Two for one? Transfer of conceptual content in bilingual number word learning

Two for one? Transfer of conceptual content in bilingual number word learning Katherine Kimura kkimura@ucsd.edu Katie Wagner kgwagner@ucsd.edu David Barner barner@ucsd.edu Department of Psychology University of California, San Diego Department of Psychology University of California, San Diego Department of Psychology University of California, San Diego Abstract Bilingual speakers are confronted with a unique challenge when learning language as they must learn to express the same concept in two separate languages. Here, we examine whether learning number words in one language (i.e., L1) facilitates the acquisition of analogous number words in a second language (i.e., L2) or whether extensive experience and familiarity with numbers within the second language is required to learn words in L2. To do so, we tested 68 bilinguals speakers between the ages of 2 and 4 years and show that conceptual knowledge of numbers in L1 reliably predicted children’s conceptual knowledge of numbers in L2, suggesting that knowledge transferred from one language to the other. The effect, however, was limited to two developmental transitions: one-knower to two-knower and subset knower to CP-knower. Familiarity with L2 numbers as well as age were also significant predictors of children’s conceptual understanding of numbers. Keywords: bilingualism; conceptual transfer; word learning; number words. Introduction When children learn language, they are confronted with the problem of discovering how words encode conceptual content and thus encode their experience of the world. Although children eventually overcome this challenge and learn to associate specific words with specific concepts, this process is slow and often involves making difficult inductive inferences regarding the meanings of words (Quine, 1960). In these cases where slow, inductive inferences are required it is often unclear whether children’s difficulty lies with forming the concept to be referenced (see Carey, 2009) merely mapping the correct linguistic symbol to the correct concept. This distinction between conceptual and linguistic development is difficult to disentangle because linguistic experience is almost always correlated with other factors that influence conceptual development including biological maturation and non-linguistic experience. Although there are some striking examples where language can be isolated from these other developmental factors, for example international adoptees as well as late learners of sign language, these cases may have limited generalizability due to severe linguistic delay or a sharp disruption of first language learning. In contrast, bilingual children sometimes have limited knowledge of their second language (i.e., L2) while still having an intact first language experience (i.e., L1). This separation of conceptual development and L2 linguistic development can provide a unique test case for exploring how linguistic competence and conceptual development are related, while avoiding the challenges introduced by late- learners of sign language and international adoptees. More specifically, bilingual speakers allows us to test whether conceptual learning accomplished first in one linguistic medium might facilitate the acquisition of corresponding content in a second language by eliminating several steps in the second language acquisition, thus resulting in a faster second language acquisition rate relative to the first language acquisition. In cases where children must acquire concepts before mapping language to those concepts, L2 acquisition of those words should be faster than L1 acquisition because these concepts can transfer from L1 to L2. In contrast, when children merely require increased exposure to the language in order to map a word to a pre-existing concept, no L2 facilitation would be expected because this process is necessarily language- specific. In the present study we explored this idea by investigating the acquisition of number words (e.g., one, two, three) – a central test case in the study of conceptual change (see Carey, 2009). To do so, we tested children learning two languages and asked whether learning number word meanings in one language (i.e., L1) facilitates the acquisition of analogous number words in a second language (i.e., L2). Early in acquisition, children as young as two years learn to recite a partial count list in a serial order (e.g., one, two, three, four, five, etc.), pointing at objects as they do so (see Gelman & Gallistel, 1978; Frye, Braisby, Lowe, Maroudas, & Nicholls, 1989; Fuson, 1988). Despite this seemingly procedural understanding of the relationship between counting and cardinality, children at this stage in development typically have little to no understanding of how counting represents number (i.e., how the last number of the count list represents the exact cardinality of the set) nor have they acquired the meanings of any of the number words (i.e., that numbers refer to specific quantities of a set). Soon, however, children begin to acquire an exact meaning for the number one, reliably giving one object when asked for one and more than one when asked for a contrasting number. After six to nine months as a ‘one- knower,’ children learn the meaning of two, becoming a ‘two-knower’ and, following this sequential pattern, learn the meanings of three and four (Wynn, 1990, 1992). During these early stages of number word learning, these children who are classified as one-, two-, three-, and four-knowers have meanings for only a subset of their number words (i.e., one, two, three, and four) and are thus collectively referred to as ‘subset knowers.’ Eventually, twelve to eighteen