Many philosophers use findings about sensory substitution devices in the grand debate about how we should individuate the senses. The big question is this: Is “vision” assisted by (tactile) sensory substitution really vision? Or is it tactile perception? Or some sui generis novel form of perception? My claim is that sensory substitution assisted “vision” is neither vision nor tactile perception, because it is not perception at all. It is mental imagery: (...) class='Hi'>visual mental imagery triggered by tactile sensory stimulation. But it is a special form of mental imagery that is triggered by corresponding sensory stimulation in a different sense modality, which I call “multimodal mental imagery.”. (shrink)

The strategies of action employed by a human subject in order to perceive simple 2-D forms on the basis of tactile sensory feedback have been modelled by an explicit computer algorithm. The modelling process has been constrained and informed by the capacity of human subjects both to consciously describe their own strategies, and to apply explicit strategies; thus, the strategies effectively employed by the human subject have been influenced by the modelling process itself. On this basis, good qualitative (...) and semi-quantitative agreement has been achieved between the trajectories produced by a human subject, and the traces produced by a computer algorithm. The advantage of this reciprocal modelling option, besides facilitating agreement between the algorithm and the empirically observed trajectories, is that the theoretical model provides an explanation, and not just a description, of the active perception of the human subject. (shrink)

In current philosophy of mind, there is lively debate over whether emotions, moods, and other affects can extend to comprise elements beyond one’s organismic boundaries. At the same time, there has been growing interest in the nature and significance of so-called existential feelings, which, as the term suggests, are feelings of one’s overall being in the world. In this article, I bring these two strands of investigation together to ask: Can the material underpinnings of existential feelings extend beyond one’s skull (...) and skin? To begin, I introduce and adopt a componential-systemic view of extended affectivity. In doing so, I specify the vehicle externalist criteria for extension employed in my analysis. I then define what existential feelings are and pinpoint several key issues in their potential extension. More specifically, I identify sensorimotor ‘know-how’ as a possibly extending component of existential feeling and posit it as the fulcrum of my argument. Finally, I move on to consider the extension of existential feeling via sensory substitution, especially through so-called Tactile Visual Sensory Substitution (TVSS) devices. Informed by both philosophical and empirical studies, I argue that, under certain conditions, (a) the agent’s implicit sensorimotor processing and a TVSS device can become coupled into a new systemic whole, which in turn (b) reconfigures the material underpinnings of the agent’s pre-intentional world-experience. This, I conclude, counts as a cogent case for extended existential feeling. (shrink)

Block (Trends Cogn Sci 7:285–286, 2003) and Prinz (PSYCHE 12:1–19, 2006) have defended the idea that SSD perception remains in the substituting modality (auditory or tactile). Hurley and Noë (Biol Philos 18:131–168, 2003) instead argued that after substantial training with the device, the perceptual experience that the SSD user enjoys undergoes a change, switching from tactile/auditory to visual. This debate has unfolded in something like a stalemate where, I will argue, it has become difficult to determine whether (...) the perception acquired through the coupling with an SSD remains in the substituting or the substituted modality. Within this puzzling deadlock two new approaches have been recently suggested. Ward and Meijer (Conscious Cogn 19:492–500, 2010) describe SSD perception as visual-like but characterize it as a kind of artificially induced synaesthesia. Auvray et al. (Perception 36:416–430, 2007) and Auvray and Myin (Cogn Sci 33:1036–1058, 2009) suggest that SSDs let their users experience a new kind of perception. Deroy and Auvray (forthcoming) refine this position, and argue that this new kind of perception depends on pre-existing senses without entirely aligning with any of them. So, they have talked about perceptual experience in SSDs as going "beyond vision". In a similar vein, MacPherson (Oxford University Press, New York, 2011a) claims that “if the subjects (SSD users) have experiences with both vision-like and touch-like representational characteristics then perhaps they have a sense that ordinary humans do not” (MacPherson in Oxford University Press, New York, 2011a, p. 139). (shrink)

According to proponents of the sensorimotor contingency theory of perception (Hurley & Noë 2003, Noë 2004, O’Regan 2011), active control of camera movement is necessary for the emergence of distal attribution in tactile-visual sensory substitution (TVSS) because it enables the subject to acquire knowledge of the way stimulation in the substituting modality varies as a function of self-initiated, bodily action. This chapter, by contrast, approaches distal attribution as a solution to a causal inference problem faced by (...) the subject’s perceptual systems. Given all of the available endogenous and exogenous evidence available to those systems, what is the most probable source of stimulation in the substituting modality? From this perspective, active control over the camera’s movements matters for rather different reasons. Most importantly, it generates proprioceptive and efference-copy based information about the camera’s body-relative position necessary to make use of the spatial cues present in the stimulation that the subject receives for purposes of egocentric object localization. (shrink)

