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Neural Plasticity and Consciousness

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Abstract

We introduce a distinction between cortical dominance andcortical deference, and apply it to various examples ofneural plasticity in which input is rerouted intermodally orintramodally to nonstandard cortical targets. In some cases butnot others, cortical activity `defers' to the nonstandard sourcesof input. We ask why, consider some possible explanations, andpropose a dynamic sensorimotor hypothesis. We believe that thisdistinction is important and worthy of further study, bothphilosophical and empirical, whether or not our hypothesis turnsout to be correct. In particular, the question of how the distinction should be explained is linked to explanatory gapissues for consciousness. Comparative and absolute explanatorygaps should be distinguished: why does neural activity in aparticular area of cortex have this qualitative expressionrather than that, and why does it have any qualitativeexpression at all? We use the dominance/deference distinction toaddress the comparative gaps, both intermodal and intramodal (notthe absolute gap). We do so not by inward scrutiny but rather by expanding our gaze to include relations between brain, body andenvironment.

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... In a nutshell there are, on one side, the defenders of the 'Deference View' who argue that TVSS-perception occurs in the substituted modality (vision, in that case), so that it gives rise to visual perceptual states (e.g. Bach-y- Rita et al., 1969;Hurley and Noë, 2003;Noë, 2004;O'Regan & Noë, 2001;Renier et al., 2005aRenier et al., , 2005bRenier et al., , 2006). On another side, some authors have argued for what has been labelled the 'Dominance View', according to which TVSS-perception occurs in the substituting modality (touch, in that case) (see Keeley, 2002;Block, 2003 andPrinz, 2006). ...
... Bach-y- Rita et al., 1969;Hurley and Noë, 2003;Noë, 2004;O'Regan & Noë, 2001;Renier et al., 2005aRenier et al., , 2005bRenier et al., , 2006); on the other side, the 'Dominance View' argues that such devices give rise to perceptual states belonging to the substituting modality (touch, in the case of the TVSS and audition, in the case of the PSVA). ...
... 964). Similarly, Hurley and Noë (2003) say: "objects are reported to be perceived as arrayed at a distance from the body in space and as standing in perceptible spatial relations such as "in front of"." (p. 142). ...
Thesis
My Dissertation is concerned with two theoretical issues that have gain considerable attention in the recent philosophical and scientific literature about our understanding of the sense modalities. The first issue focuses on the question how the senses are to be individuated, being admitted that the senses interact together in an almost systematic way? The second issue bears upon the question why do we, as folk people, believe in exactly five senses, being admitted that according to recent scientific claims humans have more than five senses? In the first part of my Dissertation, I evaluate the criteria for sense individuation and argue in favour of the Criterion of Content, according to which the senses are to be individuated in terms of the proper environmental properties they give access to. The methodological strategy, established in Chapter 1, is the following: First, I argue that in order to provide a criterion for individuating the senses one has to start from what science tells us about the senses, leaving aside any analysis of the way people conceive of the senses; second, that the choice of the criterion depends upon its ability to address scientific objections; third, that only the Content Criterion can withstand scientific objections. This strategy is developed throughout the Chapters 2 and 3. Against the Criterion of External Stimuli, I claim that the possibility to detect one and the same class of external stimuli undermines its independency—sufficiency—in that it cannot help to explain why certain senses are different (vision and thermoception for instance). Against the Neurophysiological Criterion, I claim that any attempt to individuate the senses in neurobiological terms is undermined—the consideration of the sole sensory receptors leads to the fact that different senses can be attached to similar receptors, and the consideration of subcortical and cortical areas is inappropriate as well because certain areas previously considered as unimodal can be shown to be multimodal instead (e.g. superior colliculus) or metamodal (e.g. primary area V1). Against the Criterion of Qualia, I argue that even if it can be shown that qualia properties, understood as non-representational properties, exist, it can also be suggested that these properties are reducible to content properties, and more originally that the introspectible character is not always a secure process in that one can be mislead about the way, i.e. about the type of sense, through which one perceives the world. On these grounds, I claim that we should adopt a methodological approach according to which it is our knowledge of the environment that could help scientists to decide eventually to which type of sense such and such token of sense perception belongs to. In the second part, I argue that our commonsense classification of the senses into exactly five modalities is a cultural artefact. One of the starting points of my research is the observation that the traditional philosophical strategies to identify the commonsense criterion of sense individuation demands that theorists both explain and preserve the commonsense classification of the senses into exactly five sense modalities (the five-belief hypothesis). In doing so, philosophers assume that this hypothesis imposes itself as a self-evident belief that anyone intuitively entertain. As such those authors assume that the five-belief is also universal. Nonetheless, such appeal to universalism is ambiguous, in that it can be understood in at least two ways: either the claim that our five-belief is universal results from empirical observations and notably from anthropological and ethnographic observations or it results from certain a priori arguments about our own (human) cognitive apparatus. In Chapters 4 and 5, I have introduced some data that undermine these two claims. In Chapter 4, I have reviewed a set of data and observations from anthropology and comparative linguistics, and shown that there are some variations in the way people symbolize the senses (some cultures admit more than five senses, some languages have fewer sensory verbs, and so on). This suggests that the five-belief hypothesis is at least not so intuitive after all. Nonetheless, I have also evaluated the inference that runs from these data and observations to the thesis according to which people from different cultures with different languages conceive of or categorize the senses differently (what I have called ‘Sensory Relativism’, which is a thesis about the way people think—implicitly or explicitly—about the senses). To that end, I have reconstructed and evaluated three of the main arguments in support of sensory relativism and show that they are not conclusive. Yet, such a criticism of Sensory Relativism does not imply that Sensory Universalism (the universality of the five-belief hypothesis) is right. Indeed, in Chapter 5, I discuss some aspects of the semantic classification of sensory verbs across languages and develop a model that can be informative for the Classification Question, namely, the question of the origin of our commonsense classification in five senses. Here, I provide a preliminary meta-analysis of current cross-linguistic literature and studied two additional corpuses on lexical aspects of sense perception. It has been shown that there are certain universal cross-preferences about the semantic classification of sensory verbs (Viberg, 1984), and that linguistic constructions of sensory verbs and sensory compound verbs are likely to be sensitive to several parameters: (i) to the spatial signature characteristic of sensory verbs, (ii) to our sense organs and (iii) to environmental properties of the world. The main thesis defended is that under the assumption that language is at least informative about the way we think, then the presence of sensory compound verbs can be shown to be indicative of our possession of more than five concepts of the senses. On such grounds, I propose to adopt a methodological approach that accepts from the very beginning that our commonsense classification of the senses into exactly five modalities is nothing more than a culture-based classification without accepting that the way people think about the senses do not respect specific universal constraints (yet to be discovered).
... Unlike the arbitrary tactile phonemes [20], it is possible to utilise 'native' cross-modal vocabularies. These could be thought of as the correspondences between sensory representations of different origins, which are consistent across cultures [44,52,53]. ...
... The deference thesis claims that the sensory substitution experience switches to the substituted sense (e.g. 'seeing with the skin' [104], 'seeing with the brain' [9], and 'seeing with sound' [68]) [44,71,73]. This thesis is in line with our assumption that deduced cross-modal feedback from auditory and tactile feedback would be redundant as they substituted for the same information source. ...
... The evidence from previous studies examining spatial representations with respect to sonifications is mixed. It is possible to argue that sonifications from cross-modal displays, unlike other environmental auditory sources, carry visual elements [44,72,74]. According to this line of research, it would be argued that sonifications lead to vision-like allocentric representations. ...
Thesis
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Sensory substitution phenomena transform the representation of one sensory form into an equivalent from a different sensory origin. For example, a visual feed from a camera can be turned into something that can be touched or sounds that can be heard. The immediate applications of this can be seen in developing assistive technologies that aid vestibular problems, and visual and hearing impairments. This raises the question of whether perception with sensory substitution is processed like an image, or like a surface, or a sound. Sensory substitution techniques offer a great opportunity to dissociate the stimulus, the task and sensory modality, and thus provide a novel way to explore the level of representation that is most crucial for cognition. Accordingly, state-of-the-art sensory substitution techniques contribute significantly to the understanding of how the brain processes sensory information and also represents it with distinct qualia. This progressively advances cognitive theories with respect to multisensory perception and cross-modal cognition. Due to its versatility, sensory substitution phenomena also carry the applications of cognitive theories to other interdisciplinary research areas such as human-computer interactions (HCI). In HCI, cross- modal displays utilise sensory substitution techniques to augment users by enabling them to acquire sensory information via a sensory channel of different origin. The modular and flexible nature of cross-modal displays provide a supplementary framework that can appeal to a wider range of people whose physical and cognitive capabilities vary on a continuum. The present thesis focuses on the inclusive applications of sensory substitution techniques and cross- modal displays. Chapter I outlines the inclusive design mindset and proposes a case for applications of sensory substitution techniques for all of us. Chapter II and Chapter IV evaluates cross-modal displays in digital emotion communication and navigation applications respectively. Chapter III offers a methodology to study sensory substitution in a multisensory context. The present thesis evidences that perception with cross-modal displays utilises the capabilities of various senses. It further investigates the implication of this and suggests that cross-modal displays can benefit from multisensory combination. With multisensory combination, cross-modal displays with unisensory and multisensory modes can deliver complementary feedback. In this way, it is argued users can gain access to the same inclusive information technology with customised sensory channels. Overall, the scope of the present thesis approaches sensory substitution phenomena from an HCI perspective with theoretical implications grounded in cognitive sciences.
