Ned Block’s Overflow Argument purports to establish that the neural basis of phenomenal consciousness is independent of the neural basis of access consciousness. In a recent paper, Block’s argument has been challenged by Peter Carruthers. Carruthers concedes the truth of one of the argument’s key steps, namely, that phenomenal consciousness overflows what is in working memory. At the same time, he rejects the conclusion of the argument by developing an account of this overflow that is alternative to Block’s. In this (...) paper, I argue that Carruthers’s account does not pose a real threat to the Overflow Argument. The overall plausibility of Carruthers’s account rests on the empirical plausibility of a claim concerning global broadcasting which, albeit intuitively plausible in light of a lightly-sketched picture of the impact of attention upon neural matters, he offers no sufficient empirical evidence for. Drawing on some important imaging studies that reveal striking facts about neural responses to visual stimuli, I argue for two intimately related claims: first, that the intuitive plausibility of claims like Carruthers’s is not a guarantee of empirical plausibility; second, that as concerns the same claims, strong empirical evidence is needed before confident judgments of empirical plausibility can reasonably be formulated. (shrink)

Phillips argues that Block faces a “serious internal challenge” in defending the claim that unconscious perception is of the same fundamental kind as conscious perception. This challenge is said to result from Block’s commitment to phenomenal overflow. However, in this paper, I demonstrate that Phillips’ rejection of overflow likewise renders his view on unconscious perception “internally challenged” and therefore equally problematic.

The question of whether phenomenal consciousness is limited to the capacity of cognitive access remains a contentious issue in philosophy. Overflow theorists argue that the capacity of conscious experience outstrips the capacity of cognitive access. This paper demonstrates a resolution to the overflow debate is found in acknowledging a difference in phenomenological timing required by both sides. It makes clear that the “no overflow” view requires subjects to, at the bare minimum, generate an unconscious visual image of previously presented items (...) if it is to explain performance in the change detection paradigm. It then demonstrates that conscious imagery should support better task performance than unconscious imagery because of a necessary difference in representational strength. However, this contradicts empirical findings, and so a new argument for overflow is presented without requiring the premise that subjects need to obtain a specific phenomenology of presented items during change detection. (shrink)

This paper proposes a new argument in favour of the claim that phenomenal consciousness overflows – that is, has a far higher capacity than – cognitive access. It shows that opponents of overflow implicate a necessary role for visual imagery in the change detection paradigm. However, empirical evidence suggests that there is no correlation between visual imagery abilities and performance in this paradigm. Since the use of imagery is not implicated in the performance strategy of subjects, we find a new (...) argument for consciousness without access. (shrink)

Is attention both necessary and sufficient for consciousness? Call this central question of this treatise, “Q.” We commonly have the experience of consciously paying attention to something, but is it possible to be conscious of something you are not attending to, or to attend to something of which you are not conscious? Where might we find examples of these? This treatise is a quest to find an answer to Q in two parts. Part I reviews the foundations upon which the (...) discourse on Q is built. Different inputs to Q produce different answers. After consideration of the many ways “attention” and “consciousness” have been defined, I settle upon phenomenal consciousness and Executive Attention (defined as a suite of strategies for structuring cognition for further processing implemented by the executive of working memory) as the most interesting inputs to Q, and the ones on which Part II focuses. Attention without consciousness seems relatively easy to establish empirically, but consciousness without attention is much harder. The putative candidates all seem to have major problems, but I build a strong abductive case for the hitherto ignored case of foveal phenomenal overflow. We consciously see far more detail in our foveal fields than we can Executively Attend, although there is a serious obstacle to our ever confirming that empirically—identifying conscious content relies on Executive Attentional report. Triangulating the capacity limitations of attention, consciousness, and working memory strengthens this case for consciousness without attention, and suggests that cognition must work something like my “Witches’ Hat Model,” on which content can become conscious outside of Executive Attention or working memory. I conclude with some reflections on the implications of my arguments for the discourse on Q, and for other discourses such as the ontologies of attention and consciousness, theories of consciousness, some other cognitive concepts, and ethical considerations in humans, animals, and machines. A conclusive answer to Q continues to elude us. It may perhaps be an ultimately insoluble conundrum. But it is the very essence of humanity to seek an answer, and in so doing, to improve our understanding of our own nature: “The proper study of mankind is man.”1. (shrink)

In the past two decades a number of arguments have been given in favor of the possibility of phenomenal consciousness without attentional access, otherwise known as phenomenal overflow. This paper will show that the empirical data commonly cited in support of this thesis is, at best, ambiguous between two equally plausible interpretations, one of which does not posit phenomenology beyond attention. Next, after citing evidence for the feature-integration theory of attention, this paper will give an account of the relationship between (...) consciousness and attention that accounts for both the empirical data and our phenomenological intuitions without positing phenomenal consciousness beyond attention. Having undercut the motivations for accepting phenomenal overflow along with having given reasons to think that phenomenal overflow does not occur, I end with the tentative conclusion that attention is a necessary condition for phenomenal consciousness. -/- . (shrink)