Genes, language, and the nature of scientific explanations: The case of Williams syndrome

Abstract

In this article, we discuss two experiments of nature and their implications for the sciences of the mind. The first, Williams syndrome, bears on one of cognitive science's holy grails: the possibility of unravelling the causal chain between genes and cognition. We sketch the outline of a general framework to study the relationship between genes and cognition, focusing as our case study on the development of language in individuals with Williams syndrome. Our approach emphasizes the role of three key ingredients: the need to specify a clear level of analysis, the need to provide a theoretical account of the relevant cognitive structure at that level, and the importance of the (typical) developmental process itself. The promise offered by the case of Williams syndrome has also given rise to two strongly conflicting theoretical approaches—modularity and neuroconstructivism—themselves offshoots of a perennial debate between nativism and empiricism. We apply our framework to explore the tension created by these two conflicting perspectives. To this end, we discuss a second experiment of nature, which allows us to compare the two competing perspectives in what comes close to a controlled experimental setting. From this comparison, we conclude that the “meaningful debate assumption”, a widespread assumption suggesting that neuroconstructivism and modularity address the same questions and represent genuine theoretical alternatives, rests on a fallacy.

Keywords:

• Williams syndrome
• Language
• Modularity

Notes

¹ Or at least, we should not do so until one set of concepts can be meaningfully reduced to the other.

² Fodor's full set of criteria includes: domain specificity, obligatory firing, inaccessibility to consciousness, speed, encapsulation, shallow outputs, localization, ontogenetic invariance, and characteristic breakdown patterns.

³ One of the reviewers raises the possibility that individuals with WS may interpret our sentences correctly not because they know about c-command, scope, and so on, but rather because they are using simpler “heuristics”, such as, “cat meows → no food” and “cat not meow → food”. First, notice that because we used 16 different target sentences in our experimental conditions (precede and c-command), all using different combinations of lexical items, you would need 16 separate “heuristics” like the one proposed here to account for the facts we report (e.g., a policeman/doughnut heuristic, a pirate/jewel one, etc.; see Musolino et al.'s (2010) original article for a list of the stimuli). Second, the proposed heuristic would not actually work in the “cat meowing” case. Indeed, in the case of a sentence like (20) The cat who meows will not be given a fish or milk, it is not simply that the sentence will be true if the meowing cat gets no food. To be sure, the sentence will be true if the meowing cat gets neither a fish nor milk; however, it would also be true if the meowing cat gets food other than a fish or milk. In order to appreciate that, one needs to understand the meaning of disjunction, or, and how it interacts with negation. So one could try to construct a more detailed heuristic to take that into account, and also make that heuristic abstract enough to account for cases involving policemen and doughnuts, pirates and jewels, and so on. Doing so, however, would amount to formulating the kind of abstract notions that linguists take to be underlying people's ability to correctly interpret sentences containing negation and disjunction (e.g., scope, c-command, etc.). For a more detailed discussion of this point, see Musolino et al. (2010; p. 150).

⁴ It should be pointed out that accuracy levels for our WS group were 76% correct in the experimental conditions (compared to 89.5% for mental age controls) and 90.8% in the control conditions (compared to 94.5% for MA controls). Describing these results as “fairly poor performance” might be useful for rhetorical purposes, but it is hard to see how this performance is “poor”, as it must reflect possession of a highly abstract knowledge system. From that point of view, we find it misleading to characterize the performance as “poor”.

⁵ For readers unfamiliar with the rules of chess, rooks move along straight lines and bishops along diagonals.

Additional information

Notes on contributors

Barbara Landau

This work was partially funded by grant R01 NS050876 to B. Landau.