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)

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)

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)

This paper, which has both a historical and a polemical aspect, investigates the view, dominant throughout the eighteenth and nineteenth centuries, that the sense of sight is, originally, not phenomenally three-dimensional in character, and that we must come to interpret its properly two-dimensional data by reference to the sense of 'touch'. The principal argument for this claim, due to Berkeley, is examined and found wanting. The supposedly confirming findings concerning 'Molyneux subjects' are also investigated and are shown to be either (...) irrelevant or disconfirming. Recent investigations on infant and neonatal perception are discussed and are also found to be disconfirming. An innatist version of the theory is then considered and is shown to be undermined by the largely 'Gibsonian' character of early space-perception. Finally three recent arguments in favour of the theory - two from psychologists, one from a philosopher - are considered and answered. (shrink)

Do spatial features appear the same whether they are perceived through vision or touch? This question is at stake in the puzzle that William Molyneux posed to John Locke, concerning whether a man born blind whose sight was restored would be able immediately to identify the shapes of the things he saw. A recent study purports to answer the question negatively, but I argue here that the subjects of the study likely could not see well enough for the result to (...) have been meaningful. I then propose a way to improve the study, by including cues from object motion. (shrink)

Many current neurophysiological, psychophysical, and psychological approaches to vision rest on the idea that when we see, the brain produces an internal representation of the world. The activation of this internal representation is assumed to give rise to the experience of seeing. The problem with this kind of approach is that it leaves unexplained how the existence of such a detailed internal representation might produce visual consciousness. An alternative proposal is made here. We propose that seeing is a way of (...) acting. It is a particular way of exploring the environment. Activity in internal representations does not generate the experience of seeing. The out- side world serves as its own, external, representation. The experience of seeing occurs when the organism masters what we call the gov- erning laws of sensorimotor contingency. The advantage of this approach is that it provides a natural and principled way of accounting for visual consciousness, and for the differences in the perceived quality of sensory experience in the different sensory modalities. Sev- eral lines of empirical evidence are brought forward in support of the theory, in particular: evidence from experiments in sensorimotor adaptation, visual “filling in,” visual stability despite eye movements, change blindness, sensory substitution, and color perception. (shrink)

In 1688, the Irish scientist William Molyneux sent a letter to the philosopher John Locke in which he asked whether a man who had been born blind and whose experience of the world was based on senses other than vision, would be able to distinguish and name a globe and a cube by sight alone, once he had been enabled to see. This issue immediately raised considerable interest amongst philosophers, who, for centuries, have continued to speculate about how this issue (...) might be resolved. More recently, the possibility of corrective surgery for people born with congenital cataracts, has offered a valuable opportunity to explore this topic experimentally. A discussion of how Molyneux’s question has been addressed over the centuries, allows us to investigate a number of intellectual challenges, involving a variety of fields, ranging from philosophy, psychology and the cognitive sciences, to neuroscience. For instance, Molyenux’s question raises the question of whether sensory experience is specific to each sensory modality, or rather supramodal, and if a transfer of knowledge across modalities can be established. Molyneux’s question is also relevant to the discussion of whether, how and to what extent a concept of space can be developed by blind people. More generally, it concerns the idea of how conceptual knowledge is acquired and processed when vision is lacking. The present paper aims to provide an overview of all the issues raised by Molyenux’s question. (shrink)

I aim to give a new account of picture perception: of the way our visual system functions when we see something in a picture. My argument relies on the functional distinction between the ventral and dorsal visual subsystems. I propose that it is constitutive of picture perception that our ventral subsystem attributes properties to the depicted scene, whereas our dorsal subsystem attributes properties to the picture surface. This duality elucidates Richard Wollheim’s concept of the “twofoldness” of our experience of pictures: (...) the “visual awareness not only of what is represented but also of the surface qualities of the representation.” I argue for the following four claims: (a) the depicted scene is represented by ventral perception, (b) the depicted scene is not represented by dorsal perception, (c) the picture surface is represented by dorsal perception, and (d) the picture surface is not necessarily represented by ventral perception. (shrink)

Molyneux's Question, that is, “Suppose a man born blind, and now adult, and taught by his touch to distinguish between a cube and a sphere... and the blind man made to see: Quaere, whether by his sight, before he touched them, he could now distinguish, and tell, which is the globe, which the cube”, was discussed by many theorists in the 17th and 18th centuries, and has recently been addressed by contemporary philosophers interested in the nature, and identity conditions, of (...) perceptual concepts. My main concern in this paper is to argue – against Evans, Campbell, and a number of other contemporary philosophers – that a test of the sort Molyneux envisioned, at least if carefully designed and administered, can indeed be a crucial experiment for the claim that we deploy the same perceptual concepts when identifying shapes by sight and by touch. I will explore some implications of this argument for a theory of recognitional concepts. And I’ll try to trace out some unhappy consequences of various alternative views. (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)

