Manipulating sensory and motor cues can cause an illusionary perception of ownership of a fake body part. Presumably, the illusion can work as long as the false body part’s position and appearance are anatomically plausible. Here, we introduce an illusion that challenges past assumptions on body ownership. We used virtual reality to switch and mirror participants’ views of their hands. When a participant moves their physical hand, they see the incongruent virtual hand moving. The result is an anatomically implausible configuration (...) of the fake hand. Despite the hand switch, participants reported significant body ownership sensations over the virtual hands. In the first between-group experiment, we found that the strength of body ownership over the incongruent hands was similar to that of congruent hands. Whereas, in the second within-group experiment, anatomical incongruency significantly decreased body ownership. Still, participants reported significant body ownership sensations of the switched hands. Curiously, we found that perceived levels of agency mediate the effect of anatomical congruency on body ownership. These findings offer a fresh perspective on the relationship between anatomical plausibility and assumed body ownership. We propose that goal-directed and purposeful actions can override anatomical plausibility constraints and discuss this in the context of the immersive properties of virtual reality. (shrink)

Neural devices have the capacity to enable users to regain abilities lost due to disease or injury – for instance, a deep brain stimulator (DBS) that allows a person with Parkinson’s disease to regain the ability to fluently perform movements or a Brain Computer Interface (BCI) that enables a person with spinal cord injury to control a robotic arm. While users recognize and appreciate the technologies’ capacity to maintain or restore their capabilities, the neuroethics literature is replete with examples of (...) concerns expressed about agentive capacities: A perceived lack of control over the movement of a robotic arm might result in an altered sense of feeling responsible for that movement. Clinicians or researchers being able to record and access detailed information of a person’s brain might raise privacy concerns. A disconnect between previous, current, and future understandings of the self might result in a sense of alienation. The ability to receive and interpret sensory feedback might change whether someone trusts the implanted device or themselves. Inquiries into the nature of these concerns and how to mitigate them has produced scholarship that often emphasizes one issue – responsibility, privacy, authenticity, or trust – selectively. However, we believe that examining these ethical dimensions separately fails to capture a key aspect of the experience of living with a neural device. In exploring their interrelations, we argue that their mutual significance for neuroethical research can be adequately captured if they are described under a unified heading of agency. On these grounds, we propose an “Agency Map” which brings together the diverse neuroethical dimensions and their interrelations into a comprehensive framework. With this, we offer a theoretically-grounded approach to understanding how these various dimensions are interwoven in an individual’s experience of agency. (shrink)

Brain–machine interfaces combining visual, auditory, and tactile feedback have been previously used to generate embodiment experiences during spinal cord injury rehabilitation. It is not known if adding temperature to these modalities can result in discomfort with embodiment experiences. Here, comfort levels with the embodiment experiences were investigated in an intervention that required a chronic pain SCI patient to generate lower limb motor imagery commands in an immersive environment combining visual, auditory, tactile, and thermal feedback. Assessments were made pre-/ post-, throughout (...) the intervention, and at 7 weeks follow up. Overall, high levels of embodiment in the adapted three-domain scale of embodiment were found throughout the sessions. No significant adverse effects of VR were reported. Although sessions induced only a modest reduction in pain levels, an overall reduction occurred in all pain scales at follow up. A high degree of comfort in the comfort scale for the thermal-tactile sleeve, in both the thermal and tactile feedback components of the sleeve was reported. This study supports the feasibility of combining multimodal stimulation involving visual, auditory, tactile, and thermal feedback to generate embodiment experiences in neurorehabilitation programs. (shrink)

