Colloquium (10/17/2012): Eugene Charniak (Brown University)

Bayes’ Law as Psychologically Real

Since the brain manipulates probabilities (I will argue) then it should do so according to Bayes’ Law. After all, it is normative, and Darwin would not expect us to do anything less. Furthermore there is a lot to be learned from taking Bayes seriously. I consider myself a nativist despite my statistical bent, and it tells me how to combine an informative prior with the evidence of our senses – compute the likelihood of the evidence. It then tells us that this likelihood must be a very broad generative model of everything we encounter. Lastly, since Bayes says nothing about how to do any of this, I presume that the computational methods themselves are not learned, they must be innate, and I will argue there seems to be very few options on how this can be done, with something like particle filtering being one of the few. I will illustrate these ideas with work in computational linguistics, both my own and that of others.