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The aim of this study is to explore individual capacity for self-integration, susceptibility to the Rubber Hand Illusion (RHI) and the role of temperament factors in the emergence of body schema and body image dissociation. The RHI factors, proprioceptive drift, body ownership and body disownership were assessed in 48 university students. Personali...
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... sat on a chair with their arms resting on a table with the palm facing down (Fig. 1). Three experimental conditions were used in our study: pre-test condition (no-stroking) when a baseline proprioceptive drift was measured, illusion induction condition (synchronous stroking), and no illusion induction con- trol condition (asynchronous ...
Citations
... However, body-self disturbances have not only been found in schizophrenic patients but in individuals with schizotypal personality traits [10] and in psychosis-prone subjects as well [11]. Alterations of embodiment dimensions during the RHI experiment appear to also be linked with temperamental dimensions of high Novelty-Seeking (NS) and low Harm-Avoidance (HA) [12] behaviors, as measured by Cloninger's Temperament and Character Inventory (TCI-R) [13]. This has been explained by proposing that high NS and low HA may mediate the acceptance of novel and strange bodily experiences, thus being a component in the emergence of body schema and body image dissociations. ...
(1) Background: The Embodied Sense-of-Self Scale (ESSS) is the only validated measure for self-assessing embodiment abnormalities, which differentiate people with anomalous embodied self-representations such as schizophrenic patients from controls. The aim of the current study was to translate the ESSS from English to Italian and to examine its factor structure, reliability, and validity in the Italian context. (2) Methods: We tested the fit of the original three-factor structure (agency, ownership, and narrative identity) across a community sample (N = 269) and the reliability as well as the convergent and divergent validity of the ESSS. (3) Results: The three-factor structure of the ESSS was confirmed. However, three different factors have emerged from our analysis (self-recognition, self-consistence, and self-awareness). Higher internal consistency of the ESSS was obtained by removing six items that seemed problematic. The three ESSS scales show highly intercorrelated constructs. The measure was reliable and positively correlated with schizotypy (via the Perceptual Aberration Scale) and aberrant salience (via the Aberrant Salience Inventory), and negatively correlated with empathy (via the Italian Short Empathy Quotient scale), generalized self-efficacy (via the Generalized Self-Efficacy Scale), and social self-efficacy (via the Perceived Social Self-Efficacy Scale). (4) Conclusions: The 19-item Italian version of the ESSS is a suitable measure with which to assess embodiment abnormalities in Italian samples.
... Relationships between education and bodily illusions have been rarely investigated, probably because the standards of education in experimental studies are usually matched between groups. However, recent studies with the Rubber Hand Illusion are showing that interindividual differences such as education might have an impact on bodily illusions (Haans et al., 2012;Kállai et al., 2015;Burin et al., 2019;Lush et al., 2020Lush et al., , 2021Romano et al., 2021). However, these interindividual characteristics are not sufficient to explain the individual responses to the induced illusion (David et al., 2013;Scandola et al., 2014;Ehrsson et al., 2021). ...
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.
... illusion(Kállai, Hegedüs, Feldmann, Rózsa, Darnai, Herold, et al., 2015). 83In our previous research, we decided to focus on the functioning of attention and 84 working memory in the context ofStrelau's Regulative Theory of Temperament (2008; 85Zawadzki,Strelau, 2010). ...
The temperamental predictors of visual illusions have not yet been studied, although some researchers note that individual differences may predestine susceptibility to illusions. The purpose of our study was to analyse the cognitive and temperamental predictors of susceptibility to the Müller-Lyer illusion. The cognitive predictors included field dependence–independence, the alerting, orienting, and executive control attention networks, and the mechanism of inhibiting and updating in WM. The temperamental indicators were analysed in the context of Strelau's Regulative Theory of Temperament. 170 people aged 20–33 participated in the study. The results confirmed that susceptibility to the M-L illusion is associated with field dependence. Rhythmicity as a temperament trait moderated the relationship between susceptibility to the Müller-Lyer illusion and the efficacy of alerting. At a low level of Rhythmicity, a relationship between lower efficacy of the alerting network and higher susceptibility to the illusion was observed.
... Regarding personality and RHI, it has been found that the RHI is stronger for empathic people [Asai et al. 2011;Seiryte and Rusconi 2015]. The sense of ownership in the RHI was also found to be correlated with traits like the Novelty Seeking trait (from the TCI-R questionnaire) or Psychoticism (from the SCL-90-R questionnaire) [Kállai et al. 2015]. Also, higher responses to the RHI have been reported for people suffering from personality or psychotic disorders: dissociative subtype of post-traumatic stress disorder (PTSD) [Rabellino et al. 2016], schizophrenia [Peled et al. 2000;Thakkar et al. 2011] and schizotypal personality disorder [Asai et al. 2011;Van Doorn et al. 2018]. ...
