This chapter overviews broad issues related to language acquisition research and answers fundamental questions related to first language acquisition, such as What is language? and How do children learn their first language? It begins by introducing some components of language, such as grammar, vocabulary, pronunciation, pragmatics, and discourse. It also discusses language varieties (e.g., American English vs. Indian English) and explains their legitimacy. Then, the chapter addresses language learning during the first years of a child’s life. It also discusses bilingualism, especially of those who start learning multiple languages in their early years (simultaneous bilingualism). In order to understand second language acquisition for the rest of the textbook, the chapter focuses on a question: How are children able to learn a language without formal instruction? In order to answer this question, multiple language acquisition theories will be discussed.

Chapter 1 provides an overview of the major topics in linguistics and second language acquisition (SLA) that are particularly relevant for research with second language learners. The first half of Chapter 1 sets out the foundational concepts, and defines such major terms as linguistics, second language acquisition, and heritage speakers. The chapter addresses such influences on language acquisition as age of acquisition and input quantity and quality, comparing and contrasting different types of learner population (monolingual vs. bilingual, first language vs. second language learners vs. heritage speakers). The chapter provides a brief introduction to generative linguistics and generative SLA, discussing evidence for the biological foundations of language and for Universal Grammar. In the second half of Chapter 1, the discussion moves on to the implicit vs. explicit distinction, which is manifested in second language learning, knowledge, and instruction, and which is relevant both to the nature of teaching interventions and to the measurement of learners’ resulting knowledge.

This assessment of studies of Arabic child language acquisition shows the inescapable influence of diglossia on approaches to such study and its effects on children acquiring Arabic. Observing that studies of the acquisition of Arabic as a first language are necessary but lacking, they also note with some irony that some of the studies that have been conducted, of which investigations into the phonological development of Arab children are the most numerous, examine children’s spoken productions of the formal Arabic of writing and declamation, which includes sounds not shared by their native dialects of Arabic. While agreeing that it is necessary to consider children’s attention to the phonology of MSA as an integral dimension of their Arabophone environment and therefore part of the phonological repertoire of their native dialects, they also lament the dearth and small size of studies investigating native dialect acquisition. After phonology, much of the chapter is devoted to assessing the implications of Arabic root-and-pattern morphology in child recognition and acquisition of Arabic morphosyntax and the intriguing findings of such few studies that address such matters as, for example, the acquisition of gender and case marking.

This first chapter introduces the notions of theory of mind from cognitive psychology and the one of intersubjectivity from linguistics. It introduces the new speaker-centred notion of co-actionality. It provides an overview of the literature of both domains and finally defines the desiderata for a new gradient approach to analyse speakers’ ability to project their interlocutors’ potential reactions to what is being currently said. It lists a number of assumptions that will be discussed and empirically supported throughout the book: (1) Theory of Mind is communicated through overt intersubjective strategies and/or constructions, which vary in degrees of complexity. (2) Intersubjectivity is expressed linguistically as extra-propositional surplus of meaning that is additional to the perlocutionary effects of a linguistic act. (3) There is a unidirectional pathway of increased complexity of social cognition, ranging from co-actionality, to immediate intersubjectivity (I-I) to extended intersubjectivity (E-I). (4) This increasing complexity matches the evolutionary shift from dyadic to triadic and finally to collective intentionality. This cline can be traced both in language change and ontogenetic development. (5) Neuro-typical adult interactionis however includes utterances sometimes underpinning mere co-actionality, yet mostly hinging on immediate intersubjectivity and extended intersubjectivity. (6) Language change is an important indicator of a cognitive tendency toward polysemy and increasingly complex interactional functions that subserve human needs in a community of practice.

This chapter is centred on interlocutors’ ability to spontaneously construe intersubjectified utterances throughout ontogeny and first language acquisition. The diachronic continuum illustrated in Chapter 3 is also at stake throughout children’s ontogenetic development. Children acquire the capacity to spontaneously express immediate intersubjectified (I-I) polysemies of a lexeme before they develop the skills to convey extended intersubjectified usages (E-I) of the same form. In Section 4.1 I introduce the application of the gradience model in first language acquisition and theory of mind research with reference to children's usage of the Italian construction guarda ‘look’. Section 4.2 focuses on the Mandarin construction 你看 nǐkàn ‘look, you see’ and the way new intersubjectified polysemies of 你看 nǐkàn (hinging on mirativity and opinion elicitation), significantly emerge at later stages of development than directive usages of the same form. In section 4.3 I discuss the acquisition of the Mandarin post-verbal 过 guo. Interpersonal evidential polysemies of 过 guo are spontaneously mastered by children around the seventh year of age, e.g. comparatively later than other usages of the same form. Section 4.4 is finally dedicated to the first language acquisition of the pre-nominal such and children’s progressive ability to use express generic reference to objects, entities and events to which they ascribe collective recognition. This extended intersubjective function of such emerges later than other polysemies of the same form aimed at merely establishing joint attention.

This chapter lays the foundation for how the field of second language acquisition arose. We briefly review the pioneering work in the late 1950s and 1960s in first language acquisition (e.g., Berko Gleason, Brown, Klima & Bellugi). We also review the generative revolution in linguistics and how it laid the groundwork for the idea of constrained language acquisition. We then review the seminal articles by S. Pit Corder (1967) and Larry Selinker (1972) that posited the major questions in second language acquisition, and end with the pioneering work that mirrored first language acquisition (e.g., Dulay & Burt, Krashen, Wode). We end the chapter with the major question that launched second language research in the early 1970s: Are first and second language acquisition similar or different?

Phonological acquisition and the milestones associated with it have been an important testing ground for theoretical claims since the inception of generative phonology, and the theme of this chapter builds on those from previous chapters. We have described how a sign language phonological system is influenced by the visual modality and by iconicity, how it is processed and how it emerges. We now add data from sign language acquisition to this picture, asking what evidence there is for the units proposed so far in the phonological system of a child or infant.

Typical first-language (L1) phonological acquisition is a critical piece in any child’s development as she makes contact with the world, and as we will see, it is also an important stepping-stone for reading. We also address acquisition in several other circumstances where sign language is acquired, as it pertains to second-language (L2) learners, late learners of an L1, and bilingual development. These populations are unique in ways that will become clear as they are introduced throughout the chapter.

This chapter presents empirical studies that have tested children’s ability to understand implicatures. It starts with the category of relevance implicatures, before moving to scalar implicatures. In both cases, the conclusion is that even young children during the preschool years have the ability to derive implicatures when the task is kept simple enough. The chapter then presents studies that have focused on cases of atypical development, such as autism spectrum disorders, SLI and deafness.

This chapter starts by summarizing the predictions made by various theories of implicature that have consequences for language processing. It then presents empirical evidence bearing on a number of questions related to the processing of implicatures, namely: their processing cost, the difference between particularized and generalized implicatures, the role of mental state attribution for the derivation of implicatures, the role of politeness for the derivation of implicatures.