This ambitious and stimulating volume arose from a 2005 conference sponsored by the Merrill Advanced Center at the University of Kansas and the Eunice Kennedy Shriver National Institute of Child Health and Development. A principal aim of the conference was to investigate the relationship between specific early language and cognitive abilities and later language outcomes, with a view to informing our understanding of both typical and atypical language development. As Rice argues in the Foreword, few publications in the secondary research literature have attempted to synthesise recent longitudinal data from a variety of research groups, and in this sense the contribution of this volume is particularly timely. Many of the contributors have vigorously taken up the challenge of identifying factors underlying variation in language acquisition. For example, Rice (Chapter 5) explores genetic risk factors in language delay/impairment, Colombo and Colleagues (Chapter 10) chart the relationship between early assessments of attention and later vocabulary growth, Meltzoff and Brooks (Chapter 11) explore correlations between early gaze following and later vocabulary growth, and Kuhl (Chapter 12) reviews a fascinating series of studies suggesting a strong relationship between early speech perception and variety of later language measures such as MLU, sentence complexity and lexical diversity.

A further aim of the conference was to critically assess experimental paradigms used to investigate early linguistic and cognitive abilities, and to encourage methodological innovation. Numerous chapters therefore focus on methodological issues. For example, Cohen and Brunt (Chapter 13) investigate methodological issues in word learning and categorization, describing a new questionnaire designed to test children's object category knowledge prior to their participation in word-learning studies. They also discuss the relative merits of tightly controlled experimental paradigms, such as preferential looking, versus less controlled but more ecologically valid paradigms involving interactions with the experimenter. Chapters by Waxman and Kuhl (7 and 12) are methodologically innovative in that they assess the same language/cognitive abilities using diverse paradigms, ranging from traditional forced-choice tasks to more complex automated paradigms such as eye-tracking and EEGs. Turning to issues of analysis, Gerken (Chapter 4) addresses the complex task of statistically evaluating whether children have made linguistic generalizations in studies where fast-learning children show marked familiarization and novelty effects, while slow-learning children may only demonstrate increasing familiarity. Given the wide range of experimental techniques currently in use, it is important to take stock and critically evaluate these approaches, and this is one task which the volume tackles head on.

The volume is divided into four sections. The first section, entitled ‘Recognizing Patterns’, investigates statistical learning and rule induction in young children, and the acquisition of grammatical morphology in specific language impairment (SLI). The second section, ‘From Patterns to Meaning’, investigates the role of speech perception and infants' knowledge of label–category relationships in word learning. The third section, ‘Predictors of Language Emergence’, explores the relationship between early cognitive abilities, for instance attention, gaze-following and gesture, and later linguistic measures. The final section, ‘Models and Methods to Study Infant Language’, contains a thematically diverse range of chapters dealing with both explanatory models and methodological issues. Below I briefly summarize the chapters, before providing a final appraisal.

The first section, ‘Recognizing Patterns’, begins with a chapter by Aslin and Newport that surveys the statistical learning literature since their preliminary work with Saffran (Saffran, Aslin & Newport, Reference Saffran, Aslin and Newport1996; Saffran, Newport & Aslin, Reference Saffran, Newport and Aslin1996). They explore the difference between first-order statistical learning and second-order statistical learning. While first-order probabilities merely track bigram frequencies – for example, if we put every bigram from an ordered set into a hat, what is the probability of plucking the /s/+/t/ bigram – second-order probabilities are conditional – for instance, if we hear an /s/, what is the likelihood that the next phoneme will be a /t/? They describe the problem of ‘explosive combinatorics’ confronting the statistical learning mechanism and explore ways in which such a mechanism might be constrained by, for example, gestalt principles or social cues. They also point to the limitations of statistical learning, such as adults failing to detect patterns across non-adjacent speech segments. They conclude with a comparison of statistical learning and rule-learning experiments, discussing the possible role of statistical learning in the latter. The following chapter by Saffran summarizes her research on grammatical pattern learning in artificial languages consisting of a set of non-words and a series of rewrite rules. Languages containing predictive dependencies (P-languages) are easier for children to acquire than languages without such dependencies (N-languages). Given that predictive dependencies are a defining characteristic of natural languages (e.g. the definite article predicts the following noun-phrase), Saffran's work suggests that our statistical learning mechanisms may be particularly attuned to the statistical regularities in language. Issues of domain-specificity are investigated by comparing artificial languages consisting of speech and non-speech sounds, and the uniqueness of statistical learning to the human species is investigated by comparing children with cotton-top tamarinds. Gerken investigates infants' capacity to form generalizations in tasks designed to assess the acquisition of syllable structure and morphological paradigms. The chapter discusses what kinds of generalization may be learnt, and how many cues are necessary and sufficient. The final chapter in this section, by Rice, investigates language development in children with specific language impairment. She summarizes factors typically associated with language delay, such as gender and family history, emphasizing the limited role of environmental factors. She then describes her own work on language development in this population using growth-curve analyses, attempting to tease apart those aspects of language which are delayed from those which show a ‘delay-within-a-delay’ characterized by a lower intercept.

