Empirical work and philosophical analysis have led to widespread acceptance that vision for action, served by the cortical dorsal stream, is unconscious. I argue that the empirical argument for this claim is unsound. That argument relies on subjects’ introspective reports. Yet on biological grounds, in light of the theory of primate cortical vision, introspection has no access to dorsal stream mediated visual states. It is thus wrongly assumed that introspective reports speak to absent phenomenology in the dorsal stream. In light (...) of this, I consider a different conception of consciousness’s relation to agency in terms of access. While theoretical reasons suggest that the inaccessibility of the dorsal stream to conceptual report is evidence that it is unconscious, this position begs important questions. I propose a broader notion of access in respect of the guidance of intentional agency and not, narrowly, conceptual report (Note: this paper contradicts my earlier paper, "The Case for Zombie Agency"). (shrink)

The idea that attention is necessary for consciousness (the “Necessity Thesis”) is frequently advocated by philosophers and psychologists alike. Experiments involving inattentional and change blindness are thought to support the Necessity Thesis, but they do so only if subjects failing to notice the target stimulus are also not conscious of it. This article uses commonsense phenomenological observations supplemented with empirical data to argue that some subjects failing to notice the target stimulus nonetheless experience its color. Since subjects not noticing the (...) target are commonly assumed to be not attending to it, these scenarios would be instances of consciousness without attention: instead of inattentional and change blindness supporting the Necessity Thesis, they would present counterexamples to it. (shrink)

Research into the neural correlates of consciousness (NCC) aims to identify not just those brain areas that are NCC, but also those that are not. In the received method for ruling out a brain area from being an NCC, this is accomplished by showing a brain area’s content to be consistently absent from subjects’ reports about what they are experiencing. This paper points out how this same absence can be used to infer that the brain area’s content is cognitively inaccessible, (...) in which case we would expect its content to be absent from subjects’ reports whether its content is (phenomenally) conscious or not. If so, such reports cannot count as evidence against that brain area being an NCC, and the received method fails. An alternative method (one suggested in Block, 2007) is considered. (shrink)

How should we characterize the functional role of conscious visual experience? In particular, how do the conscious contents of visual experience guide, bear upon, or otherwise inform our ongoing motor activities? According to an intuitive and philosophically influential conception, the links are often quite direct. The contents of conscious visual experience, according to this conception, are typically active in the control and guidance of our fine-tuned, real-time engagements with the surrounding three-dimensional world. But this idea is hostage to empirical fortune. (...) It is a hostage, moreover, whose safety is in serious doubt. Thus Milner and Goodale argue for a deep and abiding dissociation between the contents of conscious seeing, on the one hand, and the resources used for the on-line guidance of visuo-motor action, on the other. This ‘dual visual systems’ hypothesis, which finds many echoes in various other bodies of cognitive scientific research, poses a prima facie challenge to the Assumption of Experience-Based Control. More importantly, it provides fuel for an alternative and philosophically suggestive account of the functional role of conscious visual experience. (shrink)

Common sense suggests that visual consciousness is essential to skilled motor action, but Andy Clark—inspired by Milner and Goodale's dual visual systems theory—has appealed to a wide range of experimental dissociations to argue that such an assumption is false. Critics of Clark's argument contend that the content driving motor action is actually within subjects' experience, just not easily discovered. In this article, I argue that even if such content exists, it cannot be guiding motor action, since a review of current (...) visual neuroscience indicates that the visual brain areas producing conscious representations are distinct from those driving motor action. (shrink)

I argue that the neural realizers of experiences of trying are not distinct from the neural realizers of actual trying . I then ask how experiences of trying might relate to the perceptual experiences one has while acting. First, I assess recent zombie action arguments regarding conscious visual experience, and I argue that contrary to what some have claimed, conscious visual experience plays a causal role for action control in some circumstances. Second, I propose a multimodal account of the experience (...) of acting. According to this account, the experience of acting is a temporally extended, co-conscious collection of agentive and perceptual experiences, functionally integrated and structured both by multimodal perceptual processing as well as by what an agent is, at the time, trying to do. (shrink)

It is natural to assume that the fine-grained and highly accurate spatial information present in visual experience is often used to guide our bodily actions. Yet this assumption has been challenged by proponents of the Two Visual Systems Hypothesis , according to which visuomotor programming is the responsibility of a “zombie” processing stream whose sources of bottom-up spatial information are entirely non-conscious . In many formulations of TVSH, the role of conscious vision in action is limited to “recognizing objects, selecting (...) targets for action, and determining what kinds of action, broadly speaking, to perform” . Our aim in this study is to show that the available evidence not only fails to support this dichotomous view but actually reveals a significant role for conscious vision in motor programming, especially for actions that require deliberate attention. (shrink)