In this paper we wish to bring together two seemingly independent areas of research: synaesthesia and sensory substitution. Synaesthesia refers to a rare condition where a sensory stimulus elicits not only the sensation that stimulus evokes in its own modality, but an additional one; a synaesthete may thus hear the word “Monday”, and, in addition to hearing it, have a concurrent visual experience of a red color. Sensory substitution, in contrast, attempts to substitute a (...) sensory modality that a person has lost by transforming the information it provided so that it can be accessed through another, intact sensory modality. To make visual information accessible to a blind person, for example, data taken by a camera would be transformed into tactile or auditory information. What do synaesthesia and sensory substitution have in common? Research in both of these areas contributes to our understanding both of cross-modal cooperation and of sensory sensations or qualia, asking under what circumstances these can arise in a modality that is not stimulated. Synaesthesia reveals that this “sensory cross-activation” is possible, and sensory substitution research hopes to induce it. In this article, we will review briefly the literature on synaesthesia, and discuss the issue of qualia for this domain of research. We will then address the evidence for synaesthesia and visual qualia in the blind, and the research on sensory substitution, to finally ask whether sensory substitution may induce a ‘synthetic’ form of synaesthesia by taking advantage of the nervous system’s capacity for generating visual images in the absence of retinal input. (shrink)

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. (shrink)

Sensory substitution devices are a type of sensory prosthesis that (typically) convert visual stimuli transduced by a camera into tactile or auditory stimulation. They are designed to be used by people with impaired vision so that they can recover some of the functions normally subserved by vision. In this chapter we will consider what philosophers might learn about the nature of the senses from the neuroscience of sensory substitution. We will show how (...) class='Hi'>sensory substitution devices work by exploiting the cross-modal plasticity of sensory cortex: the ability of sensory cortex to pick up some types of information about the external environment irrespective of the nature of the sensory inputs it is processing. We explore the implications of cross-modal plasticity for theories of the senses that attempt to make distinctions between the senses on the basis of neurobiology. (shrink)

There is an overlooked similarity between three classic accounts of the conditions of object experience from three distinct disciplines. Sociology: the “inversion” that accompanies discovery in the natural sciences, as local causes of effects are reattributed to an observed object. Psychology: the “externalization” that accompanies mastery of a visual–tactile sensory substitution interface, as tactile sensations of the proximal interface are transformed into vision-like experience of a distal object. Biology: the “projection” that brings forth an animal’s (...) Umwelt, as impressions on its body’s sensory surfaces are reconfigured into perception of an external object. This similarity between the effects of scientific practice and interface-use on the one hand, and of sensorimotor interaction on the other, becomes intelligible once we accept that skillful engagement with instruments and interfaces constitutes a socio-material augmentation of our basic perceptual capacity. This enactive interpretation stands in contrast to anti-realism about science associated with constructivist interpretations of these three phenomena, which are motivated by viewing them as the internal mental construction of the experienced object. Instead, it favors a participatory realism: the sensorimotor basis of perceptual experience loops not only through our body, but also through the external world. This allows us to conceive of object experience in relational terms, i.e., as one or more subjects directly engaging with the world. Consequently, we can appreciate scientific observation in its full complexity: it is a socio-materially augmented process of becoming acquainted with the observed object that—like tool-use and perceiving more generally—is irreducibly self, other-, and world-involving. (shrink)

When a user integrates a sensory substitution device into her life, the process involves perceptual learning, that is, ‘relatively long-lasting changes to an organism’s perceptual system that improve its ability to respond to its environment’ (Goldstone 1998: 585). In this paper, I explore ways in which the extensive literature on perceptual learning can be applied to help improve sensory substitution devices. I then use these findings to answer a philosophical question. Much of the philosophical debate surrounding (...) sensory substitution devices concerns what happens after perceptual learning occurs. In particular, should the resultant perceptual experience be classified in the substituted modality (as vision), in the substituting modality (as auditory or tactile), or in a new sense modality? I propose a novel empirical test to help resolve this philosophical debate. (shrink)

Sensory substitution devices make use of one substituting modality to get access to environmental information normally accessed through another modality . Based on behavioural and neuroimaging data, some authors have claimed that using a vision-substituting device results in visual perception. Reviewing these data, we contend that this claim is untenable. We argue that the kind of information processed by a SSD is metamodal, so that it can be accessed through any sensory modality and that the phenomenology (...) associated with the use of a SSD is best described in terms of spatial phenomenology, only. (shrink)

One of the central limitations of sensory substitution devices (SSDs) is their inability to reproduce the non-sensory feelings that are normally associated with visual experiences, especially hedonic and aesthetic responses. This limitation is sometimes reported to cause SSD users frustration. To make matters worse, it is unclear that improvements in acuity, bandwidth, or training will resolve the issue. Yet, if SSDs are to actually reproduce visual experience in its fullness, it seems that the reproduction of (...) non-sensory feelings will be of some importance. We offer a novel solution. Researchers can produce hedonic and aesthetic responses by eliciting these feelings artificially, pairing distal objects that should be pleasurable to pleasurable stimulus outputs from the SSD. We outline two strategies for accomplishing this: first, by means of a prefixed, hardwired, association of pleasant distal objects to pleasant stimulus outputs from the SSD; second, by means of a flexible, feedback-based association which creates associations based on a subject-directed matching of distal objects to patterns of stimuli from the SSD which the subject takes to have the corresponding hedonic properties. We evaluate some problems with both strategies, and we argue that the feedback-based strategy is more promising. Researchers can use this strategy to help the blind, allowing them to take pleasure in the objects they perceive using SSDs. (shrink)