... Apart from applied studies investigating adaptive behaviour in humans with perceptual deficits, SS has been systematically studied to investigate the general flexibility of human perception (e.g., Auvray & Farina, 2014;Auvray & Myin, 2009;Block, 2003;Farina, 2013;Kiverstein, Farina & Clark, 2014;Renier et al., 2005), consciousness (e.g., Hurley & Noe¨, 2003;Kiverstein & Farina, 2012;Pepper, 2014), and adaptation to SS during training (Froese, McGann, Bigge, Spiers, & Seth, 2012;Haigh, Brown, Meijer, & Proulx, 2013). For example, SS research provides information about the effects on perceptual experience of cortical reorganization following sensory deprivation (Amedi et al., 2007;Proulx, 2010) and the influence of different sensorimotor contingencies on perceptual experience (Brown, Macpherson, & Ward, 2011;Hurley & Noe¨, 2003;Nagel, Carl, Kringe, Ma¨rtin, & Ko¨nig, 2005;O'Regan, 2011). ...
... Apart from applied studies investigating adaptive behaviour in humans with perceptual deficits, SS has been systematically studied to investigate the general flexibility of human perception (e.g., Auvray & Farina, 2014;Auvray & Myin, 2009;Block, 2003;Farina, 2013;Kiverstein, Farina & Clark, 2014;Renier et al., 2005), consciousness (e.g., Hurley & Noe¨, 2003;Kiverstein & Farina, 2012;Pepper, 2014), and adaptation to SS during training (Froese, McGann, Bigge, Spiers, & Seth, 2012;Haigh, Brown, Meijer, & Proulx, 2013). For example, SS research provides information about the effects on perceptual experience of cortical reorganization following sensory deprivation (Amedi et al., 2007;Proulx, 2010) and the influence of different sensorimotor contingencies on perceptual experience (Brown, Macpherson, & Ward, 2011;Hurley & Noe¨, 2003;Nagel, Carl, Kringe, Ma¨rtin, & Ko¨nig, 2005;O'Regan, 2011). Also of special interest to SS researchers is the relation between the activation of primary sensory cortical areas and the quality of sensory experience as well as the relation between the quality of sensory experience and performance accuracy (i.e., object recognition or location; Stiles & Shimojo, 2013). ...
... Research on SS may contribute to understanding the mechanisms of the reorganization of neural connections, since neural plasticity is often a consequence of SS (Deroy & Auvray, 2012;Hurley & Noe¨, 2003;Proulx, 2010;Stiles & Shimojo, 2013). Investigating the neural consequences of SS may also bring new insights to the problem of consciousness, as SSrelated neural activity can change its function and qualitative expression. ...
Article
Full-text available
Information that is normally accessed through a sensory modality (substituted modality, e.g., vision) is provided by sensory substitution devices (SSDs) through an alternative modality such as hearing or touch (i.e., substituting modality). SSDs usually support disabled users by replacing sensory inputs that have been lost, but they also offer a unique opportunity to study adaptation and flexibility in human perception. Current debates in sensory substitution (SS) literature focus mostly on its neural correlates and behavioural consequences. In particular, studies have demonstrated the neural plasticity of the visual brain regions that are activated by the substituting modality. Participants also adapt to using the devices for a broad spectrum of cognitive tasks that usually require sight. However, little is known about the SS experience. Also, there is no agreement on how the phenomenology of SS should be studied. Here, we offer guidelines for the methodology of studies investigating behavioural adaptation to SS and the effects of this adaptation on the subjective SS experience. We also discuss factors that may influence the results of SS studies: (1) the type of SSD, (2) the effects of training, (3) the role of sensory deprivation, (4) the role of the experimental environment, (5) the role of the tasks participants follow, and (6) the characteristics of the participants. In addition, we propose combining qualitative and quantitative methods and discuss how this should be achieved when studying the neural, behavioural, and experiential consequences of SS.
... Other forms of sensorimotor enactivism (e.g. Hurley 1998;Hurley and Noë 2003) emphasise both kinds of SMCs for different explanatory purposes. 13 Because we often perceptually experience features with which we are not presently interacting or in sensory contact, sensorimotor enactivism usually claims that perception requires not only that patterns of sensorimotor dependence obtain, but also that perceivers have 'knowledge' (or 'mastery', or 'understanding') of them. ...
... 13 Because we often perceptually experience features with which we are not presently interacting or in sensory contact, sensorimotor enactivism usually claims that perception requires not only that patterns of sensorimotor dependence obtain, but also that perceivers have 'knowledge' (or 'mastery', or 'understanding') of them. Importantly, such 'sensorimotor understanding' is construed as implicit and practical, rather than explicit and propositional (see Hurley 1998(ch. 4), Noë 2004), Roberts 2010). ...
... Early pioneers of sensory substitution claimed that SSDs would allow blind people to "see with their skin" (White et al., 1970) or to "see with their brains" (Bach-y-Rita and Kercel, 2003). These claims encapsulated the view that perceptual experience is deferred from one intact modality to another impaired modality, often referred to as 'cortical deference' (Hurley and Noë, 2003;O'Regan, 2011). However, others instead proposed that perception remains within the substituting modality, a view referred to as 'cortical dominance' (Block, 2003;Keeley, 2002;Prinz, 2006). ...
... As was previously mentioned (see above, section 1 Sensory Substitution: Theories and Mechanisms), the 'cortical dominance' view (e.g., Block, 2003;Keeley, 2002;Prinz, 2006) proposed that after extensive training with an auditory-visual SSD perceptual representation remains within the substituting modality (i.e., auditory) rather than the substituted modality (i.e., 'visual'). In contrast, the 'cortical deference' view (e.g., Hurley and Noë, 2003;Noë, 2004;O'Regan, 2011) proposed that the experience lies in the substituted modality, such that perception can be considered as 'visual'. These early views often made their case by emphasising the importance of one (or a combination of several) of the criteria traditionally used to distinguish between sensory modalities. ...
... Over the years, Noë has proposed different names for the theory: in collaboration with Susan Hurley (Hurley and Noë 2003) the theory was called "dynamic sensorimotor approach," whereas more recently he calls it "actionism" (Noë 2012, p. 23). We can enucleate this claim in the following thesis: T4: The perceiver is an agent that is part of a dynamical system. ...
... This is not to deny that the brain plays a fundamental role in perception, and it does not amount to a rejection of more or less specialized cortical areas. For example, Hurley and Noë (2003) do assume that distinct cortical areas are often associated to distinct kinds of experiences, like intramodal differences-e.g. cortical areas engendering a "red" instead of "yellow" experience-or intermodal differences-e.g. ...
Article
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The sensorimotor theory of vision and visual consciousness is often described as a radical alternative to the computational and connectionist orthodoxy in the study of visual perception. However, it is far from clear whether the theory represents a significant departure from orthodox approaches or whether it is an enrichment of it. In this study, I tackle this issue by focusing on the explanatory structure of the sensorimotor theory. I argue that the standard formulation of the theory subscribes to the same theses of the dynamical hypothesis and that it affords covering-law explanations. This however exposes the theory to the mere description worry and generates a puzzle about the role of representations. I then argue that the sensorimotor theory is compatible with a mechanistic framework, and show how this can overcome the mere description worry and solve the problem of the explanatory role of representations. By doing so, it will be shown that the theory should be understood as an enrichment of the orthodoxy, rather than an alternative. https://link.springer.com/article/10.1007/s11229-017-1664-9
... Exercise of the mastery of sensorimotor contingencies is a skill of an embodied subject acting in the world (Hurley and Noë 2003), and this organism-environment interaction process will also be crucially mediated by the nervous system (Fuchs 2018). Accordingly, we propose that from the perspective of sensorimotor theory it is expected that auditory perception activates the motor system of the brain. ...
... Like other theories of perception, sensorimotor theory accepts that neural activity forms an important basis of perceptual experience, but in contrast to most other theories it does not limit itself to neural activity: it extends its focus outward to the dynamic relation between brain, body, and world (Hurley and Noë 2003;Di Paolo et al. 2017). It claims that perception is a bodily doing or bodily activity, a term which refers to the specific embodiment of the perceiver and their capacity for both covert and overt movements (Myin 2016). ...
Article
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According to sensorimotor theory perceiving is a bodily skill involving exercise of an implicit know-how of the systematic ways that sensations change as a result of potential movements, that is, of sensorimotor contingencies. The theory has been most successfully applied to vision and touch, while perceptual modalities that rely less on overt exploration of the environment have not received as much attention. In addition, most research has focused on philosophically grounding the theory and on psychologically elucidating sensorimotor laws, but the theory’s ramifications for neuroscience still remain underexamined. Here we sketch the beginnings of a research program that could address these two outstanding challenges in terms of auditory perception. We review the neuroscience literature on passive listening, which is defined as listening without overt bodily movement, and conclude that sensorimotor theory provides a unique perspective on the consistent finding of motor system activation. In contrast to competing theories, this activation is predicted to be involved not only in the perception of speech- and action-related sounds, but in auditory perception in general. More specifically, we propose that the auditory processing associated with supplementary motor areas forms part of the neural basis of the exercise of sensorimotor know-how: these areas’ recognized role in (1) facilitating spontaneous motor responses to sound and (2) supporting flexible engagement of sensorimotor processes to guide auditory experience and enable auditory imagery, can be understood in terms of two key characteristics of sensorimotor interaction, its (1) “alerting capacity” (or “grabbiness”) and (2) “corporality” (or “bodiliness”), respectively. We also highlight that there is more to the inside of the body than the brain: there is an opportunity to develop sensorimotor theory into new directions in terms of the still poorly understood active processes of the peripheral auditory system.
