Cortex; a journal devoted to the study of the nervous system and behavior, Jan 9, 2018
Understanding how self-representation is built, maintained and updated across the lifespan is a f... more Understanding how self-representation is built, maintained and updated across the lifespan is a fundamental challenge for cognitive psychology and neuroscience. Studies demonstrate that the detection of body-related multisensory congruency builds bodily and facial self-representations that are crucial to developing self-recognition. Studies showing that the bodily self is more malleable than previously believed were mainly concerned with full-bodies and non-facial body parts. Crucially, however, intriguing recent evidence indicates that simple experimental manipulations could even affect self-face representation that has long been considered a stable construct impervious to change. In this review, we discuss how Interpersonal Multisensory Stimulation (IMS) paradigms can be used to temporarily induce Enfacement, i.e., the subjective illusion of looking at oneself in the mirror when in fact looking at another person's face. We show that Enfacement is a subtle but robust phenomenon...
Highlights People with body integrity dysphoria (BID) desire the removal of the affected leg Owne... more Highlights People with body integrity dysphoria (BID) desire the removal of the affected leg Ownership and agency are lower for the affected leg than the unaffected one Moral behavior is similar for BID and controls and the affected and unaffected leg Communicating self-gain lies with the affected leg further decreases ownership
Despite the increasing interest in twin studies and the stunning amount of research on face recog... more Despite the increasing interest in twin studies and the stunning amount of research on face recognition, the ability of adult identical twins to discriminate their own faces from those of their co-twins has been scarcely investigated. One's own face is the most distinctive feature of the bodily self, and people typically show a clear advantage in recognizing their own face even more than other very familiar identities. Given the very high level of resemblance of their faces, monozygotic twins represent a unique model for exploring self-face processing. Herein we examined the ability of monozygotic twins to distinguish their own face from the face of their co-twin and of a highly familiar individual. Results show that twins equally recognize their own face and their twin's face. This lack of self-face advantage was negatively predicted by how much they felt physically similar to their co-twin and by their anxious or avoidant attachment style. We speculate that in monozygotic ...
A preliminary standard neurological examination (Bisiach et al., 1986) showed that ten patients w... more A preliminary standard neurological examination (Bisiach et al., 1986) showed that ten patients with anterior damage and three patients with posterior damage presented with motor impairment. Moreover, two patients suffered from tactile sensorial deficits (one in the ...
Humans are unique in their ability to think about themselves and carry a more or less clear notio... more Humans are unique in their ability to think about themselves and carry a more or less clear notion of who they are in their mind. Here we review recent evidence suggesting that the birth, maintenance, and loss of the abstract concept of 'self' is deeply tied to interoception, the sense of internal physiological signals. Interoception influences multiple facets of the selfconcept, cutting across its material, social, moral, and agentive components. Overall, we argue that interoception contributes to the stability of the self-concept over time, unifying its layers and constraining the degree to which it is susceptible to external influences. Hence, the core features of the self-concept are those that correlate more with inner bodily states. We discuss the implications that this may have for theories of embodied cognition as well as for the understanding of psychiatric disorders in which the concept of self appears fragmented or loose. Finally, we formulate some empirical predictions that could be tested in future studies to shed further light on this emerging field.
Despite the increasing interest in twin studies and the stunning amount of research on face recog... more Despite the increasing interest in twin studies and the stunning amount of research on face recognition, the ability of adult identical twins to discriminate their own faces from those of their co-twins has been scarcely investigated. One's own face is the most distinctive feature of the bodily self, and people typically show a clear advantage in recognizing their own face even more than other very familiar identities. Given the very high level of resemblance of their faces, monozygotic twins represent a unique model for exploring self-face processing. Herein we examined the ability of monozygotic twins to distinguish their own face from the face of their co-twin and of a highly familiar individual. Results show that twins equally recognize their own face and their twin's face. This lack of self-face advantage was negatively predicted by how much they felt physically similar to their co-twin and by their anxious or avoidant attachment style. We speculate that in monozygotic twins, the visual representation of the self-face overlaps with that of the co-twin. Thus, to distinguish the self from the co-twin, monozygotic twins have to rely much more than control participants on the multi-sensory integration processes upon which the sense of bodily self is based. Moreover, in keeping with the notion that attachment style influences perception of self and significant others, we propose that the observed self/co-twin confusion may depend upon insecure attachment.