Sensory substitution devices (SSDs) aim to compensate for the loss of a sensory modality, typically vision, by converting information from the lost modality into stimuli in a remaining modality. “The vOICe” is a visual-to-auditory SSD which encodes images taken by a camera worn by the user into “soundscapes” such that experienced users can extract information about their surroundings. Here we investigated how much detail was resolvable during the early induction stages by testing the acuity of blindfolded (...) sighted, naïve vOICe users. Initial performance was well above chance. Participants who took the test twice as a form of minimal training showed a marked improvement on the second test. Acuity was slightly but not significantly impaired when participants wore a camera and judged letter orientations “live”. A positive correlation was found between participants' musical training and their acuity. The relationship between auditory expertise via musical training and the lack of a relationship with visual imagery, suggests that early use of a SSD draws primarily on the mechanisms of the sensory modality being used rather than the one being substituted. If vision is lost, audition represents the sensory channel of highest bandwidth of those remaining. The level of acuity found here, and the fact it was achieved with very little experience in sensory substitution by naïve users is promising. (shrink)

In this report, the phenomenology of two blind users of a sensory substitution device – “The vOICe” – that converts visual images to auditory signals is described. The users both report detailed visual phenomenology that developed within months of immersive use and has continued to evolve over a period of years. This visual phenomenology, although triggered through use of The vOICe, is likely to depend not only on online visualization of the auditory signal but also (...) on the users’ previous (albeit distant) experience of veridical vision (e.g. knowledge of shapes and visual perspective). Once established, the sensory substitution mapping between the auditory and visual domains is not confined to when the device is worn and, thus, may constitute an example of acquired synaesthesia. (shrink)

Sensory substitution devices (SSDs) are most familiar from their use with subjects who are deficient in a target modality (e.g. congenitally blind subjects), but there is no doubt that the use and potential value of SSDs extend to persons without such deficits. Recent work by Amedi and his team (in particular Levy-Tzedek et al. 2012) has begun to explore this. Their idea is that SSDs may facilitate behavioural transference (BT) across sense modalities. In this case, a motor skill (...) learned through visual perception might be subsequently employed in response to auditory perception, using an SSD as a mediator. They infer from the existence of such BT that the learned skill is amodally represented. After a brief overview I identify ways to more fully test for BT within this experimental paradigm and argue that their conclusion about amodal representation is premature. Additionally, I argue that their preferred SSD (Eyemusic) is of limited value for the project. While my remarks are critical, my intention is to be constructive, particularly in light of the fact that Levy-Tzedek et al. (2012), is, I believe, the first output from Amedi's lab concerning this line of research. (shrink)

Visual information can be provided to blind users through sensory substitution devices that convert images into sound. Through extensive use to develop expertise, some blind users have reported visual experiences when using such a device. These blind expert users have also reported visual phenomenology to other sounds even when not using the device. The blind users acquired synthetic synaesthesia, with visual experience evoked by sounds only after gaining such expertise. Sensorimotor learning may facilitate and (...) perhaps even be required to develop expertise in the use of multimodal information. Furthermore, other areas where expertise is acquired in dividing attention amongst cross-modal information or integrating such information might also give rise to synthetic synaesthesia. (shrink)

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. Whether perception with sensory substitution devices 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. (shrink)

Touch is the first sense to develop in the womb, yet often it is overlooked. The Senses of Touch examines the role of touching and feeling as part of the fabric of everyday, embodied experience. -/- How can we think about touch? Problems of touch and tactility run as a continuous thread in philosophy, psychology, medical writing and representations in art, from Ancient Greece to the present day. Picking through some of these threads, the book ‘feels’ its way towards writing (...) and thinking about touch as both sensory and affective experience. -/- Taking a broadly phenomenological framework that traces the tactility from Aristotle through the Enlightenment to the present day, it examines the role of touch across a range of experiences including aesthetics, digital design, visual impairment and touch therapies. The Senses of Touch thereby demonstrates the varieties of sensory experience, and explores the diverse range of our ‘senses’ of touch. (shrink)

There is a task-specificity in the visual-tactile interaction for perception: The polymodal posterior parietal cortex is related to the comparison of the shapes coded by different sensory modalities, whereas the lateral occipital complex is the part of the network for multimodal shape identification. These interactions may be mediated by some latent pathways potentiated by sensory deprivation or learning.

