Bodily self: an implicit knowledge of what is explicitly unknown

Schizophrenia and the bodily self

Despite the historically consolidated psychopathological perspective, on the one hand, contemporary organicistic psychiatry often highlights abnormalities in neurotransmitter systems like dysregulation of dopamine transmission, neural circuitry, and genetic factors as key contributors to schizophrenia. Neuroscience, on the other, has so far almost entirely neglected the first-person experiential dimension of this syndrome, mainly focusing on high-order cognitive functions, such as executive function, working memory, theory of mind, and the like. An alternative view posits that schizophrenia is a self-disorder characterized by anomalous self-experience and awareness. This view may not only shed new light on the psychopathological features of psychosis but also inspire empirical research targeting the bodily and neurobiological changes underpinning this disorder. Cognitive neuroscience can today address classic topics of phenomenological psychopathology by adding a new level of description, finally enabling the correlation between the first-person experiential aspects of psychiatric diseases and their neurobiological roots. Recent empirical evidence on the neurobiological basis of a minimal notion of the self, the bodily self, is presented. The relationship between the body, its motor potentialities and the notion of minimal self is illustrated. Evidence on the neural mechanisms underpinning the bodily self, its plasticity, and the blurring of self-other distinction in schizophrenic patients is introduced and discussed. It is concluded that brain-body function anomalies of multisensory integration, differential processing of self- and other-related bodily information mediating self-experience, might be at the basis of the disruption of the self disorders characterizing schizophrenia.

Emotional body representations: more pronounced effect of hands at a more explicit level of awareness

To understand conditions such as body dysmorphic disorder, we need to understand healthy individuals' perceptual, conceptual, and emotional representations of their bodies. Not much is known about the differences in these representations across body districts, for example, hands, feet, and whole-body, despite their differences at sensory and functional levels. To understand this, we developed more implicit and explicit measures of body satisfaction for these body districts. Sixty-seven participants (age M = 30.66, SD = 11.19) completed a series of online Implicit Association Tests (IAT) and a Body Image Satisfaction Visual Analogue Scale (BISVAS; explicit) for each body district (hands/feet/whole body). The results show no differences in the more implicit level of awareness in hands, feet and whole body, while differences are apparent at a more explicit level of awareness, with higher scores for body image satisfaction for the hands than the whole body and marginally significant lower scores for feet than hands. Those findings suggest that visual attention, level of concern attributed to a body district, and disgust drivers are possible factors affecting the experience of attitudinal body image satisfaction.

The role of identity priming on the (unconscious) bodily self-attribution

It has been recently demonstrated that hand stimuli presented in a first-, with respect to a third-, person perspective were prioritized before awareness independently from their identity (i.e., self, or other). This pattern would represent an unconscious advantage for self-related bodily stimuli rooted in spatial perspective. To deeper investigate the role of identity, we employed a breaking-Continuous Flash Suppression paradigm in which a self- or other-hand presented in first- or third-person perspective was displayed after a conscious identity-related prime (i.e., self or other face). We replicated the unconscious advantage of the first-person perspective but, crucially, we reported that within the first-person perspective, other-hand stimuli preceded by other-face priming slowed down the conscious access with respect to the other conditions. These findings demonstrate that a top-down conscious identity context modulates the unconscious self-attribution of bodily stimuli. Within a predictive processing framework, we suggest that, by adding ambiguous information, the prime forces a prediction update that slows conscious access.

To see or not to see: the parallel processing of self-relevance and facial expressions

The self, like the concept of central "gravity", facilitates the processing of information that is directly relevant to the self. This phenomenon is known as the self-prioritization effect. However, it remains unclear whether the self-prioritization effect extends to the processing of emotional facial expressions. To fill this gap, we used a self-association paradigm to investigate the impact of self-relevance on the recognition of emotional facial expressions while controlling for confounding factors such as familiarity and overlearning. Using a large and diverse sample, we replicated the effect of self-relevance on face processing but found no evidence for a modulation of self-relevance on facial emotion recognition. We propose two potential theoretical explanations to account for these findings and emphasize that further research with different experimental designs and a multitasks measurement approach is needed to understand this mechanism fully. Overall, our study contributes to the literature on the parallel cognitive processing of self-relevance and facial emotion recognition, with implications for both social and cognitive psychology.