... The sensorimotor approach was first set out by O'Regan and Noë (2001), but it has been further developed both by the theory's originators and through secondary literature (see, for example, Hurley & Noë, 2003;Noë, 2004Noë, , 2006Noë, , 2012O'Regan, 2011; for a collection of secondary works see Bishop & Martin, 2014). The approach takes perception and action to be inextricably tied together: Perception is constituted by a type of bodily skill or sensorimotor understanding. ...
... This developmental notion of sensorimotor understanding also allows the sensorimotor theorist to draw on empirical evidence from cases such as Bach-y-Rita's tactile vision substitution systems (TVSS) and vision reversing goggles. 13 Sensorimotor theorists often draw upon TVSS cases (e.g., Hurley & Noë, 2003;Noë, 2004;O'Regan & Noë, 2001). TVSS devices are composed of a head-mounted camera, which sends signals to a matrix of electrodes or vibrators attached to the subject's skin or tongue. ...
Article
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Sensorimotor enactivism takes perceptual experience to be constituted by a kind of attunement to sensorimotor contingencies – law‐like relations between sensory inputs and bodily activity. The chemical senses have traditionally been construed as especially simple and passive, and a number of philosophers have argued that flavour and smell are problem cases for the sensorimotor approach. In this article, I respond to these objections to the sensorimotor approach, and in doing so offer the beginnings of a sensorimotor account of the chemical senses.
... We side with the latter camp. Whereas most neuroscientific models of consciousness focus only on objective correlates ( Figure 1A), leaving the subjective component of experience unexplained, we agree with Ellia et al. that "there must be a reason why the canvas feels extended rather than, say, like the smell of vanilla" (1) (see also (9) for early analogies). We also agree that the explanation should target the particular structure of such experiences. ...
Preprint
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Models of consciousness need to explain both objective correlates of conscious experience as well as its subjective structure. However, such an explanation would not need to entail a reduction exclusively in terms of physical or neural systems. We briefly sketch a few points of contention with recent work on integrated information theory and some common assumptions made in the neuroscience of consciousness more generally.
... As O'Regan and Noë put it, the perceiver "must be actively exercising its mastery of these laws" (O'Regan and Noë 2001, p. 943). 7 Consider, for instance, the well-known case of a cat behind a fence (Hurley and Noë 2003;Noë 2004). Perceiving the cat is governed by the practical knowledge of the way the hidden bits of the cat would appear if I were to move myself. ...
Article
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It has been pointed out that Sensorimotor Enactivism, a theory that claims that perception is enacted and brought about by movement, says very little about the neural mechanisms that enable perception. For the proponents of the predictive approach to Sensorimotor Enactivism, this is a challenge that can be met by introducing predictive processing into the picture. However, the compatibility between these theories is not straightforward. Firstly, because they seem to differ in their stand towards representations: while Sensorimotor Enactivism is said to belong to the non-representational wing of cognitive science, predictive processing has a representational profile. And secondly, because they exhibit different explanatory strategies: while Sensorimotor Enactivism prioritizes the interactions of the embodied agent, predictive processing has internalist commitments. The aim of this paper is to address these concerns and show that a predictive approach to Sensorimotor Enactivism is viable. More specifically, I focus on the Free-Energy approach, a theory that falls within the ballpark of predictive processing. In this paper I argue for the following claims. I argue that (a) both Sensorimotor Enactivism and the Free-Energy approach may be understood for some systems in representational terms. The non-representational reading of Sensorimotor Enactivism is not mandatory and neither is the representational reading of the Free-Energy approach. (b) Sensorimotor Enactivism is, in this respect, compatible with both representational and non-representational interpretations of the FEA. So, the position towards representations of these frameworks should not stand in the way of a predictive approach to Sensorimotor Enactivism. I also show that (c) the Free-Energy approach allows for an account that prioritizes the interaction of the embodied agent with the environment. This is the explanatory strategy followed by Sensorimotor Enactivism. To justify this strategy and following other proponents of Sensorimotor Enactivism, I argue that by referring to the interactions of the embodied agent a better account of the phenomena in question is provided. On this basis, I claim that (d) Sensorimotor Enactivism and the Free-Energy approach are compatible in what concerns their explanatory strategy as well. Thus, making the case for the viability of the predictive approach to Sensorimotor Enactivism.
... One important question raised is: to which sensory modality does the perception with a sensory substitution device belong? Two opposite theses were initially put forward: the dominance thesis (e.g., Keeley, 2002) according to which perception with a sensory substitution device remains in the substituting modality (touch or audition), and the deference thesis (e.g., Hurley & Noë, 2003;Noë, 2004;O'Regan, 2011) according to which perception switches to the substituted modality (vision). The deference thesis has opened the door to over-optimistic claims involving the idea that users of visual-to-tactile substitution devices would become able to "see with the skin" (White et al., 1970) or to "see with the brain" . ...
Article
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Sensory substitution devices aim at compensating sensory deficits by converting stimuli coming from a deficient sensory modality (e.g., vision) into stimuli accessible through another modality (e.g., touch or audition). Studies conducted with these devices revealed the central nervous system to be very plastic. Various laboratories have conducted studies investigating such plasticity by means of behavioural and brain-imaging techniques. At the ISIR Laboratory, we focused on the factors underlying the learning of sensory substitution devices, their adequacy to the target population, and we explored ways of improving their design by the use of crossmodal correspondences and by taking into account individual differences in the used reference frames. We also investigated the nature of the experience with sensory substitution. In particular, we suggested moving beyond positions reducing experience to that of a single sensory modality. Rather, sensory substitution is considered as a multisensory experience, involving not only visual, but also auditory or tactile processes as well as cognitive processes. In this framework, individual differences do have an influence on the extent to which the different sensory modalities influence the experience with the devices.
... アクショニズムを支持する論者(e.g., Hurley and Noë 2003a, 2003b, 2007Noë 2002Noë , 2004Noë , 2005Noë , 2006aNoë , 2006bNoë and Hurley 2003;Noë andO'Regan 2000, 2002;Noë and Thompson 2004;O'Regan and Noë 2001 Rodriguez et al. 1999;Sehatpour et al. 2008;Uhlhaas et al. 2006 (2004) ...
... There are numerous experiments testing if SSDs can become part of extended cognitive systems (e.g. [32][33][34]). These experiments have shown that sensorysubstitution devices can indeed become part of extended cognitive systems and, additionally, these artefacts partially constitute the extended cognitive system. ...
Article
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There is a growing recognition within cognitive enhancement and neuroethics debates of the need for greater emphasis on cognitive artefacts. This paper aims to contribute to this broadening and expansion of the cognitive-enhancement and neuroethics debates by focusing on a particular form of relation or coupling between humans and cognitive artefacts: interaction-dominance. We argue that interaction-dominance as an emergent property of some human-cognitive artefact relations has important implications for understanding the attribution and distribution of causal and other forms of responsibility as well as agency relating to the actions of human-cognitive artefact couplings. Interaction-dominance is both indicated and constituted by the phenomenon of “pink noise”. Understanding the role of noise in this regard will establish a necessary theoretical groundwork for approaching the ethical and political dimensions of relations between human cognition and digital cognitive artefacts. We argue that pink noise in this context plays a salient role in the practical, ethical, and political evaluation of coupling relations between humans and cognitive artefacts, and subsequently in the responsible innovation of cognitive artefacts and human-artefact interfaces.
... Even if there has been consideration of moving beyond this boundary, they have been limited in their consideration by including sensory input and behavioural output only. Traditional views of the mind and cognition were dedicated towards the "classical sandwich model" (Hurley & Noe, 2003), where mind/cognition is sandwiched between perception (input) and action (output). The embodied cognitive approach accepts cognition as a result of active and dynamic interaction between an agent"s neural and non-neural processes. ...
Article
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For many decades, cognition has been viewed as a computational process in the brain. For cognition, the brain, body and the interaction with the environment are important. Conventional views are inclined towards the existence of discrete and internal representations realised by highly specific mechanisms in the brain. The Embodied approach challenges this view and accepts the evolution of cognitive abilities. There is a shift in focus from the belief that the brain is solely responsible for cognition to the thought that the body is somehow deeply integrated into cognition. However, it does not deny the central position of the brain in the process of cognition but opens the doors for other factors for integration. At the basic level, there are three ways in which an agent’s body can be utilised for the cognitive process. An agent’s body may help to generate, operate and distribute the cognitive processes. As a result, this approach tries to diminish the monopoly of the brain by taking into account the importance of the body and the environment for cognition.
... Aufgrund der neuronalen Plastizität 2 ist das Gehirn in der Lage, selbst solche Information zu verarbeiten, die durch sensorische Substitutionüber eine andere als die ursprünglich dafür vorgesehene Modalitätübermittelt wird [129]. Details zu dieser Thematik finden sich in der Literatur [65,88,117,118]. Die erfolgreiche Anwendung und das Potenzial der sensorischen Substitution wurde in zahlreichen Studien belegt, wobei teilweise ein zeitaufwendiger Lernprozess notwendig ist [88]. ...
