This comprehensively updated and expanded revision of the successful second edition continues to provide detailed coverage of the ever-growing range of research topics in vision. In Part I, the treatment of visual physiology has been extensively revised with an updated account of retinal processing, a new section explaining the principles of spatial and temporal filtering which underlie discussions in later chapters, and an up-to-date account of the primate visual pathway. Part II contains four largely new chapters which cover (...) recent psychophysical evidence and computational model of early vision: edge detection, perceptual grouping, depth perception, and motion perception. The models discussed are extensively integrated with physiological evidence. All other chapters in Parts II, III, and IV have also been thoroughly updated. (shrink)

Many of Margaret Cavendish’s criticisms of Thomas Hobbes in the Philosophical Letters (1664) relate to the disorder and damage that she holds would result if Hobbesian pressure were the cause of visual perception. In this paper, I argue that her “two men” thought experiment in Letter IV is aimed at a different goal: to show the explanatory potency of her account. First, I connect Cavendish’s view of visual perception as “patterning” to the “two men” thought experiment (...) in Letter IV. Second, I provide a potential reply on Hobbes’s behalf that appeals to physiological differences between perceivers’ sense organs, drawing upon Hobbes’s optics in De homine. Third, I argue that such a reply would misunderstand Cavendish’s objective of showing the limited explanatory resources available in understanding visual perception as pressing when compared to her view of visual perception as patterning. (shrink)

This paper addresses the visual culture of late-19th-century experimental physiology. Taking the case of Johann Nepomuk Czermak as a key example, it argues that images played a crucial role in acquiring experimental physiological skills. Czermak, Emil Du Bois-Reymond and other late-19th-century physiologists sought to present the achievements and perspective of their discipline by way of "immediate visual perception." However, the images they produced and presented for this purpose were strongly mediated. By means of specifically designed instruments, such (...) as the "cardioscope," the "contraction telegraph," and the "frog pistol," and of specifically constructed rooms, so-called "spectatoriums," physiologists trained and controlled the perception of their students before allowing them to conduct experiments on their own. Studying the material culture of physiological image production reveals that technological resources such as telegraphy, photography, and even railways contributed to making physiological facts anschaulich. At the same time, it shows that the more traditional image techniques of anatomy played an important role in physiological lecture halls, especially when it came to displaying the details of vivisection experiments to the public. Thus, the images of late 19th century physiology stood half-way between machines and organisms, between books and instruments. (shrink)

This paper addresses the visual culture of late-19th-century experimental physiology. Taking the case of Johann Nepomuk Czermak (1828-1873) as a key example, it argues that images played a crucial role in acquiring experimental physiological skills. Czermak, Emil Du Bois-Reymond (1818-1896) and other late-19th-century physiologists sought to present the achievements and perspective of their discipline by way of "immediate visual perception (unmittelbare Anschauung)." However, the images they produced and presented for this purpose were strongly mediated. By means of (...) specifically designed instruments, such as the "cardioscope," the "contraction telegraph," and the "frog pistol," and of specifically constructed rooms, so-called "spectatoriums," physiologists trained and controlled the perception of their students before allowing them to conduct experiments on their own. Studying the material culture of physiological image production reveals that technological resources such as telegraphy, photography, and even railways contributed to making physiological facts anschaulich. At the same time, it shows that the more traditional image techniques of anatomy played an important role in physiological lecture halls, especially when it came to displaying the details of vivisection experiments to the public. Thus, the images of late 19th century physiology stood half-way between machines and organisms, between books and instruments. (shrink)

Correspondence should be addressed to David A. Leopold [email protected] the viewing of certain patterns, widely known as ambiguous or puzzle figures, perception lapses into a sequence of spontaneous alternations, switching every few seconds between two or more visual interpretations of the stimulus. Although their nature and origin remain topics of debate, these stochastic switches are generally thought to be the automatic and inevitable consequence of viewing a pattern without a unique solution. We report here that in humans such (...) perceptual alternations can be slowed, and even brought to a standstill, if the visual stimulus is periodically removed from view. We also show, with a visual illusion, that this stabilizing effect hinges on perceptual disappearance rather than on actual removal of the stimulus. These findings indicate that uninterrupted subjective perception of an ambiguous pattern is required for the initiation of the brain-state changes underlying multistable vision.Visual perception involves coordination between sensory sampling of the world and active interpretation of the sensory data. Human perception of objects and scenes is normally stable and robust, but it falters when one is presented with patterns that are inherently ambiguous or contradictory. Under such conditions, vision lapses into a chain of continually alternating percepts, whereby a viable visual interpretation dominates for a few seconds and is then replaced by a rival interpretation. This multistable vision, or 'multistability', is thought to result from destabilization of fundamental visual mechanisms, and has offered valuable insights into how sensory patterns are actively organized and interpreted in the brain1, 2. Despite a great deal of recent research and interest in multistable perception, however, its neurophysiological underpinnings remain poorly understood. Physiological studies have suggested that disambiguation of ambiguous patterns. (shrink)

