New Empirically Based Perspectives on Multilingualism

Barbara Mertins

Multilingualism and bilingualism are topics intensively debated in various scientific, social, academic, and educational contexts. There has been a great effort within the fields of linguistics and psycholinguistics to show that using two or more languages is common for a great number of people across Europe and that multilingualism, when viewed from a global perspective, is the norm and cannot be seen as an exception (Delucchi Danhier & Mertins, 2018; Mende, 2022). Along these lines, our understanding and grasp of the multilingual mind and brain have expanded tremendously: For example, it is now widely accepted that the ability to switch between two or more languages is an indication of speakers’ competence (Costa & Santesteban, 2004; Tziampiri et al., 2024). Code-switching is clearly tied to a high level of proficiency in a given language pair and does not reveal any of the deficiencies often mistakenly attributed to confusion between languages (De Houwer, 2009; Özkara et al., 2025). Moreover, there is a consensus about the nature of the cognitive underpinning of a bilingual/multilingual mind, which is no longer understood as a sum of separate, independently operating language systems that can be turned off and on without any interactions from an active to a dormant modus (Bialystok, 2024; De Bot et al., 2005). Empirical evidence from psycholinguistic and neurophysiological research, including priming, eye-tracking, and EEG studies, shows that linguistic knowledge is highly interconnected in the bilingual/multilingual mind. Multilingual knowledge is stored in one and the same system and language processing is carried out by shared neural networks, always relying on the dual mechanism of activation/inhibition processes (Antoniou & Spanoudis, 2024; Baroncini & Torregrossa, 2025; Tarin et al., 2025). This cognitive and neuronal underpinning of the bilingual/multilingual mind and brain can easily explain natural phenomena typically observed in and experienced by multilingual persons such as coactivation, code-switching, translanguaging, or interferences.

Another important insight from the psycholinguistic research on multilingualism concerns the definition and assessment of the term bilingual/multilingual (Altarriba & Heredia, 2018; Grosjean, 2024). Although there is a high awareness in the field regarding the heterogeneity of the bilingual/multilingual speaker group, there is still a lack of objective and across-studies validated measures for the assessment of bilingualism. This poses a significant methodological challenge for multilingualism research since depending on the definition used in a particular study subjects with different bilingual experience and/or competence might end up in the same group with the label bilingual/multilingual. In this manner, studies on multilingualism rely on heterogeneous definitions of bilingualism since their assessment approach is based on different criteria from self-assessment proportions of the use or proficiency levels to the age of acquisition of the participants. In the end, such an inappropriate and ecologically questionable assessment can lead to methodologically problematic group comparisons and, in turn, even to wrong and biased data interpretations and conclusions.

This volume brings together seven original papers and reviews approaching the topic of multilingualism from different points of departures, reaching from theoretical best practice examples to large-scale empirical studies. The book covers several linguistic domains, including phonology, grammar, lexicon, and it attends to different groups of multilingual users (infants, pre-school children, heritage speakers, adult learners). In addition, the book provides new perspectives on multilingualism in different educational settings, highlighting the importance of students’ awareness of cross-linguistic influence and institutional policies of multilingual teaching.

All contributions relate their research to the Czech language, an inflectionally rich Western Slavic language used by about ten million people. Despite the fact that the Czech linguistics can be proud of its long and famous linguistic tradition and that over the last three decades there has been a lot of excellent research carried out, especially in the area of corpus linguistics and recently also in psycholinguistics (Český národní korpus, n. d.; Chromý & Tomaschek, 2024; Paillereau & Chládková, 2024), given its size, the Czech language nevertheless belongs to the group of less-studied languages. One of the aims of this book is to show that Czech is a linguistically rich and diverse language that is absolutely worth studying in many different contexts of multilingualism. The different facets of multilingualism related to Czech can be found in the Czech Republic by investigating different language constellations such as Czech-German, Czech-Vietnamese, Czech-Ukrainian, or Czech in combination with any dialectal variety existing in the Czech Republic. Given the number of Czech speakers living outside of Czechia, it is also worthwhile looking into the topic of Czech as a heritage language.

The paper by Katrin Odermann applies a well-grounded theoretical perspective and investigates language specificity of children’s development of phonological awareness anticipating the issue for the bilingual acquisition of Czech and German. The contribution demonstrates, on the one hand, the importance of linguistic differences and similarities in the early acquisition of prosodic and phonological features and, on the other hand, the importance of these features for the development of phonological awareness, one of the major players for the acquisition of literacy.

Maryam Fatemi and Barbara Mertins explore in their article the role of grammatical gender in the verbalization and conceptualization of nouns and adjectives within the framework of the Linguistic Relativity Principle (Lucy, 1997; Sapir, 1949; Slobin, 1996; Whorf, 1956). To this end, the study focuses on Czech-German bilinguals as a best practice example when studying multilingualism in languages, in which the gender marking is grammaticalized, yet differently weighted, in the underlying system. The review offers a theoretical framework to guide future research on multilingualism and calls for robust experimental designs, with increased attention to understudied languages like Czech.

The focus of the empirical study by Silvie Převrátilová lies in the adult learners’ perception of cross-linguistic differences in the context of second language acquisitions. It investigates to what extent subjectively perceived negative and positive interactions between several languages can be profitable for language learning. The findings implicate that adult learners use cross-linguistic similarities and differences as part of the learning strategies in order to transfer knowledge across their entire plurilingual repertoire.

Joël Alipaß aims in his paper at pointing out some limitations of current research on word segmentation by reviewing research on understudied acquisitional contexts. The paper focuses on methodological aspects, by looking at challenges and insights from the study of bilingual infants, taking into consideration measures of language input and language dominance, as well as bilingual-specific processing. Along these lines, the paper challenges the generalizability of previous findings predominantly based on data from monolingual acquisition, considering only a limited number of languages, and enriches the current discourse on bilingual infant research by presenting new promising avenues to future studies including understudied languages such as Czech.

Kateřina Šormová’s article examines written language production of Romani pupils in Czech primary schools, with particular attention to manifestations of ethnolectal features in their writing. This paper is one of the rare studies attending to the socially negatively marked low prestige language Romani in the natural, and yet still understudied, context of Czech-Romani bilingualism. The study shows the tight interaction between the two languages and highlights at the same the importance of understanding the different facets and effect of multilingualism, independent of social and individual prejudices.