Multimodal integration is the formation of a coherent percept from different sensory inputs such as vision, audition, and somatosensation. Most research on multimodal integration in speech perception has focused on audio-visual integration. In recent years, audio-tactile integration has also been investigated, and it has been established that puffs of air applied to the skin and timed with listening tasks shift the perception of voicing by naive listeners. The current study has replicated and extended these findings by testing (...) the effect of air puffs on gradations of voice onset time along a continuum rather than the voiced and voiceless endpoints of the original work. Three continua were tested: bilabial (“pa/ba”), velar (“ka/ga”), and a vowel continuum (“head/hid”) used as a control. The presence of air puffs was found to significantly increase the likelihood of choosing voiceless responses for the two VOT continua but had no effect on choices for the vowel continuum. Analysis of response times revealed that the presence of air puffs lengthened responses for intermediate (ambiguous) stimuli and shortened them for endpoint (non-ambiguous) stimuli. The slowest response times were observed for the intermediate steps for all three continua, but for the bilabial continuum this effect interacted with the presence of air puffs: responses were slower in the presence of air puffs, and faster in their absence. This suggests that during integration auditory and aero-tactile inputs are weighted differently by the perceptual system, with the latter exerting greater influence in those cases where the auditory cues for voicing are ambiguous. (shrink)

The transmission, emergence, and dissemination of features of racial differentiation are based on the interplay of different sensory perceptions, as this contribution will illustrate. For this purpose, examples from ethnographic travelogues from German East Africa and from the time of German colonial rule were selected to examine the functioning of tactile perception by means of the descriptions of skin colors and skin decorations. The source material reveals multisensuality in the form of synesthesia of the sense of sight with (...) the sense of touch, in that the perception of tactile stimuli is determined less by direct touch and more by the visual representation of haptic properties. (shrink)

Based on sensory integration theory, six fabric samples containing tactile and visual stimuli were selected using the sensory perceptions of designers and combined with balls. Experiments involving these toys were implemented with 15 families with preschool-aged high-functioning autistic children. The results showed that loose sequin , which possessed equal tactile and visual intensities, was strongly correlated with frequent smiling/laughing and high enjoyment levels. The fabric provided a loose tactile sensation regarding surface interweave uniformity (...) and a bright visual sensation regarding visually perceived luster; suede exhibited a greater tactile intensity than visual intensity and was correlated with eye contact and activity response. This fabric possessed a smooth visual sensation regarding visually perceived smoothness; and loose sequin , which possessed equal tactile and visual intensities, was highly correlated with finger pointing and initiation. This fabric offered a thin tactile sensation regarding surface interweave thickness and a bright visual sensation regarding visually perceived luster. We suggest applying fabrics to composite toys. Specifically, loose sequin can be used initially to encourage autistic children to interact; subsequently, suede can enable sustained parent-child interaction. The experimental results provide a reference for establishing an innovative toy-design method for autistic children. Keywords: autism; sensory integration theory; parent-child interaction; toys. (shrink)

People’s awareness of tactile stimuli has been investigated in far less detail than their awareness of stimuli in other sensory modalities. In an attempt to fill this gap, we provide an overview of studies that are pertinent to the topic of tactile consciousness. We discuss the results of research that has investigated phenomena such as “change blindness”, phantom limb sensations, and numerosity judgments in tactile perception, together with the results obtained from the study of patients affected (...) by deficits that can adversely affect tactile perception such as neglect, extinction, and numbsense. The similarities as well as some of the important differences that have emerged when visual and tactile conscious information processing have been compared using similar experimental procedures are highlighted. We suggest that conscious information processing in the tactile modality cannot be separated completely from the more general processing of spatial information in the brain. Finally, the importance of considering tactile consciousness within the larger framework of multisensory information processing is also discussed. (shrink)

Change blindness, the surprising inability of people to detect significant changes between consecutively-presented visual displays, has recently been shown to affect tactile perception as well. Visual change blindness has been observed during saccades and eye blinks, conditions under which people’s awareness of visual information is temporarily suppressed. In the present study, we demonstrate change blindness for suprathreshold tactile stimuli resulting from the execution of a secondary task requiring bodily movement. In Experiment 1, the ability of (...) participants to detect changes between two sequentially-presented vibrotactile patterns delivered on their arms and legs was compared while they performed a secondary task consisting of either the execution of a movement with the right arm toward a visual target or the verbal identification of the target side. The results demonstrated that a motor response gave rise to the largest drop in perceptual sensitivity in detecting changes to the tactile display. In Experiment 2, we replicated these results under conditions in which the participants had to detect tactile changes while turning a steering wheel instead. These findings are discussed in terms of the role played by bodily movements, sensory suppression, and higher order information processing in modulating people’s awareness of tactile information across the body surface. (shrink)