Spatial perspective and identity in visual awareness of the bodily self-other distinction

Spatial perspective and identity of visual bodily stimuli are two key cues for the self-other distinction. However, how they emerge into visual awareness is largely unknown. Here, self- or other-hands presented in first- or third-person perspective were compared in a breaking-Continuous Flash Suppression paradigm (Experiment 1) measuring the time the stimuli need to access visual awareness, and in a Binocular Rivalry paradigm (Experiment 2), measuring predominance in perceptual awareness. Results showed that, irrespectively of identity, first-person perspective speeded up the access, whereas the third-person one increased the dominance. We suggest that the effect of first-person perspective represents an unconscious prioritization of an egocentric body coding important for visuomotor control. On the other hand, the effect of third-person perspective indicates a conscious advantage of an allocentric body representation fundamental for detecting the presence of another intentional agent. Summarizing, the emergence of self-other distinction into visual awareness would strongly depend on the interplay between spatial perspectives, with an inverse prioritization before and after conscious perception. On the other hand, identity features might rely on post-perceptual processes.

A common self-advantage across the implicit and explicit levels for self-body recognition

Introduction

Although self-bias has been extensively studied and confirmed in various self-related stimuli, it remains controversial whether self-body can induce recognition advantage at the explicit level. After careful examination of previous experiments related to self-body processing, we proposed that participant strategies may influence explicit task outcomes.

Methods

To test our hypothesis, we designed a novel explicit task. For comparison, we also conducted classic explicit and implicit tasks.

Results

With the newly designed explicit task, we found clear and robust evidence of self-hand recognition advantage at the explicit level. Moreover, we found that there was a strong link between self-advantage found in the classic implicit task and the newly designed explicit task, indicating that the self-advantage processing by these two pathways may be linked.

Discussion

These findings provide new insights into the long-standing inconsistencies in previous studies and open a new avenue for studying self-bias using self-body stimuli.

Body image and self-perception in women with navel piercings

The present study investigated how women’s body image and body-perceptual processes are affected by navel piercings, an embellishment of the abdominal region women often feel negatively about. We probed perceptual (response times), cognitive (surveys), affective (aesthetic ratings) and neural (event-related potentials, ERPs) facets of (own) body perception. We found that navel piercings are primarily motivated by the desire to enhance one’s body image, and can significantly improve bodily self-perception relative to before and to imagined removal of the piercing. Hence, body image concerns in women with navel piercings were found to be comparable to those of a control group; and their aesthetic ratings of other women’s abdomens only differed, positively, for images depicting navel piercings. ERPs indicated that the sight of navel piercings enhances early structural encoding of bodies as well as late emotional-motivational processes, especially in women with navel piercings. We further found a strong self-advantage in both cortical and behavioural responses during recognition of own and others’ abdomens, especially for images displaying the piercing. Altogether, findings suggest that navel piercings become strongly, and beneficially, integrated into women’s bodily self image. Such piercings may thus be seen as expressions of body care that can protect against self-harming thoughts and behaviours.

No self-advantage in recognizing photographs of one's own hand: experimental and meta-analytic evidence

Visually recognising one’s own body is important both for controlling movement and for one’s sense of self. Twenty previous studies asked healthy adults to make rapid recognition judgements about photographs of their own and other peoples’ hands. Some of these judgements involved explicit self-recognition: “Is this your hand or another person’s?” while others assessed self-recognition implicitly, comparing performance for self and other hands in tasks unrelated to self-other discrimination (e.g., left-versus-right; match-to-sample). We report five experiments with three groups of participants performing left-versus-right (Experiment 1) and self-versus-other discrimination tasks (Experiments 2 to 5). No evidence was found for better performance with self than with other stimuli, but some evidence was found for a self-disadvantage in the explicit task. Manipulating stimulus duration as a proxy for task difficulty revealed strong response biases in the explicit self-recognition task. Rather than discriminating between self and other stimuli, participants seem to treat self-other discrimination tasks as self-detection tasks, raising their criterion and consistently responding ‘not me’ when the task is difficult. A meta-analysis of 21 studies revealed no overall self-advantage, and suggested a publication bias for reports showing self-advantages in implicit tasks. Although this may appear counter-intuitive, we suggest that there may be no self-advantage in hand recognition.

