The ‘Enfacement’ illusion: A window on the plasticity of the self

Confrontation with others' emotions changes bodily resonance differently in those with low and high levels of depersonalization

We present novel research on the cortical dynamics of atypical perceptual and emotional processing in people with symptoms of depersonalization-derealization disorder (DP-DR). We used electroencephalography (EEG)/event-related potentials (ERPs) to delineate the early perceptual mechanisms underlying emotional face recognition and mirror touch in adults with low and high levels of DP-DR symptoms (low-DP and high-DP groups). Face-sensitive visual N170 showed markedly less differentiation for emotional versus neutral face-voice stimuli in the high- than in the low-DP group. This effect was related to self-reported bodily symptoms like disembodiment. Emotional face-voice primes altered mirror touch at somatosensory cortical components P45 and P100 differently in the two groups. In the high-DP group, mirror touch occurred only when seeing touch after being confronted with angry face-voice primes. Mirror touch in the low-DP group, however, was unaffected by preceding emotions. Modulation of mirror touch following angry others was related to symptoms of self-other confusion. Results suggest that others' negative emotions affect somatosensory processes in those with an altered sense of bodily self. Our findings are in line with the idea that disconnecting from one's body and self (core symptom of DP-DR) may be a defence mechanism to protect from the threat of negative feelings, which may be exacerbated through self-other confusion. This article is part of the theme issue 'Sensing and feeling: an integrative approach to sensory processing and emotional experience'.

Novel online enfacement illusion for investigating self-perception in mental disorders: an experimental study protocol

BACKGROUND

Remote research methods and interventions for mental health disorders have become increasingly important, particularly for conditions like eating disorders (EDs). Embodiment illusions, which induce feelings of ownership over another person?s body or body parts, offer valuable insights into the mechanisms underlying self-perception issues in EDs and potential interventions. However, existing research using these illusions has been limited to face-to-face settings. We illustrate a novel online protocol to induce the enfacement illusion (embodiment illusion principles applied to one's face) in an ED-based sample.

METHODS

Participants complete a 2-hr virtual session with a researcher. First, baseline trait/state ED psychopathology measures and a self-face recognition task occur. Second, participants experience two testing blocks of the enfacement illusion involving synchronously and asynchronously mimicking a pre-recorded actor's facial expressions. After each block, subjective and objective enfacement illusion measures occur alongside state ED psychopathology reassessment.

DISCUSSION

Successfully inducing enfacement illusions online could provide an affordable, accessible virtual approach to further elucidate the mechanistic role of self-perception disturbances across psychopathologies such as EDs. Moreover, this protocol may represent an innovative, remotely-delivered intervention strategy, as 'enfacement' over another face could update negative self-representations in a cost-effective, scalable manner.

Embodiment of underweight and normal-weight avatars affects bodily self-representations in anorexia nervosa

Body image distortion (BID) is a crucial aspect of anorexia nervosa (AN), leading to body overestimation, dissatisfaction, and low self-esteem. BID significantly influences the onset, maintenance, and relapse of the pathology. We assessed whether a Full Body Illusion (FBI) using under and normal-weight avatars' bodies affects perceptual body image and body schema estimations in both individuals with anorexia nervosa (AN) and healthy controls (HC). After each embodiment procedure, we asked participants to estimate the width of their hips (Perceptual Body Image Task) and the minimum aperture width of a virtual door necessary to pass through it (Body Schema Task). Additionally, we asked participants to rate the avatars in terms of self-similarity, attractiveness, and implicit disgust (i.e., pleasant/unpleasant body odour). Whereas participants with AN (N = 26) showed changes in body schema estimations after embodying the normal-weight avatar, no changes were found in HC (N = 25), highlighting increased bodily self-plasticity in AN. Notably, individuals with AN rated the normal weight avatar as the most similar to their real body, which was also considered the least attractive and the most repulsive. These ratings correlated with BID severity. Furthermore, at the explicit level, all participants reported feeling thinner than usual after embodying the underweight avatar. Overall, our findings suggest that BID in AN engages multiple sensory channels (from visual to olfactory) and components (from perceptual to affective), offering potential targets for innovative non-invasive treatments aimed at modifying flexible aspects of body representation.

Malleability of the sense of bodily self in early childhood: 5- and 6-year-old children children show the enfacement illusion

The mechanisms underlying the developing sense of bodily self are debated. Whereas some scholars stress the role of sensory factors, others propose the importance of contextual factors. By manipulating multisensory stimulation and social familiarity with the other person, we explored two factors that are proposed to relate to young children's developing sense of bodily self. Including an adult sample allowed us to investigate age-related differences of the malleability of the bodily self. To this end, the study implemented an enfacement illusion with children (N = 64) and adults (N = 33). Participants were exposed to one trial with synchronous interpersonal multisensory stimulation and one trial with asynchronous interpersonal multisensory stimulation-either with a stranger or with the mother as the other person. A self-recognition task using morph videos of self and other and an enfacement questionnaire were implemented as dependent measures. Results revealed evidence for the presence of the enfacement effect in children in both measures. The identity of the other person had a significant effect on the self-recognition task. Contrary to our hypothesis, the effect was significantly smaller in the caregiver condition. No significant differences between children and adults emerged. Our results demonstrate the role of both multisensory stimulation and contextual-here social familiarity-factors for the construction and development of a bodily self. The study provides developmental science with a novel approach to the bodily self by showing the validity of the self-recognition task in a child sample. Overall, the study supports proposals that the sense of bodily self is malleable early in development.

Probing corporeal awareness in women through virtual reality induction of embreathment illusion

We capitalized on the respiratory bodily illusion that we discovered in a previous study and called 'Embreathment' where we showed that breathing modulates corporeal awareness in men. Despite the relevance of the issue, no such studies are available in women. To bridge this gap, we tested whether the synchronization of avatar-participant respiration patterns influenced females' bodily awareness. We collected cardiac and respiratory interoceptive measures, administered body (dis)satisfaction questionnaires, and tracked participants' menstrual cycles via a mobile app. Our approach allowed us to characterize the 'Embreathment' illusion in women, and explore the relationships between menstrual cycle, interoception and body image. We found that breathing was as crucial as visual appearance in eliciting feelings of ownership and held greater significance than any other cue with respect to body agency in both women and men. Moreover, a positive correlation between menstrual cycle days and body image concerns, and a negative correlation between interoceptive sensibility and body dissatisfaction were found, confirming that women's body dissatisfaction arises during the last days of menstrual cycle and is associated with interoception. These findings have potential implications for corporeal awareness alterations in clinical conditions like eating disorders and schizophrenia.