After more than three centuries, Molyneux's question continues to challenge our understanding of cognition and perceptual systems. Locke, the original recipient of the question, approached it as a theoretical exercise relevant to long-standing philosophical issues, such as nativism, the possibility of common sensibles, and the empiricism-rationalism debate. However, philosophers were quick to adopt the experimentalist's stance as soon as they became aware of recoveries from congenital blindness through ophtalmic surgery. Such recoveries were widely reported to support empiricist positions, suggesting that (...) the question had found its empirical answer. Contrary to this common view, we argue that studies of patients recovering from early blindness through surgery cannot provide an answer. In fact, because of the very nature of such ophtalmological interventions it is impossible to test the question in the empirical conditions outlined by Molyneux. Thus we propose that Molyneux's question be treated as an early thought experiment of a specific kind. Although thought experiments of this kind cannot be turned into actual experimental conditions, they provide a conceptual restructuring of theories. Such restructuring in turn leads to new predictions that can then be tested by “normal” experiments. In accord with this interpretation, we show that Molyneux's question can be analyzed into a hierarchy of specific questions about vision in its phenomenal and sensory-motor components. Some of these questions do lead to actual experimental conditions that could be studied empirically. (shrink)

After more than three centuries, Molyneux's question continues to challenge our understanding of cognition and perceptual systems. Locke, the original recipient of the question, approached it as a theoretical exercise relevant to long-standing philosophical issues, such as nativism, the possibility of common sensibles, and the empiricism-rationalism debate. However, philosophers were quick to adopt the experimentalist's stance as soon as they became aware of recoveries from congenital blindness through ophtalmic surgery. Such recoveries were widely reported to support empiricist positions, suggesting that (...) the question had found its empirical answer. Contrary to this common view, we argue that studies of patients recovering from early blindness through surgery cannot provide an answer. In fact, because of the very nature of such ophtalmological interventions it is impossible to test the question in the empirical conditions outlined by Molyneux. Thus we propose that Molyneux's question be treated as an early thought experiment of a specific kind. Although thought experiments of this kind cannot be turned into actual experimental conditions, they provide a conceptual restructuring of theories. Such restructuring in turn leads to new predictions that can then be tested by normal experiments. In accord with this interpretation, we show that Molyneux's question can be analyzed into a hierarchy of specific questions about vision in its phenomenal and sensory-motor components. Some of these questions do lead to actual experimental conditions that could be studied empirically. (shrink)

Molyneux’s question, whether the newly sighted might immediately recognize tactilely familiar shapes by sight alone, has produced an array of answers over three centuries of debate and discussion. I propose the first pluralist response: many different answers, both yes and no, are individually sufficient as an answer to the question as a whole. I argue that this is possible if we take the question to be cluster concept of sub-problems. This response opposes traditional answers that isolate specific perceptual features as (...) uniquely applicable to Molyneux’s question and grant viability to only one reply. Answering Molyneux’s question as a cluster concept may also serve as a methodology for resolving other philosophical problems. (shrink)

This paper contrasts two enactive theories of visual experience: the sensorimotor theory (O’Regan and Noë, Behav Brain Sci 24(5):939–1031, 2001; Noë and O’Regan, Vision and mind, 2002; Noë, Action in perception, 2004) and Susan Hurley’s (Consciousness in action, 1998, Synthese 129:3–40, 2001) theory of active perception. We criticise the sensorimotor theory for its commitment to a distinction between mere sensorimotor behaviour and cognition. This is a distinction that is firmly rejected by Hurley. Hurley argues that personal level cognitive abilities emerge (...) out of a complex dynamic feedback system at the subpersonal level. Moreover reflection on the role of eye movements in visual perception establishes a further sense in which a distinction between sensorimotor behaviour and cognition cannot be sustained. The sensorimotor theory has recently come under critical fire (see e.g. Block, J Philos CII(5):259–272, 2005; Prinz, Psyche, 12(1):1–19, 2006; Aizawa, J Philos CIV(1), 2007) for mistaking a merely causal contribution of action to perception for a constitutive contribution. We further argue that the sensorimotor theory is particularly vulnerable to this objection in a way that Hurley’s active perception theory is not. This presents an additional reason for preferring Hurley’s theory as providing a conceptual framework for the enactive programme. (shrink)