Does the body talk to the body? The relationship between different body representations while observing others' body parts

The way human bodies are represented is central in everyday activities. The cognitive system must combine internal, visceral, and somatosensory, signals to external, visually driven information generated from the spatial placement of others’ bodies and the own body in the space. However, how different body representations covertly interact among them when observing human body parts is still unclear. Therefore, we investigated the implicit processing of body parts by manipulating either the body part stimuli’ posture (conditions a and b) or the participants’ response body posture (conditions c, d, and e) in healthy participants (N = 70) using a spatial compatibility task called Sidedness task. The task requires participants to judge the colour of a circle superimposed on a task‐irrelevant body part picture. Responses are facilitated when the spatial side of the responding hand corresponds to the spatial code generated by the hand stimulus's position with respect to a body of reference. Results showed that the observation of the task‐irrelevant body parts oriented participants’ attention and facilitated responses that were spatial compatible with the spatial position such body parts have within a configural representation of the body structure (i.e., Body Structural Representation) in all the five experimental conditions. Notably, the body part stimuli were mentally attached to the body according to the most comfortable and less awkward postures, following the anatomo‐physiological constraints. Moreover, the pattern of the results was not influenced by manipulating the participants’ response postures, suggesting that the automatic and implicit coding of the body part stimuli does not rely on proprioceptive information about one's body (i.e., Body Schema). We propose that the human body's morphometry knowledge is enriched by biomechanical and anatomo‐physiological information about the real body movement possibilities. Moreover, we discuss the importance of the automatic orienting of attention based on the sidedness within the context of imitational learning.

Self-body recognition and attitudes towards body image in younger and older women

Despite the fact that ageing causes dramatic changes in bodily appearance, little is known about how self-body recognition changes across life span. Here, we investigated whether older, compared to younger women, differed in the ability of recognising their own than other women's body parts and whether this effect was associated to negative body image dispositions. Twenty-eight young (M_age: 25.93 years, SD_age = 4.74) and 25 middle-aged (M_age: 54.36 years, SD_age = 4.54) women completed an implicit task consisting of visual matching of self and others' body parts and an explicit self-other body discrimination task. Stimuli comprised of images of body parts of the participant and of other age- and BMI-matched models, which were presented in the original size or modified to look rounder or thinner. Measures of adiposity (i.e. BMI), body image concerns and appearance-related worries for specific body parts and for the whole body were also collected. Whilst both groups showed a self-body advantage in the implicit, but not in the explicit task, the advantage was notably bigger for the younger group. However, the implicit self-advantage was higher in those middle-aged women that displayed more body image concerns and worries for specific body parts. Furthermore, the two groups were comparably less able in recognising their body parts when presented thinner as compared to rounder or in their actual size. Overall, these findings open the possibility that, as women age, their implicit self-recognition abilities may decline in association with more negative body image dispositions.

Corticospinal Excitability during a Perspective Taking Task as Measured by TMS-Induced Motor Evoked Potentials

Only by understanding the ability to take a third-person perspective can we begin to elucidate the neural processes responsible for one’s inimitable conscious experience. The current study examined differences in hemispheric laterality during a first-person perspective (1PP) and third-person perspective (3PP) taking task, using transcranial magnetic stimulation (TMS). Participants were asked to take either the 1PP or 3PP when identifying the number of spheres in a virtual scene. During this task, single-pulse TMS was delivered to the motor cortex of both the left and right hemispheres of 10 healthy volunteers. Measures of TMS-induced motor-evoked potentials (MEPs) of the contralateral abductor pollicis brevis (APB) were employed as an indicator of lateralized cortical activation. The data suggest that the right hemisphere is more important in discriminating between 1PP and 3PP. These data add a novel method for determining perspective taking and add to the literature supporting the role of the right hemisphere in meta representation.

The self’s choice: Priming attentional focus on bodily self promotes loss frequency bias

When attention is focused on self representation(s), the ability to evaluate one’s internal sensations is enhanced, according to previous research by Ainley and colleagues (Consciousness and Cognition, 22(4), 1231–1238, 2013). Self-representations are usually distinguished between bodily and narrative. Both bodily and narrative representations improve decision-making processes, in that the consideration of alternatives is informed by sensations experienced deep inside the body (e.g., anxiety) as suggest by the literature (Noël, Brevers & Bechara in Frontiers in Psychiatry, 4, 179,  2013). The objective of the present study is to analyze the decision-making process in multiple conditions of stimulated self-representations. Participants played the Iowa Gambling Task three times (a baseline without stimuli and two randomly ordered stimulations to prime bodily and narrative self-representations). While no significant differences emerged regarding advantageous choices, participants showed loss frequency bias in the condition with bodily-self representation priming. Two interpretations are proposed: bodily-self focus acted as a distractor diminishing participants’ commitment to long term outcomes or enhanced interoception promoted aversion to losses. Directions are given for future research and clinical implications.

