Reviewed by Julia Herschensohn, University of Washington
This volume, an official publication of the International Association for the Study of Child Language that aims to ‘present cutting edge work which is likely to stimulate further research’ (ix), explores the use of behavioral and neurological approaches to study early language processing. The ten articles provide comparisons of more traditional paradigms such as high amplitude sucking and head turn to the recent neurological technique involving event related potentials (ERPs), showing how the two approaches complement each other in describing young children’s acquisition of phonemic discrimination, prosodic boundaries, lexical recognition, and morphosyntax.
Claudia Männel’s introductory tutorial sets the frame for subsequent chapters by describing the physiology, methodology, advantages, and disadvantages of ERPs for studying early language. Language processing induces neurological electrical impulses that can be recorded in ERP measures derived from electroencephalography (EEG); ERPs document the brain’s electrical activity from scalp-attached electrodes that record neurons responding en masse to a given stimulus. Responses are measured in terms of positivity/negativity, latency (measured in milliseconds), hemispheric location in the brain, and functional significance. Distinct responses mark different components of language processing, e.g. mismatch negativity (MMN, 100-250 ms) to phonetic distinction, the N400 (400 ms) to lexico-semantic properties; and the P600 (600-1000 ms) to syntactic anomalies. Männel notes that while ERPs are difficult to record from young children because of limited attention, stamina, and verbal skills, ERPs are advantageous in not requiring instructions or motor responses—the children passively take in the stimuli while their brain activity is recorded.
The remaining articles document ERP research on early language, showing how it provides additional evidence for the developmental stages identified by behavioral methods: establishment of the native phonemic inventory and prosodic patterns in year one, word segmentation and linking of form and meaning in year two, and mastery of phrase structure and morphology in years three and four. The studies covering English, French, Welsh, Spanish, Dutch, and German provide evidence for finer tuning of developmental chronology and for emergence of adult-like neural responses. For example, Manuela Friedrich documents a convergence of fast mapping (the vocabulary spurt of toddlers) with the appearance of the N400 neural response, leading her to suggest ‘the maturation of the N400 and the development of the fast mapping ability might reflect a causal relationship between N400 neural mechanisms and children’s word learning capacity’ (157).
The final chapter by David Poeppel and Akira Amaki gives an excellent summary of the findings presented in the volume, but it also warns of challenges accompanying the benefits of ERP research. They point out that much neurocognitive work is correlative with behavioral studies, but may not enrich our understanding of how development and cognition work. They note that interpretation of child ERP data is particularly problematic since its deviance from well-documented adult patterns is not easily explained. They conclude, however, that the ‘much richer information about the time course and distribution of neural activities’ (245) allows better comparisons of adult and child processing and hence of language development.