Sort - of symbols ?

Barsalou’s elision of the personal and sub-personal levels tends to conceal the fact that he is, at best, providing the “specs” but not yet a model for his hypothesized perceptual symbols. John Maynard Keynes was once asked if he thought in words or pictures. “I think in thoughts,” the great man is reported to have replied. Fair enough, but now what? What kind of things are thoughts, and how do you make ’em out of brainstuff? Keynes’s answer nicely alerts us to the dangers of oversimplification and false dichotomy, but is otherwise not much help. Similarly, Barsalou’s alternative answer: “we think in perceptual symbols,” is less informative than it might at first appear. There is something compelling about Barsalou’s proposal that cognitive processes be described in terms of simulators (and simulations) involving modal as opposed to amodal formats or systems of representation. Restoring to serious attention the idea that you don’t need a separate (amodal) symbol system to support cognitive functions is a worthwhile project. Moreover Barsalou has interesting suggestions about features that such a perceptuo-motor system ought to have if the brain, one way or another, is to do the work that needs to be done (“the ability to represent types and tokens, to produce categorical inferences, to combine symbols productively, to represent propositions, and to represent abstract concepts” (sect. 1.2.1), but just stipulating that this is possibly what happens in the brain does not begin to address the hard questions. What does Barsalou mean by “symbol”? He uses the familiar word “symbol” but then subtracts some of its familiar connotations. This is, in itself, a good and familiar strategy (cf. Kosslyn’s (1980) carefully hedged use of “image,” or for that matter, Fodor’s (1975) carefully hedged use of “sentence”). Once Barsalou’s subtraction is done, however, what remains? It’s hard to say. If ever a theory cried out for a computational model, it is here. He says: “perceptual symbol systems attempt to characterize the mechanisms that underlie the human conceptual system” (our emphasis; last para., sect. 2.4.6), but here he simply conflates personal and subpersonal cognitive psychology in equating mechanisms with representations; “an important family of basic cognitive processes appears to utilize a single mechanism, namely, sensory-motor representations” (last para. of sect. 2.4.7). These representations, by being presupposed to have the very content of our intuitive mental types, must be implicated in a most impressively competent larger structure about which Barsalou is largely silent. As “specs” for a cognitive system there is much to heed here, but the fact that this is only specs is easily overlooked. Moreover, if Barsalou’s perceptual symbols are not (personal level) thoughts but sub-personal items of machinery, then the content they might be said to have must be a sort of sub-personal content, on pain of reinstating vicious homuncular fallacies. Are sort-of symbols an advance on sort-of sentences and sort-of pictures? How? By not being amodal, one gathers, but also by being only somewhat, or selectively, modal: First, diagrams such as the balloon in Figure 4A should not be viewed as literally representing pictures or conscious images. Instead, these theoretical illustrations stand for configurations of neurons that become active in representing the physical information conveyed in these drawings. (para. 3 of sect. 3.1) Unless we are missing something, this is an assertion of specs without offering a clue about realization. As such, Barsalou’s proposals do not substantially improve on “pure” phenomenology – leaving all the hard work of implementation to somebody else. Consider: A simulator becomes increasingly active if (1) its frame contains an existing simulation of the individual, or if (2) it can produce a novel simulation that provides a good fit. (para. 2 of sect. 3.2.1) Fine; now let’s see a model that exhibits these interesting properties. We want to stress, finally, that we think Barsalou offers some very promising sketchy ideas about how the new embodied cognition approach might begin to address the “classical” problems of propositions and concepts. In particular, he found some novel ways of exposing the tension between a neural structure’s carrying specific information about the environment and its playing the sorts of functional roles that symbols play in a representational system. Resolving that tension in a working model, however, remains a job for another day. Commentary/Barsalou: Perceptual symbol systems BEHAVIORAL AND BRAIN SCIENCES (1999) 22:4 613 plays an important part in a variety of psychological theories of emotion. The best example here is Richard Lazarus, who identifies the appraisal component of emotion with “evaluative judgement” (Lazarus 1991). Most appraisal theories of emotion in psychology involve some such symbolic element. There are therefore a variety of emotion theories according to which these have an important symbolic dimension. In many cases, that thesis is combined with a second one, namely, that in their symbolic capacity, emotions constitute a distinct information processing system, governed by its own special affective principles and regularities, with its own special affective representational posits (Charland 1995). Emotion theories modelled along these lines come in two varieties. A good account of a “cognitive” version is Lazarus (1991). A good account of a “perceptual” version is Zajonc (1980). Damasio (1994) is an excellent example of a theory of emotion that manages to reconcile the main insights of both cognitive and perceptual approaches (Charland 1997). Much like vision and language, then, emotion can be argued to form a distinct symbol processing system of its own. Depending on the theory in question, that system can be cognitive or perceptual, or a combination of both. This is one aspect of emotion theory that is relevant to Barsalou’s project. Unfortunately, in his discussion of “representational processes” he fails to mention emotion (sect. 2.4.7). Emotion is also relevant to Barsalou’s project in another way. It is possible to argue there are specialized perceptual symbol systems within the overall affective perceptual representational dimensions of emotion. That hypothesis can be interpreted to mean there are various “modular” symbolic subsystems in emotion (Charland 1996). It can also be interpreted to mean that individual emotions have modular features of their own (de Sousa 1987). LeDoux argues this in the case of fear (LeDoux 1996). A promising example of a perceptual emotion module is the facial expressive dimension of emotion (Ekman 1992). Another is Jaak Panksepp’s hypothalamic 4 command-circuit hypothesis (Panksepp 1982; 1998). These last two hypotheses raise interesting questions about the nature and limits of cognitive penetrability, another interest of Barsalou’s (sect. 2.4.6). One final aspect of emotion theory Barsalou may want to consider has to do with the tension between cognitive and perceptual approaches in cognitive science. There is in fact a partial, but not exact, mirror image of that debate in emotion theory. Emotion theories are often classified in those terms and in a manner that pits the two approaches against one another. I have argued elsewhere that this alleged incompatibility between cognitive and perceptual theories of emotion is more pernicious than it is justified, and that a comprehensive theory of emotion can reconcile the main insights of both (Charland 1997). There may be lessons here that can inform the manner in which Barsalou frames the debate between cognitive and perceptual approaches. Of course, all of this requires a more detailed look at emotion theory than is possible here. Nevertheless, I hope I have shown that there are important connections to pursue in this regard.