Fluid face but not gender: Enfacement illusion through digital face filters does not affect gender identity

It has been shown that observing a face being touched or moving in synchrony with our own face increases self-identification with the former which might alter both cognitive and affective processes. The induction of this phenomenon, termed enfacement illusion, has often relied on laboratory tools that are unavailable to a large audience. However, digital face filters applications are nowadays regularly used and might provide an interesting tool to study similar mechanisms in a wider population. Digital filters are able to render our faces in real time while changing important facial features, for example, rendering them more masculine or feminine according to normative standards. Recent literature using full-body illusions has shown that participants' own gender identity shifts when embodying a different gendered avatar. Here we studied whether participants' filtered faces, observed while moving in synchrony with their own face, may induce an enfacement illusion and if so, modulate their gender identity. We collected data from 35 female and 33 male participants who observed a stereotypically gender mismatched version of themselves either moving synchronously or asynchronously with their own face on a screen. Our findings showed a successful induction of the enfacement illusion in the synchronous condition according to a questionnaire addressing the feelings of ownership, agency and perceived similarity. However, we found no evidence of gender identity being modulated, neither in explicit nor in implicit measures of gender identification. We discuss the distinction between full-body and facial processing and the relevance of studying widely accessible devices that may impact the sense of a bodily self and our cognition, emotion and behaviour.

Visual perspective and body ownership modulate vicarious pain and touch: A systematic review

We conducted a systematic review investigating the influence of visual perspective and body ownership (BO) on vicarious brain resonance and vicarious sensations during the observation of pain and touch. Indeed, the way in which brain reactivity and the phenomenological experience can be modulated by blurring the bodily boundaries of self-other distinction is still unclear. We screened Scopus and WebOfScience, and identified 31 articles, published from 2000 to 2022. Results show that assuming an egocentric perspective enhances vicarious resonance and vicarious sensations. Studies on synaesthetes suggest that vicarious conscious experiences are associated with an increased tendency to embody fake body parts, even in the absence of congruent multisensory stimulation. Moreover, immersive virtual reality studies show that the type of embodied virtual body can affect high-order sensations such as appropriateness, unpleasantness, and erogeneity, associated with the touched body part and the toucher's social identity. We conclude that perspective plays a key role in the resonance with others' pain and touch, and full-BO over virtual avatars allows investigation of complex aspects of pain and touch perception which would not be possible in reality.

Touch and look: The role of affective touch in promoting infants' attention towards complex visual scenes

In a complex social environment, stimuli from different sensory modalities need to be integrated to decode communicative meanings. From very early in life, infants have to combine a multitude of sensory features with social and affective attributes. Of all senses, touch constitutes a privileged channel to carry affective-motivational meanings and foster social connection. In the present study, we investigate whether sharing sensory stimulation that varies for its affective value differentially affects infants' attention towards visual stimuli. 6 to 11-month-old infants (N = 42) were familiarized with two characters respectively matched with tactile (affective or non-affective) and auditory stimulation; then repeatedly exposed to scenes where the two characters moved towards target objects. Our results showed a main effect of stimulation (sound vs. touch) on looking times during familiarization, with longer looking times when sound is provided. During scenes presentation, a main effect of the type of touch (affective vs. non affective) emerged, with longer looking times in infants that previously experienced affective touch, suggesting that this sensory experience may critically engage the self and modulate infant attention. Overall, these findings suggest that while sound acts as attention getter, affective touch supports sustained attention towards complex visual scenes beyond the stimulation period itself.

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.

Ownership of the affected leg is further reduced following deceptive behaviors in body integrity dysphoria

Although predicted by the notion of embodied morality, it remains unknown whether a reduced sense of body ownership (SoO) is associated with increased or decreased dishonesty. To clarify this issue, we tested patients with body integrity dysphoria (BID), a clinical condition characterized by chronic reductions of SoO toward one leg that patients persistently desire to have amputated. Participants with BID played a card game in which they could voluntarily tell the truth or cheat an opponent, and thus either steal or give them money. To assess whether SoO toward the effector limb influences (im)moral decisions, responses were communicated with the affected or the unaffected leg. We found that a higher number of self-gain lies was followed by further reductions of SoO toward the affected leg. Our result supports the idea that reductions of SoO may follow immoral behaviors to distance from unwanted characteristics of the self, like one's own dishonesty.

Development and validation of the Exteroceptive Body Awareness (EBA-q) questionnaire

The conscious processing of body signals influences higher-order psychological and cognitive functions, including self-awareness. Dysfunctions in the processing of these signals has been connected to neurological and psychiatric disorders characterized by altered states of self-consciousness. Studies indicate that perceiving the body through interoceptive signals (e.g., from internal organs such as heartbeat and breathing) is distinct from perceiving the body through exteroceptive signals (e.g., by relying on visual, tactile and olfactory cues). While questionnaires are available for assessing interoception, there are no validated self-report instruments for measuring bodily exterception. To fill this gap, we performed three studies to develop and validate a novel scale designed to assess bodily self-consciousness based on the processing of exteroceptive bodily signals. Exploratory factor analysis (Study 1, N = 302) led to an 18-item questionnaire comprised of four factors. We called this instrument Exteroceptive Body Awareness questionnaire (EBA-q). Confirmatory factor analysis (Study 2, N = 184) run on a second sample showed an acceptable fit for a bifactor model, suggesting researchers may use the questionnaire as a unidimensional scale reflecting exteroceptive bodily self-consciousness, or use each of its four sub-scales, reflecting "visuo-tactile body awareness", "spatial coordination", "awareness of body changes" and "awareness of clothing fit". Overall EBA-q showed good internal consistency. Convergent and divergent validity were assessed via cross-validation with existing body awareness questionnaires (Study 3, N = 366) and behavioral measures (Study 3, N = 64) of exteroceptive and interoceptive bodily self-consciousness. Research applications are discussed within a multi-faceted model of exteroception and interoception as distinct, but at the same time interconnected, dimensions of bodily self-consciousness.