Studies have explored behavioral and neural responses to the observation of pain in others. Howev... more Studies have explored behavioral and neural responses to the observation of pain in others. However, much less is known about how taking a physical perspective influences reactivity to the observation of others' pain and pleasure. To explore this issue we devised a novel paradigm in which 24 healthy participants immersed in a virtual reality scenario observed a virtual: needle penetrating (pain), caress (pleasure), or ball touching (neutral) the hand of an avatar seen from a first (1PP)- or a third (3PP)-person perspective. Subjective ratings and physiological responses [skin conductance responses (SCR) and heart rate (HR)] were collected in each trial. All participants reported strong feelings of ownership of the virtual hand only in 1PP. Subjective measures also showed that pain and pleasure were experienced as more salient than neutral. SCR analysis demonstrated higher reactivity in 1PP than in 3PP. Importantly, vicarious pain induced stronger responses with respect to the other conditions in both perspectives. HR analysis revealed equally lower activity during pain and pleasure with respect to neutral. SCR may reflect egocentric perspective, and HR may merely index general arousal. The results suggest that behavioral and physiological indexes of reactivity to seeing others' pain and pleasure were qualitatively similar in 1PP and 3PP. Our paradigm indicates that virtual reality can be used to study vicarious sensation of pain and pleasure without actually delivering any stimulus to participants' real body and to explore behavioral and physiological reactivity when they observe pain and pleasure from ego- and allocentric perspectives.
To explore the link between Sense of Embodiment (SoE) over a virtual hand and physiological regul... more To explore the link between Sense of Embodiment (SoE) over a virtual hand and physiological regulation of skin temperature, twenty-four healthy participants were immersed in virtual reality through a Head Mounted Display and had their real limb temperature recorded by means of a high-sensitivity infrared camera. Participants observed a virtual right upper limb (appearing either normally, or with the hand detached from the forearm) or limb-shaped non-corporeal control objects (continuous or discontinuous wooden blocks) from a first-person perspective. Subjective ratings of SoE were collected in each observation condition, as well as temperatures of the right and left hand, wrist and forearm. The observation of these complex, body and body-related virtual scenes resulted in increased real hand temperature when compared to a baseline condition in which a 3d virtual ball was presented. Crucially, observation of non-natural appearances of the virtual limb (discontinuous limb) and limb-shaped non-corporeal objects elicited high increase in real hand temperature and low SoE. In contrast, observation of the full virtual limb caused high SoE and low temperature changes in the real hand with respect to the other conditions. Interestingly, the temperature difference across the different conditions occurred according to a topographic rule that included both hands. Our study sheds new light on the role of an external hand's visual appearance and suggests a tight link between higher-order bodily self-representations and topographic regulation of skin temperature.
