This paper proposed a novel tactile-stimuli P300 paradigm for Brain-Computer Interface, which potentially targeted at people with less learning ability or difficulty in maintaining attention. The new paradigm using only two types of stimuli was designed, and different targets were distinguished by frequency and spatial information. The classification algorithm was developed by introducing filters for frequency bands selection and conducting optimization with common spatial pattern on the tactile evoked EEG signals. It features a combination of spatial and frequency (...) information, with the spatial information distinguishing the sites of stimuli and frequency information identifying target stimuli and disturbances. We investigated both electrical stimuli and vibration stimuli, in which only one target site was stimulated in each block. The results demonstrated an average accuracy of 94.88% for electrical stimuli and 95.21% for vibration stimuli, respectively. (shrink)

This experiment used event-related potentials to study the tactile-visual information conflict processing in a tactile-visual pairing task and its modulation by tactile-induced emotional states. Eighteen participants were asked to indicate whether the tactile sensation on their body matched or did not match the expected tactile sensation associated with the object depicted in an image. The type of tactile-visual stimuli and the valence of tactile-induced emotional states were manipulated following a 2 × 2 factorial (...) design. Electrophysiological analyses revealed a mismatched minus matched negative difference component between 420 and 620 ms after stimulus onset in the negative tactile-induced emotional state condition. This ND420-620 component was considered as a sign of the cross-modal conflict processing during the processing of incongruent tactile-visual information. In contrast, no significant mismatched minus matched negative difference component was found in the positive tactile-induced emotional state condition. Together, these results support the hypothesis that a positive emotional state induced by a positive tactile stimulation improves tactile-visual conflict processing abilities. (shrink)

The rubber hand paradigm is used to create the illusion of self-touch, by having the participant administer stimulation to a prosthetic hand while the Examiner, with an identical stimulus , administers stimulation to the participant’s hand. With synchronous stimulation, participants experience the compelling illusion that they are touching their own hand. In the current study, the robustness of this illusion was assessed using incongruent stimuli. The participant used the index finger of the right hand to administer (...) class='Hi'>stimulation to a prosthetic hand while the Examiner used a paintbrush to administer stimulation to the participant’s left hand. The results indicate that this violation of tactile expectations does not diminish the illusion of self-touch. Participants experienced the illusion despite the use of incongruent stimuli, both when vision was precluded and when visual feedback provided clear evidence of the tactile mismatch. (shrink)

The prevalence of dementia is increasing with the ever-growing population of older adults. Non-pharmacological, music-based interventions, including sensory stimulation, were reported by the Lancet Commission in 2020 to be the first-choice approach for managing the behavioural and psychological symptoms of dementia. Low frequency sinusoidal vibration interventions, related to music interventions through their core characteristics, may offer relief for these symptoms. Despite increasing attention on the effectiveness of auditory music interventions and music therapy for managing dementia, this has not included (...) low frequency vibration. This scoping review, following the JBI methodology guidelines, was conducted to investigate participants’ responses to both sound and mechanical vibration, the characteristics of the delivered interventions, methodological challenges, and the specifics of the research experiments reported. An extensive search was conducted in BMC, CINAHL, Cochrane Central Register of Controlled Trials, EMBASE, ERIC, MEDLINE, Pedro, ProQuest Central, PsycINFO, Scopus, and Web of Science. Current Controlled Trials, Clinical Trials, and Google Scholar were also searched as well as a hand search in relevant journals. Studies on adults with all types of dementia, investigating tactile low frequency sound or mechanical vibration in any context were considered. Data from eight full-length studies were extracted using the data extraction table developed by the authors and were included in the analysis and critical appraisal. Issues in quality related to, for example, control groups and blinding. Few studies addressed participants’ subjective responses to the interventions. Reporting on the intervention characteristics was unclear. It appeared more frequent sessions led to better outcomes and home-based interventions potentially addressing the issue of access and feasibility. Future research should include neuroimaging to measure and confirm the hypothesised mechanism of cerebral coherence. Standardised reporting of intervention characteristics is also needed to ensure replicability of the experiments. Higher quality research is needed to investigate the impact and effect of low frequency vibration for the symptoms of dementia and compare outcomes in meta-syntheses. (shrink)