The term "avatar" refers to the representation of users in a virtual world, in the case where they are immersed in Virtual Reality with a Head-Mounted Display and therefore cannot see their own body. Avatars have now become a major requirement in immersive virtual reality applications, increasing the need to better understand and identify the factors that influence users’ sense of embodiment towards their avatar. In this thesis, we defined three axes of research to explore the influence of several factors on the sense of embodiment, based on a categorization that did not only consider factors related to the avatar, but also factors related to the virtual environment and the user. In the first part, we have studied the influence of shared virtual environments on the sense of embodiment, in a study where users performed a task together in the same virtual environment, and in another experiment in which users even shared the control of the same avatar. In a second part, we explored interrelations within avatar-related factors influencing the sense of embodiment, using a new methodological approach with a subjective matching technique. Finally, in a third part, we investigated the influence of users’ individual differences on the sense of embodiment.
... In the literature, there is a limited amount of research regarding how individual differences and personality predispositions affect bodily self-consciousness. Since then most of the data in the literature comes from the measurements of the intensity of the rubber hand illusion (Haans et al. 2012, Kállai et al. 2015, Walsh et al. 2015. As an example, it has been found that dopamine transmission is associated with increased ownership over the rubber hand (Albrecht et al. 2011), and it was suggested that the people with novelty seeking personality a basic temperament factor, is closely associated with their dopamine levels and acceptance of the rubber hand (Cloninger et al. 1993). ...
... As an example, it has been found that dopamine transmission is associated with increased ownership over the rubber hand (Albrecht et al. 2011), and it was suggested that the people with novelty seeking personality a basic temperament factor, is closely associated with their dopamine levels and acceptance of the rubber hand (Cloninger et al. 1993). Related to those studies, previous findings showed that, participants in the synchronous visual-tactile stimulation condition experience greater proprioceptive drift, and found that their acceptance during the illusion predicts higher scores for novelty-seekers, whereas lower scores predicts higher harm avoidance (Kállai et al. 2015). Additionally, Kállai et al. (2015) found that during synchronous visual-tactile condition, elevated scores in paranoid ideation is associated with psychoticism scales. ...
... Related to those studies, previous findings showed that, participants in the synchronous visual-tactile stimulation condition experience greater proprioceptive drift, and found that their acceptance during the illusion predicts higher scores for novelty-seekers, whereas lower scores predicts higher harm avoidance (Kállai et al. 2015). Additionally, Kállai et al. (2015) found that during synchronous visual-tactile condition, elevated scores in paranoid ideation is associated with psychoticism scales. These findings can be interpreted as indicating peo-ple who experience the rubber hand illusion more easily accept inaccurate information, and thus change their body schema more readily. ...
The change in the body awareness of people depending on the dynamic processing of the multisensory signals from the body has been revealed the bodily self-consciousness approach. Recent studies have proposed that the processing and integration of multisensory signals (i.e. vestibular, somatosensory) are fundamental requirement for bodily self-consciousness. Perception of body-parts and global aspect of whole body can dynamically change depending on the congruency between signals from multiple modalities (i.e. vestibular, somatosensory). The basic assumption of the studies investigating bodily self-consciousness is that the bodily experiences are related with the multisensory signal processing. The aim of the present article is to review how the bodily self-consciousness is studied experimentally and discuss the underlying sensory processes. In addition to that, we discussed the limitations of the previous experimental studies.
... Schizotypy refers to a continuum of personality characteristics and experiences that range from normal dissociative, imaginative states to extreme states related to schizophrenia. Moreover, schizotypy is also considered to be related to the sense of ownership/agency frequently shown in many psychological studies (Asai et al., 2011;Kallai et al., 2015). ...
... There is some evidence for a similar relation between schizotypy and an individual's sense of agency/ownership. Kallai et al. (2015) found that people with high schizotypy, including feelings of depersonalization when the rubber hand illusion was induced, tended to have higher interpersonal sensitivity and vulnerability scores. Asai et al. (2011) examined the relationship between individual differences in the rubber hand illusion and empathic and schizotypal personality traits, as the existing literature suggested that schizophrenic patients would be more susceptible to the illusion. ...