When we look at our hands we are immediately aware that they belong to us and we rarely doubt abo... more When we look at our hands we are immediately aware that they belong to us and we rarely doubt about the integrity, continuity and sense of ownership of our bodies. Here we explored whether the mere manipulation of the visual appearance of a virtual limb could influence the subjective feeling of ownership and the physiological responses (Skin Conductance Responses, SCRs) associated to a threatening stimulus approaching the virtual hand. Participants observed in first person perspective a virtual body having the right hand-forearm (i) connected by a normal wrist (Full-Limb) or a thin rigid wire connection (Wire) or (ii) disconnected because of a missing wrist (m-Wrist) or a missing wrist plus a plexiglass panel positioned between the hand and the forearm (Plexiglass). While the analysis of subjective ratings revealed that only the observation of natural full connected virtual limb elicited high levels of ownership, high amplitudes of SCRs were found also during observation of the non-natural, rigid wire connection condition. This result suggests that the conscious embodiment of an artificial limb requires a natural looking visual body appearance while implicit reactivity to threat may require physical body continuity, even non-naturally looking, that allows the implementation of protective reactions to threat. Protective physiological reactions to events threatening our body depend not only on the recognition of the threat itself but also on the correct representation of our body and its attribution to ourselves. Integrating multiple sensory information and solving possible incongruences is fundamental for correctly attributing an external object to our Self. Indeed the synchronous (but not asynchronous) stroking of an external rubber hand with the participant's hidden hand can induce an illusory Feeling of Ownership (FO) over the external body-part (Rubber Hand Illusion, RHI) 1 and an increase in Skin Conductance Responses (SCRs) when a threatening stimulus is directed towards the embodied rubber hand 2. Previous research highlighted that the illusory FO is affected by the external object's shape 3,4 , anatomical and postural appearance 5–8 and by the congruency between multisensory visuo-tactile 1 , visuo-motor 9–11 and visuo-spatial 12 information (see 13 for a recent and comprehensive review of the factors affecting and promoting the illusory body ownership in healthy subjects). Moreover, recent computational models 13,14 and behavioural studies suggest that visual information play a crucial role in modulating the FO over a fake hand in brain damaged 15,16 , spinal cord injured people 17 and in healthy participants when synchronous visuo-tactile stimulation 1 is applied and when the external object is passively observed 5,18,19. By means of Immersive Virtual Reality (IVR) the original version of the RHI has been readapted to investigate the FO over virtual body parts 20–22 and full bodies 23–25 presenting a virtual surrogate at the same location as the participants' real body (thus with reduced visual, proprioceptive and spatial mismatches between the real and the virtual body). These studies highlighted the crucial role of the first-Person Perspective (1PP) 23–25 , i.e. the observation of the world from the eyes of the virtual body
Cortex; a journal devoted to the study of the nervous system and behavior, Jan 9, 2018
Understanding how self-representation is built, maintained and updated across the lifespan is a f... more Understanding how self-representation is built, maintained and updated across the lifespan is a fundamental challenge for cognitive psychology and neuroscience. Studies demonstrate that the detection of body-related multisensory congruency builds bodily and facial self-representations that are crucial to developing self-recognition. Studies showing that the bodily self is more malleable than previously believed were mainly concerned with full-bodies and non-facial body parts. Crucially, however, intriguing recent evidence indicates that simple experimental manipulations could even affect self-face representation that has long been considered a stable construct impervious to change. In this review, we discuss how Interpersonal Multisensory Stimulation (IMS) paradigms can be used to temporarily induce Enfacement, i.e., the subjective illusion of looking at oneself in the mirror when in fact looking at another person's face. We show that Enfacement is a subtle but robust phenomenon...
Highlights People with body integrity dysphoria (BID) desire the removal of the affected leg Owne... more Highlights People with body integrity dysphoria (BID) desire the removal of the affected leg Ownership and agency are lower for the affected leg than the unaffected one Moral behavior is similar for BID and controls and the affected and unaffected leg Communicating self-gain lies with the affected leg further decreases ownership
Despite the increasing interest in twin studies and the stunning amount of research on face recog... more Despite the increasing interest in twin studies and the stunning amount of research on face recognition, the ability of adult identical twins to discriminate their own faces from those of their co-twins has been scarcely investigated. One's own face is the most distinctive feature of the bodily self, and people typically show a clear advantage in recognizing their own face even more than other very familiar identities. Given the very high level of resemblance of their faces, monozygotic twins represent a unique model for exploring self-face processing. Herein we examined the ability of monozygotic twins to distinguish their own face from the face of their co-twin and of a highly familiar individual. Results show that twins equally recognize their own face and their twin's face. This lack of self-face advantage was negatively predicted by how much they felt physically similar to their co-twin and by their anxious or avoidant attachment style. We speculate that in monozygotic ...
