Opposed to Norman's proposal, processing of affordance is likely to occur not solely in the dorsal stream but also in the ventralstream. Moreover, the dorsal stream might do more than just serve an important role in motor actions. It supports egocentric location coding as well. As such, it would possess a form of representational memory, contrary to Norman's proposal.
Several lines of evidence indicate that rapid target-aiming movements, involving both the eyes and hand, can be biased by the visual context in which the movements are performed. Some of these contextual influences carry-over from trial to trial. This research indicates that dissociation between the dorsal and ventral systems based on speed, conscious awareness, and frame of reference is far from clear.
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)
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)
Today many philosophers of mind accept that the two cortical streams of visual processing in humans can be distinguished in terms of conscious experience. The ventralstream is thought to produce representations that may become conscious, and the dorsal stream is thought to handle unconscious vision for action. Despite a vast literature on the topic of the two streams, there is currently no account of the way in which the relevant empirical evidence could fit with basic Husserlian (...) phenomenology of vision. Here I offer such an account. In this article, I show how the empirical evidence ought to be understood in a way that is informed by phenomenology. The differences in the two streams are better described as differences in spatial and temporal processing. Rather than simply “unconscious,” the dorsal stream can be better described as making a special contribution to what Husserl identified as the visual horizon. (shrink)
The author argues that the theory of a dorsal/ventralstream for visual processing can be used to reconcile the constructivist and direct perception theories. My commentary discusses neurophysiological and psychophysical studies that run counter to the view. In addition, the central issue of debate between the constructionist and direct perception approaches regarding what is visual information is discussed.
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 ventralstream 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)
Our commentary focuses on the functional link between the ventral and dorsal systems implied by Norman, as they relate to overt movement. While issues relating to space perception and size constancy are the primary justification for this dual-process theory, the philosophical extensions of this approach are less consistent with examination of motor control and, in particular, motor learning.
Milner and Goodale's influential account of the primate cortical visual streams involves a division of consciousness between them, for it is the ventralstream 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 (...) class='Hi'>stream contributes to a pervasive feature of consciousness. (shrink)
Event-related potential studies have attempted to discover the processes that underlie conscious visual perception by contrasting ERPs produced by stimuli that are consciously perceived with those that are not. Variability of the proposed ERP correlates of consciousness is considerable: the earliest proposed ERP correlate of consciousness coincides with sensory processes and the last one marks postperceptual processes. A negative difference wave called visual awareness negativity , typically observed around 200 ms after stimulus onset in occipitotemporal sites, gains strong support for (...) reflecting the processes that correlate with, and possibly enable, aware visual perception. Research suggests that the early parts of conscious processing can proceed independently of top-down attention, although top-down attention may modulate visual processing even before consciousness. Evidence implies that the contents of consciousness are provided by interactions in the ventralstream, but indispensable contributions from dorsal regions influence already low-level visual responses. (shrink)
Current views of the parietal cortex have difficulty accommodating the human inferior parietal lobe (IPL) within a simple dorsal versus ventralstream dichotomy. In humans, lesions of the right IPL often lead to syndromes such as hemispatial neglect that are seemingly in accord with the proposal that this region has a crucial role in spatial processing. However, recent imaging and lesion studies have revealed that inferior parietal regions have non-spatial functions, such as in sustaining attention, detecting salient events (...) embedded in a sequence of events and controlling attention over time. Here, we review these findings and show that spatial processes and the visual guidance of action are only part of the repertoire of parietal functions. Although sub-regions in the human superior parietal lobe and intraparietal sulcus contribute to vision-for-action and spatial functions, more inferior parietal regions have distinctly non-spatial attributes that are neither conventionally 'dorsal' nor conventionally 'ventral' in nature. (shrink)