The representational dynamics of the brain is a subsymbolic process, and it has to be conceived as an "agent-free" type of dynamical self-organization. However, in generating a coherent internal world-model, the brain decomposes target space in a certain way. In doing so, it defines an "ontology": to have an ontology is to interpret a world. In this paper we argue that the brain, viewed as a representational system aimed at interpreting the world, possesses an ontology too. It decomposes target space (...) in a way that exhibits certain invariances, which in turn are functionally significant. A challenge for empirical research is to determine which are the functional regularities guiding this decomposition process. What are the explicit and implicit assumptions about the structure of reality, which at the same time shape the causal profile of the brain's motor output and the representational deep structure of the conscious mind arising from it (its "phenomenal output")? How do they constrain high-level phenomena like conscious experience, the emergence of a first-person perspective, or social cognition? By reviewing a series of neuroscientific results, we focus on the contribution the motor system makes to this process. As it turns out, the motor system constructs goals, actions, and intending selves as basic constituents of the world it interprets. It does so by assigning a single, unified causal role to them. Empirical evidence now clearly shows how the brain actually codes movements and action goals in terms of multimodal representations of organism-object relations. Under a representationalist analysis, this process can be interpreted as an internal representation of the intentionality relation itself. We try to show how such a more complex form of representational content, once it is in place, can later function as the building block for social cognition and a for more complex, consciously experienced representation of the first-person perspective as well. The motor system may therefore play a decisive role in understanding how the functional ontology of the human brain could be gradually extended into the subjective and social domains. (shrink)

Everyday visual experience constantly confronts us with things we can interact with in the real world. We literally feel the outside presence of physical objects in our environment via visual perceptual experience. The visual feeling of presence is a crucial feature of vision that is largely unexplored in the philosophy of perception, and poorly debated in vision neuroscience. The aim of this article is to investigate the feeling of presence. I suggest that visual feeling of presence depends on the visual (...) representation of a very particular spatial relation with the object we interact with: the visual representation of absolute egocentric depth, which is due to stereoscopic vision. (shrink)

Everyday life suggests that picture seeing is sometimes infused by an emotional charge. However, nobody has addressed the importance of explaining this emotional charge in picture perception. Even our best model of picture perception, the dorsal/ventral account of picture perception, which integrates the most important empirical results coming from our best model on vision in neuroscience, the two visual systems model, lacks a reference to this emotional charge. The aim of the present paper is to offer an account of picture (...) perception that is able to regain and explain this neglected emotional charge. My claim is that, as for face-to-face perception, during picture perception, we are not only in a visual perceptual state, but also in an emotional state, which is directly connected to our visual perceptual state. I also show that it is possible to offer this integration while remaining in the philosophical/empirical framework of the dorsal/ventral account of picture perception, whose explanatory power is confirmed and improved. (shrink)

The most important question concerning picture perception is: what perceptual state are we in when we see an object in a picture? In order to answer this question, philosophers have used the results of the two visual systems model, according to which our visual system can be divided into two streams, a ventral stream for object recognition, allowing one to perceive from an allocentric frame of reference, and a dorsal stream for visually guided motor interaction, thus allowing one to perceive (...) from an egocentric frame of reference. Following this model, philosophers denied that we can be in a dorsal perceptual state when perceiving a depicted object. This is because a depicted object is not physically graspable or manipulable and, in turn, it cannot be egocentrically localized, as a normal object, by the dorsal stream. Thus, the impossibility of manipulating depicted objects and of localizing them from an egocentric frame of reference has led some people to be sceptical about the possibility of a representation of action properties in the perception of objects in pictures, which pertains to the dorsal visual system. The aim of the present paper is to show that it is possible for the depicted object to be represented by dorsal perception. That means that we can ascribe action properties to depicted objects as well, even if depicted objects cannot be egocentrically localized—at least, not as much as normal objects can. (shrink)