A preliminary standard neurological examination (Bisiach et al., 1986) showed that ten patients w... more A preliminary standard neurological examination (Bisiach et al., 1986) showed that ten patients with anterior damage and three patients with posterior damage presented with motor impairment. Moreover, two patients suffered from tactile sensorial deficits (one in the ...
Humans are unique in their ability to think about themselves and carry a more or less clear notio... more Humans are unique in their ability to think about themselves and carry a more or less clear notion of who they are in their mind. Here we review recent evidence suggesting that the birth, maintenance, and loss of the abstract concept of 'self' is deeply tied to interoception, the sense of internal physiological signals. Interoception influences multiple facets of the selfconcept, cutting across its material, social, moral, and agentive components. Overall, we argue that interoception contributes to the stability of the self-concept over time, unifying its layers and constraining the degree to which it is susceptible to external influences. Hence, the core features of the self-concept are those that correlate more with inner bodily states. We discuss the implications that this may have for theories of embodied cognition as well as for the understanding of psychiatric disorders in which the concept of self appears fragmented or loose. Finally, we formulate some empirical predictions that could be tested in future studies to shed further light on this emerging field.
Despite the increasing interest in twin studies and the stunning amount of research on face recog... more Despite the increasing interest in twin studies and the stunning amount of research on face recognition, the ability of adult identical twins to discriminate their own faces from those of their co-twins has been scarcely investigated. One's own face is the most distinctive feature of the bodily self, and people typically show a clear advantage in recognizing their own face even more than other very familiar identities. Given the very high level of resemblance of their faces, monozygotic twins represent a unique model for exploring self-face processing. Herein we examined the ability of monozygotic twins to distinguish their own face from the face of their co-twin and of a highly familiar individual. Results show that twins equally recognize their own face and their twin's face. This lack of self-face advantage was negatively predicted by how much they felt physically similar to their co-twin and by their anxious or avoidant attachment style. We speculate that in monozygotic twins, the visual representation of the self-face overlaps with that of the co-twin. Thus, to distinguish the self from the co-twin, monozygotic twins have to rely much more than control participants on the multi-sensory integration processes upon which the sense of bodily self is based. Moreover, in keeping with the notion that attachment style influences perception of self and significant others, we propose that the observed self/co-twin confusion may depend upon insecure attachment.
Studies have explored behavioral and neural responses to the observation of pain in others. Howev... more Studies have explored behavioral and neural responses to the observation of pain in others. However, much less is known about how taking a physical perspective influences reactivity to the observation of others' pain and pleasure. To explore this issue we devised a novel paradigm in which 24 healthy participants immersed in a virtual reality scenario observed a virtual: needle penetrating (pain), caress (pleasure), or ball touching (neutral) the hand of an avatar seen from a first (1PP)- or a third (3PP)-person perspective. Subjective ratings and physiological responses [skin conductance responses (SCR) and heart rate (HR)] were collected in each trial. All participants reported strong feelings of ownership of the virtual hand only in 1PP. Subjective measures also showed that pain and pleasure were experienced as more salient than neutral. SCR analysis demonstrated higher reactivity in 1PP than in 3PP. Importantly, vicarious pain induced stronger responses with respect to the other conditions in both perspectives. HR analysis revealed equally lower activity during pain and pleasure with respect to neutral. SCR may reflect egocentric perspective, and HR may merely index general arousal. The results suggest that behavioral and physiological indexes of reactivity to seeing others' pain and pleasure were qualitatively similar in 1PP and 3PP. Our paradigm indicates that virtual reality can be used to study vicarious sensation of pain and pleasure without actually delivering any stimulus to participants' real body and to explore behavioral and physiological reactivity when they observe pain and pleasure from ego- and allocentric perspectives.