The rubber hand paradigm is used to create the illusion of self-touch, by having the participant administer stimulation to a prosthetic hand while the Examiner, with an identical stimulus, administers stimulation to the participant’s hand. With synchronous stimulation, participants experience the compelling illusion that they are touching their own hand. In the current study, the robustness of this illusion was assessed using incongruent stimuli. The participant used the index finger of the right hand to administer stimulation (...) to a prosthetic hand while the Examiner used a paintbrush to administer stimulation to the participant’s left hand. The results indicate that this violation of tactile expectations does not diminish the illusion of self-touch. Participants experienced the illusion despite the use of incongruent stimuli, both when vision was precluded and when visual feedback provided clear evidence of the tactile mismatch. (shrink)

Psychophysical experiments have demonstrated large and highly systematic perceptual distortions of tactile space. Such a space can be referred to our experience of the spatial organisation of objects, at representational level, through touch, in analogy with the familiar concept of visual space. We investigated the neural basis of tactile space by analysing activity patterns induced by tactile stimulation of nine points on a 3 × 3 square grid on the hand dorsum using functional magnetic resonance imaging. (...) We used a searchlight approach within pre-defined regions of interests to compute the pairwise Euclidean distances between the activity patterns elicited by tactile stimulation. Then, we used multidimensional scaling to reconstruct tactile space at the neural level and compare it with skin space at the perceptual level. Our reconstructions of the shape of skin space in contralateral primary somatosensory and motor cortices reveal that it is distorted in a way that matches the perceptual shape of skin space. This suggests that early sensorimotor areas critically contribute to the distorted internal representation of tactile space on the hand dorsum. (shrink)

Purpose: Sensory feedback for prosthetics is an important issue. The area of forearm stump skin that has evoked tactile sensation of fingers is defined as the projected finger map, and the area close to the PFM region that does not have ETS is defined as the non-projected finger map. Previous studies have confirmed that ETS can restore the tactile pathway of the lost finger, which was induced by stimulation of transcutaneous electrical nerve stimulation on the end (...) of stump skin. This study aims to reveal EEG features between the PFM and the NPFM regions of the stumps under the same TENS stimulation condition.Methods: The PFM and NPFM regions of the two subjects were stimulated with the same intensity of TENS, respectively. TENS as target stimuli are modulated according to the Oddball paradigm to evoke the P300 components.Result: The PFM regions of both subjects were able to elicit P300 components, while their NPFM regions were not able to elicit P300 components. However, this P300 appears early and has continuous positive peaks in front of it.Discussion: N30 and P300 can prove that the two subjects with PFM can perceive and recognize ETS. The heteromorphisms of the P300 waveform may be related to the difficulty in subjects’ cognition of ETS or caused by the fusion of P150, P200, and P300. (shrink)

Les résultats quantitatifs que la psychologie et la physiologie n'ont cessé d'accumuler depuis le début du siecle à propos du sens tactile laissent apparaître aujourd'hui une certaine ambiguïteé. D'un côté en effet, la préoccupation de connaître les sensibilities cutanées spécifiques telles qu'elles se présentent de manière isolée à l'analyse objective des récepteurs stimulés: les sensations de chaud et de froid, de pression et de contact, de douleur, de vibration. D'un autre côté, le désir de sauvegarder l'unité fonctionnelle du sens (...) tactile c.a.d. sa spécificité propre par rapport aux quatre autres sens traditionnels. Ainsi, par exemple, une analyse neurophysiologique des récepteurs tactiles5 ne manque pas de mentionner plusieurs catégories fonctionnelles de la sensibilité cutanée: la douleur, comme signal d'un danger qui peut menacer l'existence de l'organisme; la perception des qualités d'un objet, comme intégration du toucher et de la kinesthésie au cours d'une exploration active de la main; les expériences somatiques complexes telles que le chatouillement et les sensations sexuelles. Pour le phénoménologue, un tel compromis s'apparente à une confusion et provient des positions épistémologiques qui ont animé l'orientation méthodologique des recherches, depuis la psychophysiologie mécaniste jusqu'à la psychologie cybernétique de l'information sensorielle. En cela, la domaine de la sensation tactile reste l'apanage de la psychophysique, et nous tenterons de clarifier pourquoi cette position ne peut aboutir qu'à des résultats problématiques. A partir d'une psychologie anthropologique du sens tactile,14 nous défendrons l'idée d'une psychologie comparée qui permettrait une investigation empirique, objective des comportements animaux, sur la base de prolégomènes phénoménologiques. (shrink)