Thesis
Diese Doktorarbeit befasst sich mit der Entwicklung eines vibrotaktilen Armbands zur vielseitigen Informationsübermittlung in Mensch-Maschine-Systemen. In einem iterativen Entwicklungsprozess wurde unter gesamtheitlicher Beachtung technischer und ergonomischer Aspekte sowie der menschlichen Wahrnehmung ein ergonomisches und praxistaugliches Gerät konzipiert und als produktnaher Prototyp realisiert. Dieser zeichnet sich durch eine intuitive, orts- und richtungsdifferenzierte Informationsausgabe mit eindeutig interpretierbaren Stimulationsmustern aus. Der Funktionsumfang und damit die vielseitige Einsetzbarkeit des Geräts wurden durch die Integration von Distanzsensorik zur Hinderniserkennung im nahen Umfeld des Nutzers erweitert. Dadurch ist eine gleichzeitige Erfassung in verschiedene Richtungen sowie eine intuitive Rückmeldung von Richtung und Distanz erfasster Objekte möglich. Nutzerstudien in unterschiedlichen Anwendungen wie z.B. Kraft- und Kollisionsrückmeldung aus virtueller Realität und Telerobotik, Aufmerksamkeitslenkung in komplexen Arbeitsbereichen, neuartige Ausbildungskonzepte mit augmentierter Realität, Navigation und Unterstützung blinder Menschen belegen den erfolgreichen Einsatz des patentierten Geräts und weisen den Beitrag dieser Arbeit zur Verbesserung des Informationsflusses in Mensch-Maschine-Systemen und zur Steigerung der Immersion des Nutzers nach. Schlagworte: vibrotaktiles Feedback Gerät, multimodale Mensch-Maschine-Schnittstelle, taktile orts- und richtungsdifferenzierte Hinweise
... Following Hurley and Noë (2003), this explanatory gap can be broken down into further 'comparative' gaps and an 'absolute' gap. The first is the comparative intramodel gap. ...
Data
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Sensorimotor Theory (SMT) is the claim that it is our practical know-how of the relations between our environments and us that gives our environmental interactions their experiential qualities. Yet why should such interactions involve or be accompanied by experience? This is the 'absolute' gap question. Some proponents of SMT answer this question by arguing that our interactions with an environment involve experience when we cognitively access those interactions. In this paper, I aim to persuade proponents of SMT to accept the following three claims. First, that appeals to cognitive access fail to answer the absolute gap question. Second, that SMT can be read in a way that rejects the gap question. Third, that if proponents of SMT are prepared to read SMT in a way that rejects the absolute gap question, then they can also reject the claim that cognitive access is needed to explain experience. 2
... Following Hurley and Noë (2003), this explanatory gap can be broken down into further 'comparative' gaps and an 'absolute' gap. The first is the comparative intramodel gap. ...
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Sensorimotor Theory (SMT) is the claim that it is our practical know-how of the relations between our environments and us that gives our environmental interactions their experiential qualities. Yet why should such interactions involve or be accompanied by experience? This is the ‘absolute’ gap question. Some proponents of SMT answer this question by arguing that our interactions with an environment involve experience when we cognitively access those interactions. In this paper, I aim to persuade proponents of SMT to accept the following three claims. First, that appeals to cognitive access fail to answer the absolute gap question. Second, that SMT can be read in a way that rejects the gap question. Third, that if proponents of SMT are prepared to read SMT in a way that rejects the absolute gap question, then they can also reject the claim that cognitive access is needed to explain experience.
... A number of authors defend views closely aligned to the enactive approach, without necessarily calling themselves enactivists -for instance Andy Clark (1997), Susan Hurley (1998), and Kevin O'Regan (O'Regan and Noë, 2001a). 'Enactive' concepts have been appealed to in order to criticize established views on the neural correlates of consciousness (Noë and Thompson 2004); and to offer new approaches on neural plasticity (Hurley and Noë 2003), art (Myin 2000;Noë 2000), emotion (Ellis & Newton 2005; Colombetti and Thompson forthcoming), biology and ecology (Palacios and Bozinovic 2003), autism (Klin et al. 2003;Gallagher 2004), and other subjects. There have also been recent enactively-based studies of semiotics in organisms (Weber 2002;Weber and Varela 2002) and in robots (Ziemke and Sharkey 2001), linking the enactive approach with writers such as Susanne K. Langer, Hans Jonas and Jakob von Uexküll Is there a consistent concept of the enactive which underlies these different studies? ...
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In the decade and a half since the appearance of Varela, Thompson and Rosch's workThe Embodied Mind,enactivism has helped to put experience and consciousness, conceived of in a distinctive way, at the forefront of cognitive science. There are at least two major strands within the enactive perspective: a broad view of what it is to be an agent with a mind; and a more focused account of the nature of perception and perceptual experience. The relation between these two strands is discussed, with an overview of the papers presented in this volume.
... In particular, one important question raised is to which sensory modality does the perception with a sensory substitution device belong? Two opposite theses were, at first, put forward: The dominance thesis (e.g., Block, 2003;Humphrey, 1992;Prinz, 2006) according to which perception with a sensory substitution device remains in the substituting modality (touch or audition), and the deference thesis (e.g., Hurley and Noë, 2003;Noë, 2004;O'Regan, 2011) according to which perception switches to the substituted modality (vision). The deference thesis opened the door to over-optimistic claims, involving the idea that users of visual-to-tactile substitution devices would become able to 'see with the skin' (White et al., 1970) or to 'see with the brain' (Bachy-Rita et al., 2003). ...
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Sensory substitution devices were developed in the context of perceptual rehabilitation and they aim at compensating one or several functions of a deficient sensory modality by converting stimuli that are normally accessed through this deficient sensory modality into stimuli accessible by another sensory modality. For instance, they can convert visual information into sounds or tactile stimuli. In this article, we review those studies that investigated the individual differences at the behavioural, neural, and phenomenological levels when using a sensory substitution device. We highlight how taking into account individual differences has consequences for the optimization and learning of sensory substitution devices. We also discuss the extent to which these studies allow a better understanding of the experience with sensory substitution devices, and in particular how the resulting experience is not akin to a single sensory modality. Rather, it should be conceived as a multisensory experience, involving both perceptual and cognitive processes, and emerging on each user’s pre-existing sensory and cognitive capacities.
... However, as several authors have argued (e.g. seeHurley 2010, Hurley and Noë 2003, Ward 2012, this is not the only possible option. Again, as this is not the focus of the present discussion, we will leave the topic for another work. ...
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In this paper we suggest an understanding of the self within the conceptual framework of situated affectivity, proposing the notion of an affectively extended self and arguing that the construction, diachronic reshaping and maintenance of the self is mediated first by affective interactions. We initially consider the different variations on the conception of the extended self that have been already proposed in the literature (Clark & Chalmers 1998; Heersmink 2017, 2018; Krueger 2018; Wilson, Lenart 2015). We then propose our alternative, contextualising it within the current debate on situated affectivity. While the idea that we exploit the external environment in order to manage our affective life is now rather widespread among philosophers (e.g. Colombetti & Krueger 2015, Piredda 2019), its potential consequences for and connections with the debate on the self remain underexplored. Drawing on James' intuition of the "material self", which clearly connects the self and the emotions in agency, and broadly envisioning an extension of the self beyond its organismic boundaries, we propose our pragmatist conception of the self: an affectively extended self that relies on affective artifacts and practices to construct its identity extended beyond skin and skull.
... It is from this perspective that a skilful engagement with the environment and relevant sensorimotor contingencies may be identified. An argument is made for how the attributes of 'bodiliness' and 'grabbiness' (Hurley & Noë, 2003) might be found in a sonic environment, and how music listening might be perceived as an 'act of doing' . ...
... It is therefore not surprising that their perceptual skills developed poorly. Finally, although differences in development of neural activity in V1 are suggestive, it is not clear in general how such neural differences are related to visual experience (Hurley and Noë, 2003). ...
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Enactive cognitive science (ECS) and ecological psychology (EP) agree that active movement is important for perception, but they remain ambiguous regarding the precise role of agency. EP has focused on the notion of sensorimotor invariants, according to which bodily movements play an instrumental role in perception. ECS has focused on the notion of sensorimotor contingencies, which goes beyond an instrumental role because skillfully regulated movements are claimed to play a constitutive role. We refer to these two hypotheses as instrumental agency and constitutive agency, respectively. Evidence comes from a variety of fields, including neural, behavioral, and phenomenological research, but so far with confounds that prevent an experimental distinction between these hypotheses. Here we advance the debate by proposing a novel double-participant setup that aims to isolate agency as the key variable that distinguishes bodily movement in active and passive conditions of perception. We pilot this setup with a psychological study of width discrimination using the Enactive Torch, a haptic sensory substitution device. There was no evidence favoring the stronger hypothesis of constitutive agency over instrumental agency. However, we caution that during debriefing several participants reported using cognitive strategies that did not rely on spatial perception. We conclude that this approach is a viable direction for future research, but that greater care is required to establish and confirm the desired modality of first-person experience.
... The definition of each modality's sensorimotor contingency develops through a first elementary distinction, between intermodal explanatory gaps and intramodal ones. (Hurley & Noë, 2003) Intermodal gaps are about the dissimilarities between different sensory modalities, whereas intramodal gaps concern the differences of perception within the sensory modality itself. In both cases, the sensorimotor theory is proven to cover such gaps similarly through the definition of sensorimotor invariances to define the limits of a modality from another one, or the distinctions between instances of different perceptions within the same modality. ...
