Are Theories of Imagery Theories of Imagination? An Active Perception Approach to Conscious Mental Content
Nigel J.T. Thomas
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Page 11
Source: http://cogprints.org/5018/1/im-im-cp.htm
4 Imagery Theories and Imagination
Let us now consider how well the three contemporary theories of imagery fit together with the traditional/Romantic conception of imagination just outlined.
4.1 Description theory and Discursive Reason
Whatever its merits might be as a theory of imagery, description theory holds very little promise of providing an account of imagination in the traditional and significant sense just outlined. Its view of mental processes, even imagery processes, as consisting exclusively of the manipulation of sentential, mentalese representations, could hardly be more rationalistic. The home ground of the theory of mentalese representation is a picture of behavioral control as a process of discursive rational deliberation, the practical syllogism in modern dress: belief plus desire imply executable intention. Whether or not the mentalese sentences which are supposed to constitute imagery enter into these deliberations, it is axiomatic for description theory that they are part of the same representational system, encoded in the same format. If we embrace an account of imagination based on sentential representation we lose our grip on it as a distinctive mental faculty. Imagination would be entirely assimilated to discursive, "consequetive" reason, and thereby would essentially disappear from our understanding of the mind.
We do, of course, sometimes use "imagine" to mean something like "suppose", or "entertain the possibility of" [the truth of some proposition]. But this is not what "the folk" generally take imagination to be (Sutherland, 1971). To reduce it entirely to these bloodless terms is simply to duck the most significant issues that the concept raises. They are perfectly proper usages, but only distantly related to the idea of creative imagination (Thomas, 1997a).
4.2 Seeing As
Neither picture nor PA theories assimilate imagery and ratiocination in this way. But now consider Ryle's (1949) example of a child looking at the face of a doll and imagining she sees it smiling. (I take it that this does not mean, pace Danto (1958), that she is deluded into believing that it really is smiling.)
PA theory can accommodate this example, because the perceptual processes that it holds to be involved in imagery are precisely those processes that enable us, in perception, to see things aswhatever they are or might be taken to be--to see the duck-rabbit as a duck, for example, or a pikestaff as a pikestaff--by discovering (and perhaps selectively attending to) defining features. But there can be a continuum of cases between the extremes of veridical seeing and "pure" imagery (where the imaginal experience incorporates no aspect of what is before us). In the former, all the perceptual tests ordered by the schema are actually carried out, and all results returned by the perceptual instruments are given their full weight in determining the course of subsequent testing. In "pure" imagery, either the ordered tests are not carried out at all, or else any results that are returned by the instruments are completely ignored. Ryle's example falls between: some of the tests are carried through and responded to appropriately, and some are not. When the child determinedly scrutinizes her doll's unsmiling lips for a smile then relevant positive results, such as might come from a test for, say, pinkness, may be accepted (i.e. allowed to influence the course of further testing), but any relevant negative results (e.g. from a test for curvature) will, as in "pure" imaging, be ignored. She will continue her examination just as if she actually had confirmed the presence of a cheery upward curve.
4.2.1 Can Picture Theory Explain Seeing As?
On Ryle's reading of picture theory, the imagined smile would exist not on the doll's face but in some non-physical, Cartesian mental space, and, as he says, this is absurd. However, as it stands, this argument fails as a refutation of the real theory. For Kosslyn (and, come to that, Descartes) the "quasi-picture" is not anywhere non-physical, but in the brain, and at just the same locus where similar pictures are supposed to form during normal, veridical seeing. Indeed, the primary function of the visual buffer in this theory is, surely, the registration of images coming in from the eyes. Imagery occurs when this function is hi-jacked by information from some internal source. Since the perceptual process gives rise to perceptions of things as "out there", in the world, picture theory would seem to predict, and certainly to allow, that imagined things will also seem "out there".
But if we consider in more detail how Kosslyn might try to deal with Ryle's example I think we will see that it still raises serious problems. The only approach I can think of that does not involve ad hoc postulation of quite new, otherwise unmotivated, mechanisms is to suggest that although most of the image of the doll on the visual buffer is a percept, formed from information coming directly from the eyes, a small portion of the buffer might be reserved for an image of smiling lips generated out of information from internal sources: a mental image pasted over a part of a perceptual image, as it were.
Because our visual input is in constant flux (not least because our eyes are in constant and irregular motion) we must assume that the perceptually generated contents of the visual buffer will be being constantly updated. It might seem that a "pasted on" image of the type just suggested would be liable to be disrupted by this process12, and the smile would very quickly disappear. However, that conclusion can be avoided if we assume that images are also constantly updated, repeatedly re-written to the appropriate region of the buffer. Kosslyn already holds (1980, 1991) that such regular re-writing of images is necessary if they are not to fade away.
Now, however, suppose the doll were suddenly and unexpectedly snatched away, or the room plunged into darkness. How could the child (or her brain) know to cease writing the smile image untilafter she had registered that the doll percept had gone? The theory would surely predict that a vision of smiling lips would remain momentarily floating before the child's eyes. I have never experienced any such effect, nor come across anything like it in all my extensive reading of the imagery literature. In similar vein, Hamlet imagined the appearance of a weasel, a whale and a camel in a cloud: if the cloud had suddenly blown away would a faint weasel image have briefly remained in the sky?13 Indeed, is the notion of an image, even a diaphanous one, "pasted over" a percept even a superficially plausible explanation here? Rather than some internally generated picture being superimposed upon the percept, should we not rather say that the cloud and the lips themselves were being actually seen, but in a peculiar manner. Hamlet saw the cloud itself as weasel-like (he detected, or feigned to detect, certain weaselish features in it), the doll's actual lips were seen assmiling.
4.2.2 Can Seeing As Be Set Aside?
Faced with this argument, pictorialists could retreat, and say that quasi-pictorial theory is only intended to deal with "pure" mental imagery. Examples like the smiling lips and the weasel cloud would therefore be irrelevant to imagery theory. This move is logically unassailable, but, besides flouting Occam's razor, it leaves the smile and the weasel quite unexplained. What might a pictorialist say is going on in such cases?
Kosslyn (1991, 1994) has recently argued that there are in fact two types of imagery. In addition to quasi-pictorial imagery he also now postulates "attention based imagery", which occurs, for example "when you look at a tiled floor (. . .) and "see" a letter by attending to specific tiles" (Kosslyn, 1994)14. Except for the fact that he seems to be thinking of attention entirely in spatial terms (as a matter only of where we look rather than also of what we may be looking for), the sketchy account he gives of the mechanism of "attention based imagery" looks very much like an embryonic version of PA theory.
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