Human adaptive behavior in sensorimotor control is aimed to increase the confidence in feedforward mechanisms when sensory afferents are uncertain. It is thought that these feedforward mechanisms rely on predictions from internal models. We investigate whether the brain uses an internal model of physical laws to help estimate body equilibrium when tactile inputs from the foot sole are depressed by carrying extra weight. As direct experimental evidence for such a model is limited, we used Judoka athletes thought to have (...) built up internal models of external loads as compared with Non-Athlete participants and Dancers. Using electroencephalography, we first tested the hypothesis that the influence of tactile inputs was amplified by descending cortical efferent signals. We compared the amplitude of P1N1 somatosensory cortical potential evoked by electrical stimulation of the foot sole in participants standing still with their eyes closed. We showed smaller P1N1 amplitudes in the Load compared to No Load conditions in both Non-Athletes and Dancers. This decrease neural response to tactile stimulation was associated with greater postural oscillations. By contrast in the Judoka’s group, the neural early response to tactile stimulation was unregulated in the Load condition. This suggests that the brain can selectively increase the functional gain of sensory inputs, during challenging equilibrium tasks when tactile inputs were mechanically depressed by wearing a weighted vest. In Judokas, the activation of regions such as the right posterior inferior parietal cortex as early as the P1N1 is likely the source of the neural responses being maintained similar in both Load and No Load conditions. An overweight internal model stored in the right PPC known to be involved in maintaining a coherent representation of one’s body in space can optimize predictive mechanisms in situations with high balance constraints. This hypothesis has been confirmed by showing that postural reaction evoked by a translation of the support surface on which participants were standing wearing extra-weight was improved in Judokas. (shrink)

Artificial stimulation of the peripheral vestibular system has been shown to improve ownership of body parts in neurological patients, suggesting vestibular contributions to bodily self-consciousness. Here, we investigated whether galvanic vestibular stimulation interferes with the mechanisms underlying ownership, touch, and the localization of one’s own hand in healthy participants by using the “rubber hand illusion” paradigm. Our results show that left anodal GVS increases illusory ownership of the fake hand and illusory location of touch. We propose that these (...) changes are due to vestibular interference with spatial and/or temporal mechanisms of visual-tactile integration leading to an enhancement of visual capture. As only left anodal GVS lead to such changes, and based on neurological data on body part ownership, we suggest that this vestibular interference is mediated by the right temporo-parietal junction and the posterior insula. (shrink)

BackgroundDuring the course of a previous study, our laboratory made a serendipitous finding that just thinking about genital stimulation resulted in brain activations that overlapped with, and differed from, those generated by physical genital stimulation.ObjectiveThis study extends our previous findings by further characterizing how the brain differentially processes physical ‘touch’ stimulation and ‘imagined’ stimulation.DesignEleven healthy women participated in an fMRI study of the brain response to imagined or actual tactile stimulation of the nipple and (...) clitoris. Two additional conditions – imagined dildo self-stimulation and imagined speculum stimulation – were included to characterize the effects of erotic versus non-erotic imagery.ResultsImagined and tactile self-stimulation of the nipple and clitoris each activated the paracentral lobule and the secondary somatosensory cortex. Imagined self-stimulation of the clitoris and nipp... (shrink)

We examined the neural basis of tactile distance perception by analyzing activity patterns induced by tactile stimulation of nine points on a 3 x 3 square grid on the hand dorsum using functional magnetic resonance (fMRI). We used a searchlight approach within pre-defined regions of interests (ROIs) to compute the pairwise Euclidean distances between the activity patterns elicited by tactile stimulation. Then, we used multidimensional scaling (MDS) to reconstruct skin space at the neural level and (...) compare it with skin space at the perceptual level. Our reconstructions of the shape of skin space in contralateral primary somatosensory (SI) and motor (M1) cortices reveal that it is distorted in a way that matches the perceptual shape of skin space. This suggests that early sensorimotor areas are critical to processing tactile distance perception. (shrink)