The extensive involvement of nonconscious processes in human behaviour has led some to suggest that consciousness is much less important for the control of action than we might think. In this article I push against this trend, developing an understanding of conscious control that is sensitive to our best models of overt action control. Further, I assess the cogency of various zombie challenges—challenges that seek to demote the importance of conscious control for human agency. I argue that though nonconscious contributions (...) to action control are evidently robust, these challenges are overblown. (shrink)

The Conscious Brain brings neuroscientific evidence to bear on enduring philosophical questions. Major philosophical and scientific theories of consciousness are surveyed, challenged, and extended.

What mediates between sensory input and motor output? What makes it possible to act on what you perceive? Bence Nanay argues that pragmatic representations provide the perceptual guidance for performing actions. They play a key role in our mental lives, and help explain why the majority of our mental processes are very similar to those of animals.

This paper presents arguments from empirical research and from philosophical considerations to the effect that phenomenality and content are two distinct and independent features of mental representations, which are both relational. Thus, it is argued, classical arguments that infer phenomenality from content have to be rejected. Likewise, theories that try to explain the phenomenal character of experiences by appeal to specific types of content cannot succeed. Instead, a dynamic view of consciousness has to be adopted that seeks to explain consciousness (...) by certain ways of processing representations. Therefore, only empirical methods that are able to investigate the dynamics of the mind can be used for the “quest for consciousness” proper. Moreover, the central intuitions about consciousness are best explained when phenomenality and content are clearly distinguished. (shrink)

In response to Mole 2009, I present an argument for zombie action. The crucial question is not whether but rather to what extent we are zombie agents. I argue that current evidence supports only minimal zombie agency.

According to higher-order theories of consciousness, a mental state is conscious only when represented by another mental state. Higher-order theories must predict there to be some brain areas (or networks of areas) such that, because they produce (the right kind of) higher-order states, the disabling of them brings about deficits in consciousness. It is commonly thought that the prefrontal cortex produces these kinds of higher-order states. In this paper, I first argue that this is likely correct, meaning that, if some (...) higher-order theory is true, prefrontal lesions should produce dramatic deficits in visual consciousness. I then survey prefrontal lesion data, looking for evidence of such deficits. I argue that no such deficits are to be found, and that this presents a compelling case against higher-order theories. (shrink)

Blindsight and vision for action seem to be exemplars of unconscious visual processes. However, researchers have recently argued that blindsight is not really a kind of uncon- scious vision but is rather severely degraded conscious vision. Morten Overgaard and col- leagues have recently developed new methods for measuring the visibility of visual stimuli. Studies using these methods show that reported clarity of visual stimuli correlates with accuracy in both normal individuals and blindsight patients. Vision for action has also come under (...) scrutiny. Recent findings seem to show that information processed by the dor- sal stream for online action contributes to visual awareness. Some interpret these results as showing that some dorsal stream processes are conscious visual processes (e.g., Gallese, 2007; Jacob & Jeannerod, 2003). The aim of this paper is to provide new support for the more traditional view that blindsight and vision for action are genuinely unconscious per- ceptual processes. I argue that individuals with blindsight do not have access to the kind of purely qualitative color and size information which normal individuals do. So, even though people with blindsight have a kind of cognitive consciousness, visual information process- ing in blindsight patients is not associated with a distinctly visual phenomenology. I argue further that while dorsal stream processing seems to contribute to visual awareness, only information processed by the early dorsal stream (V1, V2, and V3) is broadcast to working memory. Information processed by later parts of the dorsal stream (the parietal lobe) never reaches working memory and hence does not correlate with phenomenal awareness. I con- clude that both blindsight and vision for action are genuinely unconscious visual processes. (shrink)

This paper examines Milner and Goodale’s hypothesis about the two visual streams and raises the questions of whether properties in egocentric space (commonly associated with the vision-for-action, or "dorsal," stream) can be part of the phenomenal content of perceptual experience, or only properties in allocentric space (commonly associated with the vision-for-perception, or "ventral," stream) can play this role, and how (if at all) properties in egocentric space differ from properties in allocentric space. These questions are reminiscent of issues raised by (...) Christopher Peacocke's "equal-sized trees" case: if you are looking at equal-sized trees on the side of a road, the trees will phenomenally look to you to be equally tall. But it is also true that a tree will take up more of the space in your visual field the closer it is to you. So, the equal-sized trees will also phenomenally look to you to have different heights. Your (visual) perceptual experience is not illusory. That is, the trees veridically look to you to have the same height, and they also veridically look to you to have different heights. Call the sort of issue raised here the "problem of dual looks." I provide a solution to the problem of dual looks that helps shed light on whether properties in egocentric space can be part of the phenomenal content of perceptual experience, and how (if at all) properties in egocentric space differ from properties in allocentric space. (shrink)