The integrated information theory equates levels of consciousness with the amount of information integrated over the elements that constitute a system. Conscious visual perception provides two observations that contradict the IIT. First, objects are accurately perceived when presented for ≪100 ms during which time no neural integration is possible. Second, an object is seen as an integrated whole and, concurrently, all constituent elements are evident. Because integration destroys information about details, IIT cannot account for perceptual detail preservation.

Specialized monographs can be useful sorts of things, but this book may not truly fit the bill. In it, Wolf-Devine offers an exegesis of Descartes' accounts of the physiology of the visual system and of our perception of light, color, situation, distance, size, and shape, along with some background discussion both of Descartes' predecessors and of Cartesian philosophy. While she also claims to be interested in the "big picture" changes in natural philosophy and epistemology to which Descartes's work (...) contributes, these concerns intrude on the work only intermittently. Still even with the more limited set of aims, the book may both overreach its monographic grasp and fall a bit short. (shrink)

To see whether the mental and the neural have common attributes that could resolve some of the traditional dichotomies, we review neuroscientific data on the visual system. The results show that neuronal and perceptual function share a parallel and hierarchical architecture which is manifest not only in the anatomy and physiology of the visual system, but also in normal perception and in the deficits caused by lesions in different parts of the system. Based on the description of (...) parallel hierarchical levels of active information processing in the visual brain, we suggest a concept of dissociable levels of perception, advocating that the phenomenal perception and recognition is realized in the functional integrity of a network of reciprocal cortico-cortical connections. The properties shared by neuronal and perceptional functions provide a basis for a neuromental monism in which both functions are attributed a causal role. (shrink)

The visual brain consists of several parallel, functionally specialized processing systems, each having several stages (nodes) which terminate their tasks at different times; consequently, simultaneously presented attributes are perceived at the same time if processed at the same node and at different times if processed by different nodes. Clinical evidence shows that these processing systems can act fairly autonomously. Damage restricted to one system compromises specifically the perception of the attribute that that system is specialized for; damage to (...) a given node of a processing system that leaves earlier nodes intact results in a degraded perceptual capacity for the relevant attribute, which is directly related to the physiological capacities of the cells left intact by the damage. By contrast, a system that is spared when all others are damaged can function more or less normally. Moreover, internally created visual percepts-illusions, afterimages, imagery, and hallucinations-activate specifically the nodes specialized for the attribute perceived. Finally, anatomical evidence shows that there is no final integrator station in the brain, one which receives input from all visual areas; instead, each node has multiple outputs and no node is recipient only. Taken together, the above evidence leads us to propose that each node of a processing-perceptual system creates its own microconsciousness. We propose that, if any binding occurs to give us our integrated image of the visual world, it must be a binding between microconsciousnesses generated at different nodes. Since any two microconsciousnesses generated at any two nodes can be bound together, perceptual integration is not hierarchical, but parallel and postconscious. By contrast, the neural machinery conferring properties on those cells whose activity has a conscious correlate is hierarchical, and we refer to it as generative binding, to distinguish it from the binding that might occur between the microconsciousnesses. (shrink)

Contributors to this book include key theorists and practitioners from media theory, Native Science, bio-media and sound art, philosophy, art history and design informatics. Collectively, they examine the becoming-technique of animal-human- machinic perceptibilities; and micro-perceptions that lie beneath the threshold of known perceptions yet create energetic vibrations. Who, what, and where perceives, and how? What are the sedimentations, inscriptions and axiologies of animal, human and machinic perceptions? What are their perceptibilities? Deleuze uses the word 'visibilities' to indicate that visual (...) perception isn't just a physiological given but cues operations productive of new assemblages. Perceptibilities are, by analogy, spatio- temporal, geolocative, kinaesthetic, audio-visual, and haptic operations that are always already memory. In the case of strong inscriptions, they are also epigenetic events. The contributors show distributed perception to be a key notion in addressing the emergence and persistence of plant, animal, human and machine relations. An invaluable reference for students and scholars in a range of areas including Media Theory, Sociology, Philosophy, Art and Design. (shrink)

