Ingles

Second-language Instinct and Instruction Effects: Nature and Nurture in Second-language Acquisition
Noriaki Yusa1,2, Masatoshi Koizumi2,3, Jungho Kim3, Naoki Kimura3, Shinya Uchida4, Satoru Yokoyama3, Naoki Miura3,5, Ryuta Kawashima3, and Hiroko Hagiwara2,6

Abstract
■ Adults seem to have greater difficulties than children in
acquiring a second language (L2) because of the alleged “window ofopportunity” around puberty. Postpuberty Japanese participants learned a new English rule with simplex sentences during one month of instruction, and then they were tested on “uninstructed complex sentences” as well as “instructed simplex sentences.” The behavioral data show that they can acquire more knowledge than is instructed, suggesting the interweaving of nature (universal principles of grammar,UG) and nurture (instruction) in L2 acquisition. The comparison in the “uninstructed complex sentences” between post-instruction and pre-instruction using functional magnetic resonance imaging reveals a significant activation in Brocaʼs area. Thus, this study provides new insight into Brocaʼs area, where nature and nurture cooperate to produce L2 learnersʼ rich linguistic knowledge. It also showsneural plasticity of adult L2 acquisition, arguing against a critical period hypothesis, at least in the domain of UG. ■

INTRODUCTION
A significant feature of language acquisition is that children, in a relatively short time, acquire a language while attaining a rich knowledge of their language which surpasses their actual experiences (Chomsky, 1980). A large discrepancy between the limitedinput that children are exposed to and the rich linguistic knowledge that they acquire poses what is called the poverty-of-the-stimulus (PoS) argument (Chomsky, 1980, 2000): how children end up knowing more than they experience. This problem has been at the heart of a heated debate since the inception of cognitive science (Carruthers, Laurence, & Stitch, 2005; Reali & Christiansen, 2005; Samuels,2004; Tomasello, 2003; Chomsky, 1980, 2000; Elman et al., 1996; Pinker, 1994). Finding an answer to the problem has engendered a wide variety of research programs. One of the solutions based on theories of biolinguistics (i.e., generative grammar) is to postulate and characterize an innate language faculty known as the language instinct or universal grammar (UG) in human brains, which provideschildren with a set of principles for developing a grammar on the basis of limited linguistic input (Chomsky, 2000; Crain & Thornton, 1998; Pinker, 1994). Thus, the PoS argument
Miyagi Gakuin Womenʼs University, Sendai-shi, Japan, 2Research Institute of Science and Technology for Society (RISTEX), Tokyo, Japan, 3Tohoku University, Sendai-shi, Japan, 4National Center of Neurology and Psychiatry,Kodaira-shi, Japan, 5Kochi University of Technology, Kami-shi, Japan, 6Tokyo Metropolitan University, Tokyo, Japan
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furnishes the most compelling rationale for the presence of UG at least in first-language (L1) acquisition. In sharp contrast to the remarkable feat of L1 acquisition, the language instinct with which humans are endowed seems to deteriorate or dysfunction with age in L2 acquisition beyond ahypothesized critical period (DeKeyser, 2000; Pinker, 1994; Bley-Vroman, 1990; Johnson & Newport, 1989). Of special interest in this connection is whether the language instinct or UG is still in place and remains operative in adult L2 acquisition, functioning as the so-called second-language instinct (White, 2003; Schwartz, 1998). If L2 acquisition were fundamentally different from L1acquisition, L2 grammars might not conform to principles of UG that constrain L1 grammars, resulting in “wild” grammars that do not exhibit properties of natural languages. If L2 learners, however, prove to have developed abstract knowledge underdetermined by their L2 input and their L1, this PoS argument strongly suggests that the innate language instinct is not “dismantled” but mediates L2 acquisition as...