The loss or absence of vision is probably one of the most incapacitating events that can befall a human being. The importance of vision for humans is also reflected in brain anatomy as approximately one third of the human brain is devoted to vision. It is therefore unsurprising that throughout history many attempts have been undertaken to develop devices aiming at substituting for a missing visual capacity. In this review, we present two concepts that have been prevalent over the (...) last two decades. The first concept is sensory substitution, which refers to the use of another sensory modality to perform a task that is normally primarily sub-served by the lost sense. The second concept is cross-modal plasticity, which occurs when loss of input in one sensory modality leads to reorganization in brain representation of other sensory modalities. Both phenomena are training-dependent. We also briefly describe the history of blindness from ancient times to modernity, and then proceed to address themeansthat have been used to help blind individuals, with an emphasis on modern technologies, invasive (various type of surgical implants) and non-invasive devices. With the advent of brain imaging, it has become possible to peer into the neural substrates of sensory substitution and highlight the magnitude of the plastic processes that lead to a rewired brain. Finally, we will address the important question of the value and practicality of the available technologies and future directions. (shrink)

In drawing out how human lives are always already inextricably entangled with the non-human elements of the world, this paper explores how stone, as a constituent of urban materiality, provokes a wealth of emotional, sensory and affective impacts in the experience of place. The paper discusses how the sonic, tactile and visual qualities of stone contribute to the sensory and affective experience of places, shape the symbolic meanings and affective impacts of diverse memorials, and trigger a (...) powerful sense of geological conviviality. (shrink)

Vision substitution by electro-stimulation has been studied since the 60s beginning with P. Bach-y-Rita. Camera pictures or movies encoded in gray levels are displayed using an electro-stimulation display device on the surface of a body part, such as the skin or the tongue. Medical-technical devices have been developed on this principle to compensate for sensory-motor disabilities such as blindness or loss of balance, or to guide specific actions, such as surgery. However, the electrical signals of stationary or moving (...) slowly moving objects, displayed on a Tongue display unit , are quickly lost due to saturation of receptors undergoing electrostimulation. We propose to add random saccades or sparkle to the displayed visual scene to increase the quality of pattern recognition by the subjects. In the present experimental trimodal study , we show that the presence of a moderate sparkle level enhances the perception of the direction of lines drawn on a TDU and reduces the response time. (shrink)

This volume is about the many ways we perceive. Contributors explore the nature of the individual senses, how and what they tell us about the world, and how they interrelate. They consider how the senses extract perceptual content from receptoral information. They consider what kinds of objects we perceive and whether multiple senses ever perceive a single event. They consider how many senses we have, what makes one sense distinct from another, and whether and why distinguishing senses may be useful. (...) They consider the extent to which the senses act in concert, rather than as discrete modalities, and whether this influence is epistemically pernicious, neutral, or beneficial. They explore both the familiar five sense modalities and other candidate sense modalities, including a sense for flavour, inner senses (e.g., a sense for pain), and various senses that may result from using sensory substitution devices. Contributors often represent competing views, and the methods they deploy sometimes differ from one essay to the next—with some drawing upon the sciences and engineering and others relying upon conceptual analysis. All contributors agree, nonetheless, that traditional theorizing about the senses is hampered by a neglect of the senses other than vision, and by the misconception that vision is a passive receptacle for an image thrown by a lens. And many contributors believe that it is unduly restrictive to think of perception as a collation of contents provided by individual sense modalities; they think that to understand perception properly, we need to build into our accounts the idea that the senses work together. The ambition of the volume is to begin to develop better paradigms for understanding the senses, and thereby to move toward a better understanding of perception. (shrink)

Many current neurophysiological, psychophysical, and psychological approaches to vision rest on the idea that when we see, the brain produces an internal representation of the world. The activation of this internal representation is assumed to give rise to the experience of seeing. The problem with this kind of approach is that it leaves unexplained how the existence of such a detailed internal representation might produce visual consciousness. An alternative proposal is made here. We propose that seeing is a way (...) of acting. It is a particular way of exploring the environment. Activity in internal representations does not generate the experience of seeing. The out- side world serves as its own, external, representation. The experience of seeing occurs when the organism masters what we call the gov- erning laws of sensorimotor contingency. The advantage of this approach is that it provides a natural and principled way of accounting for visual consciousness, and for the differences in the perceived quality of sensory experience in the different sensory modalities. Sev- eral lines of empirical evidence are brought forward in support of the theory, in particular: evidence from experiments in sensorimotor adaptation, visual “filling in,” visual stability despite eye movements, change blindness, sensory substitution, and color perception. (shrink)

Predictable somatosensory feedback leads to a reduction in tactile sensitivity. This phenomenon, called tactile suppression, relies on a mechanism that uses an efference copy of motor commands to help select relevant aspects of incoming sensory signals. We investigated whether tactile suppression is modulated by the task-relevancy of the predicted consequences of movement and the intensity of related somatosensory feedback signals. Participants reached to a target region in the air in front of a screen; visual or (...) tactile feedback indicated the reach was successful. Furthermore, tactile feedback intensity varied across two groups of participants. We measured tactile suppression by comparing detection thresholds for a probing vibration applied to the finger either early or late during reach and at rest. As expected, we found an overall decrease in late-reach suppression, as no touch was involved at the end of the reach. We observed an increase in the degree of tactile suppression when strong tactile feedback was given at the end of the reach, compared to when weak tactile feedback or visual feedback was given. Our results suggest that the extent of tactile suppression can be adapted to different demands of somatosensory processing. Downregulation of this mechanism is invoked only when the consequences of missing a weak movement sequence are severe for the task. The decisive factor for the presence of tactile suppression seems not to be the predicted action effect as such, but the need to detect and process anticipated feedback signals occurring during movement. (shrink)