Milner and Goodale's influential account of the primate cortical visual streams involves a division of consciousness between them, for it is the ventral stream that has the responsibility for visual consciousness. Hence, the dorsal visual stream is a ‘zombie’ stream. In this article, I argue that certain information carried by the dorsal stream likely plays a central role in the egocentric spatial content of experience, especially the experience of visual spatial constancy. Thus, the dorsal stream contributes to a pervasive feature (...) of consciousness. (shrink)

Although Wayne Wu correctly identifies a flaw in the way in which my 2009 article frames the debate about ‘zombie action’, he fails in his attempts to strengthen the case for thinking that our actions are under less conscious control than we usually imagine. His argument, like the arguments that my earlier paper addressed, can be blocked by allowing that an embodied demonstrative concept can contribute contents to a visual experience.

David Milner and Melvyn Goodale’s dissociation hypothesis is commonly taken to state that there are two functionally specialized cortical streams of visual processing originating in striate (V1) cortex: a dorsal, action-related “unconscious” stream and a ventral, perception-related “conscious” stream. As Milner and Goodale acknowledge, findings from blindsight studies suggest a more sophisticated picture that replaces the distinction between unconscious vision for action and conscious vision for perception with a tripartite division between unconscious vision for action, conscious vision for perception, and (...) unconscious vision for perception. The combination excluded by the tripartite division is the possibility of conscious vision for action. But are there good grounds for concluding that there is no conscious vision for action? There is now overwhelming evidence that illusions and perceived size can have a significant effect on action (Bruno & Franz, 2009; Dassonville & Bala, 2004; Franz & Gegenfurtner, 2008; McIntosh & Lashley, 2008). There is also suggestive evidence that any sophisticated visual behavior requires collaboration between the two visual streams at every stage of the process (Schenk & McIntosh, 2010). I nonetheless want to make a case for the tripartite division between unconscious vision for action, conscious vision for perception, and unconscious vision for perception. My aim here is not to refute the evidence showing that conscious vision can affect action but rather to argue (a) that we cannot gain cognitive access to action-guiding dorsal stream representations, and (b) that these representations do not correlate with phenomenal consciousness. This vindicates the semi-conservative view that the dissociation hypothesis is best understood as a tripartite division. (shrink)

The purpose of this paper is to defend what I call the action-oriented coding theory (ACT) of spatially contentful visual experience. Integral to ACT is the view that conscious visual experience and visually guided action make use of a common subject-relative or 'egocentric' frame of reference. Proponents of the influential two visual systems hypothesis (TVSH), however, have maintained on empirical grounds that this view is false (Milner & Goodale, 1995/2006; Clark, 1999; 2001; Campbell, 2002; Jacob & Jeannerod, 2003; Goodale & (...) Milner, 2004). One main source of evidence for TVSH comes from behavioral studies of the comparative effects of size-contrast illusions on visual awareness and visuo- motor action. This paper shows that not only is the evidence from illusion studies inconclusive, there is a better, ACT-friendly interpretation of the evidence that avoids serious theoretical difficulties faced by TVSH. (shrink)

Neuropsychological findings used to motivate the "two visual systems" hypothesis have been taken to endanger a pair of widely accepted claims about spatial representation in conscious visual experience. The first is the claim that visual experience represents 3-D space around the perceiver using an egocentric frame of reference. The second is the claim that there is a constitutive link between the spatial contents of visual experience and the perceiver's bodily actions. In this paper, I review and assess three main sources (...) of evidence for the two visual systems hypothesis. I argue that the best interpretation of the evidence is in fact consistent with both claims. I conclude with some brief remarks on the relation between visual consciousness and rational agency. (shrink)

The cortical visual mechanisms involved in processing spatial relationships remain subject to debate. According to one current view, the ''dorsal stream'' of visual areas, emanating from primary visual cortex and culminating in the posterior parietal cortex, mediates this aspect of visual processing. More recently, others have argued that while the dorsal stream provides egocentric coding of visual location for motor control, the separate ''ventral'' stream is needed for allocentric spatial coding. We have assessed the visual form agnosic patient DF, whose (...) lesion mainly affects the ventral stream, on a prehension task requiring allocentric spatial coding. She was presented with transparent circular disks. Each disk had circular holes cut in it. DF was asked to reach out and grasp the disk by placing her fingers through the holes. The disks either had three holes (for forefinger, middle finger, and thumb) or two holes (for forefinger and thumb). The distance between the forefinger and thumb holes, and the orientation of the line formed by them, were independently varied. DF was quite unable to adjust her grip aperture or her hand orientation in the three-hole task. Although she was able to orient her hand appropriately for the two-hole disks, she still remained unable to adjust her grip aperture to the distance between the holes. These findings are consistent with the idea that allocentric processing of spatial information requires a functioning ventral stream, even when the information is being used to guide a motor response. (shrink)