Subtle bodily sensations such as itching or fluttering that occur in the absence of any external trigger may serve to locate the spatial boundaries of the body. They may constitute the normal counterpart of extreme conditions in which body-related hallucinations and perceptual aberrations are experienced. Previous investigations have suggested that situations in which the body is spontaneously experienced as being deformed are related to the ability to perform own-body transformations, i.e., mental rotations of the body requiring disembodiment. We therefore decided (...) to consider whether the perception of SPS might relate to embodiment as assessed through the ability to perform own-body transformations and schizotypal traits, since high degrees of schizotypy in the general population have been associated with more vivid perceptions and aberrant perceptual experiences. Then participants completed a standard SPS task. Our analysis revealed that the slower the response time in the OBT task, the more frequent the perception of SPS. This suggests that difficulties in disembodying and mentally transforming one’s own body facilitate feeling oneself. Furthermore, a greater number of correct responses in the OBT task was associated with less frequent perception of SPS. This suggests that finding it easier to disembody and perform mental own-body transformations interferes with the ability to sense oneself. The results also show that higher schizotypal traits, as assessed through the SPQ, are associated with more frequent perception of SPS. Taken together, these results provide a coherent picture and suggest that embodiment is required in order to correctly feel oneself, as expressed through the perception of SPS. The ability to easily experience disembodiment reduces the sense of feeling oneself, and proneness to schizotypal traits produces body misperceptions that enhance and amplify this feeling. The results are discussed in the light of current knowledge and theories about body representations, taking into account attention and interoception as factors that influence body awareness. We offer explanations for perceptual aberrations, body-related delusions, and hallucinations based on misperceived or misinterpreted SPS, and we discuss possible mechanisms that may contribute to feeling and misperceiving oneself. (shrink)

Following the levels of intentionality and semiosis distinguished by the Semiotic Hierarchy, and the distinction between original agency and enhanced agency, we propose a model of an agency hierarchy, consisting of six layers. Consistent with the phenomenological orientation of cognitive semiotics, a central claim is that agency and subjectivity are complementary aspects of intentionality. Hence, there is no agency without at least the minimal sense/feeling of agency. This perspective rules out all artefacts as genuine agents, as well as simple organisms, (...) since it is highly unlikely that e.g. bacteria have any first-person perspective. Using this model, we review and assess recent proposals on the nature of agency from cognitive science, and neuroscience, and draw conclusions on how to incorporate aspects of them within a synthetic cognitive-semiotic framework. (shrink)

Objects which a human agent controls by efferent activities can be perceived by the agent as belonging to his or her body. This suggests that what an agent counts as “body” is plastic, depending on what she or he controls. Yet there are possible limitations for such momentary plasticity. One of these limitations is that sensations stemming from the body and sensations stemming from objects outside the body are not integrated if they do not sufficiently “match”. What “matches” and what (...) does not is conceivably determined by long–term experience with the perceptual changes that body movements typically produce. Children have accumulated less sensorimotor experience than adults have. Consequently, they express higher flexibility to integrate body-internal and body-external signals, independent of their “match” as suggested by rubber hand illusion studies. However, children’s motor performance in tool use is more affected by mismatching body-internal and body-external action effects than that of adults, possibly because of less developed means to overcome such mismatches. We review research on perception-action interactions, multisensory integration, and developmental psychology to build bridges between these research fields. By doing so, we account for the flexibility of the sense of body ownership for actively controlled events and its development through ontogeny. This gives us the opportunity to validate the suggested mechanisms for generating ownership by investigating their effects in still developing and incomplete stages in children. We suggest testable predictions for future studies investigating both body ownership and motor skills throughout the lifespan. (shrink)

History is full of references to dancing plague, dance mania, ecstatic dance, collective effervescence, choreo mania, collective psychosis, and Tarantism. In each of these cases, groups of people come together in joint activity (typically dance) and reach a prolonged ecstatic state in which they cannot stop the movement. To this day, academic literature in medicine, psychology, history, and cognitive science has not been able to answer the question; why does ecstatic dance lead to a loss of executive control? I here (...) focus on the case of group dance and provide an enactive embodied account of the loss of executive control. I argue that dancing crowds are scaffolded, self-organizing, self-perpetuating, dynamical systems. Within such systems, the majority of affordances provided to the individual agent lead to the perpetuation of the system, leading to more dancing. The embodied impact of the crowd, as an emergent entity, on the individual also leads to change in the sense of agency. Dancers experience being “unable to stop” because the sense of “who” is initiating the movements changes within crowd dance interaction. If it is unclear who is moving, then the interaction is experienced as outside individual control. (shrink)

The contributions collected in this special issue explore the phenomenology of joint action from a broad range of different disciplinary and methodological angles, including philosophical investigation (both in the analytic and the phenomenological tradition), computational modeling, experimental study, game theory, and developmental psychology. They also vastly expand the range of discussed cases beyond the standard examples of house-painting and sauce-cooking, addressing, for example, collective musical improvisations, dancing, work at the Diversity and Equity office of a university, and historical examples of (...) collective violence such as the revolutionary Terror in France and the Nazis. In our introduction to this special issue, we group the contributions into three thematic areas – 1) the phenomenological fine-structure of joint action, 2) underlying mechanisms for joint action and 3) phenomenal preconditions for joint action. The first theme is discussed under a number of issues – a) components of the phenomenology of joint action, b) the I and the we in joint action, c) the effect of group size, structure and nature on the phenomenology of joint action and d) how do phenomenal relate to normative aspects of joint action? (shrink)