Look at me now! Enfacement illusion over computer-generated faces

According to embodied cognition research, one’s bodily self-perception can be illusory and temporarily shifted toward an external body. Similarly, the so-called “enfacement illusion” induced with a synchronous multisensory stimulation over the self-face and an external face can result in implicit and explicit changes in the bodily self. The present study aimed to verify (i) the possibility of eliciting an enfacement illusion over computer-generated faces and (ii) which multisensory stimulation condition was more effective. A total of 23 participants were asked to look at a gender-matched avatar in three synchronous experimental conditions and three asynchronous control conditions (one for each stimulation: visuotactile, visuomotor, and simple exposure). After each condition, participants were asked to complete a questionnaire assessing both the embodiment and the enfacement sensations to address different facets of the illusion. Results suggest a stronger effect of synchronous vs. asynchronous stimulation, and the difference was more pronounced for the embodiment items of the questionnaire. We also found a greater effect of visuotactile and visuomotor stimulations as compared to the simple exposure condition. These findings support the enfacement illusion as a new paradigm to investigate the ownership of different face identities and the specific role of visuotactile and visuomotor stimulations with virtual reality stimuli.

The Open Virtual Mirror Framework for enfacement illusions : Enhancing the sense of agency with avatars that imitate facial expressions

Enfacement illusions are traditionally elicited by visuo-tactile stimulation, but more active paradigms become possible through the usage of virtual reality techniques. For instance, virtual mirrors have been recently proposed to induce enfacement by visuo-motor stimulation. In a virtual mirror experiment, participants interact with an avatar that imitates their facial movements. The active control over the avatar greatly enhances the sense of agency, which is an important ingredient for successful enfacement illusion induction. Due to technological challenges, most virtual mirrors so far were limited to the imitation of the participant's head pose, i.e., its location and rotation. However, stronger experiences of agency can be expected by an increase in the avatar's mimicking abilities. We here present a new open-source framework for virtual mirror experiments, which we call the Open Virtual Mirror Framework (OVMF). The OVMF can track and imitate a large range of facial movements, including pose and expressions. It has been designed to run on standard computer hardware and easily interfaces with existing toolboxes for psychological experimentation, while satisfying the requirement of a tightly controlled experimental setup. Further, it is designed to enable convenient extension of its core functionality such that it can be flexibly adjusted to many different experimental paradigms. We demonstrate the usage of the OVMF and experimentally validate its ability to elicit experiences of agency over an avatar, concluding that the OVMF can serve as a reference for future experiments and that it provides high potential to stimulate new directions in enfacement research and beyond.

Changes in self-other boundaries modulate children's body image attitudes

One's own face is a key distinctive feature of our physical appearance, yet multisensory visuo-tactile stimulation can alter self-other boundaries, eliciting changes in adult's self-face representation and social cognition processes. This study tested whether changing self-face representation by altering self-other boundaries with the enfacement illusion modulates body image attitudes toward others in 6-11-year-old children (N = 51; 31 girls; predominantly White). Across all ages, congruent multisensory information led to stronger enfacement (η²_p = 0.06). Participants who experienced a stronger enfacement illusion showed preference for larger body size, suggesting increased positive body size attitudes. This effect was stronger in 6-7-year-olds compared to 8-9-year-olds. Thus, blurring self-other boundaries successfully modulates self-face representation and body image attitudes toward others in children. Our results suggest that increased self-resemblance through self-other blurring resulting from the enfacement illusion may reduce social comparisons between self and other and result in positive body size attitudes.

The Virtual "Enfacement Illusion" on Pain Perception in Patients Suffering from Chronic Migraine: A Study Protocol for a Randomized Controlled Trial

BACKGROUND

given the limited efficacy, tolerability, and accessibility of pharmacological treatments for chronic migraine (CM), new complementary strategies have gained increasing attention. Body ownership illusions have been proposed as a non-pharmacological strategy for pain relief. Here, we illustrate the protocol for evaluating the efficacy in decreasing pain perception of the enfacement illusion of a happy face observed through an immersive virtual reality (VR) system in CM.

METHOD

the study is a double-blind randomized controlled trial with two arms, involving 100 female CM patients assigned to the experimental group or the control group. The experimental group will be exposed to the enfacement illusion, whereas the control group will be exposed to a pleasant immersive virtual environment. Both arms of the trial will consist in three VR sessions (20 min each). At the baseline and at the end of the intervention, the patients will fill in questionnaires based on behavioral measures related to their emotional and psychological state and their body satisfaction. Before and after each VR session, the level of pain, the body image perception, and the affective state will be assessed.

DISCUSSION

this study will provide knowledge regarding the relationship between internal body representation and pain perception, supporting the effectiveness of the enfacement illusion as a cognitive behavioral intervention in CM.

Face yourself: The social neuroscience of mirror gazing

In philosophical and psychological accounts alike, it has been claimed that mirror gazing is like looking at ourselves as others. Social neuroscience and social psychology offer support for this view by showing that we use similar brain and cognitive mechanisms during perception of both others’ and our own face. I analyse these premises to investigate the factors affecting the perception of one’s own mirror image. I analyse mechanisms and processes involved in face perception, mimicry, and emotion recognition, and defend the following argument: because perception of others’ face is affected by our feelings toward them, it is likely that feelings toward ourselves affect our responses to the mirror image. One implication is that negative self-feelings can affect mirror gazing instantiating a vicious cycle where the negative emotional response reflects a previously acquired attitude toward oneself. I conclude by discussing implications of this view for psychology and social studies.

Morality in the flesh: on the link between bodily self-consciousness, moral identity and (dis)honest behaviour

The sense of owning a body (ownership) and controlling its actions (agency) are two main pillars of bodily self-consciousness (BSC). Although studies suggest that BSC signals and morality may be associated, whether such association has a positive or negative direction remains unclear. To investigate this issue, we conducted two pre-registered, online studies, in which a total of 1309 participants completed BSC- and morality-related questionnaires and undertook a task where they could cheat for monetary gain. We found that participants with high sense of ownership displayed high moral identity, which supports the notion that ownership is used to associate the self with positive characteristics. Moreover, high agency was associated with increased moral identity when sense of power is high. Results regarding deception are less clear, and might relate to the impact of COVID-19. Our results concerning moral identity may inspire policies that rely on changes of corporeal awareness to contrast immorality.

Morality in the flesh: on the link between bodily self-consciousness, moral identity and (dis)honest behaviour

The sense of owning a body (ownership) and controlling its actions (agency) are two main pillars of bodily self-consciousness (BSC). Although studies suggest that BSC signals and morality may be associated, whether such association has a positive or negative direction remains unclear. To investigate this issue, we conducted two pre-registered, online studies, in which a total of 1309 participants completed BSC- and morality-related questionnaires and undertook a task where they could cheat for monetary gain. We found that participants with high sense of ownership displayed high moral identity, which supports the notion that ownership is used to associate the self with positive characteristics. Moreover, high agency was associated with increased moral identity when sense of power is high. Results regarding deception are less clear, and might relate to the impact of COVID-19. Our results concerning moral identity may inspire policies that rely on changes of corporeal awareness to contrast immorality.

