Language learning
What is language learning?
- Presented with a sequence of grammatical sentences (or words),
be able to recognize novel sentences (or words) as
grammatical or ungrammatical.
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Presented with several instances of a word in context, be able to
interpret or produce that word appropriately in a new context.
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Presented with grammatical sentences in context,
be able to interpret or produce novel sentences in new contexts.
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Presented with sentences (words), learn to find the boundaries between the units
(words, morphemes).
The language learning (acquisition) problem
- Language learners receive a finite amount of sometimes errorful input (the "poverty of the stimulus").
- Language learning is mostly unsupervised.
- Learners receive positive evidence, but no (direct) negative evidence.
- Learning is sometimes very rapid.
Kinds of information
-
| Positive evidence | Negative evidence |
|---|
 |
 |
- Positive evidence
- Information about what is correct
- Causes the system to extend its hypothesis
- Negative evidence
- Information about what is not correct
- Explicit, labeled incorrect patterns
- Correction for the system's errors
- Indirect negative evidence
- Learning algorithms that generate implicit negative evidence
- Causes the system to restrict its hypothesis
- Why it seems important
- Its role in grammar learning
- Its role in word learning
- Alternatives to negative evidence: constraints
- Built-in (innate) constraints
- Constraints from the environment (input)
The problem for word meaning
- Is word learning supervised?
- Is negative evidence available?
- Quine's problem
- Figuring out what the referent of a novel word is
- Figuring out what aspects of the referent a novel word refers to
- Which word in an utterance goes with which part of a scene?
How learning might be constrained
- Constraints on inter-lexicon relationships: mutual exclusivity
- How it could help
- The problem of taxonomies
- The problem of bilinguals
- Where would it come from?
- Constraints on kinds of categories (meanings)
- Whole object
- Taxonomic vs. thematic relations
- "Dimensional" (attentional) biases: shape, material;
language-specific biases (L. Smith, Bowerman, etc.)
- Where would they come from?
- Should we expect them in all languages?
- Second-order (case-based) learning in the Shape Bias experiment
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Syntactic bootstrapping (Gleitman, etc.):
guess the meaning of new words on the basis of the meanings of words that
occur in similar syntactic patterns
Lois gorped the brick to Clark.
- Constraints from non-linguistic behavior
The problem for grammar
- Learning English passive
- The girl is hugging the woman.
The woman is being hugged (by the girl).
- Chuck chopped the onions.
The onions were chopped (by Chuck).
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Lois became a lawyer.
*A lawyer was become (by Lois).
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Semantic bootstrapping (Pinker): use (built-in) semantic features to constrain the kinds of syntactic patterns that are possible
- Grammatical parameters (Chomsky, etc.)
Innatist vs. empiricist theories
- What could be innate
- General purpose mechanisms (not specific to language)
- Language-specific mechanisms
- Categories (noun, agent, etc.)
- Parameters: set on the basis of input
- The importance of the input
- How impoverished is it?
- How does it change with the competence of the child?
- How variable is it (within and between languages)?
- How do children learning different languages differ?
- What statistical regularities does it embody?
- Empiricist possibilities
- The role of the environment: embodied models