Facial expressions influence our experience and perception of emotions—they not only tell other people what we are feeling but also might tell us what to feel via sensory feedback. We conducted three experiments to investigate the interaction between facial feedback phenomena and different environmental stimuli, by asking participants to remember emotional autobiographical memories. Moreover, we examined how people with schizotypal traits would be affected by their experience of emotional facial simulations. We found that using a directed approach (gripping a pencil with teeth/lips) while remembering a specific autobiographical memory could successfully evoke participants’ positive (e.g., happy and excited)/negative (e.g., angry and sad) emotions (i.e., Experiment 1). When using indirective environmental stimuli (e.g., teardrop glasses), the results of our experiments (i.e., Experiments 2 and 3) investigating facial feedback and the effect of teardrop glasses showed that participants who scored low in schizotypy reported little effect from wearing teardrop glasses, while those with high schizotypy reported a much greater effect in both between- and within-subject conditions. The results are discussed from the perspective of sense of ownership, which people with schizophrenia are believed to have deficits in.
... Firstly, there is an extreme inter-individual variability in terms of RHI susceptibility within human population (Haans et al., 2012), with people reporting the illusion by simply seeing the fake hand (Rohde et al., 2011), others claiming its changing appearance (Lewis and Lloyd, 2010), others only having an impression of strangeness, and others experiencing no illusory experience at all (Wold et al., 2014). Secondly, the illusion strength is modulated by a variety of different additional factors other than the ones mentioned above: attentional fluctuations (Haans et al., 2012), interoceptive sensitivity (Tsakiris et al., 2011), temporal resolution in multisensory perception (Costantini et al., 2016), degree of empathic concern (Durgin et al., 2007;Asai et al., 2011), psychosis proneness (Asai et al., 2011;Thakkar et al., 2011;Germine et al., 2013;Kallai et al., 2015), malleability of body image (Eshkevari et al., 2012), emotional intelligence (Perepelkina et al., 2017) and hypnotic (Walsh et al., 2015)/sensory (Marotta et al., 2016) suggestibility. ...
... Indeed, in line with these hypotheses, the findings related to the "Perception and Thinking Problems" domain, allows us to hypothesize that a sort of proclivity to put together ideas and visual images in a more idiosyncratic way might be added to the tendency to perceive the world less accurately increasing the mislocalization of the own hand toward the fake hand. It is worth noting that the association between these psychosisrelated processes in the Rorschach and the RHI is consistent with previous research that linked psychosis-proneness to RHI susceptibility (Asai et al., 2011;Thakkar et al., 2011;Germine et al., 2013;Kallai et al., 2015). Taken together, these data suggest that weaker body ownership, as indexed by the RHI, could be rooted in psychosis probe traits. ...
... Overall, our results seem to indicate that persistent personality features, despite not being directly related to sensory perception, may actually influence the illusory effects, which are indeed related to specific types of sensory stimulation (i.e., visual, tactile, and proprioceptive). This is not trivial but, rather, consistent with evidence showing that, besides multisensory integration (i.e., the main process subserving the RHI), additional factors might influence the RHI (Durgin et al., 2007;Asai et al., 2011;Thakkar et al., 2011;Tsakiris et al., 2011;Eshkevari et al., 2012;Haans et al., 2012;Germine et al., 2013;Kallai et al., 2015;Costantini et al., 2016;Marotta et al., 2016). Here we suggest that personality might strongly contribute to explain the inter-individual variability of the illusion. ...
The rubber hand illusion paradigm allows investigating human body ownership by inducing an illusion of owning a life-sized fake hand. Despite the wide consensus on the fact that integration of multisensory signals is the main interpretative framework of the rubber hand illusion, increasing amount of data show that additional factors might contribute to the emergence of the illusion and, in turn, explain the strong inter-individual differences of the illusory patterns. Here, we explored whether and how personality features contribute to the emergence of the illusion by administering to healthy participants the rubber hand illusion paradigm along with two well-known personality tests, i.e., the Personality Assessment Inventory (PAI) and the Rorschach test. Results showed that two Rorschach domains (i.e., “Perception and Thinking Problems” and “Self and Other Representation”) were positively correlated with the illusory mislocalization of the own left hand toward the fake hand. Further analyses suggested that while the tendency to perceive unconventionally is related to mislocalizing the own hand toward the fake hand, the association of the RHI index and other personality features measured by the Rorschach remain uncertain. However, our findings in general suggest that personality features might have a role in the emergence of the rubber hand illusion. This, in turn, could explain the high inter-individual variability of the illusory effects.
... Previous studies have reported large variability in individuals' susceptibility to bodily illusions (Bekrater-Bodmann, Foell, Diers, & Flor, 2012;Burrack & Brugger, 2005;Haans, Kaiser, Bouwhuis, & Ijsselsteijn, 2012;Metral, Gonthier, Luyat, & Guerraz, 2017). This variability may be rooted in a specific trait(s) within individuals, as studies have reported for individual variability in responses to paranoid ideation, predisposition toward psychoticism, interpersonal sensitivity, and sensory suggestibility (Asai, Mao, Sugimori, & Tanno, 2011;Kállai et al., 2015;Marotta, Tinazzi, Cavedini, Zampini, & Fiorio, 2016;Stone, Bullock, Keizer, & Dijkerman, 2018). If the senses of body ownership and agency reflect stable trait(s) within individuals, then illusory ownership or agency should be stable across both time and variations of multisensory stimulation. ...
