Language use is a skill that requires exposure to language, feedback on usage, and practice. So children need exposure from expert speakers, feedback on the language being acquired, and on any errors children produce, and practice along the way. Languages differ, so the paths children follow within and across languages may vary, and some constructions may be harder to acquire in one language, easier in another. The goal is to learn to use language for communication. Language is essentially social, relying on common ground. Part I (Chapters 2-6) focusses on how adults talk with children; children’s analysis of the speech stream; their first production of words; and how they assign meanings to words. Part II (Chapters 7-11) focusses on children’s acquisition of structure: elaborations of information inside clauses, and combinations of clauses. They also rely on structure when coining new words. Part III (Chapters 12-14) looks at turn-taking, learning to be polite, persuasive, and informative, and how to tell stories. Children who hear two languages have two such systems to learn. Part IV (Chapters 15-16) summarizes evidence for biological specialization for language and considers how continuity and change are reflected in language processing.

Children’s first words may bear little resemblance to adult forms (/ga/ for squirrel), and they may at first produce multiple versions of words. Mastering adult pronunciations takes time and practice. Babbling allows practice with some sounds, but those sounds may only appear in words years later. Early vocalizations, at times paired with gestures, often precede recognizable words. And children take time before they can produce versions that match adult productions. Some 70% of children’s words up to age four are inaccurate and variable in form. Children may select some word forms over others in production because they are easier targets. They simplify words by substituting sounds they can manage; they assimilate some sounds to neighboring ones; they omit some sounds, especially in clusters. And they may set up templates for multisyllabic words, focussing on stressed syllables over unstressed ones. As they get older, they make spontaneous repairs to words that don’t match their stored representations, and also repair when asked by others. Finally, they practice words, to themselves, and in their daily language use. Single words are easier than word combinations, so longer utterances take still more practice.

As children add words, they also add more specificity to their utterances, hence more complexity. They start to combine words with gestures, then words with other words. They advance from one word at a time to sequences of words and then combine these under the same intonation contour. The early composition of children’s vocabulary is strongly affected by adult input, and this may determine the proportions of nouns, verbs, and adjectives available to children early on. Their early constructions are limited in scope, tied to specific lexical items. Conversational exchanges at this stage often depend on adult scaffolding. Children distinguish ‘given’ from ‘new’ information, making use of word order and stress, as well as information from inflections, to identify word classes. Early word combinations in their first constructions are very similar across languages in the meanings expressed. Early combinations may be viewed as frozen forms, as intermediate forms, and as constructed forms, depending on their history in each child’s speech. Children learn to put together new combinations as they talk with adults and so discover more of the options in the language being acquired.

How do children process language as they get older? Is there continuity in the functions assigned to specific structures? And what changes in their processing and their representations as they acquire more language? They appear to use bracketing (finding boundaries), reference (linking to meanings), and clustering (grouping units that belong together) as they analyze the speech stream and extract recurring units, word classes, and larger constructions. Comprehension precedes production. This allows children to monitor and repair production that doesn’t match the adult forms they have represented in memory. Children also track the frequency of types and tokens; they use types in setting up paradigms and identifying regular versus irregular forms. Amount of experience with language, (the diversity of settings) plus feedback and practice, also accounts for individual differences in the paths followed during acquisition. Ultimately, models of the process of acquisition need to incorporate all this to account for how acquisition takes place.

Children’s first words are remarkably consistent over languages and over time: They first talk about people (dada, mama), food (juice), body-parts (eye), clothing (sock), animals (dog), vehicles (car), toys (ball), household objects (key), routines (bye), and activities (uhoh, up). Their first productions emerge between 12 months and 24 months, and they attain some 50 words in production about 6 months later. Earlier claims about a vocabulary spurt may rather reflect increased motor skill that aids production. Do children learn to produce nouns before verbs? The proportions of nouns and verbs differ by context, e.g., toy play versus book reading. Spontaneous speech samples and parental checklists of vocabulary often differ. Overall, production lags behind comprehension. This leads to communicatively driven overextensions in production until 2;6 or so, as well as reliance on general purpose terms (do, go, that). As children add more words, they stop using earlier overextensions. Early word meanings are based on children’s existing conceptual and perceptual categories, based on their experience of the world so far. And as they take different perspectives, they begin to use of different words for the same referent (animal, dog, pug; do, mend).

Children add more information to their utterances by packing more material into a single clause. They can specify roles, modify nouns with adjectives and verbs with added locatives and adverbs. They can add demonstratives (those) and quantifiers (many) to nouns, and make clearer what they are referring to. Young children’s early constructions tend to mirror parental usage, just as their lexical choices do. They follow preferred argument structure and place given information in the Agent slot of transitive verbs, and keep the Object slot of transitives and the Subject slot of intransitives for new information. They may omit given information at this stage and only later add the relevant pronoun subjects. In both questions and negations, they take time to master the use of auxiliary verbs and rely on fixed “frames” for some time as they learn the meaning of each wh- question word. Children also take time in learning how different perspectives can be marked within the clause, with choices of causative, location, or voice alternations. Here children must learn the options verb by verb.

Young children often lack words for what they want to talk about. To fill the gaps in their lexicon, they coin new words. They rely on compounding and derivation to do this. This means identifying and analyzing parts of words – roots or stems, and affixes – and learning their meanings, as well as which combinations are possible. Some languages favor compounding and some derivation in word formation. Children are sensitive to which options are the most productive and adopt those first. Two-year-olds offer analyses of word meanings, as in running-stick (I run with it) or high-chair (it is high), and provide analyses of novel compounds where they take account of language structure (head noun first in Hebrew, second in English). They also analyze derived forms with agentive endings. They start to produce novel words from as young as age two, whether compounds in Germanic languages, or derived forms in Romance and Semitic. They begin with simple forms (minimal or no change to the root), advance to compound or derived word forms that are transparent in meaning, and opt for the most productive options in the adult language, with the goal of finding the right words to convey the child-speaker’s meaning.

Infants attend to speech, even before birth, preferring what they heard in utero over another language. In the first months, they can identify certain sounds as the same. (Other species also display categorical perception of sounds.) By 7 to 8 months, infants can identify recurring sequencies of both nonsense syllables and real words. Measures used include high-amplitude sucking, head-turn preferences, and visual fixation. In segmenting speech, infants face two problems: variation in speakers’ word uses, and which sounds to group as the same. They can also recognize a few words. By 9 to 10 months, infants attend more to distinctions in the ambient language than distinctions outside that language, and appear sensitive to legal clusters of sounds that begin and end syllables. They also prefer the prosodic stress patterns of the ambient language and so can use multiple cues to possible word-boundaries. By age three and later, children manage to recognize words even when spoken in another dialect or with a foreign accent. Their recognition of words at age three shows their representations in memory are adultlike, and not based on their own productions. They store representations of words in memory for recognizing words from other speakers, and as targets for their own production.

This concise and rigorous textbook introduces students to the subject of continuum thermodynamics, providing a complete treatment of the subject with practical applications to material modelling.

• Presents mathematical prerequisites and the foundations of continuum mechanics, taking the student step-by-step through the subject to allow full understanding of the theory.

• Introduces more advanced topics such as theories for the investigation of material models, showing how they relate to real-world practical applications.

• Numerous examples and illustrations, alongside end-of-chapter problems with helpful hints, help describe complex concepts and mathematical derivations.