observations

[Elizabeth Bates]

As a child language researcher and a by-stander in the current
debate, I would like to reassure some of the AI folks about the
good intentions on both sides.  Unfortunately, the current argument
has deteriorated to the academic equivalent of "Your mother wears
army boots!".  But there is valid stuff behind it all.  My
sympathies tend to lie more on the connectionist side, but P&P
deserve our careful attention for several reasons.  (1) They are
(in my humble view) the first of the vocal critics of PDP who have
bothered to look carefully at the details of even ONE model, as opposed
to those (like Fodor and Pylyshyn) who have pulled their 1960's
arguments out of the closet and dusted them off in the smug conviction
that nothing has changed.  (2) Although I think P&P overstate the
strength of their empirical case (i.e. they are wrong on many counts
about the intuitions of adults and the behavior of children) they do
take the empirical evidence seriously, something I wish practicioners
on BOTH sides of the aisle would do more often.  (3)  Steve Pinker is
one of the few child language researchers who has indeed put forward
a (reasonably) coherent model of the learning process.  It is far too
nativist for me, in the sense that it solves too many problems by
stipulation (..."Let us assume that the child knows some version
of X-bar theory....").  As any mathematician knows, the more you do
by assumption, the less you have to prove.  In that (limited) sense,
I agree with Steven Harnad.  But I strongly recommend that interested
network subscribers take a good look at Steve Pinker's book and
decide for themselves.  There is indeed a nasty habit of speech at
MIT, an irritating smugness that does not contribute to the progress
of science.  I probably like that less than anyone.  But there is also
real substance and a lot of sweat that has gone into the P&P work on
connectionism.  They deserve to be answered on those terms (try
ignoring the tone of voice -- you'll need the practice if you have
or plan to have adolescent children).

Having said that, let me underscore the value of looking carefully
at real human data in developing models, arguments and counterarguments
about the acquisition and use of language.  One of the worst flaws
in the R&M model was the abrupt change in the input that they used
to create a U-shaped function -- in the cherished belief, based on
many text-book accounts, that such a U-shaped development exists
in children.  To borrow a phrase from our sainted vice-president:
READ MY LIPS!  There is no U-shaped function, no sudden drop from
one way of forming the past tense to another.  There is, instead,
a protracted competition between forms that may drag on for years,
and there is considerable individual variability in the process.
I recommend that you (re)read Virginia Marchman's comments to get
a better hold of the facts.  Similar arguments can be made about
the supposedly crisp intuitions P&P claim for adults (fly --> (flew,flied)).
They have raised an interesting behavioral domain for our consideration,
but I can assure you that adult behavior and adult intuitions are not
crisp at all.  The Elman anecdote that Jay McClelland brought to our
attention is not irrelevant, nor is it isolated.  I have a reasonably
good control over the English language myself, and yet I still vacillate
in passivizing many forms (is it "sneaked" or "snuck"?).  Crisp intuitions
and U-shaped functions are idealizations invented by linguists, accepted
by psycholinguists who should have known better, passed on to computer
scientists and perpetuated in simulations even by people like R&M who
are ideologically predisposed to think otherwise.  --Elizabeth Bates
(bates at amos.ling.ucsd.edu).