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The role that the human sensory system plays in the daily interaction of individuals with the external world has far more articulated ramifications than expected from a component of human nature that appears to be so linear and straightforward. Starting from the conditions of sensory impairment as a vehicle for the analysis of the field, the multidisciplinary study of the perceptual process highlights how sight plays a dominant role compared to the other senses, and how this dominance fits into a context of dichotomies inherent in the today’s social structure, with negative impacts on the personal, psychological and social context of a part of humanity. The technical-scientific developments of the last decades, and in particular the innovations aimed at the enhancement of the human being through technology, have proved not only to be an instrument of emancipation from these hierarchical dictates, but also a space of opportunity for a reconsideration of design and research constraints, constraints generated by a bounded consideration of the sensory spectrum. The objective of the thesis in question consists in the development of an intervention in the field of visual impairments capable of suggesting an alternative to these principles through the intersection between human and technological elements in the restructuring of the perceptual approach and the analysis of the potential of the discipline of design in the exploration of alternative intervention methods. This goal will be achieved through the development of a support device for individuals with visual impairments. This device will allow the creation of a sensorial space alternative to the vision-centric standard, through the synesthetic interaction between an artificial vision system and natural systems of visual and haptic perception. In the course of the research path, the design process will be positioned in a role complementary to its usual connotation, which sees it as a tool for developing solutions and products dedicated to the specific area of intervention. It will also play a role as a creative force for new exploratory spaces where the design itself can have a functional, social and political value; spaces created in the intersection of science, speculation and interaction between the natural components and the artificial ones of organisms.
... Although the unicorn does not and cannot exist in the world, we can gain an understanding, by using counterfactuals, of how we would act if these objects were actually present (Shoemaker, 1994). For example, O'Regan and Degenaar compare a synaesthetic experience to the ability "to vividly imagine things that are absent" suggesting that the relevant cortical activity remains "dangling" (2014, p. 131): in the sense that the cortical activity is not related to current sensorimotor events happening in the environment (Hurley & Noë, 2003). Indeed, Schubotz (2007) provides evidence supporting an explanation as to how a simulation of events, including auditory events, may be realised in our sensorymotor system, even those that we are unable to reproduce ourselves. ...
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This paper presents a sensorimotor account of music-colour synaesthesia, proposing a radically different perspective than is commonly provided. Recent empirical and theoretical work in music cognition moves away from cognitivist accounts, rejects representationalism, and embraces an embodied standpoint. It has been shown that some forms of synaesthesia may be elicited from a concept alone and are often accompanied by shapes and textures. It is from this perspective that a skilful engagement with the environment and relevant sensorimotor contingencies may be identified. Here the role of embodied and enactive perception in general music cognition is extended to music-colour synaesthesia, and an argument is made for how the attributes of bodiliness and grabbiness might be found in a sonic environment, and how music listening might be perceived as an act of doing.
... Proponents of Sensorimotor Enactivism have previously tackled this gap problem by dividing it into a series of further questions (Hurley and Noë 2003). On the one hand, there are comparative gap questions. ...
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There is now an established literature on the link between later Wittgenstein and enactivist approaches in cognitive science. However, is this link not just a matter for card carrying Wittgensteinians? Can enactivists not manage perfectly well without Wittgenstein? In this paper, I show why some enactivists should care about Wittgenstein. Focusing on the enactivist view, “Sensorimotor Identity”, I argue that proponents of this view can use Wittgensteinian considerations to resolve an issue confronting their view and thereby shore up their proposed dissolution of the explanatory gap. Some enactivists thus have in fact much to gain by engaging with Wittgenstein.
... Research has shown various perspectives on environmental perception. One of them is that visual perception is dominant when people acquire and process information from their surroundings: people derive as much of their perception of distance and movement from visual cues within a space despite sometimes conflicting non-visual cues (Axelrod, 1973;Harris et al., 2000;Kopec, 2012); consequently, they become less aware of movement within a space or senses responding to other corporeal aspects if there is an abundance of visual information (O'Regan and Noë, 2001;Hurley and Noë, 2003;Sun et al., 2004). More recent studies have stressed that action and perception attribute, in tandem, to making sense of the context and content of space: action and perception are embedded in each other and bound to one's physical body and body awareness (Garner, 2018). ...
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Human perception has long been a critical subject of design thinking. While various studies have stressed the link between thinking and acting, particularly in spatial experience, the term “design thinking” seems to disconnect conceptual thinking from physical expression or process. Spatial perception is multimodal and fundamentally bound to the body that is not a mere receptor of sensory stimuli but an active agent engaged with the perceivable environment. The body apprehends the experience in which one’s kinesthetic engagement and knowledge play an essential role. Although design disciplines have integrated the abstract, metaphoric, and visual aspects of the body and its movement into conceptual thinking, studies have pointed out that design disciplines have emphasized visuality above the other sensory domains and heavily engaged with the perception of visual configurations, relying on the Gestalt principles. Gestalt psychology must be valued for its attention to a whole. However, the theories of design elements and principles over-empathizing such visuality posit the aesthetics of design mainly as visual value and understate other sensorial and perceptual aspects. Although the visual approach may provide a practical means to represent and communicate ideas, a design process heavily driven by visuality can exhibit weaknesses undermining certain aspects of spatial experience despite the complexity. Grounded in Merleau-Ponty’s notion of multisensory perception, this article discusses the relationship between body awareness and spatial perception and its implication for design disciplines concerning built environments. Special attention is given to the concepts of kinesthetic and synesthetic phenomena known as multisensory and cross-sensory, respectively. This discussion integrates the corporeal and spatiotemporal realms of human experience into the discourse of kinesthetic and synesthetic perceptions. Based on the conceptual, theoretical, and precedent analyses, this article proposes three models for design thinking: Synesthetic Translation, Kinesthetic Resonance, and Kinesthetic Engagement. To discuss the concepts rooted in action-based perception and embodied cognition, this study borrows the neurological interpretation of haptic perception, interoception, and proprioception of space. This article suggests how consideration of the kinesthetic or synesthetic body can deepen and challenge the existing models of the perceptual aspects of environmental psychology adopted in design disciplines.
... Their suggestion is that we widen our explanatory scope beyond the brain to encompass the whole embodied organism embedded in its environment and conceive of phenomenal consciousness as an ongoing dynamic interaction between subject and world. The thesis that emerges from this dynamic or enactive conception of experience holds that the metaphysical basis of phenomenality does, at times, extend beyond the brain and nervous system to include bodily and environmental elements (Varela et al., 1991;Hurley, 1998;Hurley & Noë, 2003;Noë & Thompson, 2004a, 2004bNoë, 2007). Henceforth, I will refer to this thesis as extended consciousness. ...
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For some, the states and processes involved in the realisation of phenomenal consciousness are not confined to within the organismic boundaries of the experiencing subject. Instead, the sub-personal basis of perceptual experience can, and does, extend beyond the brain and body to implicate environmental elements through one’s interaction with the world. These claims are met by proponents of predictive processing, who propose that perception and imagination should be understood as a product of the same internal mechanisms. On this view, as visually imagining is not considered to be world-involving, it is assumed that world-involvement must not be essential for perception, and thus internalism about the sub-personal basis is true. However, the argument for internalism from the unity of perception and imagination relies for its strength on a questionable conception of the relationship between the two experiential states. I argue that proponents of the predictive approach are guilty of harbouring an implicit commitment to the common kind assumption which does not follow trivially from their framework. That is, the assumption that perception and imagination are of the same fundamental kind of mental event. I will argue that there are plausible alternative ways of conceiving of this relationship without drawing internalist metaphysical conclusions from their psychological theory. Thus, the internalist owes the debate clarification of this relationship and further argumentation to secure their position.
... The sensorimotor approach takes much of its support from examples of sensorimotor disruption and adaptation. For example, the sensorimotor approach provides an explanation of evidence regarding vision inverting or displacing goggles (e.g., Hurley, 1998;O'Regan & Noë, 2001;Hurley & Noë, 2003;Degenaar, 2013;Ward, 2016). These goggles disrupt the usual sensorimotor contingencies involved in perception but users gradually adapt to novel patterns of sensorimotor contingency, allowing their perceptual experience to revert to some kind of normality. ...
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The philosophy of grief has directed little attention to bereavement’s impact on perceptual experience. However, misperceptions, hallucinations and other anomalous experiences are strikingly common following the death of a loved one. Such experiences range from misperceiving a stranger to be the deceased, to phantom sights, sounds and smells, to nebulous quasi-sensory experiences of the loved one’s presence. This paper draws upon the enactive sensorimotor theory of perception to offer a phenomenologically sensitive and empirically informed account of these experiences. It argues that they can be understood as deriving from disruption to both sensorimotor expectations and perceived opportunities for action, stemming from the upheaval of bereavement. Different facets of the enactive sensorimotor approach can help to explain different types of post-bereavement perceptual experience. Post-bereavement misperceptions can be accounted for through the way that alterations to sensorimotor expectations can result in atypical ‘amodal completion’, while bereavement hallucinations can be understood as ‘appearances’ that fail to form part of the usual patterns of sensorimotor contingency. Quasi-sensory experiences of the presence of the deceased can be understood as resulting from changes to perceived affordances. This paper aims to demonstrate the explanatory value of key aspects of the sensorimotor approach by highlighting how they can help to explain the phenomenology of post-bereavement experiences. However, it also illuminates certain areas in which the sensorimotor approach ought to be supplemented, especially if it is to account for tight connections between perception, affect, and intersubjectivity that are salient in grief.
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The phenomenology of the blind has provided an age-old, unparalleled means of exploring the enigmatic link between the brain and mind. This paper delves into the unique phenomenological experience of a man who became blind in adulthood. He subsequently underwent both an Argus II retinal prosthesis implant and training, and extensive training on the EyeMusic visual to auditory sensory substitution device, thereby becoming the first reported case to date of dual proficiency with both devices. He offers a firsthand account into what he considers the great potential of combining sensory substitution devices with visual prostheses as part of a complete visual restoration protocol. While the Argus II retinal prosthesis alone provided him with immediate visual percepts by way of electrically stimulated phosphenes elicited by the device, the EyeMusic SSD requires extensive training from the onset. Yet following the extensive training program with the EyeMusic sensory substitution device, our subject reports that the sensory substitution device allowed him to experience a richer, more complex perceptual experience, that felt more "second nature" to him, while the Argus II prosthesis (which also requires training) did not allow him to achieve the same levels of automaticity and transparency. Following long-term use of the EyeMusic SSD, our subject reported that visual percepts representing mainly, but not limited to, colors portrayed by the EyeMusic SSD are elicited in association with auditory stimuli, indicating the acquisition of a high level of automaticity. Finally, the case study indicates an additive benefit to the combination of both devices on the user's subjective phenomenological visual experience.