The chapter begins with a sketch of the empirical, theoretical, and philosophical background to nineteenth-century theories of perception, focusing on visual perception. It then considers German sensory physiology and psychology in the nineteenth century and its reception. This section gives special attention to: assumptions about nerve–sensation relations; spatial perception; the question of whether there is a two-dimensional representation in visual experience; psychophysics; size constancy; and theories of colour perception. The chapter then offers a brief (...) look at the interaction between perceptual theory and philosophical issues in epistemology and the metaphysics of mind in Britain and America, focusing on: the notion of a muscle sense; the problem of the external world; and forms of perceptual realism. It ends with an overview of psychological theories of perception in the early twentieth century and the Gestalt reaction, culminating with J. J. Gibson. (shrink)

A theoretical approach relying on quantum computation in microtubules within neurons can potentially resolve the enigmatic features of visual consciousness, but raises other questions. For example, how can delicate quantum states, which in the technological realm demand extreme cold and isolation to avoid environmental ‘decoherence’, manage to survive in the warm, wet brain? And if such states could survive within neuronal cell interiors, how could quantum states grow to encompass the whole brain? We present a physiological model for (...) class='Hi'>visual consciousness that can accommodate brain-wide quantum computation according to the Penrose–Hameroff ‘Orch OR’ model. In this view, visual consciousness occurs as a series of several-hundred-millisecond epochs, each comprising ‘crescendo sequences’ of quantum computations occurring at ∼40 Hz. (shrink)

Influences on the perception of affordances (i.e., opportunities for actions) have been primarily studied by manipulating the functional morphology of the body. However, affordances are not just determined by the functional morphology of the perceiver, but also by the physiological state of the perceiver. States of anxiety have been shown to lead to marked changes in individuals’ physiological state and their behaviour. To assess the influence of emotional state on affordance perception, the perception of action capabilities in (...) near space was examined after participants completed an anxiety-provoking task. Anxiety was induced immediately prior to tasks that assessed participants' perceived reaching ability in Experiment 1, grasping ability in Experiment 2, and the ability to pass their hands through apertures in Experiment 3. Results indicated that those participants who experienced changes in anxiety underestimated their reaching, grasping, and passing ability compared to non-anxious participants. In other words, anxious participants were more conservative in their estimations of their action capabilities. These results suggest that anxiety influences the perception for affordances in near space and are consistent with the notion that anxiety induces withdrawal behaviours. (shrink)

Is there a substantial difference between a portrait depicting the sitter’s face made by an artist and an image captured by a machine able to simulate the neuro-physiology of facial perception? Drawing on the later Wittgenstein, this paper answers this question by reference to the relation between seeing a visual pattern as (i) a series of shapes and colours, and (ii) a face with expressions. In the case of the artist, and not of the machine, the portrait’s creative (...) process involves the ability to see both aspects. From the perspective of the image’s viewer, the distinction is more difficult to draw. I address this difficulty by further distinguishing between two attributes of portraits: their representational accuracy, and their ability to convey the artist’s reflection on her experience of seeing the sitter face-to-face. While artificial intelligence can mimic this latter reflective ability, it cannot exactly reproduce it. (shrink)

We identify two aspects of the problem of maintaining perceptual stability despite an observer's eye movements. The first, visual direction constancy, is the (egocentric) stability of apparent positions of objects in the visual world relative to the perceiver. The second, visual position constancy, is the (exocentric) stability of positions of objects relative to each other. We analyze the constancy of visual direction despite saccadic eye movements.Three information sources have been proposed to enable the visual system (...) to achieve stability: the structure of the visual field, proprioceptive inflow, and a copy of neural efference or outflow to the extraocular muscles. None of these sources by itself provides adequate information to achieve visual direction constancy; present evidence indicates that all three are used.Our final question concerns how information processing operations result in a stable world. The three traditionally suggested means have been elimination, translation, or evaluation. All are rejected. From a review of the physiological and psychological evidence we conclude that no subtraction, compensation, or evaluation need take place. The problem for which these solutions were developed turns out to be a false one. We propose a “calibration” solution: correct spatiotopic positions are calculated anew for each fixation. Inflow, outflow, and retinal sources are used in this calculation: saccadic suppression of displacement bridges the errors between these sources and the actual extent of movement. (shrink)

Rafael Malach is currently a professor in the department of Neurobiology at the Weizmann Institute in Israel. His current research is aimed at understanding how the neuronal circuitry in the human brain translates a stream of sensory stimuli into meaningful perception. Rafael Malach received his PhD in physiological optics from UC Berkeley and did his post-doctorate research at MIT. Originally doing research on the organization of neuronal connections in the primate brain, his focus has recently shifted to the study (...) of the human cerebral cortex using fMRI. Professor Malach has begun this research at Massachusetts General Hospital, exploring a new object-related region called the lateral occipital complex. Since then he expanded this research, studying the human visual cortex using a variety of methods, including adaptation paradigms, backward masking, and more recently naturalistic stimuli--all aimed at deciphering the intriguing link between perceptual experience and brain activity. (shrink)

