Crosslinguistic influence

Crosslinguistic influence (CLI) refers to the different ways in which one language can affect another within an individual speaker. It typically involves two languages that can affect one another in a bilingual speaker.  An example of CLI is the influence of Korean on a Korean native speaker who is learning Japanese or French. Less typically, it could also refer to an interaction between different dialects in the mind of a monolingual speaker. CLI can be observed across subsystems of languages including pragmatics, semantics, syntax, morphology, phonology, phonetics, and orthography. Discussed further in this article are particular subcategories of CLI—transfer, attrition, the complementarity principle, and additional theories.

The question of how languages influence one another within a bilingual individual can be addressed both with respect to mature bilinguals and with respect to bilingual language acquisition. With respect to bilingual language acquisition in children, there are several hypotheses that examine the internal representation of bilinguals' languages. Volterra and Taeschner proposed the Single System Hypothesis, which states that children start out with one single system that develops into two systems. This hypothesis proposed that bilingual children go through three stages of acquisition.

In response to the Single System Hypothesis, a different hypothesis developed regarding the idea of two separate language systems from the very beginning. It was based on evidence of monolinguals and bilinguals reaching the same milestones at approximately the same stage of development. For example, bilingual and monolingual children go through identical patterns of grammar development. This hypothesis, called the Separate Development Hypothesis, held the notion that the bilinguals acquiring two languages would internalize and acquire the two languages separately. Evidence for this hypothesis comes from lack of transfer and lack of acceleration. Transfer is a grammatical property of one language used in another language. Acceleration is the acquisition of a feature in language A facilitating the acquisition of a feature in language B. In a study of Dutch-English bilingual children, there were no instances of transfer across elements of morphology and syntactic development, indicating that the two languages developed separately from each other. In addition, in a study of French-English bilingual children, there were no instances of acceleration because finiteness appeared much earlier in French than it did in English, suggesting that there was no facilitation of the acquisition of finiteness in English by acquisition in French. Under this hypothesis, bilingual acquisition would be equivalent to monolingual children acquiring the particular languages.

In response to both the previous hypotheses mentioned, the Interdependent Development Hypothesis emerged with the idea that there is some sort of interaction between the two language systems in acquisition. It proposed that there is no single language system, but the language systems are not completely separate either. This hypothesis is also known as the Crosslinguistic Hypothesis, developed by Hulk and Müller. The Crosslinguistic Hypothesis states that influence will occur in bilingual acquisition in areas of particular difficulty, even for monolingual native language acquisition. It re-examined the extent of the differentiation of the language systems due to the interaction in difficult areas of bilingual acquisition. Evidence for this hypothesis comes from delay, acceleration, and transfer in particular areas of bilingual language acquisition. Delay is the acquisition of a property of language A later than normally expected because of the acquisition of language B. CLI is seen when the child has a dominant language, such as Cantonese influencing English when Cantonese is the dominant language, and it will only occur in certain domains. Below are the two proposals represented in the Crosslinguistic Hypothesis where CLI may occur.

Since the development of the Crosslinguistic Hypothesis, much research has contributed to the understanding of CLI in areas of structural overlap, directionality, dominance, interfaces, the role of input, and the role of processing and production.

In linguistics, language transfer is defined by behaviorist psychologists as the subconscious use of behaviors from one language in another. In the applied linguistics field, it is also known as exhibiting knowledge of a native or dominant language (L1) in one that is being learned (L2). Transfer occurs in various language-related settings, such as acquiring a new language and when two languages or two dialects come into contact. Transfer may depend on how similar the two languages are and the intensity of the conversational setting. Transfer is more likely to happen if the two languages are in the same language family. It also occurs more at the beginning stages of L2 acquisition, when the grammar and lexicon are less developed. As the speaker's L2 proficiency increases, they will experience less transfer.

Jacquelyn Schachter (1992) argues that transfer is not a process at all, but that it is improperly named. She described transfer as "an unnecessary carryover from the heyday of behaviorism." In her view, transfer is more of a constraint on the L2 learners' judgments about the constructions of the acquired L2 language. Schachter stated, "It is both a facilitating and a limiting condition on the hypothesis testing process, but it is not in and of itself a process."

Language transfer can be positive or negative. Transfer between similar languages often yields correct production in the new language because the systems of both languages are similar. This correct production would be considered positive transfer. An example involves a Spanish speaker (L1) who is acquiring Catalan (L2). Because the languages are so similar, the speaker could rely on their knowledge of Spanish when learning certain Catalan grammatical features and pronunciation. However, the two languages are distinct enough that the speaker's knowledge of Spanish could potentially interfere with learning Catalan properly.