The Perceived Match Between Observed and Own Bodies, but Not Its Accuracy, Is Influenced by Movement Dynamics and Clothing Cues

Own-perceived body matching - the ability to match one's own body with an observed body - is a difficult task for both general and clinical populations. Thus far, however, own-perceived body matching has been investigated in situations that are incongruent with how we are used to experience and perceive our body in daily life. In the current study, we aimed to examine own-perceived body matching in a context that more closely resembles real life. More specifically, we investigated the effects of body movement dynamics and clothing cues on own-perceived body matching. We asked participants to match their own body with an externally perceived body that was a 3D-generated avatar based on participants' real bodies, fitted with a computer-generated dress. This perceived body was (1) either static (non-walking avatar) or dynamic (walking avatar), (2) either bigger, smaller, or the same size as participants' own body size, and (3) fitted with a dress with a size either bigger, smaller, or the same as participants' own dress size. Our results suggest that movement dynamics cues did not improve the accuracy of own-perceived body matching, but that confidence about dress fit was higher for dynamic avatars, and that the difference between dynamic and static avatars was dependent on participants' self-esteem. Furthermore, when participants were asked to rate the observed body in reference to how they wanted to represent themselves to others, dynamic avatars were rated lower than static avatars for the biggest-sized bodies only, possibly reflecting the influence of movement cues on amplifying socio-cultural stereotypes. Finally, while smaller body/dress sizes were systematically rated higher than bigger body/dress sizes for several self-report items, the interplay between body and dress size played an important role in participants' self-report as well. Thus, while our research suggests that movement and garment dynamics, allowing for realistic, concrete situations that are reminiscent of daily life, influence own-body perception, these cues did not lead to an improvement in accuracy. These findings provide important insights for research exploring (own-) body perception and bodily self-awareness, with practical (e.g., development of online avatars) and clinical (e.g., anorexia nervosa and body dysmorphic disorder) implications.

Action Sounds Informing Own Body Perception Influence Gender Identity and Social Cognition

Sensory information can temporarily affect mental body representations. For example, in Virtual Reality (VR), visually swapping into a body with another sex can temporarily alter perceived gender identity. Outside of VR, real-time auditory changes to walkers’ footstep sounds can affect perceived body weight and masculinity/femininity. Here, we investigate whether altered footstep sounds also impact gender identity and relation to gender groups. In two experiments, cisgender participants (26 females, 26 males) walked with headphones which played altered versions of their own footstep sounds that sounded more typically male or female. Baseline and post-intervention measures quantified gender identity [Implicit Association Test (IAT)], relation to gender groups [Inclusion of the Other-in-the-Self (IOS)], and perceived masculinity/femininity. Results show that females felt more feminine and closer to the group of women (IOS) directly after walking with feminine sounding footsteps. Similarly, males felt more feminine after walking with feminine sounding footsteps and associated themselves relatively stronger with “female” (IAT). The findings suggest that gender identity is temporarily malleable through auditory-induced own body illusions. Furthermore, they provide evidence for a connection between body perception and an abstract representation of the Self, supporting the theory that bodily illusions affect social cognition through changes in the self-concept.

Personality traits and body image in adults with oral piercing: a questionnaire analysis

OBJECTIVES

Due to the growing popularity of body modifications, dental practitioners are increasingly confronted with oral piercing and its implications. Successful consultation and subsequent change of patient behavior require an understanding of the patient's personality and the deep reasons that explain this self-injurious behavior. This is the first study evaluating personality traits and aspects of body perception in a cohort of adults with oral piercing.

METHOD AND MATERIALS

Sixty-two individuals with labial and/or tongue piercing completed three validated questionnaires assessing body perception and personality traits (Questionnaire for assessing one's own body; Sensation Seeking Scale; Big Five Inventory Scale). Fisher Exact probability test and Mann-Whitney U test were used to determine differences in frequency data and in psychologic parameters between subgroups.