Unlike those with type 1 blindsight, people who have type 2 blindsight have some sort of consciousness of the stimuli in their blind field. What is the nature of that consciousness? Is it visual experience? I address these questions by considering whether we can establish the existence of any structural—necessary—features of visual experience. I argue that it is very difficult to establish the existence of any such features. In particular, I investigate whether it is possible to visually, or (...) more generally perceptually, experience form or movement at a distance from our body, without experiencing colour. The traditional answer, advocated by Aristotle, and some other philosophers, up to and including the present day, is that it is not and hence colour is a structural feature of visual experience. I argue that there is no good reason to think that this is impossible, and provide evidence from four cases—sensory substitution, achomatopsia, phantom contours and amodal completion—in favour of the idea that it is possible. If it is possible then one important reason for rejecting the idea that people with type 2 blindsight do not have visual experiences is undermined. I suggest further experiments that could be done to help settle the matter. (shrink)

Research on sequence effects on learning visual categories has shown that interleaving (i.e., studying the categories in a mixed manner) facilitates category induction as compared to blocking (i.e., studying the categories one by one), but learners are unaware of the interleaving effect and prefer blocking. However, little attention has been paid to sequence effects in perceptual learning across further sensory modalities. The present (preregistered) research addresses this shortcoming by using auditory (birdcalls), olfactory (tealeaves), gustatory (ingredient mixtures), and (...) class='Hi'>tactile (stones) stimuli across four analog experiments. The number of participants per experiment was determined based on a medium effect size of interleaving. Participants studied six categories (with six exemplars, respectively) either interleaved or blocked. No single experiment showed a significant effect of interleaving. We ran a comprehensive meta‐analysis based on the data from all experiments, which revealed a significant small effect of interleaving, demonstrating its applicability to perceptual learning across all sensory modalities. Learners in the interleaved condition underestimated their classification performance. Overall, learners did not rate interleaving as less effective than blocking, which is at odds with previous studies that consistently demonstrated a metacognitive preference of blocking. Our findings suggest that learners rely less on conventional beliefs about the effectivity of study sequence when dealing with unfamiliar (blindfolded) perceptual learning tasks. (shrink)

It is hoped that modern sensory substitution and augmentation devices will be able to replace or expand our senses. But to what extent has this been achieved to date? To what extent are the experiences created by sensory substitution devices like the sensory experiences that we are trying to replace? To what extent can we augment people’s senses providing them with new information and new experiences? The first aim of this introduction is to delve deeply (...) into this question to discover the usefulness of these devices, to outline the different sorts of experience that might be created, and what the evidence tells us about these experiences. While there are some reasons to be hopeful about the powers of sensory substitution devices, there are also reasons to wonder whether they will ever really have the practical applications that we hope they might have. The second aim is to look to see whether the study of modern sensory substitution and augmentation devices can shed light on the nature of our senses and perception in general. Much of the philosophical, psychological, and neuroscientific work that takes place concerning sensory substitution and augmentation is keenly aware of the possibility that it might help our understanding and it seeks to comprehend many different aspects of perception. (shrink)

Is the brain the biological substrate of consciousness? Most naturalistic philosophers of mind have supposed that the answer must obviously be «yes » to this question. However, a growing number of philosophers working in 4e (embodied, embedded, extended, enactive) cognitive science have begun to challenge this assumption, arguing instead that consciousness supervenes on the whole embodied animal in dynamic interaction with the environment. We call views that share this claim dynamic sensorimotor theories of consciousness (DSM). Clark (2009) a founder and (...) leading proponent of the hypothesis of the extended mind, demurs, arguing that as matter of fact the biology of consciousness doesn’t allow for a brain, body and world boundary crossing architecture. We begin by looking at one of the arguments for DSM, the variable neural correlates argument. We then outline two criticisms that Clark has made of this argument and endorse his criticisms. However we finish up by using the case of sensory substitution to argue that something of this argument for DSM nevertheless survives. We suggest that Clark ought to concede sensory substitution as a case in which the conscious mind extends. (shrink)

This report highlights and explores five questions that arose from the workshop on sensory substitution and augmentation at the British Academy, March 26th through 28th, 2013.

This is an excerpt from a report on the Sensory Substitution and Augmentation Conference at the British Academy in March of 2013. This portion of the report explores the question: Does sensory substitution generate perceptual or cognitive states?

This is an excerpt from a report on the Sensory Substitution and Augmentation Conference at the British Academy in March of 2013. This portion of the report explores the question: How does sensory substitution interact with the brain’s architecture?

Sensory substitution and augmentation devices are used to replace or enhance one sense by using another. Fiona Macpherson brings together neuroscientists, psychologists and philosophers to focus on the nature of the perceptual experiences, the sensory interactions, and the changes that occur in the mind and brain while using these technologies.