Morality in the flesh: on the link between bodily self-consciousness, moral identity and (dis)honest behaviour

The sense of owning a body (ownership) and controlling its actions (agency) are two main pillars of bodily self-consciousness (BSC). Although studies suggest that BSC signals and morality may be associated, whether such association has a positive or negative direction remains unclear. To investigate this issue, we conducted two pre-registered, online studies, in which a total of 1309 participants completed BSC- and morality-related questionnaires and undertook a task where they could cheat for monetary gain. We found that participants with high sense of ownership displayed high moral identity, which supports the notion that ownership is used to associate the self with positive characteristics. Moreover, high agency was associated with increased moral identity when sense of power is high. Results regarding deception are less clear, and might relate to the impact of COVID-19. Our results concerning moral identity may inspire policies that rely on changes of corporeal awareness to contrast immorality.

Mirror, mirror, on the wall: During pandemics, how can self-perception research in people with eating disorders happen at all?

BACKGROUND

'Classic' embodiment illusions (e.g., the feeling of owning another person's hand) involves a three-way interaction between visual, proprioceptive, and tactile stimuli. These illusions have been studied in eating disorder (ED) populations given the potential implications for better understanding and improving body image concerns. Recently, several studies have employed 'tactile-reduced' methods mainly relying on the integration of visual and proprioceptive information to induce embodiment illusions in non-ED populations. To date, there has been no substantial review of these tactile-reduced approaches to consider their potential research and clinical utility in ED populations.

METHOD

This review sought to examine and integrate studies across three areas. Firstly, those that employed tactile-reduced embodiment techniques in non-ED populations. Secondly, those that used classic embodiment techniques to compare whether ED and non-ED populations differ in their susceptibility to embodiment. Thirdly, studies that investigated whether experiencing classic or tactile-reduced embodiment techniques can improve image-related concerns.

RESULTS

For the first aim five studies were identified, all of which found that tactile-reduced methods consistently induced embodiment illusions in non-ED individuals. For the second aim, seven studies comparing ED and non-ED samples were found. ED patients were more susceptible to embodiment than non-ED samples in four studies, less susceptible in one study, and equally susceptible in two studies. Finally, for aim three, amongst the seven studies that used classic or tactile-reduced embodiment methods in ED populations, six reported improvements in self-perception (i.e., reduced body size overestimation, decreased body dissatisfaction and fear of gaining weight).

CONCLUSIONS

Along with the classic approach, tactile-reduced embodiment approaches have implications for ED research and clinical practice, particularly for situations when face-to-face contact with people are restricted. Suggestions are provided for future researchers who wish to ensure best practice for planning embodiment research involving classic and tactile-reduced approaches.

Reduced ownership over a virtual body modulates dishonesty

Although studies suggest that even higher-order functions can be embodied, whether body awareness may bias moral decisions toward (dis)honesty remains underinvestigated. Here, we tested if the Sense of body Ownership (SoO) and the magnitude of monetary rewards influence the tendency to act immorally. Through a virtual body, participants played a card game in which they could lie to others to steal high or low amounts of money. To manipulate SoO, the virtual body was seen and controlled from a first-person perspective, with hands attached or detached, or from a third-person perspective. In third-person perspective, SoO was significantly reduced and more egoistic lies were produced in high reward conditions. Thus, SoO reduction and high monetary reward facilitate dishonest behavior, likely by separating the self from the dishonest actions performed through the disowned body. Because most future interactions will likely occur in a digital metaverse, our results may have crucial societal impact.

Neural correlates of disturbance in the sense of agency in schizophrenia: An fMRI study using the 'enfacement' paradigm

An altered sense of self-awareness and agency has been proposed to underlie symptoms of schizophrenia. In this study, we used the enfacement illusion paradigm - in which perception of another person's face leads to changes in perception of one's own peri-personal space - to examine the brain correlates of the sense of agency and its potential disruption in schizophrenia. Thirty-three schizophrenic patients and 27 healthy controls underwent fMRI scanning during performance of a task designed to elicit the enfacement illusion. Activations were examined using whole-brain analysis and also in an a priori identified region of interest (ROI) in the temporoparietal junction (TPJ), a region that has been described as involved in self/other differentiation and sense of agency. Both groups showed a pattern of cortical activation involving the pre and postcentral cortex, Rolandic operculum, insula, parietal, temporal and occipital cortex bilaterally as well as TPJ (but only right-side in patients). Examination of the TPJ ROI revealed significantly reduced activation on the left in the patients that was associated with poorer insight. The findings suggest brain functional abnormality in schizophrenia related to the formation or maintenance of processes related to self and/or agency. Decreased function in the TPJ may have a role in the impaired insight seen in patients with the disorder.

[To experience one's physicality through the "bizarre" experience of touching oneself]

The touch of oneself is essential in the construction of a conscious self. It contributes to the feeling of ownership of the body. Feeling touched and touching reveals the subject in a being-self inscribed in its environment. This sensory experience can be disturbing for the subject. A study conducted with adolescent girls with obesity has shown that this haptic experience, during a postural session, can generate a feeling of strangeness. This singular discovery of oneself reveals the opening towards new exploratory fields of the body self-consciousness, during our care.

Bodily Illusions and Motor Imagery in Fibromyalgia

Fibromyalgia (FM) is characterised by chronic, continuous, widespread pain, often associated with a sense of fatigue, non-restorative sleep and physical exhaustion. Due to the nature of this condition and the absence of other neurological issues potentially able to induce disorders in body representations per se, it represents a perfect model since it provides an opportunity to study the relationship between pain and the bodily self. Corporeal illusions were investigated in 60 participants with or without a diagnosis of FM by means of an ad hoc devised interview. In addition, motor imagery was investigated and illusions relating to body part movements and changes in body size, feelings of alienness, and sensations of body parts not belonging to one’s own body (disownership and somatoparaphrenic-like sensations) were found. Crucially, these symptoms do not correlate with any of the clinical measures of pain or functional deficits. The results showed that motor imagery was also impaired, and the severity of the deficits found correlated with the functional impairment of the participant. This indicates that disorders in body representations and motor imagery are part of the clinical expression of FM. However, while motor imagery seems to be linked to reduced autonomy and functional deficits, bodily illusions are independent and potentially represent a concurrent symptom.