Visual Hand Recognition in Hand Laterality and Self-Other Discrimination Tasks: Relationships to Autistic Traits and Positive Body Image

In a study concerning visual body part recognition, a "self-advantage" effect, whereby self-related body stimuli are processed faster and more accurately than other-related body stimuli, was revealed, and the emergence of this effect is assumed to be tightly linked to implicit motor simulation, which is activated when performing a hand laterality judgment task in which hand ownership is not explicitly required. Here, we ran two visual hand recognition tasks, namely, a hand laterality judgment task and a self-other discrimination task, to investigate (i) whether the self-advantage emerged even if implicit motor imagery was assumed to be working less efficiently and (ii) how individual traits [such as autistic traits and the extent of positive self-body image, as assessed via the Autism Spectrum Quotient (AQ) and the Body Appreciation Scale-2 (BAS-2), respectively] modulate performance in these hand recognition tasks. Participants were presented with hand images in two orientations [i.e., upright (egocentric) and upside-down (allocentric)] and asked to judge whether it was a left or right hand (an implicit hand laterality judgment task). They were also asked to determine whether it was their own, or another person's hand (an explicit self-other discrimination task). Data collected from men and women were analyzed separately. The self-advantage effect in the hand laterality judgment task was not revealed, suggesting that only two orientation conditions are not enough to trigger this motor simulation. Furthermore, the men's group showed a significant positive correlation between AQ scores and reaction times (RTs) in the laterality judgment task, while the women's group showed a significant negative correlation between AQ scores and differences in RTs and a significant positive correlation between BAS-2 scores and dprime in the self-other discrimination task. These results suggest that men and women differentially adopt specific strategies and/or execution processes for implicit and explicit hand recognition tasks.

Like the back of my hand: Visual ERPs reveal a specific change detection mechanism for the bodily self

The ability to identify our own body is considered a pivotal marker of self-awareness. Previous research demonstrated that subjects are more efficient in the recognition of images representing self rather than others' body effectors (self-advantage). Here, we verified whether, at an electrophysiological level, bodily-self recognition modulates change detection responses. In a first EEG experiment (discovery sample), event-related potentials (ERPs) were elicited by a pair of sequentially presented visual stimuli (vS1; vS2), representing either the self-hand or other people's hands. In a second EEG experiment (replicating sample), together with the previously described visual stimuli, also a familiar hand was presented. Participants were asked to decide whether vS2 was identical or different from vS1. Accuracy and response times were collected. In both experiments, results confirmed the presence of the self-advantage: participants responded faster and more accurately when the self-hand was presented. ERP results paralleled behavioral findings. Anytime the self-hand was presented, we observed significant change detection responses, with a larger N270 component for vS2 different rather than identical to vS1. Conversely, when the self-hand was not included, and even in response to the familiar hand in Experiment 2, we did not find any significant modulation of the change detection responses. Overall our findings, showing behavioral self-advantage and the selective modulation of N270 for the self-hand, support the existence of a specific mechanism devoted to bodily-self recognition, likely relying on the multimodal (visual and sensorimotor) dimension of the bodily-self representation. We propose that such a multimodal self-representation may activate the salience network, boosting change detection effects specifically for the self-hand.

Recognizing Your Hand and That of Your Romantic Partner

Although the hand is an important organ in interpersonal interactions, focusing on this body part explicitly is less common in daily life compared with the face. We investigated (i) whether a person's recognition of their own hand is different from their recognition of another person's hand (i.e., self hand vs. other's hand) and (ii) whether a close social relationship affects hand recognition (i.e., a partner's hand vs. an unknown person's hand). For this aim, we ran an experiment in which participants took part in one of two discrimination tasks: (i) a self-others discrimination task or (ii) a partner/unknown opposite-sex person discrimination task. In these tasks, participants were presented with a hand image and asked to select one of two responses, self (partner) or other (unknown persons), as quickly and accurately as possible. We manipulated hand ownership (self (partner)/other(unknown person)), hand image laterality (right/left), and visual perspective of hand image (upright/upside-down). A main effect of hand ownership in both tasks (i.e., self vs. other and partner vs. unknown person) was found, indicating longer reaction times for self and partner images. The results suggest that close social relationships modulate hand recognition-namely, "self-expansion" to a romantic partner could occur at explicit visual hand recognition.