Philosophers and neuroscientists often suggest that we perceptually represent objects and their properties. However, they start from very different background assumptions when they use the term “perceptual representation”. On the one hand, sometimes philosophers do not need to properly take into consideration the empirical evidence concerning the neural states subserving the representational perceptual processes they are talking about. On the other hand, neuroscientists do not rely on a meticulous definition of “perceptual representation” when they talk about this empirical evidence that (...) is supposed to show that we perceptually represent such and such properties. It seems that, on both sides, something is missed. My aim is to show that, in the light of empirical evidence from neuroscience, the case of action properties is a good candidate in order to properly talk of perceptually represented properties. My claim is that the neurophysiological states encoding action properties are perceptual processes and that these perceptual processes are representational processes. That is, in the case of those neurophysiological states involved in the detection of action properties, it is correct to speak of perceptual representational states, and hence, ipso facto, of perceptually represented properties. First, I describe a reasonable and widely agreed upon conception of perceptual representation in the philosophical literature. Then, I report evidence from vision and motor neuroscience concerning the perception of action properties, which is subserved by the ventro-dorsal stream, a portion of the dorsal visual system. Finally, I show that a strong connection can be found between the philosophical idea of perceptual representation I have reported before and the neuroscientific evidence concerning the activity of the ventro-dorsal stream, whose job is, as said, to detect action properties. (shrink)

This volume collects thirteen papers by one of the leading philosophers of his generation, who died prematurely in 1980.

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)

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)

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)

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 phenomenal character of perceptual experience involves the representation of colour, shape and motion. Does it also involve the representation of high-level categories? Is the recognition of a tomato as a tomato contained within perceptual phenomenality? Proponents of a conservative view of the reach of phenomenal content say ’No’, whereas those who take a liberal view of perceptual phenomenality say ’Yes’. I clarify the debate between conservatives and liberals, and argue in favour of the liberal view that high-level content can (...) directly inform the phenomenal character of perception. (shrink)

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.

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.

Our ability to acknowledge and recognise our own identity - our 'self' - is a characteristic doubtless unique to humans. Where does this feeling come from? How does the combination of neurophysiological processes coupled with our interaction with the outside world construct this coherent identity? We know that our social interactions contribute via the eyes, ears etc. However, our self is not only influenced by our senses. It is also influenced by the actions we perform and those we see others (...) perform. Our brain anticipates the effects of our own actions and simulates the actions of others. In this way, we become able to understand ourselves and to understand the actions and emotions of others. -/- This book is the first to describe the new field of 'Motor Cognition' - one to which the author's contribution has been seminal. Though motor actions have long been studied by neuroscientists and physiologists, it is only recently that scientists have considered the role of actions in building the self. How consciousness of action is part of self-consciousness, how one's own actions determine the sense of being an agent, how actions performed by others impact on ourselves for understanding others, differentiating ourselves from them and learning from them: these questions are raised and discussed throughout the book, drawing on experimental, clinical, and theoretical bases. -/- The advent of new neuroscience techniques, like neuroimaging and direct electrical brain stimulation, together with a renewal of behavioral methods in cognitive psychology, provide new insights into this area. Mental imagery of action, self-recognition, consciousness of actions, imitation can be objectively studied using these new tools. The results of these investigations shed light on clinical disorders in neurology, psychiatry and in neuro-development. -/- This is a major new work that will lay down the foundations for the field of motor cognition. (shrink)

"Perception is not something that happens to us, or in us," writes Alva Noe. "It is something we do." In Action in Perception, Noe argues that perception and perceptual consciousness depend on capacities for action and thought — that ...

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...

How the Body Shapes the Mind is an interdisciplinary work that addresses philosophical questions by appealing to evidence found in experimental psychology, neuroscience, studies of pathologies, and developmental psychology. There is a growing consensus across these disciplines that the contribution of embodiment to cognition is inescapable. Because this insight has been developed across a variety of disciplines, however, there is still a need to develop a common vocabulary that is capable of integrating discussions of brain mechanisms in neuroscience, behavioural expressions (...) in psychology, design concerns in artificial intelligence and robotics, and debates about embodied experience in the phenomenology and philosophy of mind. Shaun Gallagher's book aims to contribute to the formulation of that common vocabulary and to develop a conceptual framework that will avoid both the overly reductionistic approaches that explain everything in terms of bottom-up neuronal mechanisms, and inflationistic approaches that explain everything in terms of Cartesian, top-down cognitive states. Gallagher pursues two basic sets of questions. The first set consists of questions about the phenomenal aspects of the structure of experience, and specifically the relatively regular and constant features that we find in the content of our experience. If throughout conscious experience there is a constant reference to one's own body, even if this is a recessive or marginal awareness, then that reference constitutes a structural feature of the phenomenal field of consciousness, part of a framework that is likely to determine or influence all other aspects of experience. The second set of questions concerns aspects of the structure of experience that are more hidden, those that may be more difficult to get at because they happen before we know it. They do not normally enter into the content of experience in an explicit way, and are often inaccessible to reflective consciousness. To what extent, and in what ways, are consciousness and cognitive processes, which include experiences related to perception, memory, imagination, belief, judgement, and so forth, shaped or structured by the fact that they are embodied in this way? (shrink)