We experience our own body through both touch and vision. We further see that others’ bodies are similar to our own body, but we have no direct experience of touch on others’ bodies. Therefore, relations between vision and touch are important for the sense of self and for mental representation of one’s own body. For example, seeing the hand improves tactile acuity on the hand, compared to seeing a non-hand object. While several studies have demonstrated this visual enhancement (...) of touch effect, its relation to the ‘bodily self’, or mental representation of one’s own body remains unclear. We examined whether VET is an effect of seeing a hand, or of seeing my hand, using the rubber hand illusion. In this illusion, a prosthetic hand which is brushed synchronously—but not asynchronously—with one’s own hand is felt to actually be one’s hand. Thus, we manipulated whether or not participants felt like they were looking directly at their hand, while holding the actual stimulus they viewed constant. Tactile acuity was measured by having participants judge the orientation of square-wave gratings. Two characteristic effects of VET were observed: cross-modal enhancement from seeing the hand was inversely related to overall tactile acuity, and participants near sensory threshold showed significant improvement following synchronous stroking, compared to asynchronous stroking or no stroking at all. These results demonstrate a clear functional relation between the bodily self and basic tactile perception. (shrink)

This book argues that Kant's transcendental idealism has been misinterpreted: it denies not simply the super-sensory reality of space, time, and appearances, but their reality outside imagination as well. After adducing extensive and explicit textual evidence in its favor, Waxman shows this interpretation to be essential to the Transcendental Deduction, the affirmation of things in themselves, and the attempt to surmount Hume's scepticism. He further argues that Kant's much-neglected claim that, besides himself, "no psychologist has so much as even (...) thought that the imagination might be a necessary constituent of perception," should be construed so that even our consciousness of sensation itself (visual, tactile, etc.) is impossible without imagination. A compelling and original contribution to Kantian scholarship, Kant's Model of the Mind will also bear close examination by students and scholars of Hume, the philosophy of mind, and the philosophy of science. (shrink)

When subjects view stimulation of a rubber hand while feeling congruent stimulation of their own hand, they may come to feel that the rubber hand is part of their own body. This illusion of body ownership is termed ‘Rubber Hand Illusion’ . We investigated sensitivity of RHI to spatial mismatches between visual and somatic experience. We compared the effects of spatial mismatch between the stimulation of the two hands, and equivalent mismatches between the postures of the two hands. We (...) created the mismatch either by adjusting stimulation or posture of the subject’s hand, or, in a separate group of subjects, by adjusting stimulation or posture of the rubber hand. The matching processes underlying body ownership were asymmetrical. The illusion survived small changes in the subject’s hand posture, but disappeared when the same posture transformations were applied to the rubber hand. Mismatch between the stimulation delivered to the subject’s hand and the rubber hand abolished the illusion. The combination of these two situations is of particular interest. When the subject’s hand posture was slightly different from the rubber hand posture, the RHI remained as long as stimulation of the two hands was congruent in a hand-centred spatial reference frame, even though the altered posture of the subject’s hand meant that stimulation was incongruent in external space. Conversely, the RHI was reduced when the stimulation was incongruent in hand-centred space but congruent in external space. We conclude that the visual–tactile correlation that causes the RHI is computed within a hand-centred frame of reference, which is updated with changes in body posture. Current sensory evidence about what is ‘me’ is interpreted with respect to a prior mental body representation. (shrink)

Recent research has begun to investigate sensory processing in relation to nonclinical variation in traits associated with the autism spectrum disorders (ASD). We propose that existing accounts of autistic perception can be augmented by considering a role for individual differences in top-down expectations for the precision of sensory input, related to the processing of state-dependent levels of uncertainty. We therefore examined ASD-like traits in relation to the rubber-hand illusion: an experimental paradigm that typically elicits crossmodal integration of (...) class='Hi'>visual, tactile, and proprioceptive information in an unusual illusory context. Individuals with higher ASD-like traits showed reduced effects of the rubber-hand illusion on perceived arm position and reach-to-grasp movements, compared to individuals with lower ASD-like traits. These differences occurred despite both groups reporting the typical subjective experience of the illusion concerning visuotactile integration and ownership for the rubber hand. Together these results suggest that the integration of proprioceptive information with cues for arm position derived from the illusory context differs between individuals partly in relation to traits associated with ASD. We suggest that the observed differences in sensory integration can be best explained in terms of differing expectations regarding the precision of sensory estimates in contexts that suggest uncertainty. (shrink)

A refined characterisation of sensory substitution has, as a consequence, that the substituting sense plus sensory substitution device is not always appropriately classified as the substituted sense. As a result, I argue, acclimatisation to a sensory substitution device is plausibly thought of as providing presentations of properties. Externalist accounts of experience together with objectivist characterisations of such properties have the upshot that properties putatively proprietary to a sense modality can be presented in another modality (...) in cases of substitution. I consider three objections to this argument. I close by explaining how reflection on the phenomena of sensory substitution and, in particular, acclimatisation is important for the development of any kind of representationalist or relationist theory of phenomenal properties or, at the very least, suggests we need to refine the idea of certain properties - rather than particular ways in which their presentation is bundled together - being proprietary to the particular senses. (shrink)

