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<Paper uid="P89-1022">
  <Title>AUTOMATIC ACQUISITION OF THE LEXICAL SEMANTICS OF VERBS FROM SENTENCE FRAMES*</Title>
  <Section position="3" start_page="0" end_page="177" type="intro">
    <SectionTitle>
1 INTRODUCTION
</SectionTitle>
    <Paragraph position="0"> The problem of how language is learned is perhaps the most difficult puzzle in language understanding. It is necessary to understand learning in order to understand how people use and organize language. To build truly robust natural language systems, we must ultimately understand how to enable our systems to learn new forms themselves.</Paragraph>
    <Paragraph position="1"> Consider the problem of learning new lexical items in context. To take a specific example, how is it that a child can learn the difference between the verbs look and see (inspired by Landau and Gleitman(1985) )? They clearly have similar core meanings, namely ~perceive by sight&amp;quot;. One initially attractive and widely-held hypothesis is that *This work was partially supported by the DARPA grant N00014-85-K0018, and Alto grant DAA29-84-90027. The authors also wish to thank Beth Levin and the anonymotm reviewers of this paper for many helpful comments. We ~ b~efit~l greatly from disctumion of issues of verb acquisition in children with Lila Gleitman.</Paragraph>
    <Paragraph position="2"> word meaning is learned directly by observation of the surrounding non-linguistic context. While this hypothesis ultimately only begs the question, it also runs into immediate substantive difficulties here, since there is usually looking going on at the same time as seeing and vice versa. But how can one learn that these verbs differ in that look is an active verb and see is stative? This difference, although difficult to observe in the environment, is clearly marked in the different syntactic frames the two verbs are found in. For example, see, being a stative perception verb, can take a sentence complement:  (1) John saw that Mary was reading.</Paragraph>
    <Paragraph position="3"> while look cannot: (2) * John looked that Mary was reading.</Paragraph>
    <Paragraph position="4"> Also look can be used in an imperative, (3) Look at the ball! while it sounds a bit strange to command someone to see, (4) ? See the ball!  (Examples like &amp;quot;look Jane, see Spot run!&amp;quot; notwithstanding.) This difference reflects the fact that one can command someone to direct their eyes (look) but not to mentally perceive what someone else perceives (see). As this example shows, there are clear semantic differences between verbs that are reflected in the syntax, but not obvious by observation alone. The fact that children are able to correctly learn the meanings of look and see, as well as hundreds of other verbs, with minimal exposure suggests that there is some correlation between syntax and semantics that facilitates the learning of word meaning.</Paragraph>
    <Paragraph position="5"> Still, this and similar arguments ignore the fact that children do not have access to the negative  evidence crucial to establishing the active/stative distinction of the look/see pair. Children cannot know that sentences like (2) and (4) do not occur, and it is well established that children are not corrected for syntactic errors. Such evidence renders highly implausible models like that of Pinker(198?), which depend crucially on negative examples. How then can this semantic/syntactic correlation be exploited?</Paragraph>
  </Section>
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