Sex differences in implicit motor imagery: Evidence from the hand laterality task

Behavioural evidence suggest that males outperform females in mentally transforming objects, whereas whether sex differences exist in mentally transforming body part images (implicit motor imagery) is an open issue. The aim of the present study was to fill this gap testing performance of 360 healthy participants on a classical behavioural measure of implicit motor imagery: the hand laterality task. Participants had to judge handedness of hand images portrayed from back and palm and presented in different spatial orientations. Two main findings emerged. First, males were significantly faster than females in judging hands portrayed from palm, in particular left palms at 0°, 90° and 180° orientation, whereas females were faster than males in judging backs, in particular left and right backs at 0° and the left back at 90°. Second, both males and females showed a significant biomechanical effect (faster responses for hands portrayed in medial vs. lateral positions) while judging palms, albeit the effect was stronger in males, whereas only females showed a significant biomechanical effect when judging backs. Thus, males and females seem to differently exploit motor simulation processes during mental transformation of hand images depending on a specific familiarity with body parts portrayed from different views. This result might be taken into account when tailoring motor imagery tasks in applied contexts, as motor rehabilitation.

The rubber hand illusion is influenced by self-recognition

Susceptibility to the Rubber Hand Illusion (RHI) demonstrates that body ownership can be modulated by visuotactile inputs. In contrast to body-like images, other objects cannot be embodied suggesting that crossmodal interactions on body ownership are based on a 'goodness-of-fit' mechanism relative to one's own body. However, it is not clear whether visual self-recognition influences susceptibility to the RHI, although evidence for individual differences in the perceptual body image on the RHI suggests that this may be the case. We investigated the role of self-recognition on the subjective experience of the RHI and measured proprioceptive drift and onset time of the RHI between two groups, one with the ability to identify an image of their own hand and the other without this ability. A typical RHI response was found overall with no group difference in the subjective experience of the RHI. However, a larger proprioceptive drift and an earlier onset time for the RHI was found for the non-recognisers than the self-recognition group. Our findings provide evidence for a link between a visual representation of one's own body in long-term memory and plasticity of the body representation.

Self-face and self-body advantages in congenital prosopagnosia: evidence for a common mechanism

Prosopagnosia is a disorder leading to difficulties in recognizing faces. However, recent evidence suggests that individuals with congenital prosopagnosia can achieve considerable accuracy when they have to recognize their own faces (self-face advantage). Yet, whether this advantage is face-specific or not is still unclear. Here, we aimed to investigate whether individuals with congenial prosopagnosia show a self-advantage also in recognizing other self body-parts and, if so, whether the advantage for the body parts differs from the one characterizing the self-face. Eight individuals with congenital prosopagnosia and 22 controls underwent a delayed matching task in which they were required to recognize faces, hands and feet belonging to the self or to others. Controls showed a similar self-advantage for all the stimuli tested; by contrast, individuals with congenital prosopagnosia showed a larger self-advantage with faces compared to hands and feet, mainly driven by their deficit with others' faces. In both groups the self-advantages for the different body parts were strongly and significantly correlated. Our data suggest that the self-face advantage showed by individuals with congenital prosopagnosia is not face-specific and that the same mechanism could be responsible for both the self-face and self body-part advantages.

Prioritization of arbitrary faces associated to self: An EEG study

Behavioral and neuroimaging studies have demonstrated that people process preferentially self-related information such as an image of their own face. Furthermore, people rapidly incorporate stimuli into their self-representation even if these stimuli do not have an intrinsic relation to self. In the present study, we investigated the time course of the processes involved in preferential processing of self-related information. In two EEG experiments three unfamiliar faces were identified with verbal labels as either the participant, a friend, or a stranger. Afterwards, participants judged whether two stimuli presented in succession (ISI = 1500ms) matched. In experiment 1, faces were followed by verbal labels and in experiment 2, labels were followed by faces. Both experiments showed the same pattern of behavioral and electrophysiological results. If the first stimulus (face or label) was associated with self, reaction times were faster and the late frontal positivity following the first stimulus was more pronounced. The self-association of the second stimulus (label or face) did not affect response times. However, the central-parietal P3 following presentation of the second stimulus was more pronounced when the second stimulus was preceded by self-related first stimulus. These results indicate that even unfamiliar faces that are associated to self can activate a self-representation. Once the self-representation has been activated the processing of ensuing stimuli is facilitated, irrespective of whether they are associated with the self.

