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<Paper uid="W05-0501">
  <Title>The Input for Syntactic Acquisition: Solutions from Language Change Modeling</Title>
  <Section position="2" start_page="0" end_page="1" type="intro">
    <SectionTitle>
1 Introduction
</SectionTitle>
    <Paragraph position="0"> Empirically investigating what data children attend to during syntactic acquisition is a difficult task.</Paragraph>
    <Paragraph position="1"> Traditional experimental methods are not feasible on logistical and ethical grounds - we can't simply lock a group of children in a room for two years, restrict their input to whatever we want, and then see if their syntactic acquisition matches normal patterns. However, when we have a simulated group of language learners who folow a quantified model of individual acquisition, this is exactly what we can do - restrict the input to syntactic acquisition in a very specific way and then observe the results.</Paragraph>
    <Paragraph position="2"> The individual acquisition model we use is inspired by Yang's (203, 200) model of probabilistic learning for multiple grammars. By using this model in a simulated population of individuals, we provide empirical suport for two acquisition proposals that restrict children to only heed data that are unambiguous trigers (Dresher 199, Lightfoot 199, Fodor 198) and that appear in degree-0 clauses (Lightfoot 191). We use language change as a metric of &amp;quot;correct&amp;quot; acquisition, based on the folowing idea: if the simulated population that has these restrictions behaves just as the real population historically did, the simulated acquisition process is fairly similar to the real acquisition process. Language change is an excellent yardstick for acquisition proposals for exactly this reason - any theory of acquisition must not only be able to account for how children converge to a close approximation of the adult grammar, but also how they can &amp;quot;misconverge&amp;quot; slightly and allow specific types of grammatical change over time. The nature of this &amp;quot;misconvergence&amp;quot; is key. Children must end up with an Internal Language (&amp;quot;grammar&amp;quot;) that is close enough - but not to close - to the Observable Language (O-Language) in the population so that change can happen at the right pace.</Paragraph>
    <Paragraph position="3"> The language change we use as our metric is the shift in Old English from a strongly Object-Verb (OV) distribution to a strongly Verb-Object (VO) distribution between 100 and 120 A.D.</Paragraph>
    <Paragraph position="4">  The sharpest part of this shift occurs between 150 and 120 A.D., based on data from the YCOE Corpus (Taylor et al. 203) and the PPCME2 Corpus (Kroch &amp; Taylor 200). We use this corpus data to estimate the initial OV/VO distribution in the modeled population at 100 A.D. and to calibrate the modeled population's projected OV/VO distribution between 100 and 150 A.D. Then, we demonstrate that the restrictions on acquisition seem both sufficient and surprisingly necessary for the simulated Old English population to shift its distribution to be strongly VO by 120 A.D - and thus match the historical facts of Old English. In this way, we provide empirical suport that we would be hardpressed to get using traditional methods for these acquisition proposals.</Paragraph>
    <Paragraph position="5"> The rest of the paper is laid out as folows: section 2 elaborates on the two acquisition proposals of unambiguous trigers and degree-0 data; section 3 gives specific implementations of these proposals for Old English; section 4 describes the model used to simulate the population of Old English speakers and how the historical corpus data was used; sections 5 and 6 present the results and conclusion.</Paragraph>
  </Section>
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