The cortical visual mechanisms involved in processing spatial relationships remain subject to debate. According to one current view, the ''dorsal stream'' of visual areas, emanating from primary visual cortex and culminating in the posterior parietal cortex, mediates this aspect of visual processing. More recently, others have argued that while the dorsal stream provides egocentric coding of visual location for motor control, the separate ''ventral'' stream is needed for allocentric spatial coding. We have assessed the visual form (...) agnosic patient DF, whose lesion mainly affects the ventralstream, on a prehension task requiring allocentric spatial coding. She was presented with transparent circular disks. Each disk had circular holes cut in it. DF was asked to reach out and grasp the disk by placing her fingers through the holes. The disks either had three holes (for forefinger, middle finger, and thumb) or two holes (for forefinger and thumb). The distance between the forefinger and thumb holes, and the orientation of the line formed by them, were independently varied. DF was quite unable to adjust her grip aperture or her hand orientation in the three-hole task. Although she was able to orient her hand appropriately for the two-hole disks, she still remained unable to adjust her grip aperture to the distance between the holes. These findings are consistent with the idea that allocentric processing of spatial information requires a functioning ventralstream, even when the information is being used to guide a motor response. (shrink)
The Visual Brain in Action by Milner and Goodale provides a new conceptual account of how the brain processes visual information. Milner and Goodale make two major points: The dorsal stream processes visual information for motor purposes; Action and perception are two completely separate domains, the latter being an exclusive property of the ventralstream. In the first part of this review we will summarize some recent neurophysiological data shedding new light on the "pragmatic" role of the (...) visual information processed in the dorsal stream, and thus corroborating the theoretical views of Milner and Goodale . In the second part we will discuss some recent neurophysiological, neuropsychological and brain imaging studies suggesting that the dichotomy proposed by Milner and Goodale between action and perception is probably too rigid. (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 ventralstream and (...) the latter on processing in the dorsal stream. (shrink)
The etiology of visual hallucinations is largely undetermined in schizophrenia. Collerton et al.'s PAD model partly concurs with what we know about neurocognition in schizophrenia, but we need to specify the types of perceptual and attentional abnormalities that are implicated in recurrent complex visual hallucinations (RCVH). Available data suggest that abnormal attentional control and top-down processing play a larger role than the ventralstream deficits.
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 ventralstream may play a more critical role in visual awareness and qualia than mechanisms in the dorsal stream.
Deictic coding offers a useful model for understanding the interactions between the dorsal and ventral streams of visual processing in the cerebral cortex. By extending Ballard et al.'s ideas on teleassistance, I show how dedicated low-level visuomotor processes in the dorsal stream might be engaged for the services of high-level cognitive operations in the ventralstream.
Single-cell studies of monkey posterior parietal cortex (PPC) have revealed the extensive neuronal representations of three-dimensional subject motion and three-dimensional layout of the environment. I propose that navigational planning integrates this PPC information, including gravity signals, with horizontal-plane based information provided by the hippocampal formation, modified in primates by expansion of the ventralstream.
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 ventralstream can invoke stored information about the material properties of objects originally derived from the somatosensory system.
Whether or not the correspondence of dorsal stream functions to Gibsonian ecological psychology and the ventralstream functions to “constructivism” hold up, the overall goal of capturing a pragmatic realism should not be forgotten.
In the target article Pylyshyn revives the spectre of the “little green man,” arguing for a largely symbolic representation of visual imagery. To clarify this problem, we provide precise definitions of the key term “picture,” present some examples of our definition, and outline an information-theoretic analysis suggesting that the problem of addressing data in the brain requires a partially analogue and partially symbolic solution. This is made concrete in the ventralstream of object recognition, from V1 to IT (...) cortex. (shrink)
The cortical representation of concepts varies according to the information critical for their development. Living categories, being mainly based upon visual information, are bilaterally represented in the rostral parts of the ventralstream of visual processing; whereas tools, being mainly based upon action data, are unilaterally represented in a left-sided fronto-parietal network. The unilateral representation of tools results from involvement in actions of the right side of the body.