RESULTS

Eighteen single- and 44 multiple-pierced individuals completed the study (53 women, 9 men). The odds for being multiple pierced was significantly higher for tongue than for labial piercing (3.89 and 0.63, respectively; P = .003). In all psychologic parameters measured, the sample showed score distributions within reference norms. However, multiple-pierced individuals displayed a significantly lesser feeling of attractiveness, less self-confidence, and more uncertainty/anxiety towards their body than single-pierced probands (P < .05).

CONCLUSION

Psychologic characteristics of individuals with oral piercing do not fundamentally differ from those of the average population. Therefore, dental practitioners should focus on the medical and dental implications of oral piercing in the counseling of patients who have or intend to have such done.

Interoception Disorder and Insular Cortex Abnormalities in Schizophrenia: A New Perspective Between Psychoanalysis and Neuroscience

The existence of disturbances in the perception of somatic states and in the representation of the body with the presence of cœnesthetic hallucinations, of delusional hypochondriac ideas or of dysmorphophobias is a recognized fact in the psychopathology of schizophrenia. Freudian psychoanalytic theory had accorded a privileged place to the alteration of the perception of the body in schizophrenia. Freud had attributed to these phenomena a primary and prodromal role in the psychopathology of psychosis. We propose to look at this theory in a new way, starting from the perspective of recent studies about the role of the insula in the perception and representation of somatic states, since this structure has been identified as underpinning the sense of interoception. The data in the neurobiological literature about abnormalities in the insular cortex in schizophrenia has shown that insula dysfunction could constitute one of the biological substrates of disorders of body perception in schizophrenia, and could be a source of the alteration of the sense of self that is characteristic of this psychiatric pathology. Moreover, this alteration could thus be involved in the positive symptomatology of schizophrenia.

Body perception and sexuality of bariatric surgery patients

PURPOSE

This study aims to determine how body perception and sexual life are affected in obese individuals who are hospitalized to undergo bariatric surgery.

DESIGN AND METHODS

Descriptive research design and the cross-sectional method were used. The study was conducted with 53 individuals who consented to participate. The data were analyzed with the SPSS software package.

FINDINGS

Low body perception and sexual dysfunction were detected, particularly in women.

PRACTICE IMPLICATIONS

In obesity treatment, the psychological and social problems that individuals experience due to obesity should be handled and evaluated with a multidisciplinary approach.

Perception of Tactile Distance on the Back

The perceived distance between two touches is anisotropic on many parts of the body. Generally, tactile distances oriented across body width are perceived as larger than distances oriented along body length, though the magnitude of such biases differs substantially across the body. In this study, we investigated tactile distance perception on the back. Participants made verbal estimates of the perceived distance between pairs of touches oriented either across body width or along body length on (a) the left hand, (b) the left upper back, and (c) the left lower back. There were clear tactile distance anisotropies on the hand and upper back, with distances oriented across body width overestimated relative to those along body length/height, consistent with previous results. On the lower back, however, an anisotropy in exactly the opposite direction was found. These results provide further evidence that tactile distance anisotropies vary systematically across the body and suggest that the spatial representation of touch on the lower back may differ qualitatively from that on other regions of the body.

Visual body-size adaptation and estimation of tactile distance

Estimating the size of bodies is crucial for interactions with physical and social environments. Body-size perception is malleable and can be altered using visual adaptation paradigms. However, it is unclear whether such visual adaptation effects also transfer to other modalities and influence, for example, the perception of tactile distances. In this study, we employed a visual adaptation paradigm. Participants were exposed to images of expanded or contracted versions of self- or other-identity bodies. Before and after this adaptation, they were asked to manipulate the width of body stimuli to appear as 'normal' as possible. We replicated an effect of visual adaptation such that the body-size selected as most 'normal' was larger after exposure to expanded and thinner after exposure to contracted adaptation stimuli. In contrast, we did not find evidence that this adaptation effect transfers to distance estimates for paired tactile stimuli delivered to the abdomen. A Bayesian analysis showed that our data provide moderate evidence that there is no effect of visual body-size adaptation on the estimation of spatial parameters in a tactile task. This suggests that visual body-size adaptation effects do not transfer to somatosensory body-size representations.

