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[James L. McClelland]

It is true that there are different kinds of
behavior which we could assess any model with respect
to.  One kind of task involves language use (production,
comprehension) another is language judgement.  Many
connectionist models to date have addressed performance
rather than judgement, but there is no intrinsic
reason why judgements cannot be addressed in these models.
Indeed, it is becoming standard to use the goodness of match
between an expected pattern and an obtained pattern as a
measure of tacit knowledge, say, of what should follow
what in a sentence.  Such errors can be used as the basis
for some kinds of judgements.  I do not mean
to say that connectionists have already shown that
their models account for the full
range of factors that influence such judgements; but at
least many of us take the view (at least implicitly) that
the SAME connection information that governs performance
can also be used to sustain various types of judgements.

With regard to such judgements, at least as far as the
past tense is concerned, the facts seem not to fit perfectly
with Lachter and Berver's claims. Kuczaj [Child Development,
1978, p.319] reports data from children aged 3:4 to 9:0.
These children made gramaticallity judgements of a variety of kinds of
past-tense forms.  The probability that each type of form
was judged correctly is given below from his table 1 on p. 321:

                                                   Age Group
                                           Under 5  5&6  7 & up
Grammatical No-Change verbs (hit)            1.00   1.00  1.00
Regularized no-change verbs (hitted)          .28    .55   .05
Grammiatical Change verbs (ate)               .84    .94  1.00
*Regularized Change verbs (eated)             .89    .60   .26*
Past + ed forms for Change verbs (ated)       .26    .57   .23

Marked with asterisks above is the line containing what Lachter
and Bever call the overgeneralization error.  It will be seen that
children of every age group studied found these sorts of forms
acceptable at least to some degree.  It is particularly clear in the
youngest age group that such strings seem highly grammatical.
The fact that there are other error types which show a much lower
rate of acceptability for this group indicates that the high
acceptance rate for the regularized forms is not simply due to
a generalized tendency to accept anything in this age group.

I do not want to suggest that there is a perfect correlation
between performance in judgement tasks and measures obtained
from either natural or elicited production data:  One of the
few things we know for certain is that different tasks elicit
differences in performance.  However the data clearly indicate
that the child's judgements are actually strikingly similar
to the patterns seen in naturalistic regularization data
[Kuczaj, 1977, Journal of Verbal Learning and Verbal Behavior, p 589].
First, the late emergence of "ated" type forms in
natural production relative to "eated" type forms is
reflected in the judgement data.  Second, both in production
and acceptance, regularized forms of no-change verbs score low
relative to regularized forms of other types of exceptions.
Kuczaj [78] even went so far as to ask kids what they thought
their mothers would say when given a choice between
correct, regularized, and past+ed.  Their judgements of
what they thought their mothers would say were virtually identical
to their judgements of what they thought they would say at
all age groups.  In both kinds of judgements, choice of
eated type responses drops monotonically while ated type
responses peak in group 2.

Jay McClelland