The enfacement illusion in autism spectrum disorder: How interpersonal multisensory stimulation influences facial recognition of the self

At its most basic level, the sense of self is built upon awareness of one's body and the face holds special significance as the individual's most important and distinctive physical feature. Multimodal sensory integration is pivotal to experiencing one's own body as a coherent visual "self" representation is formed and maintained by matching felt and observed sensorimotor experiences in the mirror. While difficulties in individual facial identity recognition and in both self-referential cognition and empathy are frequently reported in individuals with autism spectrum disorder (ASD), studying the effect of multimodal sensory stimulation in this population is of relevant interest. The present study investigates for the first time the specific effect on Interpersonal Multisensory Stimulation (IMS) on face self-recognition in a sample of 30 adults with (n = 15) and without (n = 15) ASD, matched on age and sex. The results demonstrate atypical self-face recognition and absence of IMS effects (enfacement illusion) in adults with ASD compared to controls, indicating that multisensory integration failed in updating cognitive representations of one's own face among persons with this disorder. The results are discussed in the light of other findings indicating alterations in body enfacement illusion and automatic imitation in ASD as well as in the context of the theories of procedural perception and multisensory integration alterations.

Identifying with the beautiful: Facial attractiveness effects on unisensory and multisensory self-other distinction

People tend to evaluate their own traits and abilities favourably and such favourable self-perceptions extend to attractiveness. However, the exact mechanism underlying this self-enhancement bias remains unclear. One possibility could be the identification with attractive others through blurring of self–other boundaries. Across two experiments, we used the enfacement illusion to investigate the effect of others’ attractiveness in the multisensory perception of the self. In Experiment 1 (N = 35), participants received synchronous or asynchronous interpersonal visuo-tactile stimulation with an attractive and non-attractive face. In Experiment 2 (N = 35), two new faces were used and spatial incongruency was introduced as a control condition. The results showed that increased ratings of attractiveness of an unfamiliar face lead to blurring of self–other boundaries, allowing the identification of our psychological self with another’s physical self and specifically their face, and this seems to be unrelated to perceived own attractiveness. The effect of facial attractiveness on face ownership showed dissociable mechanisms, with multisensory integration modulating the effect on similarity but not identification, an effect that may be purely based on vision. Overall, our findings suggest that others’ attractiveness may lead to positive distortions of the self. This research provides a psychophysical starting point for studying the impact of others’ attractiveness on self-face recognition, which can be particularly important for individuals with malleable, embodied self–other boundaries and body image disturbances.

Why Does Rubin's Vase Differ Radically From Optical Illusions? Framing Effects Contra Cognitive Illusions

Many researchers use the term "context" loosely to denote diverse kinds of reference points. The issue is not about terminology but rather about the common conflation of one kind of reference points, such as rules of perception, which is responsible for optical illusions, with another kind, known as "context" or "frame," as exemplified in Rubin's vase. Many researchers regard Rubin's vase as a special kind of optical illusions. This paper rather argues that the two phenomena are radically different. Optical illusions are occasional mistakes that people quickly recognize and eagerly correct, while the different figures of Rubin's vase are not mistakes but, rather, the outcomes of different perspectives that do not need correction. The competing figures in Rubin's vase can, at best, in light of more information, be more warranted or unwarranted. This paper discusses at length one ramification of the proposed distinction. The framing effects, such as loss/gain frame, are the products of contexts and, hence, resemble greatly the figures in Rubin's vase. In contrast, cognitive illusions generated occasionally by the rules of thumb (heuristics) are mistakes and, hence, resemble optical illusions. The proposed distinction carries other ramifications regarding, e.g., happiness studies, moral judgments, and the new philosophy of science.

The inside of me: interoceptive constraints on the concept of self in neuroscience and clinical psychology

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 self-concept, 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.

Interpersonal Motor Interactions Shape Multisensory Representations of the Peripersonal Space

This perspective review focuses on the proposal that predictive multisensory integration occurring in one's peripersonal space (PPS) supports individuals' ability to efficiently interact with others, and that integrating sensorimotor signals from the interacting partners leads to the emergence of a shared representation of the PPS. To support this proposal, we first introduce the features of body and PPS representations that are relevant for interpersonal motor interactions. Then, we highlight the role of action planning and execution on the dynamic expansion of the PPS. We continue by presenting evidence of PPS modulations after tool use and review studies suggesting that PPS expansions may be accounted for by Bayesian sensory filtering through predictive coding. In the central section, we describe how this conceptual framework can be used to explain the mechanisms through which the PPS may be modulated by the actions of our interaction partner, in order to facilitate interpersonal coordination. Last, we discuss how this proposal may support recent evidence concerning PPS rigidity in Autism Spectrum Disorder (ASD) and its possible relationship with ASD individuals' difficulties during interpersonal coordination. Future studies will need to clarify the mechanisms and neural underpinning of these dynamic, interpersonal modulations of the PPS.

Body ownership as a proxy for individual and social separation and connection

Lee and Schwartz procedures of separation offer a much needed interpretation of the literature on moral cleansing. However, body ownership as a grounded mechanism of separation and connection has been neglected. We argue that embodiment may be employed to connect the self to desirable aspects of cognitive and emotional interactions and disembodiment to disconnect from undesirable elements.

Heterosexual, gay, and lesbian people's reactivity to virtual caresses on their embodied avatars' taboo zones

Embodying an artificial agent through immersive virtual reality (IVR) may lead to feeling vicariously somatosensory stimuli on one's body which are in fact never delivered. To explore whether vicarious touch in IVR reflects the basic individual and social features of real-life interpersonal interactions we tested heterosexual men/women and gay men/lesbian women reacting subjectively and physiologically to the observation of a gender-matched virtual body being touched on intimate taboo zones (like genitalia) by male and female avatars. All participants rated as most erogenous caresses on their embodied avatar taboo zones. Crucially, heterosexual men/women and gay men/lesbian women rated as most erogenous taboo touches delivered by their opposite and same gender avatar, respectively. Skin conductance was maximal when taboo touches were delivered by female avatars. Our study shows that IVR may trigger realistic experiences and ultimately allow the direct exploration of sensitive societal and individual issues that can otherwise be explored only through imagination.

