2022; though see Paap, 2023) but worse language performance (e.g., Bialystok et al, 2009;Bylund et al, 2023), at least in some respects. On the other hand, ASD, or autistic traits more broadly, are often linked to lower language and non-verbal 7 cognitive performance (e.g., Demetriou et al, 2018;Hoekstra et al, 2009;Marinopoulou et al, 2023;Nader et al, 2016;Stewart et al, 2023).…”