My pen-pal Melodye has posted a thought-provoking piece at Child's Play on negative evidence. As she rightly points out, issues of negative evidence have played a crucial role in the development of theories of language acquisition. But she doesn't think that's a good thing. Rather, it's "ridiculous, [sic] and belies a complete lack of understanding of basic human learning mechanisms."
The argument over negative evidence, as presented by Melodye, is ridiculous, but that seems to stem from (a) conflating two different types of negative evidence, and (b) misunderstanding what the argument was about.
Here's Melodye's characterization of the negative evidence argument:
[T]he argument is that because children early on make grammatical ‘mistakes’ in their speech (e.g., saying ‘mouses’ instead of ‘mice’ or ‘go-ed’ instead of ‘went’), and because they do not receive much in the way of corrective feedback from their parents (apparently no parent ever says “No, Johnny, for the last time it’s MICE”), it must therefore beimpossible to explain how children ever learn to correct these errors. How — ask the psychologists — could little Johnny ever possibly ‘unlearn’ these mistakes? This supposed puzzle is taken by many in developmental psychology to be one of a suite of arguments that have effectively disproved the idea that language can be learned without an innate grammar.What's the alternative? Children are predicting what word is going to come up in a sentence.
[I]f the child is expecting ‘mouses’ or ‘gooses,’ her expectations will be violated every time she hears ‘mice’ and ‘geese’ instead. And clearly that will happen a lot. Over time, this will so weaken her expectation of ‘mouses’ and ‘gooses,’ that she will stop producing these kinds of words in context.I can't speak for every Nativist, or for everyone who has studied over-regularization, but since Melodye cites Pinker extensively and specifically, and since I've worked on over-regularization within the Pinkerian tradition, I think I can reasonably speak for at least a variant of Pinkerianism. And I think Melodye actually agrees with us almost 100%.
My understanding of Pinker's Words and Rules account -- and recall that I published work on this theory with one of Pinker's students, so I think my understanding is well-founded -- is that children originally over-regularize the plural of mouse as mouses, but eventually learn that mice is the plural of mouse by hearing mice a lot. That is, our account is almost identical to Melodye's except it doesn't include predictive processing. I actually agree that if children are predicting mouses and hear mice, that should make it easier to correct their mistaken over-regularization. But the essential story is the same.
Where I've usually seen Nativists bring up this particular negative evidence argument (and remember there's another) is in the context of Behaviorism, on which rats (and humans) learned through being explicitly rewarded for doing the right thing and explicitly punished for doing the wrong thing. The fact that children learning language are almost never corrected (as Melodye notes) is evidence against that very particular type of Empiricist theory.
That is, we don't (and to my knowledge, never have) argued that children can only learn the word mice through Universal Grammar. Again, it's possible (likely?) that someone has made that argument. But not us.
Negative Evidence #2
There is a deeper problem with negative evidence that does implicate, if not Universal Grammar, at least generative grammars. That is, as Pinker notes in the article cited by Melodye, children generalize some things and not others. Compare:
(1) John sent the package to Mary.
(2) John sent Mary the package.
(3) John sent the package to the border.
(4) *John sent the border the package.
That * means that (4) is ungrammatical, or at least most people find it ungrammatical. Now, on a word-prediction theory that tracks only surface statistics (the forms of words, not their meaning or syntactic structure), you'd probably have to argue that whenever children have heard discussions of packages being sent to Mary, they've heard either (1) or (2), but in discussions of sending packages to borders, they've only ever heard (3) and never (4). This is surprising, and thus they've learned that (4) is no good.
The simplest version of this theory won't work, though. Since children (and you) have presumably never heard any of the sentences below (where Gazeindenfrump and Bleizendorf are people's names, the dax is an object, and a dacha is a kind of house used in Russia):
(5) Gazeidenfrump sent the dax to Bleizendorf.
(6) Gazeidenfrump sent Bleizendorf the dax.
(7) Gazeidenfrump sent the dax to the dacha.
(8) *Gazeidenfrump sent the dacha the dax.
Since we've heard (and expected) sentence #8 just as many times as we heard/expected (5-7), failures of predictions can't explain why we know (8) is bad but (5-7) isn't. (BTW If you don't like my examples, there are many, many more in the literature; these are the best I can think of off the top of my head.)
So we can't be tracking just the words themselves, but something more abstract. Pinker has an extended discussion of this problem in his 1989 book, in which he argues that the constraint is semantic: we know that you can use the double-object construction (e.g., 2, 4, 6 or 8) only if the recipient of the object can actually possess the object (that is, the dax becomes Bleizendorf's, but it doesn't become the dacha's, since dachas -- and borders -- can't own things). I'm working off of memory now, but I think -- but won't swear -- that Pinker's solution also involves some aspects of the syntactic/semantic structures above being innate.
Pinker's account is not perfect and may end up being wrong in some places, but it remains the fact that negative evidence (implicit or not) can't alone explain where children (and adults) do or do not generalize.
 Melodye quotes Pinker saying "The implications of the lack of negative evidence for children's overgeneralization are central to any discussion of learning, nativist or empiricist." That is the quote that she says is "quite frankly, ridiculous." Here is the full quote. I'll let you decide whether it's ridiculous:
This nature–nurture dichotomy is also behind MacWhinney’s mistaken claim that the absence of negative evidence in language acquisition can be tied to Chomsky, nativism, or poverty-of-the-stimulus arguments. Chomsky (1965, p. 32) assumed that the child’s input ‘consist[s] of signals classified as sentences and nonsentences _’ – in other words, negative evidence. He also invokes indirect negative evidence (Chomsky, 1981). And he has never appealed to Gold’s theorems to support his claims about the innateness of language. In fact it was a staunch ANTI-nativist, Martin Braine (1971), who first noticed the lack of negative evidence in language acquisition, and another empiricist, Melissa Bowerman (1983, 1988), who repeatedly emphasized it. The implications of the lack of negative evidence for children’s overgeneralization are central to any discussion of learning, nativist or empiricist.
PINKER, S. (2004). Clarifying the logical problem of language acquisition Journal of Child Language, 31 (4), 949-953 DOI: 10.1017/S0305000904006439
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