Can realistic dolls protect body satisfaction in young girls?

Ultra-thin fashion dolls may represent a risk factor for thin-ideal internalisation and body dissatisfaction amongst young girls. We asked thirty one 5- to 9-year-old girls to engage in interactive play with commercially available dolls which were either ultra-thin (Barbie and Monster High) or represented a putative realistic childlike shape (Lottie and Dora) and to indicate their perceived own-body size and ideal body size on an interactive computer task both before and after play. There was a significant interaction between testing phase and doll group such that playing with the ultra-thin dolls led to the girls' 'ideal self' becoming thinner. A further 46 girls played with the ultra-thin dolls and then played with either the same dolls again, the realistic childlike dolls, or with cars. Initial play with the ultra-thin dolls again produced a drop in perceived ideal own body size; however, no group showed any significant change in their body ideals during the additional play phase. These data indicate the potential benefit of dolls representing a realistic child body mass to young girls' body satisfaction and do not support the hypothesis that the negative impacts of ultra-thin dolls can be directly countered by other toys.

Visual adaptation selective for individual limbs reveals hierarchical human body representation

The spatial relationships between body parts are a rich source of information for person perception, with even simple pairs of parts providing highly valuable information. Computation of these relationships would benefit from a hierarchical representation, where body parts are represented individually. We hypothesized that the human visual system makes use of such representations. To test this hypothesis, we used adaptation to determine whether observers were sensitive to changes in the length of one body part relative to another. Observers viewed forearm/upper arm pairs where the forearm had been either lengthened or shortened, judging the perceived length of the forearm. Observers then adapted to a variety of different stimuli (e.g., arms, objects, etc.) in different orientations and visual field locations. We found that following adaptation to distorted limbs, but not non-limb objects, observers experienced a shift in perceived forearm length. Furthermore, this effect partially transferred across different orientations and visual field locations. Taken together, these results suggest the effect arises in high level mechanisms specialized for specific body parts, providing evidence for a representation of bodies based on parts and their relationships.

Ageism and Psychological Distress in Older Adults: The Moderating Role of Self-Esteem and Body Image

Ageist attitudes have been associated with negative physical consequences and psychological distress among older adults. Although holding a positive self-image and body image contributes to well-being among older adults, their combined effect on the consequences of ageism has not been examined. Accordingly, the current study examines the moderating role of both variables on the connection between ageism and psychological distress among older adults. Data were collected from 383 older adults (age range = 60-90; M = 71.44; SD = 6.62), who filled out scales assessing ageism, self-esteem, body image, and psychological distress. Psychological distress was associated with reduced self-esteem and body image. In line with the moderation hypothesis, the ageism-distress link remained significant only for individuals with low levels of both self-esteem and body image. The discussion highlights the relevance of both self-esteem and body image as important personal resources which may buffer the connection between ageism and psychological distress among older adults.

Item Reduction, Psychometric and Biometric Properties of the Italian Version of the Body Perception Questionnaire-Short Form (BPQ-SF): The BPQ-22

Body awareness disorders and reactivity are mentioned across a range of clinical problems. Constitutional differences in the control of the bodily state are thought to generate a vulnerability to psychological symptoms. Autonomic nervous system dysfunctions have been associated with anxiety, depression, and post-traumatic stress. Though interoception may be a transdiagnostic mechanism promoting the improvement of clinical symptomatology, few psychometrically sound, symptom-independent, self-report measures, informed by brain-body circuits, are available for research and clinical use. We validated the Italian version of the body perception questionnaire (BPQ)-short form and found that response categories could be collapsed from five to three and that the questionnaire retained a three-factor structure with items reduced from 46 to 22 (BPQ-22). The first factor was loaded by body awareness items; the second factor comprised some items from the body awareness scale and some from the subdiaphragmatic reactivity scale (but all related to bloating and digestive issues), and the third factor by supradiaphragmatic reactivity items. The BPQ-22 had sound psychometric properties, good convergent and discriminant validity and test-retest reliability and could be used in clinical and research settings in which the body perception assessment is of interest. Psychometric findings in light of the polyvagal theory are discussed.