This paper revisits some early applications of audio-visual imaging technologies used in physiology in a dialogue with reflections on Henri Bergson’s philosophy. It focuses on the aspects of time and memory in relation to spatial representations of movement measurements and critically discusses them from the perspective of the observing participant and the public exhibitions of scientific films. Departing from an audio-visual example, this paper is informed by a thick description of the philosophical implications and contemporary discourses surrounding the (...) scientific inventions, technologies and theories of moving image technologies, representations of time, and the measurement of bodies in motion such as those by the French physiologist Étienne-Jules Marey. The application of Bergson’s thinking will show how the scientific graphing and representations of the body through technologies inevitably stand in tension with the limits and potentials of the ‘human apparatus’ and its abilities, filters and internalised processes of perception, memory and consciousness. It proposes an ontological approach to scientific imaging technologies and a critical engagement with the ‘realism’ debate in the discourse of audio-visual media. (shrink)

This article seeks the origin, in the theories of Ibn al-Haytham (Alhazen), Descartes, and Berkeley, of two-stage theories of spatial perception, which hold that visual perception involves both an immediate representation of the proximal stimulus in a two-dimensional ‘‘sensory core’’ and also a subsequent perception of the three dimensional world. The works of Ibn al-Haytham, Descartes, and Berkeley already frame the major theoretical options that guided visual theory into the twentieth century. The field of (...) class='Hi'>visual perception was the first area of what we now call psychology to apply mathematics, through geometrical models as used by Euclid, Ptolemy, Ibn al-Haytham, and Descartes (among others). The article shows that Kepler’s discovery of the retinal image, which revolutionized visual anatomy and entailed fundamental changes in visual physiology, did not alter the basic structure of theories of spatial vision. These changes in visual physiology are advanced especially in Descartes' Dioptrics and his L'Homme. Berkeley develops a radically empirist theory vision, according to which visual perception of depth is learned through associative processes that rely on the sense of touch. But Descartes and Berkeley share the assertion that there is a two-dimensional sensory core that is in principle available to consciousness. They also share the observation that we don't usually perceived this core, but find depth and distance to be phenomenally immediate, a point they struggle to accommodate theoretically. If our interpretation is correct, it was not a change in the theory of the psychology of vision that engendered the idea of a sensory core, but rather the introduction of the theory into a new metaphysical context. (shrink)

The paper aims to show that Philoponus’ theory of sense-perception does not fit in with the spiritualist claim that the sensory process does not involve an extra material change in the sense-organ. Both the specific sense-organs and the primary sense-organ contract or expand in the perceptual process. On the other hand, the literalist claim needs to be modified as well since only the tactile sense-organ takes on the relevant qualities. Contraction or expansion in the sense-organ is triggered, not by (...) physical changes in the medium, but by the formal activities arising from the perceptible objects: colours make the visual sense-organ contract or expand. At the level of sense-organs, the physiological process underlying sense-perception has three stages. The change in specific sense-organ will be transmitted to the primary sense-organ of the particular sense , and then reaches the common sense-organ, the pneuma. The primary sense-organs are spatially distinguishable parts of the common sense-organ which is otherwise homogeneous, not allowing for qualitative differences. The homogeneity of the pneuma establishes the unity of sense-perception at the level of physiological processes. (shrink)

In my thesis I develop a theory of our mental, physiological and emotional involvement with motion pictures that accounts for the distinct role of perception in our cinematic experiences. In particular, I present a resemblance view of cinematic perception and depiction that begins with an analysis of motion picture screenings as events in the world to which audience members share perceptual access and to which we can attribute complex visual and auditory properties. By understanding the precise nature (...) of these properties and by understanding the mind's rich and dynamic relationship to visual and auditory stimuli, we can meet the demand of explaining the essential contribution of perception to our cinematic experiences. This positive theory is introduced through a philosophical and empirical critique of the work of several contemporary "cognitivist" film theorists who can been faulted for falling into the traps of traditional illusion accounts, failing to account for the perceptual nature of our film experiences, or incorrectly characterizing the nature of our perceptual relationship to cinematic content. (shrink)

During the second half of the 19th century, in the field of physiological optics, there was a strong controversy between Hermann von Helmholtz and Ewald Hering. This controversy has been usually characterized as “empiricism” vs. “nativism”. In the field of physiology of visual perception, several subjects demanded attention, among them, color vision. Helmholtz and Hering suggested different theories for the physiological correlate of color sensation and different color spaces to give an account of the relationships between colors. In (...) this article, I will argue that the controversy between the two authors could be understood as differences between styles of reasoning, and these different styles express different presuppositions. More specifically, I want to suggest that the disagreements could be linked to the discussions on how vital phenomena should be studied. (shrink)

