The Adaptable Mind: What Neuroplasticity and Neural Reuse Tell Us about Language and Cognition - John Zerilli 2021
The Language Module Reconsidered
In any reasonable construal of the language faculty, language is not cognitively special vis-à-vis other cognitive domains. There seems to be no language module, no elementary linguistic unit, no hardwired language organ. Language was likely to have been assembled from older sensory-motor and nonlinguistic materials. Neuroimaging, biobehavioral, computational, and evolutionary considerations all point to the same conclusion. Such linguistic adaptations as there have been have been coopted in many other domains of cognition. The sort of cultural environment in which language consists is too unstable to provide the conditions for typical selection scenarios in which robust phenotypes can emerge, and the brain anyway negotiates energetic constraints by repurposing existing resources to meet new challenges. Language acquisition frequently does seem effortless on the child’s part and exhibits a degree of developmental robustness. But the ease of acquisition has probably been exaggerated, and the child’s environment is not so impoverished as was once assumed. In any case, such ease of acquisition can be explained in other ways than by postulating exotic and impossible-to-evolve circuitry. Language has been shaped by the brain far more than the brain has been shaped by language. Cultural evolution is a powerful factor in human history and is more than sufficient to explain why languages seem to run so well with the grain of the human mind. It is true that language dissociates from other cognitive skills, at least in some respects, but the Redundancy Model puts this sort of modularization in its proper context. The Redundancy Model predicates functional inheritance across tasks and task categories, even when the tasks are implemented in spatially segregated neural networks. Thus dissociation evidence alone does not always indicate functional specificity. In particular, these dissociations provide no evidence that language is cognitively special.
1 The term “solitarity” is a neologism. See § 7.5.
2 See my earlier comments on domain specificity in § 4.2.3, and the discussion there more generally about “system” modules.
3 Interestingly, Fedorenko and Thompson-Schill (2014, p. 122) discuss and endorse a third, dynamic (time- rather than task-centered) approach to specialization in which “the notion of functional specialization may be linked to the stability of the node/network; a network may be functionally specialized for some mental process if its nodes are stable community members and . . . domain general if its nodes frequently change allegiances.” But this approach uses stability of activation over time as a guide to specialization in the first (neurological) sense, not the second (psychological) sense. In other words, their third approach is just that: an approach to identifying (neurologically/structurally) specialized brain regions within networks, rather than a definition of specialization per se. And the psychological sense is not specifically endorsed.
4 Within the framework I have been pursuing here, these systems would be construed as two distinct (if possibly overlapping) C-networks.
5 By “wordless” I mean without the words of a public language.
6 I do accept, of course, that Fodor performed a tremendous service in shaping the discussion of modularity in cognitive psychology.
7 “A speech episode involves the encoding and decoding of an internal representation of a sentence. . . . [I]t is clear that a very complex coding system mediates between the internal representation and the speech event” (Fodor et al. 1974, p. 21).
8 “It is not hard to show that, if the lexicon is reduced to a single element, then Merge will yield a form of arithmetic” (Chomsky 2010, p. 53).
9 For a sophisticated and fully developed computational account, see Knott (2012).
10 The term “solitarity” is Anderson’s, but while he concedes that solitarity will be “relatively rare,” he does not appear to believe that anything particularly significant follows from this. See also Anderson (2010, p. 296).
11 For a developmental twist on the type/token distinction invoked in the context of modular theorizing about the mind, see Barrett (2006).
12 This seems to be true regardless of whether the complex skills are innate or acquired.