Étude qualitative de l’expérience psychocorporelle des autotouchers faciaux spontanés chez des infirmiers portés volontaires en renfort covid

Introduction : The COVID-19 pandemic has warranted the implementation of barrier actions and the wearing of personal protective equipment (PPE). These behavioral adaptations counteract spontaneous self-touching reflex gestures. I propose to explore the mind-body experience generated by these gesture changes in this health context.Method : I conducted a qualitative study with nine nurses who volunteered as reinforcements. The semistructured interviews I carried out were analyzed using the interpretative phenomenological analysis approach.Results : The perception of the risk of self-inoculation is not related to the level of virus exposure. Facial PPE is perceived both as reassuring and difficult to put up with. The experience of self-touches is influenced by the level of attention the subject pays to his or her face and by the medical background related to this. Three kinds of mind-body adaptations are used to control self-touching : control by avoidance, control by keeping one’s hands busy, and compensatory bodily strategies. The representations of the bodily self are modified in terms of gestures and of the feeling of humanness. This generates a form of bodily abandonment and a lived experience of soiled bodies.Conclusion : The results highlight the cognitive load involved in refraining from self-touching and with the wearing of facial PPE. They emphasize the importance of questioning the implications of these sensorimotor modifications. Supporting health professionals in assessing the mind-body repercussions in a pandemic situation appears key.

Fear-related signals are prioritised in visual, somatosensory and spatial systems

The human brain has evolved a multifaceted fear system, allowing threat detection to enable rapid adaptive responses crucial for survival. Although many cortical and subcortical brain areas are believed to be involved in the survival circuits detecting and responding to threat, the amygdala has reportedly a crucial role in the fear system. Here, we review evidence demonstrating that fearful faces, a specific category of salient stimuli indicating the presence of threat in the surrounding, are preferentially processed in the fear system and in the connected sensory cortices, even when they are presented outside of awareness or are irrelevant to the task. In the visual domain, we discuss evidence showing in hemianopic patients that fearful faces, via a subcortical colliculo-pulvinar-amygdala pathway, have a privileged visual processing even in the absence of awareness and facilitate responses towards visual stimuli in the intact visual field. Moreover, evidence showing that somatosensory cortices prioritise fearful-related signals, to the extent that tactile processing is enhanced in the presence of fearful faces, will be also reported. Finally, we will review evidence revealing that fearful faces have a pivotal role in modulating responses in peripersonal space, in line with the defensive functional definition of PPS.

Face individual identity recognition: a potential endophenotype in autism

BACKGROUND

Face individual identity recognition skill is heritable and independent of intellectual ability. Difficulties in face individual identity recognition are present in autistic individuals and their family members and are possibly linked to oxytocin polymorphisms in families with an autistic child. While it is reported that developmental prosopagnosia (i.e., impaired face identity recognition) occurs in 2-3% of the general population, no prosopagnosia prevalence estimate is available for autism. Furthermore, an autism within-group approach has not been reported towards characterizing impaired face memory and to investigate its possible links to social and communication difficulties.

METHODS

The present study estimated the prevalence of prosopagnosia in 80 autistic adults with no intellectual disability, investigated its cognitive characteristics and links to autism symptoms' severity, personality traits, and mental state understanding from the eye region by using standardized tests and questionnaires.

RESULTS

More than one third of autistic participants showed prosopagnosia. Their face memory skill was not associated with their symptom's severity, empathy, alexithymia, or general intelligence. Face identity recognition was instead linked to mental state recognition from the eye region only in autistic individuals who had prosopagnosia, and this relationship did not depend on participants' basic face perception skills. Importantly, we found that autistic participants were not aware of their face memory skills.

LIMITATIONS

We did not test an epidemiological sample, and additional work is necessary to establish whether these results generalize to the entire autism spectrum.

CONCLUSIONS

Impaired face individual identity recognition meets the criteria to be a potential endophenotype in autism. In the future, testing for face memory could be used to stratify autistic individuals into genetically meaningful subgroups and be translatable to autism animal models.

Premature birth affects visual body representation and body schema in preterm children

Research has demonstrated that from the first six months of life infants show early sensitivity to body visual features and rely on sensorimotor and proprioceptive inputs in forming representations of their own bodies. Premature birth interferes with typical exposition to visual, sensorimotor and proprioceptive stimulation, thus presumably affecting the development of body representations. Here, we tested this hypothesis by comparing the performance of preterm children with that of age-matched full-termchildren in two tasks assessing, respectively, visual body processing and body schema. We found that preterm children had spared configural processing but altered holistic processing of others' bodies and showed a general difficulty in expressing visuospatial judgements on body stimuli. Furthermore, body-centered visuospatial abilities were associated with specific impairments in operating object-based visuospatial transformations. The findings of this study indicate that preterm birth might interfere with the development of body representations at the levels of body visual perceptual processing and of body schema, with effects even on visuo-spatial abilities for non-bodily stimuli. Body-centered rehabilitative interventions should be proposed to preterm children in order to enhance visuo-spatial abilities and higher-level cognitive functions.

Virtual Embodiment Using 180° Stereoscopic Video

One of the most exciting possibilities of virtual reality is inducing in participants the illusion of owning a virtual body. This has become an established methodological paradigm allowing the study of the psychological and neural correlates of various scenarios that are impossible in the real world, such as gender or age switching. Thus far, full-body ownership illusions have been implemented by using real-time body tracking and avatars based on computer-generated imagery (CGI). We propose an alternative technique to induce perceived ownership over a (photorealistic) virtual body using 180° stereoscopic video, synchronous touch, and narration. We describe the technical components of our novel technique and an example implementation as part of a science-art project that enables participants to experience virtual bodies of different ages, and present the results of an experimental evaluation study based on this experience. Consistent with previous virtual embodiment studies using CGI-based techniques, we found that participants accept a photorealistic virtual body as their own irrespective of its appearance as indicated by similar ratings of the strength of body ownership over a virtual body of a child versus an adult. We further show that our novel technique can alter participants' cognition in accordance with the characteristics of their virtual body. Specifically, young adult participants who were embodied in the virtual body of a child significantly overestimated the duration of the virtual reality experience compared to a control group who was embodied in a virtual body of their own age. This finding corresponds to chronological age differences in time estimations and extends previous research on virtual child embodiment. Overall, these findings provide initial evidence for the potential of our novel technique to create photorealistic embodiment experiences with comparable psychological effects as have been found using CGI-based techniques while reducing the costs and technical complexity in the production and application of virtual body ownership illusions.