'Somebody stuck me in a bag of sand': Lived experiences of the altered and uncomfortable body after stroke

OBJECTIVE

This study explored stroke survivors' experiences of altered body perception, whether these perceptions cause discomfort, and the need for clinical interventions to improve comfort.

DESIGN

A qualitative phenomenological study.

SETTING

Participants' homes.

PARTICIPANTS

A purposive sample of 16 stroke survivors were recruited from community support groups. Participants (median: age 59; time post stroke >2 years), were at least six-months post-stroke, experiencing motor or sensory impairments and able to communicate verbally.

INTERVENTIONS

Semi-structured, face-to-face interviews were analysed using an interpretive phenomenological approach and presented thematically.

RESULTS

Four themes or experiences were identified: Participants described (1) a body that did not exist; (2) a body hindered by strange sensations and distorted perceptions; (3) an uncontrollable body; and (4) a body isolated from social and clinical support. Discomfort was apparent in a physical and psychological sense and body experiences were difficult to comprehend and communicate to healthcare staff. Participants wished for interventions to improve their comfort but were doubtful that such treatments existed.

CONCLUSION

Indications are that altered body perceptions cause multifaceted physical and psychosocial discomfort for stroke survivors. Discussions with patients about their personal perceptions and experiences of the body may facilitate better understanding and management to improve comfort after stroke.

Being Short, Sweet, and Sour: Congruent Visuo-Olfactory Stimulation Enhances Illusory Embodiment

Bodily self-identification has shown to be easily altered through spatiotemporally congruent multimodal signals. While such manipulations are mostly studied through visuo-tactile or visuo-motor stimulation, here we investigated whether congruent visuo-olfactory cues might enhance illusory self-identification with an arbitrary object. Using virtual reality, healthy individuals saw a grapefruit from its supposed first-person perspective that was touched in synchrony with their own body. The touch attempted to replicate what was seen as softly squeezing the grapefruit. Crucially, when we additionally presented the smell of a grapefruit in synchrony with the squeezing, they self-identified stronger with the fruit than when they smelled strawberry.

Factors affecting medical healthcare-seeking behaviours of female patients according to their stage of being diagnosed with breast cancer

OBJECTIVE

The aim of study was to determine factors affecting the medical healthcare-seeking behaviours of female patients according to their stage of being diagnosed with breast cancer.

METHODS

This descriptive and correlational study was carried out with 150 women. The data were collected by a survey form, the Body Perception Scale, the Rosenberg Self-Esteem Scale and the Social Appearance Anxiety Scale.

RESULTS

About 54% of the women were diagnosed with early-stage breast cancer, 68.7% had high self-esteem, and 80% had positive body perceptions, while their social appearance anxiety levels were moderate. The patients with breast cancer at the 4th stage had a high body perception score of 174.00 ± 23.34. Self-esteem was the highest in the patients with stage 2B breast cancer with a value of 0.61 ± 0.91. The highest social anxiety mean score was found in the patients with stage 2A breast cancer as 31.65 ± 12.50. There was no statistically significant difference in the women's sociodemographic characteristics, health and breast cancer history, self-esteem, body perception and social appearance anxiety based on their stages of cancer (p > 0.05).

CONCLUSION

Nurses' identification of risky individuals in early diagnosis, information for the individual / family and society by planning trainings and raising awareness will contribute positively to the patients' medical health-seeking behaviours.

