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    1. 1. Natural Language Processing Can artificial systems acquire language the same way children do? Andrea Hill – COMP 670
    2. 2. Introduction <ul><li>I studied first and second language acquisition earlier in my college career; was always interested in how we process language </li></ul><ul><li>Natural language processing and machine translation is still a burgeoning field </li></ul><ul><li>Can we teach a machine to ‘learn’ as we do? </li></ul>
    3. 3. Not a unique idea <ul><li>Alan Turing, 1950: “ Instead of trying to produce a programme to simulate the adult mind, why not rather try to produce one which simulates the child's? If this were then subjected to an appropriate course of education one would obtain the adult brain.” </li></ul>
    4. 4. Introducing HAL <ul><li>Meet Hal. Like any 18-month-old toddler, he likes bananas, toys and playing in the park. He especially enjoys bedtime stories. </li></ul><ul><li>But while other children are flesh and blood, Hal is a chain of algorithms — a computer program that is being raised as a child and taught to speak through experiential learning in the same way as human children. </li></ul><ul><li>- Indiana Tribune, August 2001 </li></ul><ul><li>Has already passed an adaptation of the Turing test, wherein he exhibited the language skills of a 15 month old. His creators believe he will pass the Turing test in about a decade </li></ul>
    5. 5. Where to begin <ul><li>Collect a large amount of data of children utterances. These should be categorized based on the age of the child so that we can see the speed with which children can handle more complicated structures. </li></ul><ul><li>Analyze the utterances in terms of their grammatical elements. Perceived ungrammaticalities will be flagged. This will eventually help us to see if there are specific structures that pose particular challenges. </li></ul><ul><li>A second stage will involve looking at what input elicited the children’s utterances. Is the child repeating elements in the initial question, either verb conjugations or syntax? Do certain words form a semantic grouping? </li></ul>
    6. 6. Implementation <ul><li>Use XML, creating a custom DTD to describe the grammar </li></ul><ul><li>Quickly saw how daunting this task was (also, would need a DTD for each language) </li></ul><ul><li>In retrospect, another project may have been to use the input to drive the creation of the DTD (i.e. the grammar itself) rather than attempting to formulate a grammar that encompassed all possible input </li></ul>
    7. 7. How do you ‘create a grammar’ <ul><li>This is a fundamental question when it comes to child language acquisition </li></ul><ul><li>There are two main theories as to how children learn language: </li></ul><ul><ul><li>First, the child starts with a more or less blank slate, hears parents talk, mimics them, says things, hears corrections, and learns the language. </li></ul></ul><ul><ul><li>Second, the child starts with universal grammar as an innate endowment, already there, with all its parametrized options, and has only to hear how the options need to be set in his/her particular language to attain the full grammar of that language. </li></ul></ul><ul><ul><li>- Universal Language and Linguistics </li></ul></ul>
    8. 8. <ul><li>Children create utterances they have never heard before, so they cannot simply be mimicking others </li></ul><ul><li>There are certain classes of errors that children make, and others they never make. This implies some underlying rules- </li></ul>
    9. 9. <ul><li>Ask Jabba if the boy [who is watching Mickey] is happy. </li></ul><ul><ul><ul><li>a. The structure-dependent response </li></ul></ul></ul><ul><ul><ul><li>Is [the boy who is watching Mickey] _ happy? </li></ul></ul></ul><ul><ul><ul><li>b. The non-structure-dependent response </li></ul></ul></ul><ul><ul><ul><li>*Is [the boy who _ watching Mickey] is happy? </li></ul></ul></ul><ul><li>There were actually four different responses returned from the children. </li></ul>22% *Is [the boy who is watching Mickey], is he happy? 58% *Is [the boy who is watching Mickey] is happy? 0% *Is [the boy who _ watching Mickey] is happy? 38% Is [the boy who is watching Mickey] happy
    10. 10. Universal Grammar <ul><li>Universal grammar is a theory of linguistics postulating principles of grammar shared by all languages, thought to be innate to humans. It attempts to explain language acquisition in general, not describe specific languages. </li></ul>
    11. 11. Principles and parameters <ul><li>The central idea of principles and parameters is that a person's syntactic knowledge can be modelled with two formal mechanisms: </li></ul><ul><ul><li>A finite set of fundamental principles that are common to all languages; e.g., that a sentence must always have a subject, even if it is not overtly pronounced. </li></ul></ul><ul><ul><li>A finite set of parameters that determine syntactic variability amongst languages; e.g., a binary parameter that determines whether or not the subject of a sentence must be overtly pronounced (this example is sometimes referred to as the Pro-drop parameter). </li></ul></ul>
    12. 12. New design <ul><li>Refer to the framework to identify the various parameters </li></ul><ul><li>Create a DTD generic enough to allow for the various parameter settings* </li></ul><ul><li>*Default settings will be identified. Only with positive input would alternative parameters be set. This is the concept known as markedness. </li></ul>
    13. 13. Benefits? <ul><li>Build on a widely-accepted framework </li></ul><ul><li>Not so biased towards input from limited individuals </li></ul><ul><li>Easily extensible </li></ul>
    14. 14. Still not a novel idea <ul><li>Close to 20 years ago, Vivian Cook wrote a paper on PAL (Program for Acquiring Language), a parser that would use Government and Binding theory to parse input. </li></ul><ul><li>PAL takes in some data from a user, sets certain parameters based on previous input, and then attempts to parse new input using these rules. It offers specific feedback on how the input was parsed, as well as whether it conformed to the parameter settings or not. </li></ul>
    15. 15. Conclusion <ul><li>HAL has seen some success </li></ul><ul><li>PAL worked within its domain </li></ul><ul><li>Looking at how children acquire language, we may be able to develop a system that can ‘learn’, by modifying parameters based on input received </li></ul><ul><li>More studies will eventually show us if “artificial systems can acquire language the same way children do” </li></ul>
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