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This dissertation examines of the role of the body in emotional experience. I argue that in the full story of emotions, one must recognize several key notions: passive elements such as physiological responses, active elements such as action or behavioral tokens, cognitive elements such as judgments, and others. I examine these features and the capability of different emotion theories to successfully preserve them. Theories currently on offer fail to capture one or more of these features. Given the failure of those theories when construed as targeting whole emotion episodes, I aim to carve out a unified and theoretically fruitful delineation of emotion in such a way as to capture all these features. This motivates the search for a new theory. I turn to perception to help guide emotion theory since perception has similar features. While modeling emotion on perception is promising, the ‘perceptualist’ emotion theories that do so are still unable to adequately account for the above features. I therefore look toward a theory of perception that can successfully avoid these pitfalls, namely, one that relies heavily on the active and embodied nature of perception—i.e., enactive perception. Given enactive theory’s ability to accommodate the features, I then proceed to develop an account of emotion based on enactive theory—constructing an enactive perceptual account of emotion. Lastly, I revisit the key features and go on to answer objections that might be raised against my view.
Article
I argue that the phenomenal properties of conscious visual experiences are properties of the mind-independent objects to which the subject is perceptually related, mediated by the subject's practical understanding of their sensorimotor relation to those properties. This position conjoins two existing strategies for explaining the phenomenal character of perceptual experiences: accounts appealing to perceivers’ limited, non-inferential access to the details of their sensory relation to the environment, and the relationalist conception of phenomenal properties. Bringing these two positions together by emphasizing their sensorimotor common ground allows each one to respond to damaging objections using the resources of the other. The resulting ‘sensorimotor relationalism’ about conscious vision provides a promising schema for explaining phenomenal properties of perceptual states, replacing ‘Hard’ questions with tractable ones about the perceptual relation and its sensorimotor underpinnings.
Chapter
Externalism constitutes a major family of theories about how to conceive of the human mind in alternative ways. This chapter discusses externalism in the philosophy of mind and how it evolved during the twentieth century. It then examines approaches to the problem of consciousness from the perspective of externalism.
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When I am looking at my coffee machine that makes funny noises, this is an instance of multisensory perception – I perceive this event by means of both vision and audition. But very often we only receive sensory stimulation from a multisensory event by means of one sense modality. If I hear the noisy coffee machine in the next room, that is, without seeing it. The aim of this paper is to bring together empirical findings about multimodal perception and empirical findings about (visual, auditory, tactile) mental imagery and argue that on occasions like this, we have multimodal mental imagery: perceptual processing in one sense modality (here: vision) that is triggered by sensory stimulation in another sense modality (here: audition). Multimodal mental imagery is not a rare and obscure phenomenon. The vast majority of what we perceive are multisensory events: events that can be perceived in more than one sense modality – like the noisy coffee machine. And most of the time we are only acquainted with these multisensory events via a subset of the sense modalities involved – all the other aspects of these multisensory events are represented by means of multisensory mental imagery. This means that multisensory mental imagery is a crucial element of almost all instances of everyday perception.
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What is the relationship between the ‘haptic’ and the ‘tactile’ when it comes to media? We might question whether there is such a thing as ‘haptic media’; in other words, is there a type of media that invite the attention of one modality rather than another, or that foster certain types of interaction over others? If we were to speak about ‘haptic media’, to what extent does it engage directly (only) with touch, and to what extent does it involve some form of enhancement of another modality? In what ways can haptic media appeal beyond the visuocentric norm of the screen, and therefore to non-normate or disabled users? Further, to what extent does the haptic in particular benefit from ‘sensory substitution’, which is most usually of touch for vision in assisted living technologies for the blind, or of sound for touch for the deaf, for example? Certain historical instances of sensory substitution systems are discussed below, including Norbert Wiener’s ‘hearing glove’ and Bach-Y-Rita’s tactile–visual sensory substitution (TVSS) system, to make a larger argument about the role of haptic technologies, and haptic media, for more inclusive digital interactions.
Article
What happens when artificial sensors are coupled with the human senses? Using technology to extend the senses is an old human dream, on which sensory substitution and other augmentation technologies have already delivered. Laser tactile canes, corneal implants and magnetic belts can correct or extend what individuals could otherwise perceive. Here we show why accommodating intelligent sensory augmentation devices not just improves but also changes the way of thinking and classifying former sensory augmentation devices. We review the benefits in terms of signal processing and show why non-linear transformation is more than a mere improvement compared to classical linear transformation.
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BACKGROUND The objectives of the study were to assess and compare touch sensation of dominant and non-dominant hands among blind since birth, early onset blind & late onset blind participants using Moberg’s test and determine if the time of onset of blindness affected the touch sensation. METHODS 50 blind participants from various colleges in Mumbai were assessed. Detailed history about onset of blindness, motor dominance etc. of blind was asked. Participants were instructed to pick up objects (suggested by Moberg) one at a time, as fast as possible, and place them into a box using dominant and non-dominant hands alternatively. Kruskal Wallis Test was used for analysis. RESULTS Average values of Moberg’s test of dominant & non - dominant hands of blind since birth versus late onset blind were statistically significant and those of early onset blind versus late onset blind were statistically significant. Average values of Moberg’s test of blind since birth versus early onset blind were not statistically significant. Thus touch sensation was improved more in blind since birth & early onset blind compared to late onset blind participants. CONCLUSIONS Thus we conclude that in the absence of visual stimuli, touch sensation in blind since birth and early onset blind is improved compared to late onset blind participants. KEY WORDS Blind, Cross - Modal Synaptic Plasticity, Substitution of Sense. Moberg's Pick - up Test, Critical Period
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Researchers in post-war industrial laboratories such as Bell Labs and the Smith-Kettlewell Institute pioneered solutions to compensate for sensory loss through so-called sensory substitution systems, premised on an assumption of cortical and sensory plasticity. The article tracks early discussions of plasticity in psychology literature from William James, acknowledged by Wiener, but explicitly developed by Bach-y-Rita and his collaborators. After discussing the conceptual foundations of the principles of sensory substitution, two examples are discussed. First, ‘Project Felix’ was an experiment in vibrotactile communication by means of ‘hearing gloves’ for the deaf at Norbert Wiener’s laboratory at Massachusetts Institute of Technology, demonstrated to Helen Keller in 1950. Second, the tactile-visual sensory substitution system for the blind pioneered by Paul Bach-y-Rita from 1968 onwards. Cumulatively, this article underlines the crucial yet occluded history of research on sensory impairments in the discovery of underlying neurophysiological processes of plasticity and the emergent discourse of neuroplastic subjectivity.
Article
Sensory substitution presents the philosopher of cognitive science with a particularly interesting case. Using prosthetics to map visual stimuli onto other modalities, such as touch or audition, otherwise blind individuals may develop perceptual capacities and behaviours commonly associated with sight. Experienced users can distinguish ‘visually’ presented objects and will even jerk back from a looming surface (Bach-y-Rita [1972]). Whether perception with sensory substitution devices (SSDs) should be classed as a type of vision, some other modality, or a new sense remains a matter of debate, however. In the following, I review arguments commonly used to rebut the visual interpretation and, drawing on recent experimental studies and phenomenological self-reports, construct a novel case for treating sensory substitution as a visual process. 1 Introduction 2 Background 3 What Users Access 4 Visual Processing 5 Studies of Phenomenology 6 Conclusion
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The chief problem for the theory of mind is that of presence. In this paper I offer an explanation of this claim, and I indicate how my own “enactive” approach to mind has tried to address this problem. I also argue that other approaches, such as that undertaken by Hutto and Myin, have side-stepped the problem, instead of addressing it; their position opts for reductionism and eliminativism. This essay has two parts. The first is an exposition of the enactive approach, as I understand it, and the second is a critical evaluation of Hutto and Myin.
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Alva Noë (2004, 2008, 2012) understands what he calls “perceptual presence” (2004, 59) as the experience of whole, voluminous objects being ‘right there’, present for us in their entirety, even though not each and every part of them impinges directly on our senses at any given time. How is it possible that we perceptually experience voluminous objects as voluminous directly and apparently effortlessly, with no need of inferring their three-dimensionality from experience of the part of them that is directly stimulating our sense organs? For Noë, this is the ‘problem of perceptual presence’. In this paper, I integrate Noë’s view by articulating a different view of what perceptual presence at a more basic level amounts to. This new account of perceptual presence which, I believe, can clarify and make an enactive account of presence richer. The view I suggest revolves around the idea, developed especially by Merleau-Ponty (1945, 1947) and Kelly (2005, 2007, 2010), that perceptual experience is in an important sense indeterminate. Indeterminacy, I argue, is key if we want to understand perceptual presence and the ‘problem’ Noë solves.
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In this paper I outline and defend a novel approach to conscious perception, which I label "radical sensorimotor enactivism". The aims of the paper are twofold: (1) to respond to a common objection to theories like radical sen-sorimotor enactivism-that they are empirically vacuous-and explain why, because radical sensorimotor enactivism uses (a non-representational version of) predictive processing to operationalize its sub-personal aspects, this objection cannot be levelled at the theory; and, (2) to argue that radical sen-sorimotor enactivism provides a better empirical account of conscious perception than predictive processing taken as a stand-alone theory. I conclude that radical sensorimotor enactivism provides one with a strong over-arching conceptual framework for the scientific study of conscious perception which clarifies the relation between existing strands of empirical work and provides practical guidance for future research. As such, it is worthy of further development , study, and application in empirical settings.
