Abstract
I examine John Campbell’s claim that the determination of the reference of a perceptual demonstrative requires conscious visual object-based selective attention. I argue that although Campbell’s claim to the effect that, first, a complex binding parameter is needed to establish the referent of a perceptual demonstrative, and, second, that this referent is determined independently of, and before, the application of sortals is correct, this binding parameter does not require object-based attention for its construction. If object-based attention were indeed required then the determination of the referent would necessarily involve the application of sortal concepts, since object-based attention initiates top-down cognitive effects on visual processing. I also examine Mohan Matthen’s claim that reference to objects is established only through the visual processing in the dorsal visual stream and argue that although it is true that processing in the dorsal stream can determine reference, a thesis that goes against Campbell’s view that the determination of the referent requires conscious attention, processing along the ventral visual stream can also establish the reference of perceptual demonstratives. It also claim that Matthen’s account of dorsal processing underestimates the kind of information processed along the dorsal stream and this has some implications regarding perceptual demonstratives reference fixing.
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Notes
Campbell explains that he uses the term “acquaintance” the same way that Russell, who introduced the term, does.
Confusion arises if one does not take that point into account. Clark (2006, p. 181), for instance, claims that the issue of the sortal dependence of perceptual contents should not be treated as a claim about how to focus one’s attention, that is, whether attention focusing requires the application of sortals (Clark takes this to be Campbell’s main point against conceptualism). Rather, the issue is “if we think it true that in using some expression a subject is referring to object x, and not to y, what are the conditions necessary for this to happen? To answer that question it seems we must consider how the subject represents x, whether the subject represents the thing as an x, or as a y: and there the suggestion that mastery of sortal concepts might be required is not so silly at all.” Now, a subject represents an object x as an x only if sortal concepts are applied; one cannot represent an animal as a tiger unless one has applied the sortal “tiger” and “animal”. However, this is not what is at stake in the problem of fixing the referents of perceptual demonstratives. The issue here is not whether the expressions that subjects use to refer involve sortals, of course they do. The issue is whether to refer to objects in a visual scene through perceptual demonstratives the application of sortals is required. And the answer to that issue is, ‘of course not’. It should be mentioned though that Campbell’s (1997, 2002) treatment of the issue is ambiguous enough to validate Clark’s worries. Campbell frequently confounds perceptual demonstratives with expressions of reference. Campbell (1997, p. 55), for example, writes that the problem of reference to objects by means of perceptual demonstratives is a problem of relating concepts to imagistic content. “Imagistic content” is the content involved in imagistic or pictorial representations, which largely preserve the spatial structure of the scene they represent. It is the content of our experiences as we consciously access it and use it to see things as being such and such: “looking out of the window, then we may discuss the castle before us, identifying it as ‘that castle,’ the one we can see”.
Cussins (1990) calls the content of a representation “non-conceptual,” by which he means those representations whose contents are canonically characterized by means of concepts which are such that the organism need not have those concepts in order to have that content. More specifically, for any state S with content, S has non-conceptual content P, iff the fact that X is in S does not imply that X possesses the concepts that canonically characterize P, meaning that X does not need to possess the concepts that would normally enter in a report of the content of S that adequately specifies that content.
Although phenomenal content, what Smith (2002) and others call sensations, is inherent into perceptual experience it is not the object of awareness of this experience, the object of awareness is a specific object with its properties. Smith distinguishes between sensation and perception. Sensations or sensory qualities or qualia are inherent features of experiences themselves. However, sensations lack intentionality. They do not refer to something beyond them; they are not properties, a sense-datum, of which one is aware. Although sensations are presented in consciousness as intrinsic properties of the experience itself, they do not function as the immediate objects of awareness of this experience. When one perceives, one is not aware of these properties as properties of one’s experience, one is aware of objects outside our bodies carrying these properties. One is aware of sensations only in cases of non-perceptual sensations.