This article reviews experimental evidence for a specific sensorimotor function which can be dissociated from higher level representations of space. It attempts to delineate this function on the basis of results obtained by psychophysical experiments performed with brain damaged and healthy subjects. Eye and hand movement control exhibit automatic features, such that they are incompatible with conscious control. In addition, they rely on a reference frame different from the one used by conscious perception. Neuropsychological cases provide a strong support for (...) this specific motor representation of space, which can be spared in patients with lesions of primary sensory systems who have lost conscious perception of visual, tactile or proprioceptive stimuli. Observation of these patients also showed that their motor behavior can be ''attracted'' by a goal only under specific conditions, that is, when the response is immediate and when no cognitive representation of this goal is elaborated at the same time. Beyond the issue of the dissociation between an implicit motor representation and more cognitive processing of spatial information, the issue of the interaction between these two systems is thus a matter of interest. It is suggested that the conscious, cognitive representation of a stimulus can contaminate or override the short-lived motor representation, but no reciprocal influence seem to occur. The interaction observed in patients can also be investigated in normals. The literature provides examples of interaction between sensorimotor and cognitive framing of space, which confirm that immediate action is not mediated by the same system as delayed action, and that elaborating a categorial representation of the action goal prevents the expression of the short-lived sensorimotor representation. It is concluded that action can be controlled by a sensory system which is specialized for on-line processing of relevant goal characteristics. The temporal constraints of this system are such that it can affect the action before a full sensory analysis of this goal has been completed. The performance obtained on the basis of this spatial sensory processing suggests that short-lived motor representations may rather be considered as real ''presentation'' of the action world, which share its metric properties. (shrink)

Sensory substitution devices provide through an unusual sensory modality (the substituting modality, e.g., audition) access to features of the world that are normally accessed through another sensory modality (the substituted modality, e.g., vision). In this article, we address the question of which sensory modality the acquired perception belongs to. We have recourse to the four traditional criteria that have been used to define sensory modalities: sensory organ, stimuli, properties, and qualitative experience (Grice, 1962), (...) to which we have added the criteria of behavioral equivalence (Morgan, 1977), dedication (Keeley, 2002), and sensorimotor equivalence (O’Regan & Noe¨, 2001). We discuss which of them are fulfilled by perception through sensory substitution devices and whether this favors the view that perception belongs to the substituting or to the substituted modality. Though the application of a number of criteria might be taken to point to the conclusion that perception with a sensory substitution device belongs to the substituted modality, we argue that the evidence leads to an alternative view on sensory substitution. According to this view, the experience after sensory substitution is a transformation, extension, or augmentation of our perceptual capacities, rather than being something equivalent or reducible to an already existing sensory modality. We develop this view by comparing sensory substitution devices to other ‘‘mind-enhancing tools’’ such as pen and paper, sketchpads, or calculators. An analysis of sensory substitution in terms of mind-enhancing tools unveils it as a thoroughly transforming perceptual experience and as giving rise to a novel form of perceptual interaction with the environment. (shrink)

Philosophical considerations as well as several recent studies from neurophysiology, neuropsychology, and psychophysics converged in showing that the peripersonal space is structured in a body-centred manner and represented through integrated sensory inputs. Multisensory representations may deserve the function of coding peripersonal space for avoiding or interacting with objects. Neuropsychological evidence is reviewed for dynamic interactions between space representations and action execution, as revealed by the behavioural effects that the use of a tool, as a physical extension of the reachable (...) space, produces on visual–tactile extinction. In particular, tool-use transiently modifies action space representation in a functionally effective way. The possibility is discussed that the investigation of multisensory space representations for action provides an empirical way to consider in its specificity pre-reflexive self-consciousness by considering the intertwining of self-relatedness and object-directness of spatial experience shaped by multisensory and sensorimotor integrations. (shrink)

Summary In this contribution, I discuss the perceptual potential of certain genres of experimental and contemporary music, commonly grouped under the label “sound-based music”. The sonic patterns typical of this music are mostly associated, during listening, with visual and tactile sensory qualities and can evoke mental representations as shapes in motion. These are the result of physical-acoustic energies organized according to a perceptual grammar whose organization follows a series of Gestalt and kinaesthetic principles. The paper explores the (...) nature of the relationship between sound patterns of sound-based music and their mental images. Based on morphodynamic theory, it is proposed the emergence of cognitive image schemas, which are at the centre of this relationship. The image schemas depict the forces and tensions of our experience of the world (e.g., figure-background, near-far, superimposition, compulsion, blockage), as being the cognitive and experiential response to the incoming sound patterns. The sense of this music activates precisely the basic structures of sensorimotor experience by which we encounter a world that we can understand and act within, leading to a rich series of high-level associations and responses. (shrink)