The Relationship Between Referral of Touch and the Feeling of Ownership in the Rubber Hand Illusion

The rubber hand illusion (RHI) is one of the most commonly used paradigms to examine the sense of body ownership. Touches are synchronously applied to the real hand, hidden from view, and a false hand in an anatomically congruent position. During the illusion one may perceive that the feeling of touch arises from the false hand (referral of touch), and that the false hand is one's own. The relationship between referral of touch and body ownership in the illusion is unclear, and some articles average responses to statements addressing these experiences, which may be inappropriate depending on the research question of interest. To address these concerns, we re-analyzed three freely available datasets to better understand the relationship between referral of touch and feeling of ownership in the RHI. We found that most participants who report a feeling of ownership also report referral of touch, and that referral of touch and ownership show a moderately strong positive relationship that was highly replicable. In addition, referral of touch tends to be reported more strongly and more frequently than the feeling of ownership over the hand. The former observations confirm that referral of touch and ownership are related experiences in the RHI. The latter, however, indicate that when pooling the statements one may obtain a higher number of illusion ‘responders’ compared to considering the ownership statements in isolation. These results have implications for the RHI as an experimental paradigm.

Evidence for a Third Visual Pathway Specialized for Social Perception

Existing models propose that primate visual cortex is divided into two functionally distinct pathways. The ventral pathway computes the identity of an object; the dorsal pathway computes the location of an object, and the actions related to that object. Despite remaining influential, the two visual pathways model requires revision. Both human and non-human primate studies reveal the existence of a third visual pathway on the lateral brain surface. This third pathway projects from early visual cortex, via motion-selective areas, into the superior temporal sulcus (STS). Studies demonstrating that the STS computes the actions of moving faces and bodies (e.g., expressions, eye-gaze, audio-visual integration, intention, and mood) show that the third visual pathway is specialized for the dynamic aspects of social perception.

Patients With Super Obesity Do Not Perceive Themselves as Being at Higher Risk for a More Severe Course of COVID-19 Infection

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic has led to major health-related concerns in the population. Several risk factors for a severe course of COVID-19 disease have been identified, with obesity taking an important role. However, it is unclear whether this association is only known in the expert world or whether individuals also experience themselves as risk patients due to their obesity and whether the desire for weight reduction may also be associated with a hoped-for risk reduction. These questions were addressed in a cross-sectional study of patients who have presented to an obesity center in order to lose body weight.

METHODS

Patients (n = 155) of the obesity center were asked to complete an ad hoc questionnaire to assess whether the desire to lose weight is also associated with a hoped-for risk reduction with respect to COVID-19 disease during the middle of the pandemic in the period between October 2020 and April 2021. We additionally assessed their perceived general stress using the Perceived Stress Questionnaire (PSQ).

RESULTS

In our explorative study, overall worries correlated significantly with worries about contracting COVID-19 (r = 0.483, p < 0.001). There has been an association with concerns about severe COVID-19 progression and psychological distress from the COVID-19 pandemic (r = 0.543, p < 0.001). In addition, a correlation was found between persons who worry about contracting COVID-19 and feeling like an at-risk patient (r = 0.530, p < 0.001). Interestingly, the higher the BMI (>50 kg/m²), the lower were the worries in PSQ (ANOVA p = 0.046). However, COVID-19-related worry was nonetheless present in the higher BMI subgroups. The most intense worries were experienced by individuals with a BMI between 35 and 39 (PSQ worries 50.44), immediately followed by individuals with a BMI between 40 and 49 (PSQ worries 49.36).

DISCUSSION AND CONCLUSION

An increased risk for a more severe course of COVID-19 infection is not generally perceived by obese individuals. In particular, individuals with very high BMI (>50)-although being at very high risk for a severe course of the COVID-19 disease-do not display increased worries, which might point toward heightened denial.

Duplication of the bodily self: a perceptual illusion of dual full-body ownership and dual self-location