Cognitive Processes Unfold in a Social Context: A Review and Extension of Social Baseline Theory

Psychologists often assume that social and cognitive processes operate independently, an assumption that prompts research into how social context influences cognitive processes. We propose that social and cognitive processes are not necessarily separate, and that social context is innate to resource dependent cognitive processes. We review the research supporting social baseline theory, which argues that our default state in physiological, cognitive, and neural processing is to incorporate the relative costs and benefits of acting in our social environment. The review extends social baseline theory by applying social baseline theory to basic cognitive processes such as vision, memory, and attention, incorporating individual differences into the theory, reviewing environmental influences on social baselines, and exploring the dynamic effects of social interactions. The theoretical and methodological implications of social baseline theory are discussed, and future research endeavors into social cognition should consider that cognitive processes are situated within our social environments.

Role of the occipito-temporal theta rhythm in hand visual identification

Neuroimaging and EEG studies have shown that passive observation of the full body and of specific body parts is associated with 1) activity of an occipito-temporal region named the extrastriate body area (EBA), 2) amplitude modulations of a specific posterior event-related potential (ERP) component (N1/N190), and 3) a theta-band (4–7 Hz) synchronization recorded from occipito-temporal electrodes compatible with the location of EBA. To characterize the functional role of the occipito-temporal theta-band increase during the processing of body-part stimuli, we recorded EEG from healthy participants while they were engaged in an identification task (match-to-sample) of images of hands and nonbody control images (leaves). In addition to confirming that occipito-temporal electrodes show a larger N1 for hand images compared with control stimuli, cluster-based analysis revealed an occipito-temporal cluster showing an increased theta power when hands are presented (compared with leaves) and show that this theta increase is higher for identified hands compared with nonidentified ones while not being significantly different between not identified nonhand stimuli. Finally, single trial multivariate pattern analysis revealed that time-frequency modulation in the theta band is a better marker for classifying the identification of hand images than the ERP modulation. The present results support the notion that theta activity over the occipito-temporal cortex is an informative marker of hand visual processing and may reflect the activity of a network coding for stimulus identity.

NEW & NOTEWORTHY Hands provide crucial information regarding the identity of others, which is a key information for social processes. We recorded EEG activity of healthy participants during the visual identification of hand images. The combination of univariate and multivariate pattern analysis in time- and time-frequency domain highlights the functional role of theta (4–7 Hz) activity over visual areas during hand identification and emphasizes the robustness of this neuromarker in occipito-temporal visual processing dynamics.

Characterizing Body Image Distortion and Bodily Self-Plasticity in Anorexia Nervosa via Visuo-Tactile Stimulation in Virtual Reality

We combined virtual reality and multisensory bodily illusion with the aim to characterize and reduce the perceptual (body overestimation) and the cognitive-emotional (body dissatisfaction) components of body image distortion (BID) in anorexia nervosa (AN). For each participant (20 anorexics, 20 healthy controls) we built personalized avatars that reproduced their own body size, shape, and verisimilar increases and losses of their original weight. Body overestimation and dissatisfaction were measured by asking participants to choose the avatar that best resembled their real and ideal body. Results show higher body dissatisfaction in AN, caused by the desire of a thinner body, and no body-size overestimation. Interpersonal multisensory stimulation (IMS) was then applied on the avatar reproducing participant’s perceived body, and on the two avatars which reproduced increases and losses of 15% of it, all presented with a first-person perspective (1PP). Embodiment was stronger after synchronous IMS in both groups, but did not reduce BID in participants with AN. Interestingly, anorexics reported more negative emotions after embodying the fattest avatar, which scaled with symptoms severity. Overall, our findings suggest that the cognitive-emotional, more than the perceptual component of BID is severely altered in AN and that perspective (1PP vs. 3PP) from which a body is evaluated may play a crucial role. Future research and clinical trials might take advantage of virtual reality to reduce the emotional distress related to body dissatisfaction.

Multisensory stimulation modulates perceptual and post perceptual face representations: Evidence from event-related potentials

Seeing a face being touched in spatial and temporal synchrony with the own face produces a bias in self-recognition, whereby the other face becomes more likely to be perceived as the self. The present study employed event-related potentials to explore whether this enfacement effect reflects initial face encoding, enhanced distinctiveness of the enfaced face, modified self-identity representations, or even later processing stages that are associated with the emotional processing of faces. Participants were stroked in synchrony or asynchrony with an unfamiliar face they observed on a monitor in front of them, in a situation approximating a mirror image. Subsequently, event-related potentials were recorded during the presentation of (a) a previously synchronously stimulated face, (b) an asynchronously stimulated face, (c) observers' own face, (d) filler faces, and (e) a to-be-detected target face, which required a response. Observers reported a consistent enfacement illusion after synchronous stimulation. Importantly, the synchronously stimulated face elicited more prominent N170 and P200 responses than the asynchronously stimulated face. By contrast, similar N250 and P300 responses were observed in these conditions. These results suggest that enfacement modulates early neural correlates of face encoding and facial prototypicality, rather than identity self-representations and associated emotional processes.

The "embreathment" illusion highlights the role of breathing in corporeal awareness

Recent theories posit that physiological signals contribute to corporeal awareness, the basic feeling that one has a body (body ownership) that acts according to one's will (body agency) and occupies a specific position (body location). Combining physiological recordings with immersive virtual reality, we found that an ecological mapping of real respiratory patterns onto a virtual body illusorily changes corporeal awareness. This new way of inducing a respiratory bodily illusion, called "embreathment," revealed that breathing is almost as important as visual appearance for inducing body ownership and more important than any other cue for body agency. These effects were moderated by individual levels of interoception, as assessed through a standard heartbeat-counting task and a new "pneumoception" task. By showing that respiratory, visual, and spatial signals exert a specific and weighted influence on the fundamental feeling that one is an embodied agent, we pave the way for a comprehensive hierarchical model of corporeal awareness.NEW & NOTEWORTHY Our body is the only object we sense from the inside; however, it is unclear how much inner physiology contributes to the global sensation of having a body and controlling it. We combine respiration recordings with immersive virtual reality and find that making a virtual body breathe like the real body gives an illusory sense of ownership and agency over the avatar, elucidating the role of a key physiological process like breathing in corporeal awareness.

Getting closer: Synchronous interpersonal multisensory stimulation increases closeness and attraction toward an opposite-sex other in female participants

Experiencing tactile facial stimulation while seeing synchronous stimulations delivered to another's face induces enfacement, i.e. the subjective experience of ownership over the other's face. The synchronous Interpersonal Multisensory Stimulation (IMS) procedure leading to enfacement induces changes beyond the bodily sense of self, such as increased feeling of closeness between self and other. However, evidence for such an influence of IMS on higher-level self-other representations remains limited. Moreover, research has been restricted to settings involving a same-sex other. The current study tested, in female participants, whether IMS could promote social closeness and attraction toward an opposite-sex other. Across two experiments, enfacement with an opposite-sex face was successfully obtained. Synchronous (vs. asynchronous) IMS yielded greater closeness with the other and induced greater Liking and Attraction scores. These novel findings add further evidence to the existence of a link between body representation and social cognition. Implications for interpersonal attraction are discussed.