Obsessive-compulsive disorder (OCD) is a deeply enigmatic psychiatric condition associated with immense suffering worldwide. Efficacious therapies for OCD, like exposure and response prevention (ERP) are sometimes poorly tolerated by patients. As many as 25 percent of patients refuse to initiate ERP mainly because they are too anxious to follow exposure procedures. Accordingly, we proposed a simple and tolerable (immersive yet indirect) low-cost technique for treating OCD that we call “multisensory stimulation therapy.” This method involves contaminating a rubber hand during (...) the so-called “rubber hand illusion” (RHI) in which tactile sensations may be perceived as arising from a fake hand. Notably, Jalal and Ramachandran (2015), showed that such fake hand contamination during the RHI provokes powerful disgust reactions in healthy volunteers. In the current study, we explored the therapeutic potential of this novel approach. OCD patients (n = 29) watched as their hidden real hand was being stroked together with a visible fake hand; either synchronously (inducing the RHI) (i.e., the experimental condition; n = 16) or asynchronously (i.e., the control condition; n = 13). After 5 minutes of tactile stimulation, the rubber hand was contaminated with fake feces, simulating conventional exposure therapy. Intriguingly, results suggested sensory assimilation of contamination sensations into the body image via the RHI: patients undergoing synchronous stimulation did not report greater contamination sensations when the fake hand was initially contaminated relative to asynchronous stroking. But contrary to expectations, they did so after the rubber hand had been contaminated for 5 minutes; as assessed via disgust facial expressions (a secondary outcome) and in vivo exposure (upon discontinuing the illusion). Further to our surprise, synchronous and asynchronous stroking induced an equally vivid and fast emerging illusion, which helps explain why both conditions initially (5 minutes after initiating tactile stimulation) provoked contamination reactions of equal magnitude. This study is the first to suggest heightened malleability of body image in OCD. Importantly, it may pave the way for a tolerable technique for the treatment of OCD—highly suitable for poorly resourced and emergency settings, including low-income and developing countries with minimal access to high-tech solutions like virtual reality. (shrink)

Reduced Environmental Stimulation Therapy (REST) alters the balance of sensory input to the nervous system by systematically attenuating sensory signals from visual, auditory, thermal, tactile, vestibular, and proprioceptive channels. Previous research from our group has shown that REST via floatation acutely reduces anxiety and blood pressure while simultaneously heightening interoceptive awareness in clinically anxious populations. Anorexia nervosa (AN) is an eating disorder characterized by elevated anxiety, distorted body representation, and abnormal interoception, raising the question of whether REST might (...) positively impact these symptoms. However, this approach has never been studied in eating disorders and it is unknown whether exposure to REST might worsen AN symptoms. To examine these possibilities we conducted an open-label study to investigate the safety and tolerability of REST in AN. We also explored the impact of REST on affective symptoms, body image disturbance, and interoception. Twenty-one partially weight-restored AN outpatients completed a protocol involving four sequential sessions of REST: reclining in a zero-gravity chair, floating in an open pool, and two sessions of floating in an enclosed pool. All sessions were 90 minutes, approximately one week apart. We measured orthostatic blood pressure before and immediately after each session (primary outcome), in addition to collecting blood pressure readings every 10 minutes during the session using a wireless waterproof system as a secondary outcome measure. Each participant's affective state, awareness of interoceptive sensations, and body image was assessed before and after every session (exploratory outcomes). There was no evidence of orthostatic hypotension following floating, and no adverse events (primary outcome). Secondary analyses revealed that REST induced statistically significant reductions in blood pressure, anxiety and negative affect, heightened awareness of cardiorespiratory but not gastrointestinal sensations, and reduced body image dissatisfaction. The findings from this initial trial suggest that individuals with AN can safely tolerate the physical effects of REST via floatation. Future randomized controlled trials will need to investigate whether these initial observations of improved anxiety, interoception, and body image disturbance can be effectively extended to acutely ill AN populations. (shrink)

Self-produced tactile stimulation usually feels less tickly—is perceptually attenuated—relative to the same stimulation produced externally. This is not true, however, for individuals with schizophrenia. Here, we investigate whether the lack of attenuation to self-produced stimuli seen in schizophrenia also occurs for normal participants following REM dreams. Fourteen participants were stimulated on their left palm with a tactile stimulation device which allowed the same stimulus to be generated by the participant or by the experimenter. The level (...) of self-tickling attenuation did not differ between REM and non-REM sleep awakening conditions, where presence or absence of an accompanying dream was not controlled for. However, for the female participants, when awakening occurred from an REM sleep dream, self-stimulation ratings were higher than for external stimulation, whereas ratings after NREM sleep unaccompanied by a dream were lower for self-stimulation than for external stimulation. These results indicate deficits in self-monitoring and a confusion between self- and externally generated stimulation accompany REM dream formation. (shrink)