Thus, there is a distinction between having a sensation of something and being perceptually conscious of something. Sensations can occur either perceptually or non-perceptually, depending on whether they are properties of perceptual states or not, respectively. In the former case they are perceptual sensations (Smith 2002, p. 92). In the latter case sensations give us no awareness of physical objects only of some properties. The faculty that makes us aware of objects is perception.
Now, “there is an analogy between familiar ways of reporting seeing and the units into which objects of sight may be articulated. The latter are divisible in roughly the way we tend to parse linguistic components of sentences” (Vision 1997, p. 85). In other words, perceptual states have the object-attribute form.
Peacocke (1992, pp. 61–62) makes roughly the same point in elaborating his notion of scenarios. Peacocke searches for a level of non-conceptual content on which to anchor concepts in a non-circular way. This kind of non-conceptual content is provided by the spatial types ‘the type being that under which fall precisely those ways of filling the space around the subject that are consistent with the correctness of the content.’ To specify the spatial types one needs to fix an origin and the axes of the resulting frame. These elements cannot be defined with reference to the real world, since a spatial type may be instantiated at different places. Thus, the point of origin and the axes should be defined with respect to a thing that is always present irrespective of the location at which the type is instantiated; this is the body of the subject. The point of origin may be the center of gravity of the body and the axes of reference the directions of right-left, up-down, and back-front, as defined on the subject’s body.
Besides there is an empirical problem, which is fatal to Matthen’s three stage account of bodily action. Evidence (see Raftopoulos, in press, Chap. 2, for an extensive discussion) shows that activation can reach the motor cortex through the dorsal system at about 130 ms after stimulus onset. At that point in time the activation along the ventral system has barely solved the binding problem and it has not necessarily reached the mnemonic circuits. The identification and recognition of an object as indexed by the elicitation of the P300 component of ERP scanning takes place at about 270–300 ms after the stimulus onset. This means that if the dorsal system to initiate action had to rely always on information regarding the identity of the target coming from the ventral system, then action would be much more delayed that it actually is.
This is suggested from the following evidence. The ventral system stores size information in a relational scene-based framework. Thus it falls victim to the size-contrast illusion in which one object is perceived to be larger than another one although they both have the same size just because smaller objects surround it. The dorsal system, on the other hand, due to the absolute perceiver-center framework that it uses to represent information is not victimized by the illusion as the fact that the same person who perceives one object to be larger than the other, when asked to grasp them her grip is the same, which means that the calibration of the grip does not fall victim to the illusion. This, by the way, shows that the dorsal system processes size information on its own and does not have to wait for that information to be transmitted to it from the ventral system. Now, when action is delayed, the calibration of the grip falls victim to the illusion. The reason is that, since the dorsal system works in real time the time delay of the action causes the loss of the size information retrieved in the dorsal stream and, therefore, any action has to rely on size information stored in memory along the ventral stream. However sizes in the ventral system are represented in a relational framework and, thus, are subject to the size-contrast illusion. This leads the dorsal system that uses the ventral information to fall victim to the illusion.
LRP is processing that involves lateral and top-down flow of information, in addition to FFS. However, the information that flows top-down originates from sites within the circuits of early vision and thus does not entail the cognitive penetrability of early vision by conceptual information.
To use Dehaene’s et al. (1998) terminology, the signal enters the global working space.
Of course, Campbell could argue that only in categorical perception one can be construed as properly referring to an object, but such an argument is missing and, furthermore, I find it hard to see how this is something more than an exercise in mere semantics of the term “reference”.
We saw that object-based attention is registered at about 200–300 ms after stimulus onset. This coincides with the onset of GRP, a fact that shows that object-based attention is inextricably related to the function of memory and other cognitive centers. If the reader looks back at the example of how the biased competition account of attention accounts for the search of a feature in a visual scene, she will see that, indeed, attention that locks on to objects/features requires working memory.
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Raftopoulos, A. Reference, perception, and attention. Philos Stud 144, 339–360 (2009). https://doi.org/10.1007/s11098-008-9213-5
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DOI: https://doi.org/10.1007/s11098-008-9213-5