The first stage of combinatorial speech is better described as variable than uniform. Talk of variants obscures two different aspects of language (knowledge and use) and two different aspects of language development -- acquisition of the grammar (competence) and deployment of the grammar in speaking and listening (performance). Null subjects and…

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 commentary critiques Ambridge's radical exemplar model of language acquisition using research from the Longitudinal Study of Early Language, which has tracked the language development of 30+ children with Autism Spectrum Disorders (ASD) since 2002. This research has demonstrated that the children's capacity for abstraction at the grammatical…

Professor of Second Language Acquisition (SLA) Robert DeKeyser is from the School of Languages, Literatures, and Cultures at the University of Maryland. His research builds bridges between the theory of second language acquisition with major concerns in cognitive aspects such as implicit and explicit learning mechanism, age differences, and…

This article offers commentary that the Multiple Grammar (MG) language acquisition theory proposed by Luiz Amaral and Tom Roeper (A&R) in the present issue lacks elaboration of the psychological mechanisms at work in second language acquisition. Topics discussed include optionality in a speaker's grammar and the rules of verb position in…

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…

In this commentary, the author defends the Multiple Grammars (MG) theory proposed by Luiz Amaral and Tom Roepe (A&R) in the present issue. Topics discussed include second language acquisition, the concept of developmental optionality, and the idea that structural decisions involve the lexical dimension. The author states that A&R's…

This article offers the author's commentary on the Multiple Grammars (MG) language acquisition theory proposed by Luiz Amaral and Tom Roeper in the present issue. Multiple Grammars advances the claim that optionality is a constitutive characteristic of any one grammar, with interlanguage grammars being perhaps the clearest examples of a…

This article offers commentary on the Multiple Grammars (MG) language acquisition theory proposed by Luiz Amaral and Tom Roeper in this issue. It argues that more precise definitions are needed for the terms "rule," "simple," and "productive." Topics discussed include Amaral and Roeper's verb second (V2) rule,…

Amaral & Roeper's Multiple Grammars (MG) proposal offers an appealingly simple way of thinking about the linguistic representations of bilingual speakers. This article presents a commentary on the MG language acquisition theory proposed by Luiz Amaral and Tom Roeper in this issue, focusing on the theory's implications for child…

Optionality is a central phenomenon in second language acquisition (SLA), for which any adequate theory must account. Amaral and Roeper (this issue; henceforth A&R) offer an appealing approach to it, using Roeper's Multiple Grammars Theory, which was created with first language in mind but which extends very naturally to SLA. They include…

This article offers the author's commentary on the Multiple Grammar (MG) language acquisition theory proposed by Luiz Amaral and Tom Roeper in the present issue and touches on other second language acquisition research. Topics discussed include the concept of second language (L2) optionality, a hypothesis regarding the acquisition of the…

In this response to Demestre's comment, we first discuss the terms "legal" and "prohibited," applied to syntactic structures, stressing that there are boundaries in which the legality of certain constructions appears imprecise and is a matter of discussion. This coalesces with actual and daily use by native speakers of a language, who can normally…

This article questions how two very similar sets of experiments can yield such very different findings, and comments on the differences between the studies. Here Annamarie Kerkhoff presents a commentary on some perceived differences between the studies in areas such as age groups and group sizes evaluated. Kerkhoff also comments on some…

The article by Amaral and Roeper (this issue; henceforth A&R) presents many interesting ideas about first and second language acquisition as well as some experimental data convincingly illustrating the difference between production and comprehension. The article extends the concept of Universal Bilingualism proposed in Roeper (1999) to second…