An increasing number of research teams are investigating the efficacy of brain-computer interface (BCI)-mediated interventions for promoting motor recovery following stroke. A growing body of evidence suggests that of the various BCI designs, most effective are those that deliver functional electrical stimulation (FES) of upper extremity (UE) muscles contingent on movement intent. More specifically, BCI-FES interventions utilize algorithms that isolate motor signals—user-generated intent-to-move neural activity recorded from cerebral cortical motor areas—to drive electrical stimulation of individual muscles or muscle (...) synergies. BCI-FES interventions aim to recover sensorimotor function of an impaired extremity by facilitating and/or inducing long-term motor learning-related neuroplastic changes in appropriate control circuitry. We developed a non-invasive, electroencephalogram (EEG)-based BCI-FES system that delivers closed-loop neural activity-triggered electrical stimulation of targeted distal muscles while providing the user with multimodal sensory feedback. This BCI-FES system consists of three components: (1) EEG acquisition and signal processing to extract real-time volitional and task-dependent neural command signals from cerebral cortical motor areas, (2) FES of muscles of the impaired hand contingent on the motor cortical neural command signals, and (3) multimodal sensory feedback associated with performance of the behavioral task, including visual information, linked activation of somatosensory afferents through intact sensorimotor circuits, and electro-tactile stimulation of the tongue. In this report, we describe device parameters and intervention protocols of our BCI-FES system which, combined with standard physical rehabilitation approaches, has proven efficacious in treating UE motor impairment in stroke survivors, regardless of level of impairment and chronicity. (shrink)

We investigated how motor agency in the voluntary control of body movement influences body awareness. In the Rubber Hand Illusion , synchronous tactile stimulation of a rubber hand and the participant’s hand leads to a feeling of the rubber hand being incorporated in the participant’s own body. One quantifiable behavioural correlate of the illusion is an induced shift in the perceived location of the participant’s hand towards the rubber hand. Previous studies showed that the induced changes in body (...) awareness are local and fragmented: the proprioceptive drift is largely restricted to the stimulated finger. In the present study, we investigated whether active and passive movements, rather than tactile stimulation, would lead to similarly fragmented body awareness. Participants watched a projected image of their hand under three conditions: active finger movement, passive finger movement, and tactile stimulation. Visual feedback was either synchronous or asynchronous with respect to stimulation of the hand. A significant overall RHI, defined as greater drifts following synchronous than asynchronous stimulation, was found in all cases. However, the distribution of the RHI across stimulated and non-stimulated fingers depended on the kind of stimulation. Localised proprioceptive drifts, specific to the stimulated finger, were found for tactile and passive stimulation. Conversely, during active movement of a single digit, the proprioceptive drifts were not localised to that digit, but were spread across the whole hand. Whereas a purely proprioceptive sense of body-ownership is local and fragmented, the motor sense of agency integrates distinct body-parts into a coherent, unified awareness of the body. (shrink)

Objects are central to perception and our interactions with the world. We perceive the world as parsed into discrete entities that instantiate particular properties, and these items capture our attention and shape how we interact with the environment. Recently there has been some debate about whether the sense of smell allows us to perceive odours as discrete objects, with some suggesting that olfaction is aspatial and doesn’t allow for object-individuation. This paper offers two empirically tractable criteria for assessing whether particular (...) objects are exhibited in perceptual experience— susceptibility to figure-ground segregation and perceptual constancies—and argues that these criteria are fulfilled by olfactory perception, and thus there are olfactory objects. I argue that there are, in fact, two different ways that olfaction allows for figure-ground segregation. First, I look at various Gestalt grouping principles, which are thought to govern when features are perceived as grouped into structured wholes, segregated from everything around them. I argue that these principles apply to olfactory experience, providing evidence of non-spatial figure-ground segregation. Second, I defend the contentious idea that a spatial variety of figure-ground segregation can also occur in olfaction. To see this, however, we need to look to empirical evidence showing that tactile stimulation and bodily movements play a crucial role in olfactory phenomenology. Finally, I draw on empirical evidence and olfactory phenomenology to argue that there are perceptual constancies in olfactory experience, allowing us to perceive odours as coherent objects that survive shifts in our perspectives on the world. (shrink)

In rubber hand illusions and full body illusions, touch sensations are projected to non-body objects such as rubber hands, dolls or virtual bodies. The robustness, limits and further perceptual consequences of such illusions are not yet fully explored or understood. A number of experiments are reported that test the limits of a variant of the rubber hand illusion. Methodology/Principal Findings -/- A variant of the rubber hand illusion is explored, in which the real and foreign hands are aligned in personal (...) space. The presence of the illusion is ascertained with participants' scores and temperature changes of the real arm. This generates a basic illusion of touch projected to a foreign arm. Participants are presented with further, unusual visuotactile stimuli subsequent to onset of the basic illusion. Such further visuotactile stimulation is found to generate very unusual experiences of supernatural touch and touch on a non-hand object. The finding of touch on a non-hand object conflicts with prior findings, and to resolve this conflict a further hypothesis is successfully tested: that without prior onset of the basic illusion this unusual experience does not occur. Conclusions/Significance -/- A rubber hand illusion is found that can arise when the real and the foreign arm are aligned in personal space. This illusion persists through periods of no tactile stimulation and is strong enough to allow very unusual experiences of touch felt on a cardboard box and experiences of touch produced at a distance, as if by supernatural causation. These findings suggest that one's visual body image is explained away during experience of the illusion and they may be of further importance to understanding the role of experience in delusion formation. The findings of touch on non-hand objects may help reconcile conflicting results in this area of research. In addition, new evidence is provided that relates to the recently discovered psychologically induced temperature changes that occur during the illusion. (shrink)