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In what follows, we reproduce (in alphabetic order) the commentaries made by Kevin Connolly, Ophélia Deroy, Julian Kiverstein and Michael J. Proulx, during the Mind & Language Symposium, held in May 2015, on the Brains Blog, about our paper, 'Sensory Substitution is Substitution' (published in Mind & Language) and our replies to those comments.
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Maps of sensory surfaces are a fundamental feature of sensory cortical areas of the brain. The relative roles of afferents and targets in forming neocortical maps in higher mammals can be examined in ferrets in which retinal inputs are directed into the auditory pathway. In these animals, the primary auditory cortex contains a systematic representation of the retina (and of visual space) rather than a representation of the cochlea (and of sound frequency). A representation of a two-dimensional sensory epithelium, the retina, in cortex that normally represents a one-dimensional epithelium, the cochlea, suggests that the same cortical area can support different types of maps. Topography in the visual map arises both from thalamocortical projections that are characteristic of the auditory pathway and from patterns of retinal activity that provide the input to the map.
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Primary visual cortex receives visual input from the eyes through the lateral geniculate nuclei, but is not known to receive input from other sensory modalities. Its level of activity, both at rest and during auditory or tactile tasks, is higher in blind subjects than in normal controls, suggesting that it can subserve nonvisual functions; however, a direct effect of non-visual tasks on activation has not been demonstrated. To determine whether the visual cortex receives input from the somatosensory system we used positron emission tomography (PET) to measure activation during tactile discrimination tasks in normal subjects and in Braille readers blinded in early life. Blind subjects showed activation of primary and secondary visual cortical areas during tactile tasks, whereas normal controls showed deactivation. A simple tactile stimulus that did not require discrimination produced no activation of visual areas in either group. Thus in blind subjects, cortical areas normally reserved for vision may be activated by other sensory modalities.
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Cross-modal plasticity in blind subjects contributes to sensory compensation when vision is lost early in life, but it is not known if it does so when visual loss occurs at an older age. We used (H2O)-O-15 positron emission tomography to identify cerebral regions activated in association with Braille reading, and repetitive transcranial magnetic stimulation to induce focal transient disruption of function during Braille reading, in 8 subjects who became blind after age 14 years (late-onset blind), after a lengthy period of normal vision. Results were compared with those previously reported obtained from congenitally and early-onset blind subjects. As shown by (H2O)-O-15 positron emission tomographic scanning, the occipital cortex was strongly activated in the congenitally blind and early-onset blind groups but not in the late-onset blind group. Occipital repetitive transcranial magnetic stimulation disrupted the Braille reading task in congenitally blind and early-onset blind subjects but not in late-onset blind subjects. These results indicate that the susceptible period for this form of functionally relevant cross-modal plasticity does not extend beyond 14 years.
Chapter
Studies with tactile vision substitution for congenitally blind persons provide an unusual opportunity to observe the acquisition of “visual” spatial concepts in adolescents and adults. Since all aspects of the training are under the experimenter’s control, the effects of each component of the process can be studied. In this paper the relationship between motor processes and cognition will be examined; specifically, the effect of placing the “eye” (television camera) under the control of the blind subject. We have noted that as long as the subject can control the movement of the camera, he can perceive in terms of the three-dimensional visual spatial world of which he is a part. It is possible to change the location and even the orientation of the tactile array (e.g., from the skin of the back to the abdomen), or the motor system controlling camera movement (either hand held, or located on spectacle frames and thus controlled by neck muscles), without compromising accurate spatial orientation.
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A key issue in developmental neuroscience is the role of activity-dependent mechanisms in the epigenetic induction of functional organization in visual cortex. Ocular blindness and ensuing visual deprivation is one of the rare models available for the investigation of experience-dependent cortical reorganization in man. In a PET study we demonstrate that congenitally blind subjects show task-specific activation of extrastriate visual areas and parietal association areas during Braille reading, compared with auditory word processing. In contrast, blind subjects who lost their sight after puberty show additional activation in the primary visual cortex with the same tasks. Studies in blind-raised monkeys show that crossmodal responses in extrastriate areas can be elicited by somatosensory stimulation. This is consistent with the crossmodal extrastriate activations elicited by tactile processing in our congenitally blind subjects. Since primary visual cortex does not show crossmodal responses in primate studies, the differential activation in late and congenitally blind subjects highlights the possibility of reciprocal activation by visual imagery in subjects with early visual experience.
Chapter
In recent years considerable success has been achieved in the development and utilization of apparatus designed to provide the blind with a substitute visual input. Several groups of investigators have used the skin to relay the output of a camera to the central nervous system, one of the best known results being the Bliss-Linvill Optacon, to enable the blind to read printed matter (7). Our own endeavors at the Smith-Kettlewell Institute of Visual Sciences have been directed toward development of a tactile vision substitution system (TVSS) to present pictorial information to the blind (3, 4, 5, 12, 30). Briefly, with the TVSS, optical images picked up through a television camera are presented as a two-dimensional pattern of pulses to a mosaic of stimulators arranged on the skin of the trunk. Information of the patterned stimuli is then transmitted via the ascending somatosensory system to cortical areas for analysis and interpretation. Several factors indicate that the pictorial information can be interpreted as “visual”.
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WE report a follow-up study of a patient who initially suffered from carpal tunnel syndrome in the right hand, that was alleviated by surgery. Subsequently, the patient's right arm was amputated, and a phantom limb was experienced. Originally, stimuli applied to different areas on the right side of the face evoked sensations that were referred to the phantom by precise topographic mapping. On follow-up, one year after our initial studies, the topography of referred mapping had become extremely disorganized. Furthermore, a new, equally disorganized, pattern of referred sensations was now found upon stimulation of the left side of the face.
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To explore the neural networks used for Braille reading, we measured regional cerebral blood flow with PET during tactile tasks performed both by Braille readers blinded early in life and by sighted subjects. Eight proficient Braille readers were studied during Braille reading with both right and left index fingers. Eight-character, non-contracted Braille-letter strings were used, and subjects were asked to discriminate between words and non-words. To compare the behaviour of the brain of the blind and the sighted directly, non-Braille tactile tasks were performed by six different blind subjects and 10 sighted control subjects using the right index finger. The tasks included a non-discrimination task and three discrimination tasks (angle, width and character). Irrespective of reading finger (right or left), Braille reading by the blind activated the inferior parietal lobule, primary visual cortex, superior occipital gyri, fusiform gyri, ventral premotor area, superior parietal lobule, cerebellum and primary sensorimotor area bilaterally, also the right dorsal premotor cortex, right middle occipital gyrus and right prefrontal area. During non-Braille discrimination tasks, in blind subjects, the ventral occipital regions, including the primary visual cortex and fusiform gyri bilaterally were activated while the secondary somatosensory area was deactivated. The reverse pattern was found in sighted subjects where the secondary somatosensory area was activated while the ventral occipital regions were suppressed. These findings suggest that the tactile processing pathways usually linked in the secondary somatosensory area are rerouted in blind subjects to the ventral occipital cortical regions originally reserved for visual shape discrimination.
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Long-term visual deprivation from birth leads to reorganization of the anterior ectosylvian region of the cat's cortex. A visual area in the fundus of anterior ectosylvian sulcus (AES)—anterior ectosylvian visual (AEV) area, in which neurons normally respond briskly to visual stimuli, is taken over almost completely by auditory and somatosensory inputs. Auditory neurons are sharply tuned to the location of a sound source in azimuth. A higher than normal proportion of neurons in the AES of visually deprived cats responds to multimodal stimuli. Takeover of visual regions by non-visual inputs can be explained by the same mechanisms that are invoked for developmental plasticity within the visual system; neural activity and competition among different inputs leads to the changes in synaptic efficacy. Additional sprouting cannot be excluded. The radical changes of sensory modality within the AES, caused by visual deprivation, suggest that the same code is used by visual, auditory and somatosensory maps in this region to represent the sensory environment and lead to sensorimotor transformation.
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In the past decade, the notion of a neural correlate of consciousness (or NCC) has become a focal point for scientific research on consciousness (Metzinger, 2000a). A growing number of investigators believe that the first step toward a science of consciousness is to discover the neural correlates of consciousness. Indeed, Francis Crick has gone so far as to proclaim that ‘we need to discover the neural correlates of consciousness. For this task the primate visual system seems especially attractive. No longer need one spend time attempting to endure the tedium of philosophers perpetually disagreeing with each other. Consciousness is now largely a scientific problem’ (Crick, 1996, p. 486). Yet the question of what it means to be a neural correlate of consciousness is actually far from straightforward, for it involves fundamental empirical, methodological, and philosophical issues about the nature of consciousness and its relationship to the brain. Even if one assumes, as we do, that states of consciousness causally depend on states of the brain, one can nevertheless wonder in what sense there is, or could be, such a thing as a neural correlate of consciousness.
