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)

The views expressed in the commentaries challenge many of the tenets of the planning–control model as espoused in the target article. This response is aimed at addressing the most serious of these challenges as well as clarifying errors of interpretation. It is argued that the majority of the challenges from brain and behavior, although meritorious, can nonetheless be incorporated within the planning–control model. It is concluded that only some minor revision of the model with regard to anatomy is necessary at (...) this time. (shrink)

Evidence for a dichotomy between the planning of an action and its on-line control in humans is reviewed. This evidence suggests that planning and control each serve a specialized purpose utilizing distinct visual representations. Evidence from behavioral studies suggests that planning is influenced by a large array of visual and cognitive information, whereas control is influenced solely by the spatial characteristics of the target, including such things as its size, shape, orientation, and so forth. Evidence from brain imaging and neuropsychology (...) suggests that planning and control are subserved by separate visual centers in the posterior parietal lobes, each constituting part of a larger network for planning and control. Planning appears to rely on phylogenetically newer regions in the inferior parietal lobe, along with the frontal lobes and basal ganglia, whereas control appears to rely on older regions in the superior parietal lobe, along with the cerebellum. Key Words: action; apraxia; control; illusions; optic ataxia; PET; planning; reaching;. (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)

This textbook on vision reflects the integrated computational approach of modern research scientists, combining psychological, computational and neuroscientific perspectives.

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)

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.

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.

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...

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)

First published in 1995, The Visual Brain in Action remains a seminal publication in the cognitive sciences. It presents a model for understanding the visual processing underlying perception and action, proposing a broad distinction within the brain between two kinds of vision: conscious perception and unconscious 'online' vision. It argues that each kind of vision can occur quasi-independently of the other, and is separately handled by a quite different processing system. In the 11 years since publication, the book has provoked (...) considerable interest and debate - throughout both cognitive neuroscience and philosophy, while the field has continued to flourish and develop. -/- For this new edition, the text from the original edition has been left untouched, standing as a coherent statement of the authors' position. However, a very substantial epilogue has been added to the book in which Milner and Goodale review some of the key developments that support or challenge the views that were put forward in the first edition. The new chapter summarizes developments in various relevant areas of psychology, neuroscience and behaviour. It notably supplements the main text by updating the reader on the contributions that have emerged from the use of functional neuroimaging, which was in its infancy when the first edition was written. Neuroimaging, and functional MRI in particular, has revolutionized the field over the past 11 years by allowing investigators to plot in detail the patterns of activity within the visual brains of behaving and perceiving humans. The authors show how its use now allows scientists to test and confirm their proposals, based as they then were largely on evidence accrued from primate neuroscience in conjunction with studies of neurological patients. (shrink)

Fleshing out Ramsey-sentence functionalism; against Lewis's "mad pain" mixed theory; relating functionalism to the causal theory of properties. Empirical functionalism is chauvinistic so probably false. A terrific, in-depth paper.

Is vision informationally encapsulated from cognition or is it cognitively penetrated? I shall argue that intentions penetrate vision in the experience of visual spatial constancy: the world appears to be spatially stable despite our frequent eye movements. I explicate the nature of this experience and critically examine and extend current neurobiological accounts of spatial constancy, emphasizing the central role of motor signals in computing such constancy. I then provide a stringent condition for failure of informational encapsulation that emphasizes a computational (...) condition for cognitive penetration: cognition must serve as an informational resource for visual computation. This requires proposals regarding semantic information transfer, a crucial issue in any model of informational encapsulation. I then argue that intention provides an informational resource for computation of visual spatial constancy. Hence, intention penetrates vision. (shrink)

Milner and Goodale's model of the primate cortical visual system has been justly influential in shaping recent empirical and theoretical work on the neural basis of conscious vision. In this commentary I examine the extent to which their model accounts for recent neuropsychological findings from patients with visual neglect and extinction, two profound disorders of visual consciousness that arise after unilateral brain damage. I begin by outlining two key claims from their model: first, that the characteristic loss of awareness for (...) contralesional sensory inputs in neglect reflects disruption of ventral, object-recognition processes, rather than dorsal processes as has commonly been thought; and second, that extinction of the more contralesional of two concurrent stimulus events is primarily a disorder of orienting and action-related attention arising from damage to the dorsal, visuomotor stream. I then present recent findings that cast some doubt on these claims. Visual neglect arising from damage to the inferior parietal lobe can involve a significant visuomotor impairment, independent of any perceptual deficit. Moreover, visual extinction can be modulated by perceptual factors that are likely to call upon the ventral object-recognition stream. These findings suggest that neglect and extinction, two relatively common and striking disorders of consciousness, are not readily accommodated within Milner and Goodale's two visual streams model. (shrink)