Hommel et al. propose that high-level perception and action planning share a common representational domain, which facilitates the control of intentional actions. On the surface, this point of view appears quite different from an alternative account that suggests that “action” and “perception” are functionally and neurologically dissociable processes. But it is difficult to reconcile these apparently different perspectives, because Hommel et al. do not clearly specify what they mean by “perception” and “action planning.” With respect to the visual control of (...) action, a distinction must be made between conscious visual perception and unconscious visuomotor processing. Hommel et al. must also distinguish between the what and how aspects of action planning, that is, planning what to do versus planning how to do it. (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...

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)

O'Regan & Noë run into some difficulty in trying to reconcile their “seeing as acting” proposal with the perception and action account of the functions of the two streams of visual projections in the primate cerebral cortex. I suggest that part of the problem is their reluctance to acknowledge that the mechanisms in the ventral stream may play a more critical role in visual awareness and qualia than mechanisms in the dorsal stream.

Two major functions of the visual system are discussed and contrasted. One function of vision is the creation of an internal model or percept of the external world. Most research in object perception has concentrated on this aspect of vision. Vision also guides the control of object-directed action. In the latter case, vision directs our actions with respect to the world by transforming visual inputs into appropriate motor outputs. We argue that separate, but interactive, visual systems have evolved for the (...) perception of objects on the one hand and the control of actions directed at those objects on the other. This 'duplex' approach to high-level vision suggests that Marrian or 'reconstructive' approaches and Gibsonian or 'purposive-animate-behaviorist' approaches need not be seen as mutually exclusive, but rather as complementary in their emphases on different aspects of visual function. (shrink)

Visual systems first evolved not to enable animals to perceive the world, but to provide distal sensory control of their movements. Conscious sight is a relatively recent invention, but its emergence has enabled organisms such as humans and other primates to carry out complex cognitive operations on a detailed perceptual representation of the world. The two streams of visual processing that have been identified in the primate cerebral cortex are a reflection of these two functions of vision. The dorsal 'action' (...) stream projecting from early visual areas to the posterior parietal cortex mediates the visual control of skilled motor acts. The ventral 'perceptual' stream projecting from early visual areas to the temporal lobe provides a perceptual experience of the world beyond our bodies. Both streams work together in the production of adaptive behavior. (shrink)

Vision is so closely identified with visual phenomenology that we sometimes forget that the visual system does more than deliver our experience of the world. Vision also plays a critical role in the control of our movements, from picking up our coffee cups to playing tennis. But the visual control of movement has, until recently, been relatively neglected. Indeed, traditional accounts of vision, while acknowledging the role of vision in motor control, have simply regarded such control as part of a (...) larger function – that of constructing an internal model of the external world. Even though such accounts might postulate separate ‘modules’ for the processing of different visual features, such as motion, colour, texture, and form, in most of these accounts there is an implicit assumption that, in the end, vision delivers a single representation of the external world – a kind of simulacrum of the real thing that serves as the perceptual foundation for all visually driven thought and action. (shrink)

Grasping. Avarice. Covetousness. Miserliness. Insatiable cupidity. Overreaching ambition. Desire spun out of control. The deadly sin of Greed goes by many names, appears in many guises, and wreaks havoc on individuals and nations alike. In this lively and generous book, Phyllis A. Tickle argues that Greed is "the Matriarch of the Deadly Clan," the ultimate source of Pride, Envy, Sloth, Gluttony, Lust, and Anger. She shows that the major faiths, from Hinduism and Taoism to Buddhism and Christianity regard Greed (...) as the greatest calamity humans can indulge in, engendering further sins and eviscerating all virtues. As the Sikh holy book Adi Granth asks: "Where there is greed, what love can there be?" Tickle takes a long view of Greed, from St. Paul to the present, focusing particularly on changing imaginative representations of Greed in Western literature and art. Looking at such works as the Psychomachia, or "Soul Battle" of the fifth-century poet Aurelius Clemens Prudentius, the paintings of Peter Bruegel and Hieronymous Bosch, the 1987 film Wall Street, and the contemporary Italian artist Mario Donizetti, Tickle shows how our perceptions have evolved from the medieval understanding of Greed as a spiritual enemy to a nineteenth-century sociological construct to an early twentieth-century psychological deficiency, and finally to a new view, powerfully articulated in Donizetti's mystical paintings, of Greed as both tragic and beautiful. Engaging, witty, brilliantly insightful, Greed explores the full range of this deadly sin's subtle, chameleon-like qualities, and the enormous destructive power it wields, evidenced all too clearly in the world today. (shrink)