As an explicit organizing metaphor, memory aid, and conceptual framework, the prefrontal cortex may be viewed as a five-member ‘Executive Committee,’ as the prefrontal-control extensions of five sub-and-posterior-cortical systems: the ‘Perceiver’ is the frontal extension of the ventral perceptual stream which represents the world and self in object coordinates; the ‘Verbalizer’ is the frontal extension of the language stream which represents the world and self in language coordinates; the ‘Motivator’ is the frontal cortical extension of a subcortical (...) extended-amygdala stream which represents the world and self in motivational/emotional coordinates; the ‘Attender’ is the frontal cortical extension of a subcortical extended-hippocampal stream which represents the world and self in spatiotemporal coordinates and directs attention to internal and external events; and the ‘Coordinator’ is the frontal extension of the dorsal perceptual stream which represents the world and self in body- and eye-coordinates and controls willed action and working memory. This tutorial review examines the interacting roles of these five systems in perception, working memory, attention, long - term memory, motor control, and thinking. (shrink)
As many as two million people in the United Kingdom repeatedly see people, animals, and objects that have no objective reality. Hallucinations on the border of sleep, dementing illnesses, delirium, eye disease, and schizophrenia account for 90% of these. The remainder have rarer disorders. We review existing models of recurrent complex visual hallucinations (RCVH) in the awake person, including cortical irritation, cortical hyperexcitability and cortical release, top-down activation, misperception, dream intrusion, and interactive models. We provide evidence that these can neither (...) fully account for the phenomenology of RCVH, nor for variations in the frequency of RCVH in different disorders. We propose a novel Perception and Attention Deficit (PAD) model for RCVH. A combination of impaired attentional binding and poor sensory activation of a correct proto-object, in conjunction with a relatively intact scene representation, bias perception to allow the intrusion of a hallucinatory proto-object into a scene perception. Incorporation of this image into a context-specific hallucinatory scene representation accounts for repetitive hallucinations. We suggest that these impairments are underpinned by disturbances in a lateral frontal cortex–ventral visual stream system. We show how the frequency of RCVH in different diseases is related to the coexistence of attentional and visual perceptual impairments; how attentional and perceptual processes can account for their phenomenology; and that diseases and other states with high rates of RCVH have cholinergic dysfunction in both frontal cortex and the ventral visual stream. Several tests of the model are indicated, together with a number of treatment options that it generates. Key Words: Blindness; Charles Bonnet; cholinergic; cortical release; delirium; dementia; dream intrusion; hallucination; Perception and Attention Deficit (PAD) model; schizophrenia. (shrink)
I examine John Campbell’s claim that the determination of the reference of a perceptual demonstrative requires conscious visual object-based selective attention. I argue that although Campbell’s claim to the effect that, first, a complex binding parameter is needed to establish the referent of a perceptual demonstrative, and, second, that this referent is determined independently of, and before, the application of sortals is correct, this binding parameter does not require object-based attention for its construction. If object-based attention were indeed required then (...) the determination of the referent would necessarily involve the application of sortal concepts, since object-based attention initiates top-down cognitive effects on visual processing. I also examine Mohan Matthen’s claim that reference to objects is established only through the visual processing in the dorsal visual stream and argue that although it is true that processing in the dorsal stream can determine reference, a thesis that goes against Campbell’s view that the determination of the referent requires conscious attention, processing along the ventral visual stream can also establish the reference of perceptual demonstratives. It also claim that Matthen’s account of dorsal processing underestimates the kind of information processed along the dorsal stream and this has some implications regarding perceptual demonstratives reference fixing. (shrink)
Machine generated contents note: -- 1. Introduction -- Consciousness and Sensorimotor Dynamics: Methodological Issues -- 2. Computational consciousness, D. Ballard -- 3. Explaining what people say about sensory qualia, J. Kevin O'Regan -- 4. Perception, action, and experience: unraveling the golden braid, A. Clark -- The Two-Visual Systems Hypothesis -- 5. Cortical visual systems for perception and action, A.D. Milner and M.A. Goodale -- 6. Hermann Lotze's Theory of 'Local Sign': evidence from pointing responses in an illusory figure, (...) D.R. Melmoth -- Understanding Agency and Object Perception -- 7. Two visual systems and the feeling of presence, M. Matthen -- 8. Spatial coordinates and phenomenology in the two-visual systems model, P. Jacob and F. de Vignemont -- 9. Perceptual experience and the capacity to act, S. Schellenberg -- Perception and Action: Studies in Cognitive Neuroscience -- 10. Why does the perception-action functional dichotomy not match the ventral-dorsal streams in anatomical segregation: optic ataxia and the function of the dorsal stream, Y. Rossetti et al -- 11. Mapping the neglect syndrome onto neurofunctional streams, G. Vallar and F. Mancini -- 12. Motor representations and the perception of space: perceptual judgments of the boundary of action space, Y. Delevoye-Turrell -- The Role of Action and Sensorimotor Knowledge in Sensorimotor Theories of Perception -- 13. Vision without representation, A. Noe -- 14. Sensorimotor knowledge and the contents of experience, J. Kiverstein -- Boundaries of the Agent -- 15. Extended vision, R. A. Wilson. (shrink)