Uncontroversially, individuals exercise agency in acting; can we say the same about believing? This paper argues that subjects do indeed exercise agency over their beliefs and provides an account by which this is possible. On my picture, self-awareness is fundamental to the nature of doxastic agency. Drawing on work in the philosophy of action, I argue that subjects exercise agency in performing mental actions that form and sustain their beliefs, where they are aware of these actions as part of reasoning (...) and exercising agency over their beliefs. (shrink)

This paper examines the enactment of agency in the Mars Exploration Rover mission. We argue that MER functioned as a distributed cognitive system, made up of highly specialized, though complementary, elements. To explain how a sense of shared agency was attained therein, we augment the distributed account with Tollefsen and Gallagher’s Philosophy of the Social Sciences, 47, 95-110, theory of joint agency. It claims joint actions involve a cascade of shared distal, proximal, and motor intentions, each with its own content (...) and timescale, and that narrative processes are crucial for stabilizing shared intentions. We argue MER possessed these three levels of intention, though they fell on different elements of the distributed cognitive system, and their timescales were longer than mundane cases of joint action. Scientists, collaborating with engineers, enacted shared distal and proximal intentions, while rovers enacted the motor intentions. Moreover, we show that we-narratives, including a commitment to consensus-based operations and an epistemic strategy for discovering the geological history of Mars, constrained the formation of distal and proximal intentions such that they could genuinely be attributed to the group. Nonetheless, our distributed account does not fully capture how rovers shaped the sense of embodiment of team members. Scientists and engineers described themselves as ‘becoming the rover,’ which allowed them to have a sense of presence on Mars. We argue this can be explained by the Material Engagement Theory, which complements the distributed cognition theory. (shrink)

To offer engaging neurorehabilitation training to neurologic patients, motor tasks are often visualized in virtual reality. Recently introduced head-mounted displays allow to realistically mimic the body of the user from a first-person perspective in a highly immersive VR environment. In this immersive environment, users may embody avatars with different body characteristics. Importantly, body characteristics impact how people perform actions. Therefore, alternating body perceptions using immersive VR may be a powerful tool to promote motor activity in neurologic patients. However, the ability (...) of the brain to adapt motor commands based on a perceived modified reality has not yet been fully explored. To fill this gap, we “tricked the brain” using immersive VR and investigated if multisensory feedback modulating the physical properties of an embodied avatar influences motor brain networks and control. Ten healthy participants were immersed in a virtual environment using an HMD, where they saw an avatar from first-person perspective. We slowly transformed the surface of the avatar from human to stone. We enforced this visual change by repetitively touching the real arm of the participant and the arm of the avatar with a hammer, while progressively replacing the sound of the hammer against skin with stone hitting sound via loudspeaker. We applied single-pulse transcranial magnetic simulation to evaluate changes in motor cortical excitability associated with the illusion. Further, to investigate if the “stone illusion” affected motor control, participants performed a reaching task with the human and stone avatar. Questionnaires assessed the subjectively reported strength of embodiment and illusion. Our results show that participants experienced the “stone arm illusion.” Particularly, they rated their arm as heavier, colder, stiffer, and more insensitive when immersed with the stone than human avatar, without the illusion affecting their experienced feeling of body ownership. Further, the reported illusion strength was associated with enhanced motor cortical excitability and faster movement initiations, indicating that participants may have physically mirrored and compensated for the embodied body characteristics of the stone avatar. Together, immersive VR has the potential to influence motor brain networks by subtly modifying the perception of reality, opening new perspectives for the motor recovery of patients. (shrink)

There are few concepts as relevant as that of intentional action in shaping our sense of self and the interaction with the environment. At the same time, few concepts are so elusive. Indeed, both conceptual and neuroscientific accounts of intentional agency have proven to be problematic. On the one hand, most conceptual views struggle in defining how agents can adequately exert control over their actions. On the other hand, neuroscience settles for definitions by exclusion whereby key features of human intentional (...) actions, including goal-directness, remain underspecified. This paper reviews the existing literature and sketches how this gap might be filled. In particular, we defend a gradualist notion of intentional behaviour, which revolves around the following key features: autonomy, flexibility in the integration of causal vectors, and control. (shrink)