It is our contention that the concept of planning in Glover's model is too broadly defined, encompassing both action/goal selection and the programming of the constituent movements required to acquire the goal. We argue that this monolithic view of planning is untenable on neuropsychological, neurophysiological, and behavioural grounds. The evidence demands instead that a distinction be made between action planning and the specification of the initial kinematic parameters, with the former depending on processing in the ventral stream and the latter (...) on processing in the dorsal stream. (shrink)

The visual control of action is a critical ability for interacting with the visual environment. Visual perception, however, is necessary for recognizing and memorizing different aspects of this environment. According to an influential proposal by Goodale and Milner, these two distinct visual functions are mediated by different cortical areas. The ventral visual stream mediates perception and the dorsal stream mediates the visual control of action. In this review, we focus on behavioral evidence looking at potential differences in the principles governing (...) visual organization for perception and action. We propose that, unlike visual perception, which is largely governed by relational and Gestalt representations of objects, visually-guided action treats objects in a more analytic fashion. We review evidence from visual illusions, studies of object–shape perception, and psychophysical studies of visual resolution of size to support this idea. We conclude that the visual perception of objects and their relations tends to be holistic and contextual in nature, whereas the visual control of skilled actions is more analytical, circumscribed, and tuned to the real metrics of the visual environment. (shrink)

Scientific and philosophical literature on causality has become highly specialised. It is hard to find suitable access points for students, young researchers, or professionals outside this domain. This book provides a guide to the complex literature, explains the scientific problems of causality and the philosophical tools needed to address them.

Dijkerman & de Haan (D&dH) propose a convincing model of somatosensory organization that is inspired by earlier perception-action models of the visual system. In this commentary, we suggest that the dorsal and ventral visual streams both contribute to the control of action, but in different ways. Using the example of grip and load force calibration, we show how the ventral stream can invoke stored information about the material properties of objects originally derived from the somatosensory system.

A revision of the author's thesis, University of Michigan, 1969. Bibliography: p. [154]-161. Includes index.

After a decade of intense debate about mechanisms, there is still no consensus characterization. In this paper we argue for a characterization that applies widely to mechanisms across the sciences. We examine and defend our disagreements with the major current contenders for characterizations of mechanisms. Ultimately, we indicate that the major contenders can all sign up to our characterization.

American policymakers and health policy analysts have a love-hate relationship with job-based health insurance. The policy press routinely runs articles about the demise of the current system of voluntary employer-sponsored health insurance coverage. Conservatives argue that it ought to be replaced with individually-purchased insurance, such as tax-favored spending accounts. Liberals assert that government insurance ought to supplant it.Meanwhile, as the debate rages on about the future of employer coverage, states and the federal government pass legislation buttressing and building on the (...) existing employment-based system. Most recently, California has passed an employer mandate requiring employers to cover their workers and Maine has adopted a universal coverage initiative that includes a voluntary small employer insurance program offered through a state agency. (shrink)

In this updated and extended edition of their book, Goodale and Milner explore one of the most extraordinary neurological cases of recent years--one that profoundly changed scientific views on the visual brain. Taking us on a journey into the unconscious brain, this book is a fascinating illustration of the power of the 'unconscious' mind.

The issues involved in deciding whether to use artificial methods of delivering hydration and nutrition are often very difficult for patients, families, and health care providers. Once private and personal matters, these decisions now frequently involve the judicial system. Five years ago, Hospice of Washington recognized the need for a written policy and wrote the one published here. Its goal is to respect individual preferences and family concerns while addressing the nutrition and hydration needs of dying patients. The policy sets (...) parameters on the issue, provides basic information, and encourages crafting the most fitting resolution to each situation. (shrink)