To learn a visual code in an unsupervised manner, one may attempt to capture those features of the stimulus set that would contribute signiﬁcantly to a statistically eﬃcient representation. Paradoxically, all the candidate features in this approach need to be known before statistics over them can be computed. This paradox may be circumvented by conﬁning the repertoire of candidate features to actual scene fragments, which resemble the “what+where” receptive ﬁelds found in the ventral visual stream in primates. We (...) describe a single-layer network that learns such fragments from unsegmented raw images of structured objects. The learning method combines fast imprinting in the feedforward stream with lateral interactions to achieve single-epoch unsupervised acquisition of spatially localized features that can support systematic treatment of structured objects . (shrink)
Sewards and Sewards argue that while computations necessary for object recognition occur throughout the ventral visual stream, object recognition awareness involves the anterior temporal lobe and the medial orbital prefrontal cortex. The present paper suggests, however, that the medial orbital prefrontal cortex has a unique contribution, namely that of producing a basic experience of a perceptual object. It is further argued that the mechanisms that produce this experience also result in making the object more important than its subparts (...) and features. Finally, it is argued that a reduction in this importance may account for some perceptual difficulties in high-functioning autism. This view is consistent with evidence for early selective abnormalities in other systems involving the medial prefrontal cortex in autism. (shrink)
Milner and Goodale have advanced a justly influential theory of the structure of the human visual system. In broad outline, Milner and Goodale hold that the ventral neural pathway is associated with recognition and experiential awareness, and with a kind of indirect control of action. And they hold that, by contrast, the dorsal neural stream is associated with the non-conscious, direct control of visually informed action. Most of the relevant empirical research has focused on the visual control of (...) close-in, “personal space,” reaching and/or grasping. While their view has not escaped controversy and debate, we think that Milner and Goodale have a compelling story to tell about the visual guidance of such close in, “personal space” action. However, the question of whether their scheme applies to behavior with visually specified targets that are outside of the space accessible by simply reaching and grasping is largely unstudied. And it should be studied, since this is the arena of much human behavior. We provide good reason to think that the Milner and Goodale scheme may well not apply to important classes of mid-range, ‘action space’ behavior. But the matter is in the end to be decided in the lab. We describe a research program to do this. (shrink)
The basic components of James’s stream of consciousness are considered concretely and in a way that tends to be relatively neutral from a theoretical perspective. My ultimate goal is a general description of the states of consciousness, but I try here to be more “observational” than “theoretical” about them. Giving attention to James’s reports of his personal firsthand evidence, I proceed as though I were conversing with this most phenomenological and radically empirical of psychological authors. I disagree with James (...) on some points but, also, I find many of his claims acceptable and base my own view on a thesis fundamental to his perspective: A stream of consciousness consists of a succession, one at a time, of unitary states and all of the other mental occurrences that are conscious are features of such states. This is an effort to see more clearly together with James, not an exercise of correcting errors in how he treated of our topic. (shrink)
In his paper, “The Dorsal Stream and the Visual Horizon,” Michael Madary argues that “dorsal stream processing plays a main role in the spatiotemporal limits of visual perception, in what Husserl identified as the visual horizon” (Madary 2011, p. 424). Madary regards himself as thereby providing a theoretical framework “sensitive to basic Husserlian phenomenology” (Madary 2011). In particular, Madary draws connections between perceptual anticipations and the experience of the indeterminate spatial margins, on the one hand, and the Husserlian (...) spatiotemporal visual horizons, on the other. I argue that Madary’s arguments, for a Husserlian view of the two visual systems, are not convincing. When the notion of visual horizon is adequately understood as a constitutive notion, there will be reason to regard the connections between dorsal processing and the Husserlian spatiotemporal horizons as tenuous at best. (shrink)
_Stream of Consciousness_ is about the phenomenology of conscious experience. Barry Dainton shows us that stream of consciousness is not a mosaic of discrete fragments of experience, but rather an interconnected flowing whole. Through a deep probing into the nature of awareness, introspection, phenomenal space and time consciousness, Dainton offers a truly original understanding of the nature of consciousness.