Early Brain Damage Affects Body Schema and Person Perception Abilities in Children and Adolescents with Spastic Diplegia

Early brain damage leading to cerebral palsy is associated to core motor impairments and also affects cognitive and social abilities. In particular, previous studies have documented specific alterations of perceptual body processing and motor cognition that are associated to unilateral motor deficits in hemiplegic patients. However, little is known about spastic diplegia (SpD), which is characterized by motorial deficits involving both sides of the body and is often associated to visuospatial, attentional, and social perception impairments. Here, we compared the performance of a sample of 30 children and adolescents with SpD (aged 7-18 years) and of a group of age-matched controls with typical development (TD) at two different tasks tapping on body representations. In the first task, we tested visual and motor imagery abilities as assessed, respectively, by the object-based mental rotation of letters and by the first-person transformations for whole-body stimuli. In the second task, we administered an inversion effect/composite illusion task to evaluate the use of configural/holistic processing of others' body. Additionally, we assessed social perception abilities in the SpD sample using the NEPSY-II battery. In line with previously reported visuospatial deficits, a general mental imagery impairment was found in SpD patients when they were engaged in both object-centered and first-person mental transformations. Nevertheless, a specific deficit in operating an own-body transformation emerged. As concerns body perception, while more basic configural processing (i.e., inversion effect) was spared, no evidence for holistic (i.e., composite illusion) body processing was found in the SpD group. NEPSY-II assessment revealed that SpD children were impaired in both the theory of mind and affect recognition subtests. Overall, these findings suggested that early brain lesions and biased embodied experience could affect higher-level motor cognition and perceptual body processing, thus pointing to a strict link between motor deficits, body schema alterations, and person processing difficulties.

An interoceptive illusion of effort induced by false heart-rate feedback

Interoception, or the sense of the internal state of the body, is key to the adaptive regulation of our physiological needs. Recent theories contextualize interception within a predictive coding framework, according to which the brain both estimates and controls homeostatic and physiological variables, such as hunger, thirst, and effort levels, by orchestrating sensory, proprioceptive, and interoceptive signals from inside the body. This framework suggests that providing false interoceptive feedback may induce misperceptions of physiological variables, or "interoceptive illusions." Here we ask whether it is possible to produce an illusory perception of effort by giving participants false acoustic feedback about their heart-rate frequency during an effortful cycling task. We found that participants reported higher levels of perceived effort when their heart-rate feedback was faster compared with when they cycled at the same level of intensity with a veridical feedback. However, participants did not report lower effort when their heart-rate feedback was slower, which is reassuring, given that failing to notice one's own effort is dangerous in ecologically valid conditions. Our results demonstrate that false cardiac feedback can produce interoceptive illusions. Furthermore, our results pave the way for novel experimental manipulations that use illusions to study interoceptive processing.

Touching! An Augmented Reality System for Unveiling Face Topography in Very Young Children

Developmental body topography, particularly of the face, is a fundamental research topic in the current decade. However, empirical investigation of this topic for very young children faces a number of difficulties related to the task requirements and technical procedures. In this study, we developed a new task to study the spatially-sensed position of facial parts in a self-face recognition task for 2.5- and 3.5-year-old children. Using the technique of augmented reality (AR) and 3D face tracking technology, we presented participants with their projected self-image on a screen, accompanied by a digital mark located on parts of their face. We prepared a cheerful visual and auditory reward on the screen when participants showed correct localization of the mark. We then tested whether they could indicate the position of the mark on their own faces and remain motivated for task repetition. To assess the efficacy of this task, 31 2.5- and 11 3.5-year-old children participated in this study. About half of the 2.5-year-olds and 80% of the 3.5-year-olds could perform more than 30 trials. Our new task, then, was to maintain young children’s motivation for task repetition using the cheerful visual and auditory reward. The analysis of localization errors suggested the uniqueness of spatial knowledge of self-face in young children. The efficacy of this new task for studying the development of body image has been confirmed.

Malleability of the self: electrophysiological correlates of the enfacement illusion

Self-face representation is fundamentally important for self-identity and self-consciousness. Given its role in preserving identity over time, self-face processing is considered as a robust and stable process. Yet, recent studies indicate that simple psychophysics manipulations may change how we process our own face. Specifically, experiencing tactile facial stimulation while seeing similar synchronous stimuli delivered to the face of another individual seen as in a mirror, induces 'enfacement' illusion, i.e. the subjective experience of ownership of the other's face and a bias in attributing to the self, facial features of the other person. Here we recorded visual Event-Related Potentials elicited by the presentation of self, other and morphed faces during a self-other discrimination task performed immediately after participants received synchronous and control asynchronous Interpersonal Multisensory Stimulation (IMS). We found that self-face presentation after synchronous as compared to asynchronous stimulation significantly reduced the late positive potential (LPP; 450-750 ms), a reliable electrophysiological marker of self-identification processes. Additionally, enfacement cancelled out the differences in LPP amplitudes produced by self- and other-face during the control condition. These findings represent the first direct neurophysiological evidence that enfacement may affect self-face processing and pave the way to novel paradigms for exploring defective self-representation and self-other interactions.

Personality assimilation across species: enfacing an ape reduces own intelligence and increases emotion attribution to apes

Seeing another person's face while that face and one's own face are stroked synchronously or controlling a virtual face by moving one's own induces the illusion that the other face has become a part of oneself-the enfacement effect. Here, we demonstrate that humans can enface even members of another species and that this enfacement promotes "feature migration" in terms of intelligence and emotional attribution from the representation of other to the representation of oneself, and vice versa. We presented participants with a virtual human face moving in or out of sync with their own face, and then morphed it into an ape face. Participants tended to perceive the ape face as their own in the sync condition, as indicated by body-ownership and inclusion-of-others-in-the-self ratings. More interestingly, synchrony also reduced performance in a fluid-intelligence task and increased the willingness to attribute emotions to apes. These observations, which fully replicated in another experiment, fit with the idea that self and other are represented in terms of feature codes, just like non-social events (as implied by the Theory of Event Coding), so that representational self-other overlap invites illusory conjunctions of features from one representation to the other.