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 longterm effects of what can be learned best during childhood. Our findings revealed that adults learning a language speak with a more nativelike
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.
The prevailing wisdom is that children cannot learn a language by merely overhearing it (Pinker, 1994; Rice, 1983; Sachs, Bard, & Johnson, 1981; Snow et al., 1976). Yet little is known about what might best reveal the effects of childhood overhearing, namely, later acquisition of an overheard language. Finding such effects would benefit current understanding of language-learning mechanisms (Au & Romo, 1997). Consider the timing of input. If deprived of early linguistic input, children generally do not fully acquire a language—especially its phonology and morphosyntax even when input is available later (e.g., Curtiss, 1977; Flege, 1987; Flege, Yeni-Komshian, & Liu, 1999; Johnson & Newport, 1989; Newport, 1990; Oyama, 1976). This implies that language learners can best make use of relevant input during certain maturational states. Despite its significance, input timing has thus far been investigated only in linguistic deprivation studies focusing on what cannot be learned readily beyond childhood. The study of childhood overhearing reported here constitutes a first step in exploring long-term effects of what can be learned readily during childhood. Specifically, it explored whether adults learning a language would have more nativelike mastery of its phonology and morphosyntax if
they overheard the language regularly during childhood than if they did not.
This study also has applied implications. Although there are advantages to being bilingual (e.g., Taylor, Meynard, & Rheault, 1977), raising bilingual children in a predominantly monolingual environment such as the United States is not easy (Taylor, 1987; Wong-Fillmore, 1991). Is there any point for bilingual parents so situated to try? If childhood experience with a language—even if incomplete or discontinued— turns out to help older learners master that language, the answer would be “yes” after all. It would then also make sense for policymakers to allocate more resources to language programs for young children. Our study focused on phonology and morphosyntax because these aspects of language seem easy for children to acquire and difficult for adults to master. They are therefore good candidates for revealing long-term effects of childhood overhearing.
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, Knightly, Jun, & Oh, 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
The loss of first language phonetic perception in adopted Koreans
Does early exposure to a language leave permanent traces in the brain? We examine this issue by testing a group of native Koreans who were adopted by French-speaking families and have stopped using their first language for many years. Previous results suggest that they are not able to recognize Korean sentences, nor to identify Korean words (Pallier et al. 2003). In the present study, we focus on the possible remnants of L1 phonology, by assessing the adoptees’ capacity to discriminate Korean voiceless consonants which are difficult to perceive by native
French speakers. Data from groups of adoptees, native speakers of French, and native speakers of Korean, show that the adoptees do not perceive the differences between Korean phonemes better than native French speakers previously unexposed to Korean. Also, adoptees having been reexposed to Korean and those without reexposure perform similarly on this task. These results demonstrate that the Korean adoptees do not have easy access to the phonetic categories of the Korean language.
Early childhood language memory in the speech perception of international adoptees
It is as yet unclear whether the benefits of early linguistic experiences can be maintained without at least some minimal continued exposure to the language. This study compared 12 adults adopted from Korea to the US as young children (all but one prior to age one year) to 13 participants who had no prior exposure to Korean to examine whether relearning can aid in accessing early childhood language memory. All 25 participants were recruited and tested during the second week of first-semester college Korean language classes. They completed a language background questionnaire and interview, a childhood slang task and a Korean phoneme identification task. Results revealed an advantage for adoptee participants in identifying some Korean phonemes, suggesting that some components of early childhood language memory can remain intact despite many years of disuse, and that relearning a language can help in accessing such a memory.
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.