Merging the information from different senses is essential for successful interaction with real-life situations. Indeed, sensory integration can reduce perceptual ambiguity, speed reactions, or change the qualitative sensory experience. It is widely held that integration occurs at later processing stages and mostly in higher association cortices; however, recent studies suggest that sensory convergence can occur in primary sensory cortex. A good model for early convergence proved to be the auditory cortex, which can be modulated by visual and tactile (...) class='Hi'>stimulation; however, given the large number and small size of auditory fields, neither human imaging nor microelectrode recordings have systematically identified which fields are susceptible to multisensory influences. To reconcile findings from human imaging with anatomical knowledge from nonhuman primates, we exploited high-resolution imaging (functional magnetic resonance imaging) of the macaque monkey to study the modulation of auditory processing by visual stimulation. Using a functional parcellation of auditory cortex, we localized modulations to individual fields. Our results demonstrate that both primary (core) and nonprimary (belt) auditory fields can be activated by the mere presentation of visual scenes. Audiovisual convergence was restricted to caudal fields [prominently the core field (primary auditory cortex) and belt fields (caudomedial field, caudolateral field, and mediomedial field)] and continued in the auditory parabelt and the superior temporal sulcus. The same fields exhibited enhancement of auditory activation by visual stimulation and showed stronger enhancement for less effective stimuli, two characteristics of sensory integration. Together, these findings reveal multisensory modulation of auditory processing prominently in caudal fields but also at the lowest stages of auditory cortical processing. (shrink)

Recent studies of the rubber hand illusion (RHI) have shown that the sense of body ownership is constrained by several factors and yet is still very flexible. However, exactly how flexible is our sense of body ownership? In this study, we address this issue by investigating the following question: is it possible that one may have the illusory experience of owning four hands? Under visual manipulation, the participant adopted the experimenter’s first-person perspective (1PP) as if it was his/her own. Sitting (...) face to face, the participant saw four hands—the experimenter’s two hands from the adopted 1PP together with the subject’s own two hands from the adopted third-person perspective (3PP). We found that: (1) the four-hand illusion did not occur in the passive four-hand condition. (2) In the active four-hand condition, the participants tapped their index fingers, imitated by the experimenter. When tactile stimulations were not provided, the key illusion was not induced, either. (3) Strikingly, once all four hands began to act with the same pattern and received synchronous tactile stimulations at the same time, many participants felt as if they had two more hands. These results show that the sense of body ownership is much more flexible than most researchers have suggested. (shrink)

Body ownership concerns what it is like to feel a body part or a full body as mine, and has become a prominent area of study. We propose that there is a closely related type of bodily self-consciousness largely neglected by researchers—experiential ownership. It refers to the sense that I am the one who is having a conscious experience. Are body ownership and experiential ownership actually the same phenomenon or are they genuinely different? In our experiments, the participant watched a (...) rubber hand or someone else’s body from the first-person perspective and was touched either synchronously or asynchronously. The main findings: (1) The sense of body ownership was hindered in the asynchronous conditions of both the body-part and the full-body experiments. However, a strong sense of experiential ownership was observed in those conditions. (2) We found the opposite when the participants’ responses were measured after tactile stimulations had ceased for 5 s. In the synchronous conditions of another set of body-part and full-body experiments, only experiential ownership was blocked but not body ownership. These results demonstrate for the first time the double dissociation between body ownership and experiential ownership. Experiential ownership is indeed a distinct type of bodily self-consciousness. (shrink)

To form a coherent percept of the environment, our brain combines information from different senses. Such multisensory integration occurs in higher association cortices; but supposedly, it also occurs in early sensory areas. Confirming the latter hypothesis, we unequivocally demonstrate supra-additive integration of touch and sound stimulation at the second stage of the auditory cortex. Using high-resolution fMRI of the macaque monkey, we quantified the integration of auditory broad-band noise and tactile stimulation of hand and foot in anaesthetized (...) animals. Integration was found posterior to and along the lateral side of the primary auditory cortex in the caudal auditory belt. Integration was stronger for temporally coincident stimuli and obeyed the principle of inverse effectiveness: greater enhancement for less effective stimuli. These findings demonstrates that multisensory integration occurs early and close to primary sensory areas and—because it occurs in anaesthetized animals—suggests that this integration is mediated by preattentive bottom-up mechanisms. (shrink)