This paper defends and develops the structuring account of conscious attention: attention is the conscious mental process of structuring one’s stream of consciousness so that some parts of it are more central than others. In the first part of the paper, I motivate the structuring account. Drawing on a variety of resources I argue that the phenomenology of attention cannot be fully captured in terms of how the world appears to the subject, as well as against an atomistic conception (...) of attention. In the second part of the paper, I show how the structuring account can be made precise: attention causes and causally sustains phenomenal relations to hold between the parts of the stream of consciousness; most importantly the relation of one part being peripheral to another. I end by pointing out consequences for both the scientific study of attention as well as for several areas of central philosophical interest. (shrink)
This paper explores the relation of thought and the stream of consciousness in the light of an ontological argument raised against cognitive phenomenology views. I argue that the ontological argument relies on a notion of ‘processive character’ that does not stand up to scrutiny and therefore it is insufficient for the argument to go through. I then analyse two more views on what ‘processive character’ means and argue that the process-part account best captures the intuition behind the argument. Following (...) this view, I reconstruct the ontological argument and argue that it succeeds in establishing that some mental episodes like judging, understanding and occurrent states of thought do not enter into the stream but fails to exclude episodes like entertaining. Contrary to what it might seem, this conclusion fits well with cognitive phenomenology views, given that, as I show, there is a way for non-processive mental episodes to be fundamentally related to processive ones, such that they cannot be excl.. (shrink)
William James described the stream of thought as having two components: (1) a nucleus of highly conscious, often perceptual material; and (2) a fringe of dimly felt contextual information that controls the entry of information into the nucleus and guides the progression of internally directed thought. Here I examine the neural and cognitive correlates of this phenomenology. A survey of the cognitive neuroscience literature suggests that the nucleus corresponds to a dynamic global buffer formed by interactions between different regions (...) of the brain, while the fringe corresponds to a set of mechanisms in the frontal and medial temporal lobes that control the contents of this global buffer. A consequence of this account is that there might be conscious imagistic representations that are not part of the nucleus. I argue that phenomenology can be linked to psychology and neuroscience and a meaningful way that illuminates both. (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)
Logic is widely considered the basis of rationality. Logical choices, however, are often influenced by emotional responses, sometimes to our detriment, sometimes to our advantage. To understand the neural basis of emotionally neutral and emotionally salient reasoning we studied 19 volunteers using event-related fMRI, as they made logical judgments about arguments that varied in emotional saliency. Despite identical logical form and content categories across “hot” and “cold” reasoning conditions, lateral and ventral medial prefrontal cortex showed reciprocal response patterns as (...) a function of emotional saliency of content. “Cold” reasoning trials resulted in enhanced activity in lateral/dorsal lateral prefrontal cortex and suppression of activity in ventral medial prefrontal cortex. By contrast, “hot” reasoning trials resulted in enhanced activation in VMPFC and suppression of activation in L/DLPFC. This reciprocal engagement of L/DLPFC and VMPFC provides evidence for a dynamic neural system for reasoning, the configuration of which is strongly influenced by emotional saliency. (shrink)
Although patient data have traditionally implicated the left prefrontal cortex in hypothesis generation, recent lesion data implicate right PFC in hypothesis generation tasks that involve set shifts. To test the involvement of the right prefrontal cortex in a hypothesis generation task involving set shifts, we scanned 13 normal subjects with fMRI as they completed Match Problems and a baseline task. In Match Problems subjects determined the number of possible solutions for each trial. Successful solutions are indicative of set shifts. In (...) the baseline condition subjects evaluated the accuracy of hypothetical solutions to match problems. A comparison of Match Problems versus baseline trials revealed activation in right ventral lateral PFC and left dorsal lateral PFC. A further comparison of successfully versus unsuccessfully completed Match Problems revealed activation in right ventral lateral PFC, left middle frontal gyrus and left frontal pole, thus identifying the former as a critical component of the neural mechanisms of set-shift transformation. By contrast, activation in right dorsal lateral PFC covaried as a function of the number of solutions generated in Match Problems, possibly due to increased working memory demands to maintain multiple solutions ‘on-line’, conflict resolution, or progress monitoring. These results go beyond the patient data by identifying the ventral lateral aspect of right PFC as being a critical component of the neural systems underlying lateral transformations, and demonstrate a dissociation between right VLPFC and DLPFC in hypotheses generation and maintenance. (shrink)
Only in the stream of thought and life do words have meaning. The belief in karma and rebirth, according to which actions performed in one lifetime bear fruit in a subsequent one, is widespread, some version of it being common among Hindu, Buddhist, Sikh, Jain, and some other religious traditions. Ethnographic studies sometimes provide examples of how this belief manifests in people’s lives. For instance, fieldwork carried out by Richard and Candy Shweder in the eastern Indian town of Bhubaneswar (...) yielded interview footage exhibiting how members of the Hindu community apply the concepts of karma and rebirth in describing their situations. A poignant case is that of an eighty-three-year-old high-caste .. (shrink)
Experimental data suggest that the division between the visual ventral and dorsal pathways may indeed indicate that static and dynamical information is processed separately. Contrary to Hurford, it is suggested that the ventral pathway primarily generates representations of objects, whereas the dorsal pathway produces representations of events. The semantic object/event distinction may relate to the morpho-syntactic noun/verb distinction.
This paper combines views of Wittgenstein and Heidegger into an account of mind/ action. It does this by suggesting that these two philosophers be viewed in part as descendants of Life?philosophy (Lebensphilosophie). Part I describes the conception of life that informs and emerges from these thinkers. Parts Two and Three detail particular aspects of this conception: Wittgenstein on the constitution of states of life and Heidegger on the flow?structure of the stream of life. The Conclusion offers reasons for believing (...) their combined viewpoint. (shrink)