Commentary on Peter Carruthers
Abstract: 55 words.
Main Text: 987 words.
References: 172 words.
Total Text: 1214 words.
Carruthers invokes a number of controversial assumptions to support his thesis. Most are questionable and unnecessary to investigate the wider relevance of language in cognition. A number of research programs (e.g., interactionist psycholinguistics and cognitive linguistics) have for years pursued a similar thesis, and provide a more empirically grounded framework for investigating language's cognitive functions.
The wider role of language in cognition is an important and interesting question, and can be studied from many directions. In some ways, the claim that language should be implicated in wider cognition seems almost self-evident. One is reluctant to approach Carruthers' general thesis with skepticism, because it seems intuitive that language is a kind of cognitive intersection for social, perceptual, and motor information. Indeed, to many researchers in the cognitive sciences, this is an important theoretical primary.
Contrary to Carruthers' assertions, however, many of these researchers do not endorse the purely communicative conception of language. The reason for this is simple: Many researchers do not hold that language is a distinct input-output module. In general, there is a prominent trend to reject the assumption that cognition is largely modular. Because Carruthers assumes modularity as a core premise, he alienates many who would be interested in the target article's argument, and whose research efforts are very relevant to a cognitive conception of language. Carruthers appears to suspect this, and asks the reader to hold in abeyance any sentiments against the assumption. However, there are two additional assumptive burdens that are borne by those who are willing to grant his premises: reification of thought and Chomsky's use of logical form (LF). In what follows, we discuss research that brings into question these three assumptions. Most importantly, this research offers, in our opinion, a more empirically grounded approach to investigating the cognitive functions of language.
First, as a minor assumption, Carruthers invokes LF representations as a vehicle for propositional thought. He provides little justification for recruiting this framework beyond the fact that Chomsky has proposed it. In fact, to our knowledge, there has been little or no empirical work substantiating the psychological relevance of LF. Because Carruthers' thesis is supposed to be a psychological one, one would expect that a firmly established psychological framework for thought would be employed in his argument. However, there is no such framework, and even those who lean toward a more classical Chomskyan perspective on language seem to be acknowledging that such purely discrete structural representations are not psychologically plausible (e.g., Ferreira, Bailey, & Ferraro, 2002; Sanford & Sturt, 2002).
A second assumption, closely related to the previous, is Carruthers' claim that thoughts are discrete, semantically-evaluable, and have component structure. Whether or not we deny him LF for want of experimental validation, Carruthers' general position that mental states have these overall properties should be questioned. Research using headband-mounted eye-tracking suggests that mental states are dynamic and continuous rather than discrete, and are only occasionally semantically-evaluable with component structure. Eye-tracking has provided psycholinguists with behavioral data about how rapidly multi-modal information is integrated in cognitive processes. For example, Tanenhaus, Spivey-Knowlton, Eberhard and Sedivy (1995) used eye-tracking to demonstrate that, during spoken language comprehension, syntactic ambiguity resolution as well as word recognition can be immediately influenced by visual context. Conversely, Spivey, Tyler, Eberhard, and Tanenhaus (2001) demonstrated that linguistic information actively influences the temporal dynamics of conjunctive visual search. Both of these processes unfold very rapidly and probabilistically, and they appear to share their continuously updated partial (or underspecified) representations with one another.
This brings us to modularity, Carruthers' most controversial assumption. Within the cognitive sciences, the notion of modularity has been refined in various ways, and has gradually become, though not by any means to consensus, a neurophysiological postulate that has lost much of its strict Fodorian content. Carruthers knows this, but still ends up with a "conceptual" modularity that finesses ongoing debate in the cognitive and brain sciences (e.g., Kingsbury & Finlay, 2001). In short, it seems to us inappropriate to assume a mosaic of innate domain-specific modules when the verdict is still out. This firm commitment to conceptual modularity also leads Carruthers to some questionable speculation that should engender skepticism even from those who accept it. For example, he hypothesizes the existence of an abductive reasoning module, neglecting a recent argument (from the father of modern modularity himself) that such a module is exactly what modularity cannot offer (Fodor, 2000).
So how should the cognitive functions of language be studied? Carruthers fails to mention that there are active areas of research in the cognitive sciences dedicated to the cognitive, rather than purely communicative, properties of language. For example, the fast-growing approach to language dubbed cognitive linguistics takes as a central tenet that language is inherently scaffolded by the rest of perception and cognition (Tomasello, 2002). Also, for almost three decades, the interactionist and connectionist approaches in psycholinguistics have aimed to establish broad integration of information in language processing (e.g., Marslen-Wilson, 1975; Rumelhart, 1977). Researchers in this area seek an answer to more general questions: How fluid is the interaction between language and other systems? Do they mutually influence each other in cognitive processing? In fact, the empirical data are supporting a view that language is very much like the "cross-modular" entity that Carruthers proposes. The problem is that visual perception, and audition, and motor cortex, etc. also seem to integrate information across modalities. If these various modalities (including language) are already in the business of interacting continuously on essentially the same level, then there is no need for an exclusive linguistic switchboard function using logical form, or any other format of representation.
To summarize, there are good reasons to doubt the assumptions in which Carruthers couches his version of the cognitive conception of language. The target article's ornate network of assumptions and speculation is slightly frustrating given Carruthers' hope to establish a "factual claim" and not some "modal claim arrived at by some sort of task-analysis." He seems instead to have established a quasi-factual claim arrived at by an analysis of many assumptions and scant evidence. His proposal for a more cognitive conception of language, however, is important, and should be pursued. We have discussed a few lines of research engaged in this question, and would welcome Carruthers to consider them as well.
Ferreira, F., Bailey, K.G.D. & Ferraro, V. (2002) Good-enough representations in language comprehension. Current Directions in Psychological Science 11: 11-15
Fodor, J. (2000) The mind doesn't work that way: the scope and limits of computational psychology. MIT Press.
Kingsbury, M.A. & Finlay, B.L. (2001) The cortex in multidimensional space: where do cortical areas come from? Development Science 4: 125-157.
Marslen-Wilson, W. (1975). Sentence perception as an interactive parallel process. Science 189: 226-228.
Rumelhart, D. (1977). Toward an interactive model of reading. In: Attention & Performance VI, ed. S. Dornic. Erlbaum.
Sanford, A.J. & Sturt, P. (2002) Depth of processing in language
comprehension: not noticing the evidence. TRENDS in Cognitive Sciences 6: 382-386.
Spivey, M.J., Tyler, M.J., Eberhard, K.M. & Tanenhaus, M.K. (2001) Linguistically mediated visual search. Psychological Science 12: 282-286.
Tanenhaus, M.K., Spivey-Knowlton, M.J., Eberhard, K.M. & Sedivy, J.C. (1995) Integration of visual and linguistic information in spoken language comprehension. Science 268: 1632-1634.
Tomasello, M., ed. (1998) The new psychology of language: cognitive and functional approaches to language structure. Lawrence Erlbaum Associates.