According to Block's diagnosis, the present scientific evidence is compatible with the hypothesis that the neural machinery underlying cognitive accessibility is not a constitutive part of the neural machinery underlying visual phenomenology. The evidence shows that locally recurrent activity within the occipital areas is not sufficient for cognitive accessibility: the latter requires broadcasting to a global workspace involving frontal and parietal areas by means of long-range projections from the occipital areas. But the evidence does not rule out the hypothesis that recurrent activity within occipital areas is sufficient for visual phenomenology. I find Block's diagnosis compelling and his hypothesis quite plausible. Here, I want to press him on a pair of conceptual issues respectively raised by his present conception of cognitive accessibility and by his present conception of visual phenomenology.
Block's hypothesis presupposes the acceptance of some such psychological distinction as the distinction between belief (or judgment) and phenomenal experience. One can visually experience (or see) an object that exemplifies the determinate property F without using (or even possessing) the concept of F. But one cannot believe that some object is F unless one possesses the concept of property F.
As Block recognizes, the belief–experience distinction faces a direct challenge from the behaviorist reliance on reportability. Since the content of one's report depends on what one believes, not on the content of one's visual experience, one basic reason for rejecting the distinction between experiencing and believing is the behaviorist suspicion that, unlike the content of one's belief, the content of one's experience runs the risk of being unreportable and thereby escaping the scope of scientific investigation.
If one accepts the belief–experience distinction, then the question may also arise: What does it take to be aware of one's own experiences? At one extreme is Dretske's (1993; 1994) view that one might have a conscious experience and not be conscious of having it. At another extreme is Dennett's (1991) first-person operationalist view, according to which one cannot be aware of a stimulus unless one believes that one is aware of it.
Block rejects first-personal operationalism. But instead of endorsing the view that one might have a conscious experience and not be conscious of it, he considers a deflationary view and the “same order” view. I wonder why. On the deflationary view, one is supposed to experience one's experience just as one dances one's dance or one smiles one's smile. On the same order view, a conscious experience is reflexive. The deflationary view sounds to me like a failed attempt at dissolving rather than solving the problem of self-awareness. Certainly, one is not having a visual experience of one's own visual experience of a red rose when one is having a visual experience of a red rose. Nor is it clear that the same order view can accommodate Block's explicit purpose of providing a unified account of experience: Is a mouse in a reflexive state of awareness when it sees a piece of cheese?
Furthermore, Block sometimes gives, I think, the misleading impression that the function he assigns to the mechanisms of cognitive accessibility is to make one aware, not of features of distal stimuli, but of one's own phenomenology or of features of one's own phenomenally conscious experiences. For example, early on he introduces cognitive accessibility in terms of Fodor's criterion of modularity according to which we do not have cognitive access to some of our own perceptual states and representations. This is slightly misleading because Block's view is that by being broadcasted to the global workspace for further processing, the content of a dominant visual representation makes one cognitively aware of visible features of one's non-mental environment, not of one's own psychological life (or computational architecture).
I now turn to Block's present conception of visual phenomenology. So far as I can see, none of Block's arguments in this paper presupposes his (2003; 2007) anti-representationalist view of the character of phenomenal visual experiences. Given my own representionalist bias, this independence makes his arguments for the view that the neural machinery of visual phenomenology does not include the neural machinery of cognitive accessibility more easily acceptable. In particular, I fully concur with the main line of Block's accounts of the Sperling experiment, change blindness experiments, and the Landman et al. experiment.
Consider Block's present account of the Sperling experiment. To say of subjects that they visually experience the whole array of 12 alphanumeric characters is to say that they are able to bring each character under the general concept “letter.” The reason they fail to report more than 4–5 of such characters is that they fail to bring more than 4–5 of them under the concepts of their distinctive shapes. On this view, the content of a reportable representation seems to stand to the phenomenal character of a non-reportable experience of one and the same stimulus just as the concept of a determinate shape property (e.g., rectangle) stands to the concept of a determinable shape property (e.g., polygon). If so, then the question arises: Is the rejection of representationalism, which Block has endorsed elsewhere, consistent with his present account of visual phenomenology?
The question, I think, is made more pressing by the fact that Block is willing to draw a contrast between two memory systems with different storage capacities: The capacity of the so-called visual phenomenal memory system is said to overflow the capacity of working memory. But on the face of it, the argument for the view that the neural machinery for visual phenomenology does not contain the neural machinery for cognitive accessibility seems to presuppose that only contents that are cognitively accessible, not the contents of visual phenomenology, are available for further processing by such cognitive mechanisms as attention, memory, and reasoning. Would Block be willing to postulate a special phenomenal attention system and a special phenomenal reasoning system for visual phenomenology? If not, then why not? Why single out visual phenomenal memory among other cognitive mechanisms?