Vision, more than any other sense, dominates our mental life. Our visual experience is just so rich, so detailed, that we can hardly distinguish that experience from the world itself. Even when we just think about the world and don't look at it directly, we can't help but 'imagine' what it looks like. We think of 'seeing' as being a conscious activity--we direct our eyes, we choose what we look at, we register what we are seeing. The series of events (...) described in this book radically altered this attitude towards vision. This book describes one of the most extraordinary neurological cases of recent years--one that profoundly changed scientific views on consciousness. It is the story of Dee Fletcher--a woman recently blinded--who became the subject of a series of scientific studies. As events unfolded, Milner and Goodale found that Dee wasn't in fact blind--she just didn't know that she could see. Taking us on a journey into the unconscious brain, the two scientists who made this incredible discovery tell the amazing story of their work, and the surprising conclusion they were forced to reach. Written to be accessible to students and popular science readers, this book is a fascinating illustration of the power of the 'unconscious' mind. (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)

In the past decade, the notion of a neural correlate of consciousness (or NCC) has become a focal point for scientific research on consciousness (Metzinger, 2000a). A growing number of investigators believe that the first step toward a science of consciousness is to discover the neural correlates of consciousness. Indeed, Francis Crick has gone so far as to proclaim that ‘we … need to discover the neural correlates of consciousness.… For this task the primate visual system seems especially attractive.… No (...) longer need one spend time attempting … to endure the tedium of philosophers perpetually disagreeing with each other. Con- sciousness is now largely a scientific problem’ (Crick, 1996, p. 486).2 Yet the question of what it means to be a neural correlate of consciousness is actually far from straightforward, for it involves fundamental empirical, methodological, and _philosophical _issues about the nature of consciousness and its relationship to the brain. Even if one assumes, as we do, that states of consciousness causally depend on states of the brain, one can nevertheless wonder in what sense there is, or could be, such a thing as a neural correlate of consciousness. (shrink)

In this lucid portrayal of human behavior, Fred Dretske provides an original account of the way reasons function in the causal explanation of behavior.

Tye's book develops a persuasive and, in many respects, original argument for the view that the qualitative side of our mental life is representational in..

The aim of the present article is three-fold. First, it aims to show that perception requires action. This is most evident for some types of visual percept. Second, it aims to show that the distinction of the cortical visual processing into two streams is insufficient and leads to possible misunderstandings on the true nature of perceptual processes. Third, it aims to show that the dorsal stream is not only responsible for the unconscious control of action, but also for the conscious (...) awareness of space and action. (shrink)

Philosophers have suggested that, in order to understand the particular visual state we are in during picture perception, we should focus on experimental results from vision neuroscience—in particular, on the most rigorous account of the functioning of the visual system that we have from vision neuroscience, namely, the ‘Two Visual Systems Model’. According to the initial version of this model, our visual system can be dissociated, from an anatomo-functional point of view, into two streams: a ventral stream subserving visual recognition, (...) and a dorsal stream subserving the visual guidance of action. Following this model, philosophers have suggested that, since the two streams have different functions, they represent different properties of a picture. However, the original view proposed by the ‘Two Visual Systems Model’ about the presence of a strong anatomo-functional dissociation between the two streams has recently been questioned on both philosophical and experimental grounds. Indeed, the analysis of several new pieces of evidence seems to suggest that many visual representations in our visual system, related to different tasks, are the result of a deep functional interaction between the streams. In the light of the renewed status of the ‘Two Visual Systems Model’, also our best philosophical model of picture perception should be renewed, in order to take into account a view of the process of picture perception informed by the new evidence about such interaction. Despite this, no account fulfilling this role has been offered yet. The aim of the present paper is precisely to offer such an account. It does this by suggesting that the peculiar visual state we are in during picture perception is subserved by interstream interaction. This proposal allows us to rely on a rigorous philosophical account of picture perception that is, however, also based on the most recent results from neuroscience. Unless the explanation offered in this paper is endorsed, all the recent evidence from vision neuroscience will remain unexplained under our best empirically informed philosophical theory of picture perception. (shrink)