Visual Agnosia is a comprehensive and up-to-date review of disorders of higher vision that relates these disorders to current conceptions of higher vision from cognitive science, illuminating both the neuropsychological disorders and the nature of normal visual object recognition.Brain damage can lead to selective problems with visual perception, including visual agnosia the inability to recognize objects even though elementary visual functions remain unimpaired. Such disorders are relatively rare, yet they provide a window onto how the normal brain might accomplish the (...) complex task of vision. Visual Agnosia reviews a century of case studies of higher-level visual deficits following brain damage, places them in the general context of current neuroscience, and draws relevant conclusions about the organization of normal visual processing. It is unique in drawing on research in cognitive psychology, computational vision, visual neurophysiology, and neuropsychology to interpret the agnosias and draw inferences from them about visual object recognition.Following a historical account of agnosia research, Visual Agnosia offers a taxonomy of a wide range of agnosia syndromes, describing and interpreting the syndromes in terms of the latest theoretical models of visual processing and ultimately bringing them to bear as evidence on a variety of questions in the study of higher vision.Martha J. Farah is Associate Professor of Psychology at Carnegie Mellon University. Visual Agnosia is included in the Issues in Biology of Language and Cognition series, edited by John Marshall. (shrink)

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)

Philosophical discussions of Molyneux's problem within contemporary philosophy of mind tend to characterize the problem as primarily concerned with the role innately known principles, amodal spatial concepts, and rational cognitive faculties play in our perceptual lives. Indeed, for broadly similar reasons, rationalists have generally advocated an affirmative answer, while empiricists have generally advocated a negative one, to the question Molyneux posed after presenting his famous thought experiment. This historical characterization of the dialectic, however, somewhat obscures the role Molyneux's problem has (...) played in spawning debates within the empiricist tradition. Fortunately, the differences between various empiricist accounts have been widely recognized and discussed among historians of philosophy working on the topic. The focus of the present essay is to develop an interpretation of John Locke's views on Molyneux's problem that best coheres with his other views on human understanding as well as with the predominant scientific opinion about the nature of perception during the period in which he lived. (shrink)

There have recently been various empirical attempts to answer Molyneux’s question, for example, the experiments undertaken by the Held group. These studies, though intricate, have encountered some objections, for instance, from Schwenkler, who proposes two ways of improving the experiments. One is “to re-run [the] experiment with the stimulus objects made to move, and/or the subjects moved or permitted to move with respect to them” (p. 94), which would promote three dimensional or otherwise viewpoint-invariant representations. The other is “to use (...) geometrically simpler shapes, such as the cube and sphere in Molyneux’s original proposal, or planar figures instead of three-dimensional solids” (p. 188). Connolly argues against the first modification but agrees with the second. In this article, I argue that the second modification is also problematic (though still surmountable), and that both Schwenkler and Connolly are too optimistic about the prospect of addressing Molyneux’s question empirically. (shrink)

A recent empirical study claims to show that the answer to Molyneux’s question is negative, but, as John Schwenkler points out, its findings are inconclusive: Subjects tested in this study probably lacked the visual acuity required for a fair assessment of the question. Schwenkler is undeterred. He argues that the study could be improved by lowering the visual demands placed on subjects, a suggestion later endorsed and developed by Kevin Connolly. I suggest that Connolly and Schwenkler both underestimate the difficulties (...) involved in rectifying the study they seek to fix. The problem is that the experimental paradigm under consideration fails to account for the role that rational inference plays in newly sighted subjects’ ability or inability to recognize spatial properties across modalities. Since answering Molyneux’s question requires establishing whether spatial properties can be recognized, across modalities, by newly sighted subjects without recourse to rational inference, this is a problem. Indeed, it is a problem that may be worsened by Schwenkler and Connolly’s suggestions regarding the lowering of visual demands on subjects in cross-modal matching tasks. (shrink)

How do we recognize identities between seen shapes and felt ones? Is this due to associative learning, or to intrinsic connections these sensory modalities? We can address this question by testing the capacities of newly sighted subjects to match seen and felt shapes, but only if it is shown that the subjects can see the objects well enough to form adequate visual representations of their shapes. In light of this, a recent study by R. Held and colleagues fails to demonstrate (...) that their newly sighted subjects’ inability to match seen and felt shape was due to a lack of intermodal connections rather than a purely visual deficit, as they may not have been able visually to represent 3D shape in the perspective-invariant way required for intermodal matching. However, the study could be modified in any of several ways to help avoid this problem. (shrink)