The next section, ‘From Patterns to Meaning’, investigates the role of speech perception, social cognition and conceptual development in language acquisition. Werker and Fennell explore the paradox that while many children appear to have acquired a wide range of native phonemic contrasts by the age of fourteen months, they fail at word-learning tasks, which depend on such contrasts (Stager & Werker, Reference Stager and Werker1997). They compare and contrast two models, the Representational Discontinuity model (Brown & Matthews, Reference Brown, Matthews, Hannahs and Young-Scholten1997), which argues that phonemic representations change as a result of lexical learning, and the Resource Limitations approach, which argues that despite sophisticated phonemic inventories children are hampered by the processing demands of word learning. The authors present data in favour of the Resource Limitations approach. The focus then shifts to category knowledge, with Waxman surveying data from a series of experiments inviting children to form object, property and event categories using props and labels such as ‘find the blicket’. Using both a traditional picture/object selection task, and an automated preferential looking task providing eye-tracking data, the chapter tracks the emergence of object, property and event categories in children aged eleven months and above. The following chapter by DeLoache, Ganea and Jaswal explores how early learning is influenced by language. They investigate the link between labelling and tasks such as object individuation, category formation and inductive inference. Further sections assess children's linguistic–cognitive sophistication; for instance, the extent to which they trust the testimony of an unreliable adult, and whether they can update their representation of an absent object. The chapter concludes with research on picture-book interactions, and whether photos or iconic images provide better word-learning contexts.

The third section deals with predictors of language emergence. The first chapter, by Colombo and colleagues, addresses early attentional predictors of vocabulary in childhood. They summarize a variety of psychophysical measures based on combined heart rate and looking times for a simple experimental paradigm whereby infants are shown a series of children's faces. Using these psychophysical measures, the researchers conduct cluster analyses to distinguish groups of children with distinct attentional profiles, and then relate these clusters to later vocabulary and grammatical measures from the MacArthur CDI. The next chapter (Meltzoff and Brooks) investigates the role of gaze following in early word learning, exploring correlations between measures of early gaze following and later vocabulary. The chapter deals with recent experimental studies designed to differentiate between following gaze and following direction of head turn. Goldin-Meadow explores a wide variety of data suggesting that gesture may underpin language learning For example, there is a strong association between the age at which children produce word and gesture combinations, and the onset of two-word utterances. Furthermore, the number of gestures produced at twenty-four months is a strong predictor of later vocabulary.

The final section, entitled ‘Models and Methods to Study Infant Language’, unites a diverse array of papers. Kuhl begins with a fascinating chapter on the relationship between infant speech perception and later language acquisition. She begins by describing the inverse relationship between perception of native and non-native contrasts in young children (7·5 months). Such data suggest that as children tune into native-language contrasts, they simultaneously inhibit non-native contrasts. Children who are quick to tune-in/inhibit demonstrate faster lexical development at later stages. Interestingly, EEG data from a mismatch negativity task showed a similar association. Those children presenting with greater negativity for native language contrasts, and reduced negativity for non-native contrasts, demonstrated faster development across a variety of linguistic domains. Kuhl explains the findings from the perspective of her own model of auditory development, the Native Language Magnet – Expanded (Kuhl, Conboy, Coffey-Corina, Padden, Rivera-Gaxiola & Nelson, Reference Kuhl, Conboy, Coffey-Corina, Padden, Rivera-Gaxiola and Nelson2008). The following chapter by Cohen and Brunt explores early word learning and categorization. As mentioned above, this chapter deals with a host of methodological issues involved in early word-learning studies, for example, the trade-off between experimental control and ecological validity, ways of controlling for the past experience of the child, techniques to disentangle novelty and familiarity effects, and designs which can isolate the role of social referencing. Marcus and Rabagliati take an evolutionary perspective to address the paradox that while language performance clearly correlates with performance in other domains, some cases exist, such as certain cases of SLI, which demonstrate a sharp dissociation between language and cognition. The answer may lie in ‘descent with modification’, the gradual accrual over generations of mutations which provide an evolutionary advantage. This process explains how organs or traits with a common genetic origin may diversify over time. Hands and feet, for example, develop under the influence of an overlapping set of genes, but in humans these organs have become more functionally specialized. Language and cognition may have followed a similar trajectory, which, according to Marcus and Rabagliati, may account for the paradox of population-wide association, yet occasional intra-individual dissociation. The authors construct an intriguing argument which they hope may unite researchers from disparate theoretical backgrounds in pursuit of a common goal. Chapter 15 briefly summarizes an exciting and ambitious programme of research using MRI to develop a map of whole-brain and regional brain structures during development, using data collected from sleeping as opposed to sedated infants. By mapping and understanding natural variability, that is, anatomical variation which is not manifested at the behavioural level, we will be in a better position to identify and understand developmental disorders. The final chapter (MacCardle, Freund and Marcus) summarizes the research described in the volume and maps out future challenges.

Overall, this is an extremely diverse volume covering a wide variety of theoretical models and research paradigms. Read from front to back there is often little thematic relationship between one chapter and next, and the book is clearly not designed as an introduction to any particular subfield of language acquisition. Some of the chapters are quite condensed, possibly due to word limits, and may be difficult for a reader who is not well-read in the relevant area. For example, Chapter 4 refers to Bayesian approaches to generalization, but only provides a three-line summary of this particular model of induction. Nonetheless, the volume is an important resource for any researcher in the field of early language acquisition, or anyone with an interest in cognitive factors affecting language development, and should therefore be considered a vital addition for most university libraries. Almost all the chapters provide a valuable overview of theoretical and methodological issues and possible future developments. They therefore serve as gateways to the wider research literature, either for the researcher who wishes to update their knowledge of their own field, or for researchers wishing to investigate another field. The volume certainly succeeds in its aim to bring recent longitudinal research to a wider audience, and foster the critical analysis and development of new research paradigms. It should prove an inspiration for future developments in both theory and methodology.