This special issue revisits a classic topic in linguistic theory, A-bar movement, applied to developing and bilingual grammars. We claim that A-bar movement, or filler-gap dependencies, is still the quintessential linguistic phenomenon to illustrate the interaction between the biological endowment, the experience with language (past and present),…

Third language (L3) lexical acquisition is still underexplored. In this article I overview theoretical and empirical evidence on L3 lexical acquisition and the role of cross-linguistic influence (CLI) in learning L3 words. I explain the mechanism of CLI as resulting from language co-activation in the multilingual learner's/user's mind.…

Research on multilingualism and the acquisition of language(s) faces numerous challenges given its inherently interdisciplinary character. This discussion will focus on the notion of internal context, a concept that forcefully demonstrates the need for integrating linguistically-oriented research with cognitive research in general. Investigating…

In this commentary, I question Westergaard's argument that third language (L3) data can be used to decide between theories such as Full Transfer Full Access, involving wholesale transfer initially, and Full Transfer Potential, involving property-by-property transfer. I suggest that much L3 data will be amenable to explanation under either theory.…

This article is a response to commentaries on the article, "Microvariation in Multilingual Situations: The Importance of Property-by-Property Acquisition" (EJ1300541). This response is divided into sections focusing on the following issues: (1) full transfer and the notion of copying; (2) the definition of linguistic proximity; (3) some…

The present systematic review examines what factors determine when, how and to what extent previous linguistic experience (from the first language, second language or both languages) affects the initial stages and beyond of adult third language (L3) acquisition. In doing so, we address what a bird's eye view of the data tells us regarding…

In this article, I argue that first language (L1), second language (L2) and third language (L3) acquisition are fundamentally the same process, based on learning by parsing. Both child and adult learners are sensitive to fine linguistic distinctions, and language development takes place in small steps. While the bulk of the article focuses on…

This commentary discusses Westergaard's (2021) keynote article, which presents a comprehensive model of first language (L1), second language (L2), and third language (L3) acquisition. The commentary presents evidence from a previous study of L3 learners that provides support for Westergaard's property-by-property transfer proposal. The commentary…

Amaral and Roeper (this issue; henceforth A&R) argue that all speakers -- regardless of whether monolingual or bilingual -- have multiple grammars in their mental language representations. They further claim that this simple assumption can explain many things: optionality in second language (L2) language behaviour, multilingualism, language…

This paper presents an extension of the Multiple Grammars Theory (Roeper, 1999) to provide a formal mechanism that can serve as a generative-based alternative to current descriptive models of interlanguage. The theory extends historical work by Kroch and Taylor (1997), and has been taken into a computational direction by Yang (2003). The proposal…

Several studies on L3 lexicon, and recently also some on L3 syntax, have convincingly shown a qualitative difference between the acquisition of a true L2 and the subsequent acquisition of an L3. Some studies even indicate that L2 takes on a stronger role than L1 in the initial state of L3 syntax (e.g. Bardel and Falk, 2007; Rothman and Cabrelli…

The present article addresses the following question: what variables condition syntactic transfer? Evidence is provided in support of the position that third language (L3) transfer is selective, whereby, at least under certain conditions, it is driven by the typological proximity of the target L3 measured against the other previously acquired…

This article addresses the role of previously acquired languages in the acquisition of a third language (L3) in two experimental studies on object expression in Brazilian Portuguese (BP). Participants were English-speaking learners of BP as L3 with knowledge of Spanish as a second language (L2) and Spanish-speaking learners of BP with knowledge of…

In this review article it is argued that while the number of neuro-imaging (NI) studies on multilingual processing has exploded over the last few years, the contribution of such studies to enhance our understanding of the process of multilingual processing has not been very substantial. There are problems on various levels, which include the…

This study investigates transfer at the third-language (L3) initial state, testing between the following possibilities: (1) the first language (L1) transfer hypothesis (an L1 effect for all adult acquisition), (2) the second language (L2) transfer hypothesis, where the L2 blocks L1 transfer (often referred to in the recent literature as the "L2…