"Like the palm of my hands": Motor imagery enhances implicit and explicit visual recognition of one's own hands

A key point in motor imagery literature is that judging hands in palm view recruits sensory-motor information to a higher extent than judging hands in back view, due to the greater biomechanical complexity implied in rotating hands depicted from palm than from back. We took advantage from this solid evidence to test the nature of a phenomenon known as self-advantage, i.e. the advantage in implicitly recognizing self vs. others' hand images. The self-advantage has been actually found when implicitly but not explicitly judging self-hands, likely due to dissociation between implicit and explicit body representations. However, such a finding might be related to the extent to which motor imagery is recruited during implicit and explicit processing of hand images. We tested this hypothesis in two behavioural experiments. In Experiment 1, right-handed participants judged laterality of either self or others' hands, whereas in Experiment 2, an explicit recognition of one's own hands was required. Crucially, in both experiments participants were randomly presented with hand images viewed from back or from palm. The main result of both experiments was the self-advantage when participants judged hands from palm view. This novel finding demonstrate that increasing the "motor imagery load" during processing of self vs. others' hands can elicit a self-advantage in explicit recognition tasks as well. Future studies testing the possible dissociation between implicit and explicit visual body representations should take into account the modulatory effect of motor imagery load on self-hand processing.

Losing self control

Our brain is less able to move one of our hands if an illusion makes us feel like the hand does not belong to us.

Implicit and Explicit Routes to Recognize the Own Body: Evidence from Brain Damaged Patients

Much research suggested that recognizing our own body-parts and attributing a body-part to our physical self-likely involve distinct processes. Accordingly, facilitation for self-body-parts was found when an implicit, but not an explicit, self-recognition was required. Here, we assess whether implicit and explicit bodily self-recognition is mediated by different cerebral networks and can be selectively impaired after brain lesion. To this aim, right- (RBD) and left- (LBD) brain damaged patients and age-matched controls were presented with rotated pictures of either self- or other-people hands. In the Implicit task participants were submitted to hand laterality judgments. In the Explicit task they had to judge whether the hand belonged, or not, to them. In the Implicit task, controls and LBD patients, but not RBD patients, showed an advantage for self-body stimuli. In the Explicit task a disadvantage emerged for self-compared to others' body stimuli in controls as well as in patients. Moreover, when we directly compared the performance of patients and controls, we found RBD, but not LBD, patients to be impaired in both the implicit and explicit recognition of self-body-part stimuli. Conversely, no differences were found for others' body-part stimuli. Crucially, 40% RBD patients showed a selective deficit for implicit processing of self-body-part stimuli, whereas 27% of them showed a selective deficit in the explicit recognition of their own body. Additionally, we provide anatomical evidence revealing the neural basis of this dissociation. Based on both behavioral and anatomical data, we suggest that different areas of the right hemisphere underpin implicit and explicit self-body knowledge.

The use of an exoskeleton to investigate the self advantage phenomenon

This paper presents an upper extremity exoskeleton with an original application in neuroscience. The novelty of this study is the investigation of the self-advantage phenomenon under various experimental conditions. Usually this kind of experiments lies only on human visual ability to explicitly and/or implicitly recognize their own arm movements. Using an exoskeleton to replay recorded trajectories allows to give another perspective to the previous studies in including the proprioceptive ability of humans. Twelve healthy subjects were involved in this study. The results show that the self advantage phenomenon is even more present in the implicit tasks.

Who is speaking? Implicit and explicit self and other voice recognition

In the domain of self-recognition, voice is a critical feature for self/other distinction. The aim of this study was to explore if people have an implicit and/or explicit knowledge of their voice. A group of healthy participants were submitted to an implicit and an explicit self-voice recognition task. They listened to pairs of pre-recorded auditory stimuli (words or pseudowords) pronounced by themselves, by a familiar or an unfamiliar person. Afterwards, in the "Implicit task" participants had to judge whether the pair of stimuli were pronounced by same or different speakers; in the "Explicit task" they had to identify if one of the stimuli was or not their own voice. Results showed a difference between Implicit and Explicit tasks since participants were more accurate in implicit than explicit self voice-recognition. Moreover, in the Implicit task, participants had the same level of accuracy when they had to judge stimuli pronounced with self or others' voice, whereas when an explicit voice-recognition was required, they were less accurate with self than with others' voice.