Illusory senses of ownership and agency (that the hand or effector that we see belongs to us and moves at our will, respectively) support the embodiment of prosthetic limbs, tele-operated surgical devices, and human-machine interfaces. We exposed forty-eight individuals to four different procedures known to elicit illusory ownership or agency over a fake visible rubber hand or finger. The illusory ownership or agency arising from the hand correlated with that of the finger. For both body parts, sensory stimulation across different modalities (visual with tactile or visual with kinesthetic) produced illusions of similar strength. However, the strengths of the illusions of ownership and agency were unrelated within individuals, supporting the proposal that distinct neuropsychological processes underlie these two senses. Developing training programs to enhance susceptibility to illusions of agency or ownership for people with lower natural susceptibility could broaden the usefulness of the above technologies.
... Regarding personality and RHI, it has been found that the RHI is stronger for empathic people [2,61]. The sense of ownership in the RHI was also found correlated with traits like the Novelty Seeking trait (from the TCI-R questionnaire) or Psychoticism (from the SCL-90-R questionnaire) [35]. Also, higher responses to the RHI have been reported for people suffering from personality or psychotic disorders: dissociative subtype of post-traumatic stress disorder (PTSD) [56], schizophrenia [52,70] and schizotypal personality disorder [2,73]. ...
With the increasing use of avatars (i.e. the virtual representation of the user in a virtual environment) in virtual reality, it is important to identify the factors eliciting the sense of embodiment or the factors that can disrupt this feeling. This paper reports an exploratory study aiming at identifying internal factors (personality traits and body awareness) that might cause either a resistance or a predisposition to feel a sense of embodiment towards a virtual avatar. To this purpose, we conducted an experiment (n=123) in which participants were immersed in a virtual environment and embodied in a gender-matched generic virtual avatar through a head-mounted display. After an exposure phase in which they had to perform a number of visuomotor tasks (during 2 minutes) a virtual character entered the virtual scene and stabbed the participants' virtual hand with a knife. The participants' sense of embodiment was measured, as well as several personality traits (Big Five traits and locus of control) and body awareness, to evaluate the influence of participants' personality on the acceptance of the virtual body. The major finding of the experiment is that the locus of control is linked to several components of embodiment: the sense of agency is positively correlated with an internal locus of control and the sense of body ownership is positively correlated with an external locus of control. Interestingly, both components are not influenced by the same traits, which confirms that they can appear independently. Taken together our results suggest that the locus of control could be a good predictor of the sense of embodiment when the user embodies an avatar with a similar physical appearance. Yet, further studies are required to confirm these results.
... For example, it has been suggested that temperament affects proprioceptive drift. 37 As well, individual differences might be caused by methodological factors, such as the potential influence of nonsystematic variation in tactile stimulation or the social context in which the illusion was administered. ...
Background:
Schizophrenia is a disorder of basic self-disturbance. Evidence suggests that people with schizophrenia may have aberrant experiences of body ownership: they may feel that they are not the subject of their own body experiences. However, little is known about the development of such disturbances.
Methods:
Using a rubber hand illusion paradigm, we assessed body ownership in patients with schizophrenia (n = 54), healthy controls (n = 56), children/adolescents at increased familial risk of developing schizophrenia (n = 24) or mood disorders (n = 33), and children/adolescents without this risk (n = 18). In this paradigm, a rubber hand (visible) and a participant’s real hand (invisible) were stroked synchronously and asynchronously; we then measured subjective illusory experiences and proprioceptive drift.
Results:
All groups showed the expected effect of the rubber hand illusion: stronger proprioceptive drift and increased subjective illusory experiences after synchronous versus asynchronous stroking. The effect of synchronicity on subjective experiences was significantly weaker in patients with schizophrenia than in healthy controls, and subjective ratings were positively correlated with delusions in patients. We found no significant differences between children/adolescents with and without increased familial risk.
Limitations:
Large individual differences raised questions for future research.
Conclusion:
We found subtle disturbances in body-ownership experiences in patients with schizophrenia, which were associated with delusions. We found no evidence for impairments in children/adolescents at increased familial risk of developing schizophrenia or a mood disorder. Longitudinal data might reveal whether impairments in body ownership are predictive of psychosis onset.