To explore the link between Sense of Embodiment (SoE) over a virtual hand and physiological regul... more To explore the link between Sense of Embodiment (SoE) over a virtual hand and physiological regulation of skin temperature, twenty-four healthy participants were immersed in virtual reality through a Head Mounted Display and had their real limb temperature recorded by means of a high-sensitivity infrared camera. Participants observed a virtual right upper limb (appearing either normally, or with the hand detached from the forearm) or limb-shaped non-corporeal control objects (continuous or discontinuous wooden blocks) from a first-person perspective. Subjective ratings of SoE were collected in each observation condition, as well as temperatures of the right and left hand, wrist and forearm. The observation of these complex, body and body-related virtual scenes resulted in increased real hand temperature when compared to a baseline condition in which a 3d virtual ball was presented. Crucially, observation of non-natural appearances of the virtual limb (discontinuous limb) and limb-shaped non-corporeal objects elicited high increase in real hand temperature and low SoE. In contrast, observation of the full virtual limb caused high SoE and low temperature changes in the real hand with respect to the other conditions. Interestingly, the temperature difference across the different conditions occurred according to a topographic rule that included both hands. Our study sheds new light on the role of an external hand's visual appearance and suggests a tight link between higher-order bodily self-representations and topographic regulation of skin temperature.
When we look at our hands we are immediately aware that they belong to us and we rarely doubt abo... more When we look at our hands we are immediately aware that they belong to us and we rarely doubt about the integrity, continuity and sense of ownership of our bodies. Here we explored whether the mere manipulation of the visual appearance of a virtual limb could influence the subjective feeling of ownership and the physiological responses (Skin Conductance Responses, SCRs) associated to a threatening stimulus approaching the virtual hand. Participants observed in first person perspective a virtual body having the right hand-forearm (i) connected by a normal wrist (Full-Limb) or a thin rigid wire connection (Wire) or (ii) disconnected because of a missing wrist (m-Wrist) or a missing wrist plus a plexiglass panel positioned between the hand and the forearm (Plexiglass). While the analysis of subjective ratings revealed that only the observation of natural full connected virtual limb elicited high levels of ownership, high amplitudes of SCRs were found also during observation of the non-natural, rigid wire connection condition. This result suggests that the conscious embodiment of an artificial limb requires a natural looking visual body appearance while implicit reactivity to threat may require physical body continuity, even non-naturally looking, that allows the implementation of protective reactions to threat. Protective physiological reactions to events threatening our body depend not only on the recognition of the threat itself but also on the correct representation of our body and its attribution to ourselves. Integrating multiple sensory information and solving possible incongruences is fundamental for correctly attributing an external object to our Self. Indeed the synchronous (but not asynchronous) stroking of an external rubber hand with the participant's hidden hand can induce an illusory Feeling of Ownership (FO) over the external body-part (Rubber Hand Illusion, RHI) 1 and an increase in Skin Conductance Responses (SCRs) when a threatening stimulus is directed towards the embodied rubber hand 2. Previous research highlighted that the illusory FO is affected by the external object's shape 3,4 , anatomical and postural appearance 5–8 and by the congruency between multisensory visuo-tactile 1 , visuo-motor 9–11 and visuo-spatial 12 information (see 13 for a recent and comprehensive review of the factors affecting and promoting the illusory body ownership in healthy subjects). Moreover, recent computational models 13,14 and behavioural studies suggest that visual information play a crucial role in modulating the FO over a fake hand in brain damaged 15,16 , spinal cord injured people 17 and in healthy participants when synchronous visuo-tactile stimulation 1 is applied and when the external object is passively observed 5,18,19. By means of Immersive Virtual Reality (IVR) the original version of the RHI has been readapted to investigate the FO over virtual body parts 20–22 and full bodies 23–25 presenting a virtual surrogate at the same location as the participants' real body (thus with reduced visual, proprioceptive and spatial mismatches between the real and the virtual body). These studies highlighted the crucial role of the first-Person Perspective (1PP) 23–25 , i.e. the observation of the world from the eyes of the virtual body
Uploads
Papers