Can we learn without consciousness? When the eminent neuropsychologist, Lawrence Weiskrantz first coined the term 'blindsight' to describe a condition whereby a patient could demonstrate that they were aware of some object, yet insist that they were completely unaware of its existence, the response from some in the scientific community was one of extreme skepticism. Even now, there are those who question the existence of unconscious learning, and the topic remains one of the most actively researched and debated in psychology. (...) In recent years evidence for unconscious processing across a range of sensory modalities have come from studies of vision, audition, memory, emotion, and action. Never before have these studies of unconscious processing in the different senses been brought together into a single volume. In a book dedicated to Lawrence Weiskrantz, some of the leading psychologists and cognitive neuroscientists of the day explain what we know about unconscious processing in the different senses. Including contributions from, amongst others, David Milner, Jon Driver, Alan Cowey, and Ray Dolan, the book presents a state of the art account of what we now know about 'the unconscious'. The book will provide a fascinating account for students and researchers in psychology, cognitive neuroscience, and philosophy. (shrink)

It seems to be self-evident that through perception we gain access to the material world. That visual perception takes an important role seems self-evident as well. But what exactly do we see? The objects themselves or just their perceptible properties? How do we manage to see something at all? Are we capable of seeing solely through optical and physiological processes or does viewing something asks for presupposed terms in order to help us to see something as something? (...) These questions, currently discussed at great length within the framework of cognitive and epistemological theory, were already cause for intensive debate in the early modern times. In many aspects, those discussions in the 17th and 18th century laid the groundwork for today’s theories: on one hand, they identified the problems with great clarity and on the other, they provided strategies for possible solutions which are still of value today. This volume will provide new access to those debates (from Descartes to Reid) and will present these debates to an audience interested in philosophical questions. The book shows that the early modern times is not just a respectable museum in the history of philosophy, but on the contrary, a very productive and stimulating philosophical epoch which invites further discussion. (shrink)

Since the 1980s, several studies of visual perception have persuasively argued that important aspects of human vision are best accounted for not by recourse to inner mental representations but rather through socially observable actions and behaviors (e.g. Lynch 1985, Latour 1986, Lynch 1990, Goodwin 1994, Goodwin 1997, Sharrock & Coulter 1998). While there are clearly physiological mechanisms required for vision, psychological accounts of perception in terms of inner mental representations have been dislodged from their position as the (...) basic term in the interface between human beings and their environment and replaced with terms such as "social practice," and "vernacular intelligibility." The focus for these .. (shrink)

The behavioral immune system (BIS) includes perceptual mechanisms for detecting cues of contamination. Former studies have indicated that moisture has a disgusting property. Therefore, moisture could be a target for detecting contamination cues by the BIS. We conducted two experiments to examine the psychophysical basis of moisture perception and clarify the relationship between the perception of moisture and the BIS. We assumed that the number of high luminance areas in a visual image provided optical information that would (...) enable the visual perception of moisture. In two experiments, we presented eight images of dough that contained different amounts of moisture as experimental stimuli. The amount of moisture shown in the images was increased in eight steps, from 28.6% to 42.9% of the total weight of the dough. In Experiment 1, the images were randomly presented on a computer display, and the participants (n = 22) were asked to rank the images in the order of the visually perceived moisture content. In Experiment 2, the participants (n = 15) completed pairwise comparisons based on the perceived moistness of the images. Furthermore, to examine the BIS responses, the participants rated the strength of disgust evoked by the stimuli, their motivation to avoid touching the stimuli, and the estimated magnitude of the risk of contamination by physical contact with the stimuli. The results indicated that the moisture content and the numbers of high luminance areas in the images accurately predicted the perception of moisture, suggesting that the detection of visual moisture was highly accurate, and the optical information served as an essential perceptual cue for detecting moisture. On the other hand, the BIS responses peaked in response to stimuli having approximately 33% to 39% moisture content. These results show that objects containing a moderate amount of moisture could be the target of visually detecting pathogens by the BIS. (shrink)