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Investigated adaptation in an inverted visual field. An eight day experiment was conducted on one S. When lenses inverting the visual field were not worn, the eyes were blind folded. The experience was carefully recorded everyday. Six days of the experiment are reported wherein from a feeling of abnormal position of the body, the S learnt to adjust to movement, localization of touch and sound. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
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Regarding perception as a complex interaction between behavior and sensory inputs, the author develops a systematic theory which he tested at crucial points by such experiments as the wearing of reversing spectacles. Harvard Book List (edited) 1964 #270 (PsycINFO Database Record (c) 2012 APA, all rights reserved)
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The most important clarification we bring in our reply to commentators concerns the problem of the “explanatory gap”: that is, the gulf that separates physical processes in the brain from the experienced quality of sensations. By adding two concepts (bodiliness and grabbiness) that were not stressed in the target article, we strengthen our claim and clarify why we think we have solved the explanatory gap problem, – not by dismissing qualia, but, on the contrary, by explaining why sensations have a “feel” and why “feels” feel the way they do. We additionally clarify our views on: internal representations (we claim internal representations cannot explain why sensation has a feel), on behaviorism (we are not behaviorists), on perception and action (we believe there can be perception without action), and on the brain (we believe the brain does do something important in perception).
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Illusions have historically been of great use to psychology for what they can reveal about perceptual processes. We report here an illusion in which tactile sensations are referred to an alien limb. The effect reveals a three-way interaction between vision, touch and proprioception, and may supply evidence concerning the basis of bodily self-identification.
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This paper investigates the idea that perception can be, at once, a mode of direct awareness of the world and an encounter, in the first instance, with mere appearances. In developing this point, I introduce a sensorimotor account of perception according to which the senses are ways of exploring the environment mediated by different patterns of sensorimotor contingency (i.e. by the distinctive ways in which what the perceiver does affects how things appear). © 2002 University of Southern California and Blackwell Publishers Ltd.
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Functionalism, a philosophical theory, has empirical consequences. Functionalism predicts that where systematic transformations of sensory input occur and are followed by behavioral accommodation in which normal function of the organism is restored such that the causes and effects of the subject's psychological states return to those of the period prior to the transformation, there will be a return of qualia or subjective experiences to those present prior to the transform. A transformation of this type that has long been of philosophical interest is the possibility of an inverted spectrum. Hilary Putnam argues that the physical possibilty of acquired spectrum inversion refutes functionalism. I argue, however, that in the absence of empirical results no a priori arguments against functionalism, such as Putnam's, can be cogent. I sketch an experimental situation which would produce acquired spectrum inversion. The mere existence of qualia inversion would constitute no refutation of functionalism; only its persistence after behavioral accommodation to the inversion would properly count against functionalism. The cumulative empirical evidence from experiments on image inversion suggests that the results of actual spectrum inversion would confirm rather than refute functionalism.
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Susan Hurley has attacked the ''Duplication Assumption'', the assumption thatcreatures with exactly the same internal states could function exactly alike inenvironments that are systematically distorted. She argues that the dynamicalinterdependence of action and perception is highly problematic for the DuplicationAssumption when it involves spatial states and capacities, whereas no such problemsarise when it involves color states and capacities. I will try to establish that theDuplication Assumption makes even less sense for lightness than for some ofthe spatial cases. This is due not only to motor factors, but to the basic physicalasymmetry between black and white. I then argue that the case can be extendedfrom lightness perception to hue perception. Overall, the aims of this paper are:(1) to extend Susan Hurley''s critique of the Duplication Assumption; (2) to argueagainst highly constrained versions of Inverted Spectrum arguments; (3) to proposea broader conception of the vehicle for color perception.
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The paper proposes a way of bridging the gapbetween physical processes in the brain and the ''''felt''''aspect of sensory experience. The approach is based onthe idea that experience is not generated by brainprocesses themselves, but rather is constituted by theway these brain processes enable a particular form of''''give-and-take'''' between the perceiver and theenvironment. From this starting-point we are able tocharacterize the phenomenological differences betweenthe different sensory modalities in a more principledway than has been done in the past. We are also ableto approach the issues of visual awareness andconsciousness in a satisfactory way. Finally weconsider a number of testable empirical consequences,one of which is the striking prediction of thephenomenon of ''''change blindness''''.
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We all know about the vehicle/content distinction (see Dennett 1991a, Millikan 1991, 1993). We shouldn't confuse properties represented in content with properties of vehicles of content. In particular, we shouldn't confuse the personal and subpersonal levels. The contents of the mental states of subject/agents are at the personal level. Vehicles of content are causally explanatory subpersonal events or processes or states. We shouldn't suppose that the properties of vehicles must be projected into what they represent for subject/agents, or vice versa. This would be to confuse the personal and subpersonal levels.
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WE describe here a vision substitution system which is being developed as a practical aid for the blind and as a means of studying the processing of afferent information in the central nervous system. The theoretical neurophysiological basis1 and the physical concept of the instrumentation2 have been discussed previously, and results obtained with preliminary models have been briefly reported3. A detailed description of the apparatus will appear elsewhere (manuscript in preparation).
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Linking propositions are statements that relate perceptual states to physiological states, and as such are one of the fundamental building blocks of visual science. A brief history of the concept of linking proposition is presented. Five general families of linking propositions--Identity, Similarity, Mutual Exclusivity, Simplicity and Analogy--are discussed, and examples of each are developed. Two specific linking propositions, involving the explanation of perceptual phenomena on the basis of the activity of single neurons, are explicated and their limitations are explored in detail. Finally, the question of the empirical testability and falsifiability of linking propositions is discussed.
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We report a follow-up study of a patient who initially suffered from carpal tunnel syndrome in the right hand, that was alleviated by surgery. Subsequently, the patient's right arm was amputated, and a phantom limb was experienced. Originally, stimuli applied to different areas on the right side of the face evoked sensations that were referred to the phantom by precise topographic mapping. On follow-up, one year after our initial studies, the topography of referred mapping had become extremely disorganized. Furthermore, a new, equally disorganized, pattern of referred sensations was now found upon stimulation of the left side of the face.
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Although there is a vast clinical literature on phantom limbs, there have been no experimental studies on the effects of visual input on phantom sensations. We introduce an inexpensive new device--a 'virtual reality box'--to resurrect the phantom visually to study inter-sensory effects. A mirror is placed vertically on the table so that the mirror reflection of the patient's intact had is 'superimposed' on the felt position of the phantom. We used this procedure on ten patients and found the following results. 1. In six patients, when the normal hand was moved, so that the phantom was perceived to move in the mirror, it was also felt to move; i.e. kinesthetic sensations emerged in the phantom. In D.S. this effect occurred even though he had never experienced any movements in the phantom for ten years before we tested him. He found the return of sensations very enjoyable. 2. Repeated practice led to a permanent 'disappearance' of the phantom arm in patient D.S. and the hand became telescoped into the stump near the shoulder. 3. Using an optical trick, impossible postures--e.g. extreme hyperextension of the fingers--could be induced visually in the phantom. In one case this was felt as a transient 'painful tug' in the phantom. 4. Five patients experienced involuntary painful 'clenching spasms' in the phantom hand and in four of them the spasms were relieved when the mirror was used to facilitate 'opening' of the phantom hand; opening was not possible without the mirror. 5. In three patients, touching the normal hand evoked precisely localized touch sensations in the phantom. Interestingly, the referral was especially pronounced when the patients actually 'saw' their phantom being touched in the mirror. Indeed, in a fourth patient (R.L.) the referral occurred only if he saw his phantom being touched: a curious form of synaesthesia. These experiments lend themselves readily to imaging studies using PET and fMRI. Taken collectively, they suggest that there is a considerable amount of latent plasticity even in the adult human brain. For example, precisely organized new pathways, bridging the two cerebral hemispheres, can emerge in less than three weeks. Furthermore, there must be a great deal of back and forth interaction between vision and touch, so that the strictly modular, hierarchical model of the brain that is currently in vogue needs to be replaced with a more dynamic, interactive model, in which 're-entrant' signalling plays the main role.
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Long-term visual deprivation from birth leads to reorganization of the anterior ectosylvian region of the cat's cortex. A visual area in the fundus of AES, area AEV, in which neurons normally respond briskly to visual stimuli, is taken over almost completely by auditory and somatosensory inputs. Auditory neurons are sharply tuned to the location of a sound source in azimuth. A higher than normal proportion of neurons in the AES of visually deprived cats responds to multimodal stimuli. Takeover of visual regions by non-visual inputs can be explained by the same mechanisms that are invoked for developmental plasticity within the visual system: neural activity and competition between different inputs leads to changes in synaptic efficacy. Additional sprouting cannot be excluded. The radical changes of sensory modality within the AEs, caused by visual deprivation, suggest that the same code is used by visual, auditory and somatosensory maps in this region to represent the sensory environment and lead to sensorimotor transformation.
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We demonstrate that interleukin-10 (IL-10) can inhibit T-cell apoptosis. T cells, within a PBMC (peripheral blood mononuclear cell) population, were stimulated via the T-cell receptor and grown in the presence of IL-2. These cells had less apoptosis when in the continuous presence of IL-10, compared with cells grown in the absence of IL-10. Conversely, when stimulated and grown in the presence of neutralizing antibody of IL-10, there was an increase in T-cell apoptosis. The in vitro rescue from apoptotic cell death of other lymphoid cells, such as germinal centre B cells, has been shown by others to involve a Bcl-2 pathway. We therefore investigated whether IL-10 might affect the Bcl-2 expression on cultured T cells. By Western blotting we demonstrated that continuous exposure of IL-10 to T cells (within a PBMC population) enhanced the expression of Bcl-2. Furthermore, T cells protected from apoptotic cell death by IL-10 were indistinguishable from viable untreated cells in their ability to proliferate to either immobilized anti-CD3 or IL-2. Thus, we have shown that continuous culture of T cells in the presence of IL-10 will inhibit T-cell apoptosis because of, at least in part, the upregulation of Bcl-2, and this is associated with a normal proliferative function.