Cathy Davidson:

Jeopardy operates on far clearer linguistic rules than ordinary speech and ordinary conversation.   A 5th grader, even a smart one, doesn’t have Watson’s data base so cannot begin to know all those answers to all those clearly formulated, explicit questions.   However, Watson doesn’t remotely have a 5th grader’s life-long “data base” of language formations, colloquialisms, neologisms, and grammatical errors that still “compute” (i.e. you can figure out what is meant despite the error–if you are a 5th grader, but probably not if you are Watson).   Watson “hears” questions by anticipating the sentence patterns of the Jeopardy questions and, searching among hundreds or even thousands of possible grammatical place holders, figures out what the subject and the relevant adjectives and even a few verbs are, pulls those out of the sentence, searches for complex integrated matches from its gigantic data bases, and then goes for the answer with the highest probability of being right.