It seems to be self-evident that through perception we gain access to the material world. That visual perception takes an important role seems self-evident as well. But what exactly do we see? The objects themselves or just their perceptible properties? How do we manage to see something at all? Are we capable of seeing solely through optical and physiological processes or does viewing something asks for presupposed terms in order to help us to see something as something? (...) These questions, currently discussed at great length within the framework of cognitive and epistemological theory, were already cause for intensive debate in the early modern times. In many aspects, those discussions in the 17th and 18th century laid the groundwork for today’s theories: on one hand, they identified the problems with great clarity and on the other, they provided strategies for possible solutions which are still of value today. This volume will provide new access to those debates (from Descartes to Reid) and will present these debates to an audience interested in philosophical questions. The book shows that the early modern times is not just a respectable museum in the history of philosophy, but on the contrary, a very productive and stimulating philosophical epoch which invites further discussion. (shrink)

Il testo si apre con una breve descrizione divulgativa della biologia della visione, dalla percezione delle linee complesse ai colori, e di come questa si sia evoluta nel corso dei millenni, da meccanismo pro-sopravvivenza legato all'analisi dell’ambiente naturale e dei propri simili, a strumento di valutazione e apprezzamento della composizione artistica. Indaga le analogie tra lo sviluppo del cervello nei bambini affetti da disturbi dello spettro affettivo e relazionale (autismo) e le rappresentazioni iconografiche degli uomini primitivi, dal paleolitico al neolitico. (...) Un’ampia sezione descrive dinamiche cerebrali dovute ai cosiddetti neuroni specchio e di come questi influiscono sull’espressione e la fruizione dell’opera d’arte, analizzando le produzioni di due degli artisti contemporanei più famosi: Damien Hirst e Jeff Koons, collegati da una complementarità culturale ancestrale, quella tra eros e thanatos, che affonda le radici nell’arte funeraria etrusca. Il testo continua con l’analisi neuroestetica della visione e i suoi effetti sull’organismo umano, seguendo l’evoluzione che ha subito il punto di visuale. Dal basso verso l’alto nel barocco, dal basso a “volo d’uccello” nell’arte futurista e dall’alto verso il basso nella produzione pittorica dell’archistar anglo-irachena Zaha Hadid. Lo stesso punto di vista che fugge i confini della rappresentazione pittorica, fino ad abbandonare totalmente i confini del corpo e le dinamiche cerebrali nell’arte riferita al metaumanesimo e transumanesimo. (shrink)

This chapter examines a question at the intersection of the mind-body problem and the analysis of mental representation: the question of the direction of constraint between psychological fact and theory and neurophysiological or physical fact and theory. Does physiology constrain psychology? Are physiological facts more basic than psychological facts? Or do psychological theories, including representational analyses, guide and constrain physiology? Despite the antireductionist bent of functionalist positions, it has generally been assumed that physics or physiology are more basic than, and (...) hence contraining on, psychological fact and theory. Section 1 sketches the intuitions that would lead one to adopt such a view. The chapter then examines whether one-sided constraint has been and should be found in practice. It argues that philosophical analysis of psychological science shows that rigorous functional analyses can be carried out in advance of physiological knowledge. Indeed, in the investigation of sensory perception, ascription of psychological function leads the way in the individuation and investigation of neurophysiology. We shall look at several cases in visual perception (binocular single vision, stereopsis, and color vision), in which psychological results have provided a basis for physiological research. It is tempting to think that the psychological functions that enable physiological investigation would be Wrightian teleofunctions. It is, thus, natural to suppose that psychologists and neurophysiologists have proceeded with a conception of the purpose of a given neural structure, and have viewed neural anatomy and neural activity as the substrate for or instantiation of various properly psychological functions. For example, neuroscientists surely understand that the eye and visual system are for seeing, rather than for detecting an electric discharge in the vicinity of the retina (which sighted humans can do, via the subjective light produced by such discharges), and they guide their investigations of the eye, visual cortex, and intervening pathways accordingly. As a result, they will view rods and cones in the eye as photoreceptors, even though these structures will produce "output" (will respond with hyperpolarization) to other forms of energy. At the same time, there may be cases in which the functions that have guided research are in fact precisely determined input-output functions, whose teleofunctional status is absent or misdescribed. I will argue that in the case of trichromatic color matches, the psychological function involved is an input-output function, and that this result has implications for the description of color vision as a psychological capacity. (shrink)

This is a book about how we see: the environment around us (its surfaces, their layout, and their colors and textures); where we are in the environment; whether or not we are moving and, if we are, where we are going; what things are good for; how to do things (to thread a needle or drive an automobile); or why things look as they do.The basic assumption is that vision depends on the eye which is connected to the brain. The (...) author suggests that natural vision depends on the eyes in the head on a body supported by the ground, the brain being only the central organ of a complete visual system. When no constraints are put on the visual system, people look around, walk up to something interesting and move around it so as to see it from all sides, and go from one vista to another. That is natural vision—and what this book is about. (shrink)

The article examines the polemic in the surangama sutra against the possibility of establishing any spacial relation between consciousness, the sense organs, and the external world. the arguments lead to the negative conclusion that consciousness cannot be said to have spacial location without contradicting experience. the article then takes this argument and applies it to the physiology of vision showing that visual perception cannot, in principle, be located neurologically.