In the past decade, the notion of a neural correlate of consciousness has become a focal point for scientific research on consciousness. A growing number of investigators believe that the first step toward a science of consciousness is to discover the neural correlates of consciousness. Indeed, Francis Crick has gone so far as to proclaim that ‘we need to discover the neural correlates of consciousness. For this task the primate visual system seems especially attractive. No longer need one spend time (...) attempting to endure the tedium of philosophers perpetually disagreeing with each other. Consciousness is now largely a scientific problem’. Yet the question of what it means to be a neural correlate of consciousness is actually far from straightforward, for it involves fundamental empirical, methodological, and philosophical issues about the nature of consciousness and its relationship to the brain. Even if one assumes, as we do, that states of consciousness causally depend on states of the brain, one can nevertheless wonder in what sense there is, or could be, such a thing as a neural correlate of consciousness. (shrink)

In the reported, experiment participants hit a ball to aim at the vertex of a Müller–Lyer configuration. This configuration either remained stable, changed its shaft length or the orientation of the tails during movement execution. A significant illusion bias was observed in all perturbation conditions, but not in the stationary condition. The illusion bias emerged for perturbations shortly after movement onset and for perturbations during execution, the latter of which allowed only a minimum of time for making adjustments . These (...) findings indicate that allocentric information is exploited for online control when people make rapid adjustments in response to a sudden change in the environment and not when people guide their limb movements to interact with a stable environment. (shrink)

According to an influential view, the detection of action possibilities and the selection of a plan for action are two segregated steps throughout the processing of visual information. This classical approach is committed with the assumption that two independent types of processing underlie visual perception: the semantic one, which is at the service of the identification of visually presented objects, and the pragmatic one which serves the execution of actions directed to specific parts of the same objects. However, as our (...) knowledge of vision has improved over the years, this established view has turned out to be only an approximation. This paper sets out the details of a non-modularist approach to visual perception of action possibilities and explains how to resist the lure of cognitive segregation. (shrink)

Although the mechanics of how the eye works are well understood, debate still exists as to how the complex machinery of the brain interprets neural impulses...

What is the role of conscious visual experience in the control and guidance of human behaviour? According to some recent treatments, the role is surprisingly indirect. Conscious visual experience, on these accounts, serves the formation of plans and the selection of action types and targets, while the control of 'online' visually guided action proceeds via a quasi-independent non-conscious route. In response to such claims, critics such as (Wallhagen [2007], pp. 539-61) have suggested that the notions of control and guidance invoked (...) are unacceptably vague, and that that the image of 'zombie systems' guiding action fails to take account of the possibility that there is genuine but unconceptualized, unnoticed, and/or unreportable experience taking place and guiding or controlling the actions. I address both sets of concerns. I try to show that refining and clarifying the key notions of control and guidance leaves the original argument intact, as does the appeal to unconceptualized, unnoticed, or unreportable experiences. The exercise serves, however, to highlight an important complex of considerations concerning the relations between control, agency, and experience. Better understanding these relations is, I suggest, an important source of insights concerning the nature of phenomenal experience. (shrink)

Questions about the function of consciousness have long been central to discussions of consciousness in philosophy and psychology. Intuitively, consciousness has an important role to play in the control of many everyday behaviors. However, this view has recently come under attack. In particular, it is becoming increasingly common for scientists and philosophers to argue that a significant body of data emerging from cognitive science shows that conscious states are not involved in the control of behavior. According to these theorists, nonconscious (...) states control most everyday behaviors. Andy Clark does an admirable job of summarizing and defending the most important data thought to support this view. In this paper, I argue that the evidence available does not in fact threaten the view that conscious states play an important and intimate role in the control of much everyday behavior. I thereby defend a philosophically intuitive view about the functions of conscious states in action. (shrink)

Ways of Seeing is a unique collaboration between an eminent philosopher and a world famous neuroscientist. It focuses on one of the most basic human functions - vision. What does it mean to 'see'. It brings together electrophysiological studies, neuropsychology, psychophysics, cognitive psychology, and philosophy of mind. The first truly interdisciplinary book devoted to the topic of vision, it will make a valuable contribution to the field of cognitive science.

David Milner and Melvyn Goodale, and the many psychologists and philosophers who have been influenced by their work, claim that ‘the visual system that gives us our visual experience of the world is not the same system that guides our movements in the world’. The arguments that have been offered for this surprising claim place considerable weight on two sources of evidence — visual form agnosia and the reaching behaviour of normal subjects when picking up objects that induce visual illusions. (...) The present article shows that, if we are careful to consider the possibility that a demonstrative gesture can contribute content to a conscious experience, then neither source of evidence is compelling. (shrink)