Salvaging a Childhood Language.

Childhood experience with a language seems to help adult learners speak it with a more native-like accent. Can analogous benefits be found beyond phonology? This study focused on adult learners of Spanish who had spoken Spanish as their native language before age 7 and only minimally, if at all, thereafter until they began to re-learn Spanish around age 14 years. They were compared with native speakers, childhood overhearers, and typical late-second-language (L2)-learners of Spanish. Both childhood speakers and overhearers spoke Spanish with a more native-like accent than typical late-L2-learners. On grammar measures, childhood speakers-although far from native-like-reliably outperformed childhood overhearers as well as typical late-L2-learners. These results suggest that while simply overhearing a language during childhood could help adult learners speak it with a more native-like phonology, speaking a language regularly during childhood could help re-learners use it with more native-like grammar as well as phonology.

Production benefits of childhood overhearing.

The current study assessed whether overhearing Spanish during childhood helps later Spanish pronunciation in adulthood. Our preliminary report based on a subset of the data [Au et al., Psychol. Sci. 13, 238-243 (2002)] revealed that adults who overheard Spanish during childhood had better Spanish pronunciation, but not better morphosyntax, than adult learners of Spanish who had no childhood experience with Spanish. We now present data from the full sample with additional morphosyntax and pronunciation assessments, as well as measures to help rule out possible confounding prosodic factors such as speech rate, phrasing, and stress placement. Three groups of undergraduates were compared: 15 Spanish-English bilinguals (native Spanish speakers), 15 late learners of Spanish who overheard Spanish during childhood (childhood overhearers), 15 late learners of Spanish who had no regular experience with Spanish until middle or high school (typical late L2 learners). Results confirmed a pronunciation advantage for the childhood overhearers over the typical late L2 learners on all measures: phonetic analyses (VOT and degree of lenition), accent ratings (phoneme and story production), but no benefit in morphosyntax. Importantly, the pronunciation advantage did not seem attributable to prosodic factors. These findings illustrate the specificity of overhearers' advantage to phonological production.

Holding on to childhood language memory.

While early language experience seems crucial for mastering phonology, it remains unclear whether there are lasting benefits of speaking a language regularly during childhood if the quantity and quality of speaking drop dramatically after childhood. This study explored the accessibility of early childhood language memory. Specifically, it compared perception and production of Korean speech sounds by childhood speakers who had spoken Korean regularly for a few years during childhood to those of two other groups: (1) childhood hearers who had heard Korean regularly during childhood but had spoken Korean minimally, if at all; and (2) novice learners. All three groups were enrolled in first-year college Korean language classes. Childhood speakers were also compared to native speakers of Korean to see how native-like they were. The results revealed measurable long-term benefits of childhood speaking experience, underscoring the importance of early language experience, even if such experience diminishes dramatically beyond childhood.

Overhearing a language during childhood.

Despite its significance for understanding of language acquisition, the role of childhood language experience has been examined only in linguistic deprivation studies focusing on what cannot be learned readily beyond childhood. This study focused instead on long-term effects of what can be learned best during childhood. Our findings revealed that adults learning a language speak with a more native like accent if they overheard the language regularly during childhood than if they did not. These findings have important implications for understanding of language-learning mechanisms and heritage-language acquisition.