There is a long-lasting quest of demarcating a minimally representational behavior. Based on neurophysiologically-informed behavioral studies, we argue in detail that one of the simplest cases of organismic behavior based on low-resolution spatial vision–the visually-guided obstacle avoidance in the cubozoan medusaTripedalia cystophora–implies already a minimal form of representation. We further argue that the characteristics and properties of this form of constancy-employing structural representation distinguish it substantially from putative representational states associated with mere sensory indicators, and we reply to some possible (...) objections from the liberal representationalists camp by defending and qualitatively demarcating the minimal nature of our case. Finally, we briefly discuss the implications of our thesis within a naturalistic framework. (shrink)

What is the relationship between a visual percept and the underlying neuronal activity in parts of the brain? This manifesto reviews the theoretical framework of Crick and Kochfor answering these questions based on the neuroanatomy and physiology of mammalian cortex and associated subcortical structures. This evidence suggests that primates are not directly aware of neural activity in primary visual cortex, although they may be aware of such activity in extrastriate cortical areas. Psychophysical evidence in humans supporting this hypothesis (...) is discussed. (shrink)

Given its simplicity and enormous unifying and explanatory power, the predictive mind approach to mental architecture (predictive processing) is becoming an increasingly attractive way of carrying out theoretical and experimental research in cognitive science. According to this view, the mind is constantly attempting to minimize the discrepancy between its expectations (or sensory predictions) and its actual incoming sensory signals. In the interoceptive inference view of emotion (IIE), the principles of the predictive mind have been extended to account for emotion. IIE (...) holds that, in direct analogy to visual perception, emotions arise from interoceptive predictions of the causes of current interoceptive afferents. In this paper, I argue that this view is problematic, as there are arguably no regularities pertaining to emotion in the physiological inner milieu, from which the relevant interoceptive expectations could be learned. Therefore, it is unlikely that our expectations relative to emotion involve interoceptive expectations in the way required by IIE. The latter view should then be amended. In this respect, I suggest that emotions might arise via external interoceptive active inference: by sampling and modifying the external environment in order to change a valenced feeling. Thus, if the predictive mind approach is on track, emotions are not to be understood in direct analogy to perception (e.g., vision). Rather, I suggest that the view of emotion that emerges from the predictive mind is in line with motivational approaches to emotion. In the suggested view, (almost) just as drives (or ‘homeostatic motivations’), emotions are suited for the active regulation of the inner milieu by sampling the environment in order to finesse our emotion expectations. In this view, emotions are individuated, and differ from drives, in virtue of the distinctive sampling policies (‘actions’) characteristic of the high levels of the predictive hierarchy. (shrink)

It is tough to relate visual perception or other achievements to physiological processing in the central nervous system. The diagrammatic, algebraic, and verbal pictures of how sights seem to Lehar do not advance understanding of how we manage to see what is in the world. There are well-known conceptual reasons why no such purely introspective approach can be productive.

The physiological blind spot corresponds to the optic disc where the retina contains no light-detecting photoreceptor cells. Our perception seemingly fills in this gap in input. Here we suggest that rather than an active process, such perceptual filling-in could instead be a consequence of the integration of visual inputs at higher stages of processing discounting the local absence of retinal input. Using functional brain imaging, we resolved the retinotopic representation of the physiological blind spot in early human (...) class='Hi'>visual cortex and measured responses while participants perceived filling-in. Responses in early visual areas simply reflected the absence of visual input. In contrast, higher extrastriate regions responded more to stimuli in the eye containing the blind spot than the fellow eye. However, this signature was independent of filling-in. We argue that these findings agree with philosophical accounts that posit that the concept of filling-in of absent retinal input is unnecessary. (shrink)

This thesis falls into two parts, a characterizing part, and an explanatory part. In the first part, I outline some of the core aspects of our ordinary understanding of visual perception, and how we regard it as a means of knowing. What explains the fact that I know that the lemon before me is yellow is my visual perception: I know that the lemon is yellow because I can see it. Some explanations of how one knows (...) specify that in virtue of which one genuinely knows, as opposed to merely believes, some content. Such explanations are epistemically satisfactory explanations. We think that visual perceptual explanations of knowledge can be epistemically satisfactory. I argue that that is what it is to regard visual perception as being among our means of knowing. In the second part, I explore how we might explain the fact that visual perception is a means of knowing (assuming that it is a fact). I ask what makes it the case that visual perception is a means of knowing (in the way we ordinarily think that it is)? I suggest that part of the answer to this question is that visual perception, given the nature it has, has a reason giving role. And that is just to say that the nature of visual perception is such that visually perceiving can ensure the satisfaction of some important condition on knowledge (namely, that if one knows that something is the case one must have a good reason to believe that it is the case). In concluding I suggest that giving this sort of explanation doesn't require a specific theory of perception. (shrink)