Previous research has shown that it is possible to use multisensory stimulation to induce the perceptual illusion of owning supernumerary limbs, such as two right arms. However, it remains unclear whether the coherent feeling of owning a full-body may be duplicated in the same manner and whether such a dual full-body illusion could be used to split the unitary sense of self-location into two. Here, we examined whether healthy human participants can experience simultaneous ownership of two full-bodies, located either close in parallel or in two separate spatial locations. A previously described full-body illusion, based on visuo-tactile stimulation of an artificial body viewed from the first-person perspective (1PP) via head-mounted displays, was adapted to a dual-body setting and quantified in five experiments using questionnaires, a behavioural self-location task and threat-evoked skin conductance responses. The results of experiments 1-3 showed that synchronous visuo-tactile stimulation of two bodies viewed from the 1PP lying in parallel next to each other induced a significant illusion of dual full-body ownership. In experiment 4, we failed to find support for our working hypothesis that splitting the visual scene into two, so that each of the two illusory bodies was placed in distinct spatial environments, would lead to dual self-location. In a final exploratory experiment (no. 5), we found preliminary support for an illusion of dual self-location and dual body ownership by using dynamic changes between the 1PPs of two artificial bodies and/or a common third-person perspective in the ceiling of the testing room. These findings suggest that healthy people, under certain conditions of multisensory perceptual ambiguity, may experience dual body ownership and dual self-location. These findings suggest that the coherent sense of the bodily self located at a single place in space is the result of an active and dynamic perceptual integration process.

The "cheerleader effect" in facial and bodily attractiveness: A result of memory bias and not perceptual encoding

Individual faces are rated as more attractive when presented in a group compared with when presented individually; a finding dubbed the "cheerleader effect." As a relatively recent discovery, the conditions necessary to observe the effect are not clearly understood. We sought to better define these conditions by examining two parameters associated with the effect. Our first aim was to determine whether the effect is specific to faces or occurs also for human bodies. Both face and body images were rated as being more attractive when presented in groups than when presented in isolation, demonstrating that the cheerleader effect is not restricted to faces. Furthermore, the effect was significantly larger for bodies than faces. Our second aim was to determine whether the cheerleader effect originates from a bias in memory or occurs during perceptual encoding. Participants in the "memory" condition provided attractiveness ratings after images had been removed from the testing screen, whereas participants in the "perceptual" condition provided ratings while the images remained visible, thereby eliminating the memory components of the paradigm. Significant cheerleader effects were only observed in the memory condition. We conclude that the cheerleader effect for faces and bodies is due to a bias in memory and does not occur at an initial stage of perceptual encoding.

Physical Activity, Physical Fitness and the Sense of Coherence-Their Role in Body Acceptance among Polish Adolescents

The aim of the study was to investigate the protective role of physical activity (PA) and other health-related bio-psycho components (physical fitness, body composition, body perception and the sense of coherence (SOC)) in body acceptance. We searched for gender differences in those relationships. We investigated 231 adolescents aged 13-16 years from an urban area in Poland. We conducted objective measurements of height, weight, fat% and relative value of minute oxygen consumption. Questionnaires for PA, SOC Body Figure Perception and body acceptance were applied. Linear regression was used for analyzing determinants of body acceptance. We found that more physically active girls reported a less slim ideal vision of their figure (p < 0.05). Physical fitness is a better predictor of body acceptance than physical activity. In the final model, the sense of coherence, body mass index (BMI), and gender (being a boy) were also predictors of body acceptance (F(6,92) = 13.084, p < 0.0001). Gender differences were discussed in the present study. Fitness enhancing physical activity should be recommended for adolescents to achieve the protective psychosocial effect especially among girls. Physical activity on a daily basis brings positive results in a more adequate and reasonable body assessment and it can play a protective role in terms of mental wellbeing. Body satisfaction varies between genders and it is a more sensitive issue among girls than boys during adolescence.

Combined Neural Tuning in Human Ventral Temporal Cortex Resolves the Perceptual Ambiguity of Morphed 2D Images

We have an amazing ability to categorize objects in the world around us. Nevertheless, how cortical regions in human ventral temporal cortex (VTC), which is critical for categorization, support this behavioral ability, is largely unknown. Here, we examined the relationship between neural responses and behavioral performance during the categorization of morphed silhouettes of faces and hands, which are animate categories processed in cortically adjacent regions in VTC. Our results reveal that the combination of neural responses from VTC face- and body-selective regions more accurately explains behavioral categorization than neural responses from either region alone. Furthermore, we built a model that predicts a person's behavioral performance using estimated parameters of brain-behavior relationships from a different group of people. Moreover, we show that this brain-behavior model generalizes to adjacent face- and body-selective regions in lateral occipitotemporal cortex. Thus, while face- and body-selective regions are located within functionally distinct domain-specific networks, cortically adjacent regions from both networks likely integrate neural responses to resolve competing and perceptually ambiguous information from both categories.

