A unity of the self or a multiplicity of locations? How the graphesthesia task sheds light on the role of spatial perspectives in bodily self-consciousness

Somatosensory and dynamic balance improvement in older adults with diabetic peripheral neuropathy through sensorimotor exercise: A multisite randomized controlled trial

PURPOSE

To examine the effect of the Feldenkrais method on lower legs and foot somatosensory postural control-related function, dynamic balance, fear of falling and quality of life in adults with diabetic polyneuropathy in the short and mid-term.

METHODS

A single-blinded, parallel, multicentric randomized control trial was conducted in two health hospitals. Subjects with diabetic polyneuropathy and older than 55 years with a history of falls or dynamic balance dysfunction were recruited from the hospital databases and randomly allocated to the experimental or control group. The experimental group received 16 sessions of sensorimotor training based on the Feldenkrais method. Both groups received diabetic foot care instructions. The results were measured at the 3 and 6-month follow-up periods.

RESULTS

The mean age was 70 ± 8. A total of 44 participants were enrolled in the study, and 27 completed the process. No adverse events were reported. After the intervention, significant somatosensory results were obtained (p < 0.001). The results of the Up and Go and POMA tests were significant after the intervention (p < 0.001) and during the 3-month follow-up period for POMA (p = 0.018). The fear of falling showed significant results at the 3-month follow-up period (p = 0.03), and the quality of life in all measurements.

CONCLUSIONS

Significant short-term effects were obtained on somatosensory postural control-related function, dynamic balance, and fear of falling. Significant short and mid-term effects were achieved on quality of life. Older adults with diabetic polyneuropathy, dynamic balance impairment, or a history of falls can improve their abilities through the Feldenkrais method.

TRIAL REGISTRATION

Clinicaltrials.gov: NCT05262946.

Three key questions to move towards a theoretical framework of visuospatial perspective taking

What would a theory of visuospatial perspective taking (VSPT) look like? Here, ten researchers in the field, many with different theoretical viewpoints and empirical approaches, present their consensus on the three big questions we need to answer in order to bring this theory (or these theories) closer.

Interoceptive abilities facilitate taking another's spatial perspective

Information can be perceived from a multiplicity of spatial perspectives, which is central to effectively understanding and interacting with our environment and other people. Interoception, the sense of the physiological state of our body, is also a fundamental component contributing to our perception. However, whether the perception of our inner body signals influences our ability to adopt and flexibly change between different spatial perspectives remains poorly understood. To investigate this, 90 participants completed tasks assessing multiple dimensions of interoception (interoceptive sensibility, cardiac interoceptive accuracy and awareness) and the Graphesthesia task to assess tactile spatial perspective-taking and its flexibility. The results revealed that higher cardiac interoceptive awareness is associated with greater consistency in adopting a perspective decentred from the self. Second, higher cardiac interoceptive accuracy was associated with slower and less accurate performance in switching from a decentred to an egocentred perspective. These results show that interoceptive abilities facilitate decentred spatial perspective-taking, likely reflecting stronger perceived boundaries between internal states and the external world.

Sensory Perception Mechanism for Preparing the Combinations of Stimuli Operation in the Architectural Experience

Sensory stimuli in an architectural space play an important role in the human perception of the indoor environment, no matter whether they are static or dynamic, isolated, or combined. By enhancing some perceptions in the sensory stimuli, the overall perceptions of an architectural space can be improved, especially for an intelligent architectural space. As yet, there are few studies reported about the sensory perception mechanism for the sensory stimuli operation in the architectural experience. In this research, a wooden micro building was prepared for the study of the sensitivity level of participants to various sensory stimuli in the same and in different sensory domains. Participants’ visual, auditory, olfactory, tactile and kinaesthesia perceptions were discussed statistically in terms of the sensitivity level. Based on the study, the effect of a single dynamic sensory stimulus (a dynamically coloured light) on the participants’ perception was studied in a paper architectural model from two aspects including preference and emotion. The dynamically coloured light was discussed statistically in terms of the level of preference. The study showed that there are significant differences among participants’ levels of sensitivity to the different sensory domains and to the different sensory stimuli. In particular, the sensitivity level to the stimulus that is the colour of a space is the highest of all stimuli. As a single changing sensory stimulus, a dynamically coloured light can lead to significant mood fluctuations and changes in the preference level. In particular, yellow is the favourite colour of light. The object of this study is expected to provide a theoretical foundation that is related to sensory choice, sensory perception enhancement and the combination forms of sensory perceptions. Based on the theoretical foundation, the perception design of overlapped multi-sensory stimuli and a single dynamic stimulus can be conducted to improve the quality of the indoor environment of normal and intelligent multi-sensory architecture.