This study investigated the effect of stroking vs. simple human presence on later reactions of dairy cows to routine veterinary handling. While in two groups of cows the experimenter stroked the ventral part of the neck or the withers for three consecutive weeks, the third group was exposed to close visual presence. After the treatment period the cows were subjected to rectal palpation. The three groups differed significantly in stepping during rectal palpation, which occurred less often in Neck- and Withers-animals (...) than in control animals. Heart rate increase was significantly higher in the control group than in the two stroking groups. Previous stroking led to fewer stress reactions during the rectal palpation, possibly due to a combined effect of improved relationship towards and thus perception of humans and lasting anti-stress effects of tactile stimulation. (shrink)

Self-location—the sense of where I am in space—provides an experiential anchor for one's interaction with the environment. In the studies of full-body illusions, many researchers have defined self-location solely in terms of body-location—the subjective feeling of where my body is. Although this view is useful, there is an issue regarding whether it can fully accommodate the role of 1PP-location—the sense of where my first-person perspective is located in space. In this study, we investigate self-location by comparing body-location and 1PP-location: using (...) a head-mounted display (HMD) and a stereo camera, the subjects watched their own body standing in front of them and received tactile stimulations. We manipulated their senses of body-location and 1PP-location in three different conditions: the participants standing still (Basic condition), asking them to move forward (Walking condition), and swiftly moving the stereo camera away from their body (Visual condition). In the Walking condition, the participants watched their body moving away from their 1PP. In the Visual condition, the scene seen via the HMD was systematically receding. Our data show that, under different manipulations of movement, the spatial unity between 1PP-location and body-location can be temporarily interrupted. Interestingly, we also observed a “double-body effect.” We further suggest that it is better to consider body-location and 1PP-location as interrelated but distinct factors that jointly support the sense of self-location. (shrink)

This study investigated the effect of stroking vs. simple human presence on later reactions of dairy cows to routine veterinary handling. While in two groups of cows the experimenter stroked the ventral part of the neck or the withers for three consecutive weeks, the third group was exposed to close visual presence. After the treatment period the cows were subjected to rectal palpation. The three groups differed significantly in stepping during rectal palpation, which occurred less often in Neck- and Withers-animals (...) than in control animals. Heart rate increase was significantly higher in the control group than in the two stroking groups. Previous stroking led to fewer stress reactions during the rectal palpation, possibly due to a combined effect of improved relationship towards and thus perception of humans and lasting anti-stress effects of tactile stimulation. Keywords: cattle; tactile stimulation; human–animal relationship; animal welfare. (shrink)

In a recent study (Chen et al., 2018), we conducted a series of experiments that induced the “four-hand illusion”: using a head-mounted display (HMD), the participant adopted the experimenter’s first-person perspective (1PP) as if it was his/her own 1PP. The participant saw four hands via the HMD: the experimenter’s two hands from the adopted 1PP and the subject’s own two hands from the adopted third-person perspective (3PP). In the active four-hand condition, the participant tapped his/her index fingers, imitated by the (...) experimenter. Once all four hands acted synchronously and received synchronous tactile stimulations at the same time, many participants felt as if they owned two more hands. In this paper, we argue that there is a philosophical implication of this novel illusion. According to Merleau-Ponty (1945/1962) and Legrand (2010), one can experience one’s own body or body-part either as-object or as-subject but cannot experience it as both simultaneously, i.e., these two experiences are mutually exclusive. Call this view the Experiential Exclusion Thesis. We contend that a key component of the four-hand illusion—the subjective experience of the 1PP-hands that involved both “kinesthetic sense of movement” and “visual sense of movement” (the movement that the participant sees via the HMD)—provides an important counter-example against this thesis. We argue that it is possible for a healthy subject to experience the same body-part both as-subject and as-object simultaneously. Our goal is not to annihilate the distinction between body-as-object and body-as-subject, but to show that it is not as rigid as suggested by the phenomenologists. (shrink)

Upshot: In the model simulation and the human experiment, we observed that attention shifted from a tool to a task. This was accompanied by bodily extension. However, our experiments lack a sense of bodily incorporation (the sense of ownership. Based on the valuable commentaries, we would like to discuss the necessary conditions for possible bodily incorporation in terms of redundant degrees of freedom, synchronous visual tactile stimulation, and 1/f noise.

