Consciousness is a mongrel concept: there are a number of very different "consciousnesses." Phenomenal consciousness is experience; the phenomenally conscious aspect of a state is what it is like to be in that state. The mark of access-consciousness, by contrast, is availability for use in reasoning and rationally guiding speech and action. These concepts are often partly or totally conflated, with bad results. This target article uses as an example a form of reasoning about a function of "consciousness" based on (...) the phenomenon of blindsight. Some information about stimuli in the blind field is represented in the brains of blindsight patients, as shown by their correct "guesses," but they cannot harness this information in the service of action, and this is said to show that a function of phenomenal consciousness is somehow to enable information represented in the brain to guide action. But stimuli in the blind field are BOTH access-unconscious and phenomenally unconscious. The fallacy is: an obvious function of the machinery of access-consciousness is illicitly transferred to phenomenal consciousness. (shrink)

How can we disentangle the neural basis of phenomenal consciousness from the neural machinery of the cognitive access that underlies reports of phenomenal consciousness? We can see the problem in stark form if we ask how we could tell whether representations inside a Fodorian module are phenomenally conscious. The methodology would seem straightforward: find the neural natural kinds that are the basis of phenomenal consciousness in clear cases when subjects are completely confident and we have no reason to doubt their (...) authority, and look to see whether those neural natural kinds exist within Fodorian modules. But a puzzle arises: do we include the machinery underlying reportability within the neural natural kinds of the clear cases? If the answer is ‘Yes’, then there can be no phenomenally conscious representations in Fodorian modules. But how can we know if the answer is ‘Yes’? The suggested methodology requires an answer to the question it was supposed to answer! The paper argues for an abstract solution to the problem and exhibits a source of empirical data that is relevant, data that show that in a certain sense phenomenal consciousness overflows cognitive accessibility. The paper argues that we can find a neural realizer of this overflow if assume that the neural basis of phenomenal consciousness does not include the neural basis of cognitive accessibility and that this assumption is justified by the explanations it allows. (shrink)

This article concerns the interplay between two issues that involve both philosophy and neuroscience: whether the content of phenomenal consciousness is 'rich' or 'sparse', whether phenomenal consciousness goes beyond cognitive access, and how it would be possible for there to be evidence one way or the other.

GY, an extensively studied human hemianope, is aware of salient visual events in his cortically blind field but does not call this ''vision.'' To learn whether he has low-level conscious visual sensations or whether instead he has gained conscious knowledge about, or access to, visual information that does not produce a conscious phenomenal sensation, we attempted to image process a stimulus s presented to the impaired field so that when the transformed stimulus T(s) was presented to the normal hemifield it (...) would cause a sensation similar to that caused by s in the impaired field. While degradation of contrast, spatio-temporal filtering, contrast reversal, and addition of smear and random blobs all failed to match the response to a flashed bar sf, moving textures of low contrast were accepted to match the response to a moving contrast-defined bar, sm. Orientation and motion direction discrimination of the perceptually matched stimuli [sm and T(sm)] was closely similar. We suggest that the existence of a satisfactory match indicates that GY has phenomenal vision. (shrink)

We explored whether information processed subconsciously in blindsight is qualitatively different from normal conscious processing. On each trial the blindsight patient GY was presented with a square-wave grating either in an upper or lower quadrant of his visual field and was asked to report the opposite of its location . We found that while GY was able to follow these exclusion instructions in his normal field, he tended to erroneously respond with the real location when the grating appeared in his (...) blind field. Remarkably, his error rate actually increased with increasing grating contrast in his blind field. The interpretation of these results does not rely on subjective reports and thus cannot be criticized on the grounds that subjective reports are unreliable. We conclude that blindsight is unlike normal conscious vision. (shrink)

Experimenters generally infer whether participants have visual experiences based on metacognitive responses. We showed a well-studied blindsight participant, GY, several definitions of the term “qualia” and then questioned him about whether he felt or he experienced qualia in his normal and blind fields. We found, contrary to others who have used different methods for measuring qualia, that GY does not have qualia for stationary stimuli in his blind field. This novel method for directly assessing qualia embraces the idea that experiences (...) should be related by the experiencer, not the experimenter. (shrink)

First published in 1995, The Visual Brain in Action remains a seminal publication in the cognitive sciences. For this new edition, a very substantial and illustrated epilogue has been added to the book in which Milner and Goodale review the key developments that support or challenge the views that were put forward in the first edition.

On a remarkably thin base of evidence – largely the spectral analysis of points of light – astronomers possess, or appear to possess, an abundance of knowledge about the structure and history of the universe. We likewise know more than might even have been imagined a few centuries ago about the nature of physical matter, about the mechanisms of life, about the ancient past. Enormous theoretical and methodological ingenuity has been required to obtain such knowledge; it does not invite easy (...) discovery by the untutored. It may seem odd, then, that we have so little scientific knowledge of what lies closest at hand, apparently ripe for easy discovery, and of greatest importance for our quality of life: our own conscious experience – our sensory experiences and pains, for example, our inner speech and imagery, our felt emotion. Scientists know quite a bit about human visual capacities and the brain processes involved in vision, much less about the subjective experience of seeing; a fair bit about the physiology of emotion, almost nothing about its phenomenology. Philosophers began in earnest in the seventeenth and eighteenth centuries to describe and classify our patterns of conscious experience. John Locke, for instance, divided experienced “ideas” into those that arise from sensation and those that arise from reflection, and he began to classify them into. (shrink)

within-field task as testing proceeded. (In any case, the two-field task is presumably a more difficult one than the one-field task. ...

In this introductory paper, we assess the current status of blindsight -- the phenomenon in which patients with damage to their primary visual cortex retain the ability to detect, discriminate and localize visual stimuli presented in areas of their visual field in which they report that they are subjectively blind. Blindsight has garnered a great deal of interest and critical research, in part because of its important implications for the philosophy of mind. We briefly consider why this is so, and (...) then go on to examine three empirical questions which have fuelled challenges to the validity of blindsight as a distinct neuropsychological phenomenon. First, is blindsight simply degraded normal vision? Second, does blindsight depend on undamaged areas of primary visual cortex? Third, does evidence that blindsight patients are aware of moving stimuli undermine the apparent dissociation between access to visual information and visual experience in blindsight? In the course of the review we introduce the four other papers on blindsight in this issue. We conclude that, although patients with primary visual cortex damage may indeed perceive moving stimuli, there is still good evidence for a dissociation between access to information and phenomenal experience which cannot be accounted for in terms of degraded normal vision or undamaged primary visual cortex. (shrink)