Consumer Consciousness in Multisensory Extended Reality

The reality-virtuality continuum encompasses a multitude of objects, events and environments ranging from real-world multisensory inputs to interactive multisensory virtual simulators, in which sensory integration can involve very different combinations of both physical and digital inputs. These different ways of stimulating the senses can affect the consumer's consciousness, potentially altering their judgements and behaviours. In this perspective paper, we explore how technologies such as Augmented Reality (AR) and Virtual Reality (VR) can, by generating and modifying the human sensorium, act on consumer consciousness. We discuss the potential impact of this altered consciousness for consumer behaviour while, at the same time, considering how it may pave the way for further research.

Spatial perspective-taking: insights from sensory impairments

Information can be perceived from a multiplicity of spatial perspectives, which is central to effectively understanding and interacting with our environment and other people. Sensory impairments such as blindness are known to impact spatial representations and perspective-taking is often thought of as a visual process. However, disturbed functioning of other sensory systems (e.g., vestibular, proprioceptive and auditory) can also influence spatial perspective-taking. These lines of research remain largely separate, yet together they may shed new light on the role that each sensory modality plays in this core cognitive ability. The findings to date reveal that spatial cognitive processes may be differently affected by various types of sensory loss. The visual system may be crucial for the development of efficient allocentric (object-to-object) representation; however, the role of vision in adopting another's spatial perspective remains unclear. On the other hand, the vestibular and the proprioceptive systems likely play an important role in anchoring the perceived self to the physical body, thus facilitating imagined self-rotations required to adopt another's spatial perspective. Findings regarding the influence of disturbed auditory functioning on perspective-taking are so far inconclusive and thus await further data. This review highlights that spatial perspective-taking is a highly plastic cognitive ability, as the brain is often able to compensate in the face of different sensory loss.

Interactions between interoception and perspective-taking: Current state of research and future directions

Interoception, the sense of the physiological state of the body, and perspective-taking, the ability to take another's point of view, are two fundamental components contributing to our perception and interaction with the external world. However, whether the perception of our inner body influences how we perceive the external world and other people remains poorly understood. Here, we review recent behavioural and neuroimaging evidence investigating the links between dimensions of interoception (i.e., accuracy, sensibility and awareness) and perspective-taking (i.e., affective, cognitive and visual). So far, only a limited subset of these dimensions has been investigated together and the results suggest that interoceptive abilities may only interact with perspective-taking when embodied mental transformations are required. Furthermore, mainly the emotional aspects of perspective-taking are related to interoception, influencing the ability to empathise with others. Future research should systematically investigate the links between all dimensions of interoception and perspective-taking to provide full understanding of the specific role interoception has on how we perceive the world and take another's point of view.

When irrelevant information helps: Extending the Eriksen-flanker task into a multisensory world

Charles W. Eriksen dedicated much of his research career to the field of cognitive psychology, investigating human information processing in those situations that required selection between competing stimuli. Together with his wife Barbara, he introduced the flanker task, which became one of the standard experimental tasks used by researchers to investigate the mechanisms underpinning selection. Although Eriksen himself was primarily interested in investigating visual selection, the flanker task was eventually adapted by other researchers to investigate human information processing and selection in a variety of nonvisual and multisensory situations. Here, we discuss the core aspects of the flanker task and interpret the evidence of the flanker task when used in crossmodal and multisensory settings. "Selection" has been a core topic of psychology for nearly 120 years. Nowadays, though, it is clear that we need to look at selection from a multisensory perspective-the flanker task, at least in its crossmodal and multisensory variants, is an important tool with which to investigate selection, attention, and multisensory information processing.

The interaction of the visuo-spatial and the vestibular system depends on sensory experience in development

In hearing individuals, vestibular and visuo-spatial functions seem to be functionally linked. Previous studies have suggested that congenitally deaf individuals are at a higher risk for vestibular problems, which in hearing adults have often been found to be associated with impairments in visuo-spatial processing. However, communicating in a sign language provides extensive practice in visuo-spatial processing, which might counteract negative effects of vestibular impairments. Here, we investigated whether the functional link between vestibular and visuo-spatial functions is mandatory, that is whether it is impenetrable to experience or context, or whether it is dependent on specific sensory and cognitive experiences. To this end, we tested a group of congenitally deaf native signers and a group of hearing nonsigners on mental rotation and balance tasks. Compared to hearing nonsigners, mental rotation was superior in the deaf signers in conditions crucial for sign language comprehension. By contrast, the balance performance of the group of deaf signers was impaired. While in the group of hearing nonsigners, balance skills correlated with mental rotation abilities, no such relationship was observed in the group of deaf signers. These results suggest that the link between vestibular and visuo-spatial functions is not fixed but can be altered or even cancelled out by certain sensory or cognitive experiences, such as the acquisition of a sign language.