This paper presents the results of some recent experiments in neuroscience and introspectionist psychology that reveal the role of virtual reality in normal visual perception, and the use of television information compression technology by the visual brain. This involves particularly the cholinergic system in the forebrain. This research throws new light on the nature of consciousness, in particular in connection with the debate between Naïve Realists and Physiological Realists.

According to Kepler and Descartes, the geometry of the triangle formed by the two eyes when focused on a single point affords perception of the distance to that point. Kepler characterized the processes involved as associative learning. Descartes described the processes as a “ natural geometry.” Many interpreters have Descartes holding that perceivers calculate the distance to the focal point using angle-side-angle, calculations that are reduced to unnoticed mental habits in adult vision. This article offers a purely psychophysiological interpretation (...) of Descartes’s natural geometry. In his account of perceived limb position from the Treatise on Man, he envisioned a central brain state that controls ocular convergence and thereby co-varies with the distance from observer to object. A psychophysiological law relates the visual perception of distance to this brain state. Descartes also invokes more traditional theories of distance and size perception based on unnoticed judgments, yielding a hybrid account. (shrink)

In Word and Object, W.V. Quine made thinkable the idea that speech and cognition bear a burden of semantic indeterminacy. On Quine’s account, the upshot of semantic indeterminacy is that meaning and mentalism resist successful naturalization, and thus fail the test of scientific respectibility. For Quine, semantic indeterminacy is a fatal shortcoming.Recent attempts to naturalize meaning in our thought and our talk (e.g. Dretske 1981, Fodor 1987), belonging to a tradition that has thrived in reaction to Quine, have sought to (...) nail down semantic properties in a scientifically respectable fashion, avoiding the scourge of indeterminacy. However, both Quine and the new redeemers of mentalism may have missed the boat. Three case studies offered here will suggest that a thriving theory of visual perception still makes room for some rather striking indeterminacies. (shrink)

This paper deals with the mutations in Wittgenstein’s treatment of the notions of “generality” and of “singularity”, from his first philosophy, in the Tractatus Logico-Philosophicus, to his later mature philosophy represented by the Philosophical Investigations. As we shall see, Wittgenstein’s philosophical handling of the notion of “visual perception” plays a key role in those conceptual transformations.

Different explanations of color vision favor different philosophical positions: Computational vision is more compatible with objectivism (the color is in the object), psychophysics and neurophysiology with subjectivism (the color is in the head). Comparative research suggests that an explanation of color must be both experientialist (unlike objectivism) and ecological (unlike subjectivism). Computational vision's emphasis on optimally prespecified features of the environment (i.e., distal properties, independent of the sensory-motor capacities of the animal) is unsatisfactory. Conceiving of visual perception instead (...) as the visual guidance of activity in an environment that is determined largely by that very activity suggests new directions for research. (shrink)

It is argued that seeing that P is a mode of knowing that P that is to be explained in terms of the exercise of visual-perceptual recognitional abilities. The nature of those abilities is described. The justification for believing that P, when one sees that P, is provided by the fact that one sees that P. Access to this fact is explained in terms of an ability to recognize of seen objects that one is seeing them. Reasons for resistance (...) to such an account are considered. The distinction between merely reasonable belief and well-founded belief is emphasised. (shrink)

Quilty-Dunn et al.'s wide-ranging defense of the Language of Thought Hypothesis (LoTH) argues that vision traffics in abstract, structured representational formats. We agree: Vision, like language, is compositional – just as words compose into phrases, many visual representations contain discrete constituents that combine in systematic ways. Here, we amass evidence extending this proposal, and explore its implications for how vision interfaces with the rest of the mind.

The catastrophe of the eye -- A new view of seeing -- Applying the new view of seeing -- The illusion of seeing everything -- Some contentious points -- Towards consciousness -- Types of consciousness -- Phenomenal consciousness, raw feel, and why they're hard -- Squeeze a sponge, drive a porsche : a sensorimotor account of feel -- Consciously experiencing a feel -- The sensorimotor approach to color -- Sensory substitution -- The localization of touch -- The phenomenality plot -- (...) Consciousness. (shrink)