Does childhood language experience help adult learners?

Two studies compared first-ti me adult learners of Korean/Spanish to re-learners with different kinds of prior experience, STUDY 1: 18 adult native English speakers were tested on their grammaticality judgement and production of Korean after a first-year college-level Korean course. They included 3 fluent speakers, 6 limited speakers (spoke for several years during early childhood), 2 addressees (were spoken to only), 4 overhearers, and 3 first-time learners. Only large effects (effect sizes >.8) are reported here. FINDINGS: (1) The re-learners comprehended words involving a tense or lax consonant better than the first-time learners. (2) The re-learners were better than the first-time learners at making grammaticality judgements regarding subject versus object case markers. STUDY 2:31 adult native English speakers, upon finishing a first-year college-level Spanish course, were tested on grammaticality judgement (listening) and whole-sentence production of Spanish (3 fluent speakers, 2 limited speakers, 2 addressees, 4 overhearers, 15 high-school learners, 5 first-time learners). FINDINGS: The re-learners exposed to Spanish during childhood outperformed those who began to learn Spanish late (in high school or college) in morphosyntax (e.g., agreement, case marking, verb morphology). Re-learners with prior speaking experience (during childhood or high school) had better whole-sentence pronunciation. These studies suggest that childhood experience with a language - even if incomplete and/or discontinued - helps adults learn what is typically most challenging to late learners (e.g., phonology, morphosyntax). By focusing on the benefits of early experience, this work complements studies of linguistic deprivation that focus on what cannot be learned readily beyond childhood. These findings bear on theoretical issues such as language acquisition without negative feedback (e.g., through overhearing and/or being spoken to) and applied issues such as whether language experience - at home or at school - for young children could have lasting and measurable benefits.