Dissociation of the subjective and objective bodies: Out-of-body experiences following the development of a posterior cingulate lesion

An out‐of‐body experience (OBE) is a phenomenon whereby an individual views his/her body and the world from a location outside the physical body. Previous studies have suggested that the temporoparietal junction (TPJ), the brain region responsible for integrating multisensory signals, is responsible for OBE development. Here, however, we first present a case of OBE after brain tumour development in the posterior cingulate cortex (PCC). The patient was a 46‐year‐old right‐handed female; she underwent brain surgery. She reported that she had experienced OBEs several times monthly (during daily life) before surgery but never after surgery. She defined her OBEs explicitly; she drew pictures. Her OBEs exhibited phenomenological, overt dissociation of the subjective and objective bodies. We discuss the mechanisms underlying this phenomenon and the relationship between OBEs and the PCC in terms of anatomical and functional brain connectivity. Our case sheds some light on the mechanism involved in creating spatial (dis)unity between the self and the body.

Somatosensory Loss Influences the Adoption of Self-Centered Versus Decentered Perspectives

The body and the self are commonly experienced as forming a unity. Experiencing the external world as distinct from the self and the body strongly relies on adopting a single self-centered perspective which results in integrating multisensory sensations into one egocentric body-centered reference frame. Body posture and somatosensory representations have been reported to influence perception and specifically the reference frame relative to which multisensory sensations are coded. In the study reported here, we investigated the role of somatosensory and visual information in adopting self-centered and decentered spatial perspectives. Two deafferented patients who have neither tactile nor proprioceptive perception below the head and a group of age-matched control participants performed a graphesthesia task, consisting of the recognition of ambiguous letters (b, d, p, and q) drawn tactilely on head surfaces. To answer which letter was drawn, the participants can adopt either a self-centered perspective or a decentered one (i.e., centered on a body part or on an external location). The participants' responses can be used, in turn, to infer the way the left-right and top-bottom letters' axes are assigned with respect to the left-right and top-bottom axes of their body. In order to evaluate the influence of body posture, the ambiguous letters were drawn on the participants' forehead, left, and right surfaces of the head, with the head aligned or rotated in yaw relative to the trunk. In order to evaluate the role of external information, the participants completed the task with their eyes open in one session and closed in another one. The results obtained in control participants revealed that their preferred perspective varied with body posture but not with vision. Different results were obtained with the deafferented patients who overall do not show any significant effect of their body posture on their preferred perspective. This result suggests that the orientation of their self is not influenced by their physical body. There was an effect of vision for only one of the two patients. The deafferented patients rely on strategies that are more prone to interindividual differences, which highlights the crucial role of somatosensory information in adopting self-centered spatial perspectives.

Implied tactile motion: Localizing dynamic stimulations on the skin

We report two experiments designed to investigate how the implied motion of tactile stimuli influences perceived location. Predicting the location of sensory input is especially important as far as the perception of, and interaction with, the external world is concerned. Using two different experimental approaches, an overall pattern of localization shifts analogous to what has been described previously in the visual and auditory modalities is reported. That is, participants perceive the last location of a dynamic stimulus further along its trajectory than is objectively the case. In Experiment 1, participants judged whether the last vibration in a sequence of three was located closer to the wrist or to the elbow. In Experiment 2, they indicated the last location on a ruler attached to their forearm. We further pinpoint the effects of implied motion on tactile localization by investigating the independent influences of motion direction and perceptual uncertainty. Taken together, these findings underline the importance of dynamic information in localizing tactile stimuli on the skin.

Does Proprioception Influence Human Spatial Cognition? A Study on Individuals With Massive Deafferentation

When navigating in a spatial environment or when hearing its description, we can develop a mental model which may be represented in the central nervous system in different coordinate systems such as an egocentric or allocentric reference frame. The way in which sensory experience influences the preferred reference frame has been studied with a particular interest for the role of vision. The present study investigated the influence of proprioception on human spatial cognition. To do so, we compared the abilities to form spatial models of two rare participants chronically deprived of proprioception (GL and IW) and healthy control participants. Participants listened to verbal descriptions of a spatial environment, and their ability to form and use a mental model was assessed with a distance-comparison task and a free-recall task. Given that the loss of proprioception has been suggested to specifically impair the egocentric reference frame, the deafferented individuals were expected to perform worse than controls when the spatial environment was described in an egocentric reference frame. Results revealed that in both tasks, one deafferented individual (GL) made more errors than controls while the other (IW) made less errors. On average, both GL and IW were slower to respond than controls, and reaction time was more variable for IW. Additionally, we found that GL but not IW was impaired compared to controls in visuo-spatial imagery, which was assessed with the Minnesota Paper Form Board Test. Overall, the main finding of this study is that proprioception can influence the time necessary to use spatial representations while other factors such as visuo-spatial abilities can influence the capacity to form accurate spatial representations.