Ned Block argues, “the machinery of cognitive access is not included in the machinery of phenomenology” (target article, sect. 9, para. 13). His argument is plausible, but I think psychological considerations support his conclusion, independently of neurological conjecture.

The view that all consciousness must be available to higher cognitive faculties is motivated by worry that without “reportability,” consciousness cannot be studied scientifically. Either the view tries to rule apriori on empirical matters – how could it be apriori that animals that lack propositional attitudes cannot feel pain? – or it envisions too narrow a range of possible empirical evidence. Block has widened the range. Here, I think he underplays psychological considerations.

In the Sperling (Reference Sperling1960), Landman et al. (Reference Landman, Spekreijse and Lamme2003), and Sligte et al. (Reference Sligte, Scholte and Lamme2008) experiments, subjects, using iconic memory, take themselves to have seen a relatively specific number of items, experimentally investigated to have been in the 8 to 32 range. The items are displayed long enough for normal perceptual processing to be completed. In any given trial, using working memory, subjects can make use of information on only four instances of specific types of items, say, specific alphanumeric characters. They can do this for specific types of any 4 of 8 to 32, if cued after presentation.

I believe these experiments support two conclusions: (a) In any given trial, there are phenomenally conscious perceptions of specific types of items not accessed by working memory; and (b) causal machinery produces specific types of phenomenal consciousness on given occasions, but on those occasions does not register those types in working memory.

Block accepts, but does not highlight, conclusions (a) and (b). He argues for a stronger conclusion: (c) The machinery of working memory does not overlap the machinery of phenomenal consciousness. He reaches this third conclusion in three steps. First, he holds that if one accepts the Sperling-type experiments at face value, the minimum concessions required of someone who believes working memory (and through it, “reportability”) is constitutive to phenomenal consciousness are: (d) “the ‘capacity’ of … the visual phenomenal memory system, is greater than that of the working memory buffer that governs reporting” (sect. 9, para. 11), and (e) “the machinery of phenomenology is at least somewhat different from the machinery of cognitive accessibility” (sect. 9, para. 13). (That is, (a)-(b) entails (d)-(e), but not vice-versa.) Second, he argues for accepting Sperling-type experiments at face value. Third, he invokes neurological conjecture to support (c).

One might accept (a)-(b) and (d)-(e), but insist that working memory and “reportability” are constitutive to phenomenal consciousness. One might hold that although some specific phenomenally conscious items do not appear in working memory, all phenomenal consciousness depends constitutively on some items' being accessible to working memory. Block marshals neurological considerations for (c) against such a position.

In his second stage, Block opposes Dehaene's attempts to avoid taking Sperling-type experiments at face value. Block effectively criticizes postulating what he calls a refrigerator-light illusion, and points out that it is question-begging to invoke “change-blindness” to support the position that the subjects in Sperling-type experiments are under an illusion that they had phenomenal experiences of items that do not appear in working memory. The two cases are disanalogous in a way that Block does not note. On Dehaene's view that Sperling-type subjects are phenomenally conscious only of items actually in working memory, the subjects cannot have had, before the cue that selects those items retained in working memory, a phenomenologically conscious perception of any of the specific 8–32 items that they seem to have experienced. On that view, subjects' sense of having consciously perceived even specific retained items before they appear in working memory is illusion. No one postulates analogous total illusion in “change-blindness” cases. Even proponents of the (I think mistaken) view that items that change unnoticed are not consciously seen do not claim that nothing is consciously seen.

I believe that Sperling-type experiments support (c), not just (a), (b), (d), (e). I argue by dilemma. If retained and unretained items are held not to be conscious before any items are retained in working memory, what is the evidence that memory of their having been conscious is total illusion? Exposure is long enough for perceptual processing to be complete. Why should phenomenology, even of specific retained items, have been missing? We have independent evidence about working memory. It does have constructive functions: making consciousness more vivid, rehearsing to facilitate retention and reproduction of imagery (Andrade Reference Andrade and Andrade2001; Pearson Reference Pearson and Andrade2001). But its primary function is to preserve perception already formed. Holding that its preservations convey systematic illusion is ad hoc. The fact that subjects seem to remember having seen all items, and could be cued to retain any item specifically, supports believing that even specific unretained items are phenomenally conscious. Now suppose that all, or at least the retained, specific items are held to be conscious before being preserved in working memory. What is the evidence that mere accessibility to working memory is constitutive to their being occurrently conscious beforehand? Such a view labors under heavy empirical burden. Consciousness is an occurrent, not a dispositional, condition. We have no good idea how mere dispositional accessibility to working memory could be causally necessary to occurrence of consciousness before working memory operates. Why should the door's being open matter to the occurrence of something that does not use the door until after it already occurs? Such a view would require very special evidence and explanation. In the absence of specific empirical support, the idea is not a serious contender. The best explanation of current evidence is that conscious perception of the specifics of items later retained, indeed of all 8–32 items, occurs independently of working memory. The machinery of phenomenal consciousness appears to be independent of the machinery of working memory. Conclusion (c) is supported independently of Block's neurological conjecture.

Further evidence for (c) may lie in the formation speed of at least generic phenomenally conscious aspects of visual perception. Some super-ordinate object categorization occurs in less than 150 msec – before a signal even reaches working memory (VanRullen & Thorpe Reference VanRullen and Thorpe2001; Rousselet et al. Reference Rousselet, Thorpe and Fabre-Thorpe2004a; Reference Rousselet, Thorpe and Fabre-Thorpe2004b). Such considerations are tentative. But it is important not to be so fixed on neurological matters that one underrates the force of psychological considerations in supporting psychological conclusions.