TESTING THE FUNDAMENTAL DIFFERENCE HYPOTHESIS

The fundamental difference hypothesis (FDH; Bley-Vroman, 1989, 1990) contends that the nature of language in natives is fundamentally different from the nature of language in adult nonnatives. This study tests the FDH in two ways: (a) via second language (L2) poverty-of-the-stimulus (POS) problems (e.g., Schwartz & Sprouse, 2000) and (b)via a comparison between adult and child L2 learners, whose first language (L1) is the same, in terms of their developmental route (e.g., Schwartz, 1992, 2003). The phenomena under investigation are Korean ^-constructions with negative polarity items (NPIs). Korean has subject (S)-object (O)-verb (V) as its canonical word order and it is also a wfr-in-situ language, but scrambling of the object to presubject position (i.e., movement that results in OSV word order) is generally optional; however, in the context of negative questions with a NPI subject (e.g., amwuto "anyone"), (a) object wfr-phrases must scramble on the wfr-question reading and (b) the nonscrambled order has a yes/no-question reading. These properties of Korean wfr-constructions with NPIs constitute POS problems for nonnatives whose L1 is English (as well as for native Korean-acquiring children). L1-English adult L2 learners (n = 15) and L1-English child L2 learners (n = 10), independently assessed for Korean proficiency, as well as L1-Korean children (n = 23) and L1-Korean adults (n = 15) completed an elicited-produc-tion task, an acceptability-judgment task, and an interpretation-verification task. The results show that (a) high-proficiency (adult and child) L2 learners performed like the native adult controls on all three tasks, thereby demonstrating L2 POS effects; and (b) adult and child L2 learners follow the same (inferred) route to convergence, a route differing from—yet subsuming—the L1-child route. Both sets of results lead us to conclude that, contra the FDH, the nature of language is fundamentally similar in natives and (adult or child) nonnatives.