title: The acceleration of spoken-word processing in children's native-language acquisition: an ERP cohort study.
abstract: Healthy adults can identify spoken words at a remarkable speed, by incrementally analyzing word-onset information. It is currently unknown how this adult-level speed of spoken-word processing emerges during children's native-language acquisition. In a picture-word mismatch paradigm, we manipulated the semantic congruency between picture contexts and spoken words, and recorded event-related potential (ERP) responses to the words. Previous similar studies focused on the N400 response, but we focused instead on the onsets of semantic congruency effects (N200 or Phonological Mismatch Negativity), which contain critical information for incremental spoken-word processing. We analyzed ERPs obtained longitudinally from two age cohorts of 40 primary-school children (total n=80) in a 3-year period. Children first tested at 7 years of age showed earlier onsets of congruency effects (by approximately 70ms) when tested 2 years later (i.e., at age 9). Children first tested at 9 years of age did not show such shortening of onset latencies 2 years later (i.e., at age 11). Overall, children's onset latencies at age 9 appeared similar to those of adults. These data challenge the previous hypothesis that word processing is well established at age 7. Instead they support the view that the acceleration of spoken-word processing continues beyond age 7.
authors.affiliation: Department of Language Sciences, Graduate School of Humanities, Tokyo Metropolitan University, Minami-Osawa, Hachioji, Tokyo 192-0397, Japan; Research Institute of Science and Technology for Society (RISTEX), Japan Science and Technology Agency (JST), Nibancho, Chiyoda-ku, Tokyo 100-0004, Japan; Centre for Advanced Research on Logic and Sensibility, Global COE Program, Graduate School of Human Relations, Keio University, Minato-ku, Tokyo 108-0073, Japan.
authors.forename: Shiro
authors.initials: S
authors.lastname: Ojima
authors.affiliation: Research Institute of Science and Technology for Society (RISTEX), Japan Science and Technology Agency (JST), Nibancho, Chiyoda-ku, Tokyo 100-0004, Japan.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Matsuba-Kurita
authors.affiliation: Department of Language Sciences, Graduate School of Humanities, Tokyo Metropolitan University, Minami-Osawa, Hachioji, Tokyo 192-0397, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Nakamura
authors.affiliation: Department of Language Sciences, Graduate School of Humanities, Tokyo Metropolitan University, Minami-Osawa, Hachioji, Tokyo 192-0397, Japan; Research Institute of Science and Technology for Society (RISTEX), Japan Science and Technology Agency (JST), Nibancho, Chiyoda-ku, Tokyo 100-0004, Japan. Electronic address: hagiwara@tmu.ac.jp.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Hagiwara
mesh_terms: D000367:Age Factors; D000704:Analysis of Variance; D058256:Brain Waves / Q000502:physiology; D002648:Child; D015331:Cohort Studies; D004569:Electroencephalography / Q000379:methods; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006801:Humans; D007802:Language; D007804:Language Development; D008297:Male; D011930:Reaction Time / Q000502:physiology; D014825:Vocabulary