Differences in infant caregiving behavior between cultures have long been noted, although the quantified comparison of touch-based caregiving using uniform standardized methodology has been much more limited. The Parent-Infant Caregiving Touch scale was developed for this purpose and programming effects of early parental tactile stimulation on infant hypothalamic-pituitary adrenal -axis functioning, cardiovascular regulation and behavioral outcomes, similar to that reported in animals, have now been demonstrated. In order to inform future studies examining such programming effects in India, we (...) first aimed to describe and examine, using parametric and non-parametric item-response methods, the item-response frequencies and characteristics of responses on the PICTS, and evidence for cross-cultural differential item functioning in the United Kingdom and India. Second, in the context of a cultural favoring of male children in India, we also aimed to test the association between the sex of the infant and infant “stroking” in both cultural settings. The PICTS was administered at 8–12 weeks postpartum to mothers in two-cohort studies: The Wirral Child Health and Development Study, United Kingdom and the Bangalore Child Health and Development Study, India. Mokken scale analysis, parametric item-response analysis, and structural equation modeling for categorical items were used. Items for two dimensions, one for stroking behavior and one for holding behavior, could be identified as meeting many of the criteria required for Mokken scales in the United Kingdom, only the stroking scale met these criteria in the sample from India. Thus, while a comparison between the two cultures was possible for the stroking construct, comparisons for the other non-verbal parenting constructs within PICTS were not. Analyses revealed higher rates of early stroking being reported for the United Kingdom than India, but no sex differences in rates in either country and no differential sex difference by culture. We conclude that PICTS items can be used reliably in both countries to conduct further research on the role of early tactile stimulation in shaping important child development outcomes. (shrink)

The image of a copy of Praxiteles’ Aphrodite—nude but demurely shielding her pubic region—which adorns the dust cover of Pearson’s superb monograph, Aristotle on Desire</i>), suggests to the casual book buyer that the volume encased therein will explain Aristotle’s thoughts about sexual desire—perhaps as a central part or the paradigm case of his general theory of desire. But the goddess likes being tricky: Aristotle has very little to say about sexual desire (at best it is a subcategory of <i>epithumia</i>, set (...) alongside the desires for eating and drinking and reduced to tactile stimulation), and it is not immediately apparent that he possesses a general theory or account of desire. No doubt, Aristotle discusses many aspects of <i>orexis</i> (Aristotle’s general term for desire) in relationship to human action, in his consideration of the rhetorical manipulation of the emotions, and in his examination of animate motion. But as Pearson notes, neither in Aristotle’s catalog of writings nor in his surviving works is there an Aristotelian <i>peri orexeôs</i>. Pearson’s monograph, which is the “distant descendant” of a Ph.D. completed at Cambridge in 2004, thus is an exercise in detective work which combs through Aristotle’s discussions of desire throughout the corpus (albeit with focus on the ethical treatises, the <i>Rhetoric</i>, and <i>De Anima</i>) in order to reconstruct what a general theory of desire would look like for Aristotle. Pearson does a masterful job at drawing together into a coherent whole many of Aristotle’s scattered remarks about the different aspects of desire and provides a model for textual analysis of philosophically abstruse passages. Along the way, he overturns a number of scholarly orthodoxies (for instance, that Aristotle’s account of <i>thumos</i> retains elements of Platonic <i>thumos</i> or “spiritedness” or that <i>thumos</i> has a unique relationship to the <i>kalon</i> or what is fine) and situates Aristotle’s theory amidst contemporary philosophers of desire such as Thomas Nagle, Thomas Scanlon, and G.F. Schuler. The result is a landmark work of scholarship that scholars working on Aristotle’s moral psychology will need to engage and argue with. Whether the work warrants the adornment of Aphrodite is a question to which I will return in my conclusion. (shrink)

Tactile perception is often impaired during movement. The present study investigated whether such sensory suppression also occurs during back movements, and whether this would be modulated by attention. In two tactile detection experiments, participants simultaneously engaged in a movement task, in which they executed a back-bending movement, and a perceptual task, consisting of the detection of subtle tactile stimuli administered to their upper or lower back. The focus of participants’ attention was manipulated by raising the probability that (...) one of the back locations would be stimulated. The results revealed that tactile detection was suppressed during the execution of the back movements. Furthermore, the results of Experiment 2 revealed that when the stimulus was always presented to the attended location, tactile suppression was substantially reduced, suggesting that sensory suppression can be modulated by top-down attentional processes. The potential of this paradigm for studying tactile information processing in clinical populations is discussed. (shrink)