The "wanna" facts are a classic Poverty of Stimulus (PoS) problem: "Wanna" is grammatical in certain contexts ("Who do you want PRO to play with?") but not others ("Who do you want who[strikethrough] to play with you?"). On a standard analysis, "contraction" to "wanna" is blocked by some…

Heritage languages (HLs) are acquired in contexts of unbalanced input, or situations in which children receive primary exposure to the family/HL and experience an abrupt shift after the child begins formal schooling. As a consequence, HL speakers normally become more dominant in the environmental language, while the development of the HL is…

This special issue contains reports of research on a variety of variables that are hypothesized to have an impact on how practice affects language learning. This includes spacing of practice opportunities, the provision of feedback, training working memory, and oral versus written input. Each study is complex and clearly contextualized within the…

The words in children's language learning environments are strongly predictive of cognitive development and school achievement. But how do we measure language environments and do so at the scale of the many words that children hear day in, day out? The quantity and quality of words in a child's input are typically measured in terms of total amount…

Beginning with the classic work of Shepard, Hovland, & Jenkins (1961), Type II visual patterns (e.g., exemplars are large white squares OR small black triangles) have held a special place in investigations of human learning. Recent research on Type II "linguistic" patterns has shown that they are relatively frequent across languages…

The 'root infinitive' phenomenon in child speech is known from major languages such as Dutch. In this case study, a child acquiring the Papuan language Nungon in a remote village setting in Papua New Guinea uses two different non-finite verb forms as predicates of main clauses ('root' contexts) between ages 2;3 and 3;3. The first root non-finite…

The concept of an output-driven map formally characterizes an intuitive notion about phonology: that disparities between the input and the output are introduced only to the extent necessary to satisfy restrictions on outputs. When all of the grammars definable in a phonological system are output-driven, the implied structure provides significant…

Historically, first language acquisition research was a painstaking process of observation, requiring the laborious hand coding of children's linguistic productions, followed by the generation of abstract theoretical proposals for how the developmental process unfolds. Recently, the ability to collect large-scale corpora of children's language…

Adult second language (L2) learners often experience difficulty with novel L2 phonological contrasts, limiting their ability to establish contrastive lexical representations of L2 words. It has been demonstrated that the availability of orthographic input (OI), and variables interacting with OI, can shape the inferences learners make about L2…

A generative approach to language acquisition is no different from any other in assuming that target language input is crucial for language acquisition. This discussion note addresses the place of input in generative second language acquisition (SLA) research and the perception in the wider field of SLA research that generative SLA…

An evaluation measure (EM) guides a learner's choice of grammar when more than one is compatible with available input. EM must be universal, so children receiving comparable input acquire comparable grammars. It must favor the choices children actually make. The theoretical shift from rule-based grammars to principles-and-parameter-based grammars…

It has long been recognized that there is a natural dependence between theories of knowledge representation and theories of knowledge acquisition, with the idea that the right knowledge representation enables acquisition to happen as reliably as it does. Given this, a reasonable criterion for a theory of knowledge representation is that it be…

This paper presents an argument for how second language acquisition (SLA) research should be carried out if a researcher is genuinely interested in learner grammar (i.e., knowledge of language), its acquisition and use. SLA research has expanded greatly over many years and currently spans many subfields, but researchers share one main goal: to…

There has been a great deal of research on first language (L1) and second language (L2) learning through meaning-focused input since Nagy, Herman & Anderson's (1985) seminal study of incidental vocabulary learning through reading. Two strands of research within this area are incidental vocabulary learning through listening and guessing from…

We present a framework of second and additional language (L2/L"n") acquisition motivated by recent work on socio-indexical knowledge in first language (L1) processing. The distribution of linguistic categories covaries with socio-indexical variables (e.g., talker identity, gender, dialects). We summarize evidence that implicit…