Learning Word Meaning

Positive and Negative Evidence

• Children get positive examples of words (this is a cat), but they usually do not get negative examples (but it's not a dog)
• With positive examples alone, the learner may overgeneralize.

Some Facts

• Beginning in their second year, children learn words very rapidly, at a rate of about 9 words per day for several years.
• Unlike grammar, words can be taught, at least in part, but usually they aren't.
• Quine's problem: Given a new word in context, how can the child pick out which of an almost infinite set of possible features is signaled by the word?

How Could Words Be Learned?

• One view: children are guided by innate constraints.
  • Whole-object assumption: A label refers to the object as a whole and not to its parts, substance, color, etc.
  • Taxonomic assumption: A label refers to objects of the same taxonomic category, not to objects that are thematically related.
  • Mutual exclusivity assumption: Each object will have only one label.
• Another view: children actually do get negative evidence, though perhaps indirectly.
• Another view: children learn the supposedly innate constraints.

[L645 Syllabus]