Psychopathology of the bodily self and the brain: the case of schizophrenia

In the present paper, we review the recent empirical evidence on the neurobiological basis of a minimal notion of the self, the bodily self. We show the relationship between the body, its motor potentialities and the notion of minimal self. We argue that this approach can shed new light onto self-disturbances and social deficits characterizing schizophrenia. We discuss our approach with other views on the neural correlates of self-disturbances in schizophrenia and propose that cognitive neuroscience can today address the classical topics of psychopathology by adding a new level of description, finally enabling the correlation between the first-person experiential aspects of psychiatric diseases and their neurobiological roots.

Dissociations between the horizontal and dorsoventral axes in body-size perception

Body size can vary throughout a person's lifetime, inducing plasticity of the internal body representation. Changes in horizontal width accompany those in dorsal-to-ventral thickness. To examine differences in the perception of different body axes, neural correlates of own-body-size perception in the horizontal and dorsoventral directions were compared using functional magnetic resonance imaging. Original and distorted (-30, -10, +10 and +30%) images of the neck-down region of their own body were presented to healthy female participants, who were then asked whether the images were of their own body or not based explicitly on body size. Participants perceived body images distorted by -10% as their own, whereas those distorted by +30% as belonging to others. Horizontal width images yielded slightly more subjective own-body perceptions than dorsoventral thickness images did. Subjective perception of own-body size was associated with bilateral inferior parietal activity. In contrast, other-body judgments showed pre-supplementary motor and superior parietal activity. Expansion in the dorsoventral direction was associated with the left fusiform gyrus and the right inferior parietal lobule, whereas horizontal expansions were associated with activity in the bilateral somatosensory area. These results suggest neural dissociations between the two body axes: dorsoventral images of thickness may require visual processing, whereas bodily sensations are involved in horizontal body-size perception. Somatosensory rather than visual processes can be critical for the assessment of frontal own-body appearance. Visual body thickness and somatosensory body width may be integrated to construct a whole-body representation.

Jaspers, the body, and schizophrenia: the bodily self

Karl Jaspers laid the foundations of contemporary psychopathology. Among Jaspers' contributions was his powerful vision of psychiatry as a crucial way to shed light on the human condition and existence by integrating the scientific study of psychic diseases with a theoretical approach focused on human experience. This perspective should be revitalized. In the present paper we start from the role Jaspers assigns to the body when discussing the notion of 'personalization'. We explore the relationship between a minimal notion of the self, the 'bodily self', and its potentiality for movement - the self's 'power for action'. Based on recent empirical evidence, we then propose a connection between the implicit bodily self-experience and important psychopathological aspects of schizophrenia by showing that schizophrenic patients exhibit a disruption of implicit bodily self-knowledge. We propose that the bodily nature of the implicitly experiencing self might enable the continuum of experience along which all visions of the world are located - both in healthy and psychotic individuals. The power for action might provide the possibility to give form to the bodily presence characterizing in the first place our being selves.

A Sensorimotor Network for the Bodily Self

Neuroscientists and philosophers, among others, have long questioned the contribution of bodily experience to the constitution of self-consciousness. Contemporary research answers this question by focusing on the notions of sense of agency and/or sense of ownership. Recently, however, it has been proposed that the bodily self might also be rooted in bodily motor experience, that is, in the experience of oneself as instantiating a bodily structure that enables a specific range of actions. In the current fMRI study, we tested this hypothesis by making participants undergo a hand laterality judgment task, which is known to be solved by simulating a motor rotation of one's own hand. The stimulus to be judged was either the participant's own hand or the hand of a stranger. We used this task to investigate whether mental rotation of pictures depicting one's own hands leads to a different activation of the sensorimotor areas as compared with the mental rotation of pictures depicting another's hand. We revealed a neural network for the general representation of the bodily self encompassing the SMA and pre-SMA, the anterior insula, and the occipital cortex, bilaterally. Crucially, the representation of one's own dominant hand turned out to be primarily confined to the left premotor cortex. Our data seem to support the existence of a sense of bodily self encased within the sensorimotor system. We propose that such a sensorimotor representation of the bodily self might help us to differentiate our own body from that of others.