Factor Structure and Psychometric Properties of the Body Perception Questionnaire-Short Form (BPQ-SF) Among Chinese College Students

Objective

Body perception, including body awareness and reactivity, is featured in a range of mental health conditions. However, research on Chinese questionnaires assessing body perception has been surprisingly absent. The present study aimed to investigate the factor structure and psychometric properties of the Body Perception Questionnaire–Short Form (BPQ-SF) among Chinese.

Methods

the current sample included 688 Chinese college students. Self-report scales were used to measure body perception, somatization, and depressive somatic and psychological symptoms.

Results

Confirmatory factor analysis supported a three-factor model of the BPQ-SF, involving body awareness, supradiaphragmatic reactivity, and subdiaphragmatic reactivity. Good internal consistency and test–retest reliability were observed. Convergent validity was established by significant correlations with scores of somatization and somatic symptoms of depression. Divergent validity was evidenced by non-significant association with ratings on psychological symptoms of depression. The very short form of the body awareness subscale of BPQ can be an alternative to the body awareness subscale when scale length is the priority.

Conclusion

The BPQ-SF possessed three latent factors and demonstrated good psychometric properties that can measure body perception among Chinese in a reliable and valid way.

How chimpanzees and children perceive other species' bodies: Comparing the expert effect

Human adults are better at recognizing upright bodies than inverted bodies. This inversion effect is also found for objects with which they have expertise, which is called the expert effect. This study aims to investigate its evolutionary and developmental aspects by testing humans' closest relatives, chimpanzees, and preschool children. Chimpanzees show the inversion effect to chimpanzee bodies, but it is not clear how they perceive other species' bodies. We tested seven chimpanzees in matching-to-sample tasks on touch screens using upright and inverted stimuli, and examined their accuracy and response time. In a previous study, they did not show the inversion effect for bipedal humans in unfamiliar postures, but here in this study they showed it to bipedal humans with familiar postures or crawling postures. This suggests the existence of the expert effect in non-human primates, and that visual or embodied experience is needed to invoke it. It is also supported by the inversion effect they exhibit for horses who share quadrupedal postures, but which they have never seen. Additionally, for conspecifics, the inversion effect was shown regardless of the postures. We tested 33 preschool children using a similar method. They showed the inversion effect to human bodies, but not houses, suggesting the configural processing for bodies, which is found to be stable at the preschool stage. They also showed the inversion effect for chimpanzees and horses, indicating the important role of experience in shaping the ways of object processing.

Explicit and Implicit Own's Body and Space Perception in Painful Musculoskeletal Disorders and Rheumatic Diseases: A Systematic Scoping Review

Background: Pain and body perception are essentially two subjective mutually influencing experiences. However, in the field of musculoskeletal disorders and rheumatic diseases we lack of a comprehensive knowledge about the relationship between body perception dysfunctions and pain or disability. We systematically mapped the literature published about the topics of: (a) somatoperception; (b) body ownership; and (c) perception of space, analysing the relationship with pain and disability. The results were organized around the two main topics of the assessment and treatment of perceptual dysfunctions.

Methods: This scoping review followed the six-stage methodology suggested by Arksey and O'Malley. Ten electronic databases and grey literature were systematically searched. The PRISMA Extension for Scoping Reviews was used for reporting results. Two reviewers with different background, independently performed study screening and selection, and one author performed data extraction, that was checked by a second reviewer.

Results: Thirty-seven studies fulfilled the eligibility criteria. The majority of studies (68%) concerned the assessment methodology, and the remaining 32% investigated the effects of therapeutic interventions. Research designs, methodologies adopted, and settings varied considerably across studies. Evidence of distorted body experience were found mainly for explicit somatoperception, especially in studies adopting self-administered questionnaire and subjective measures, highlighting in some cases the presence of sub-groups with different perceptual features. Almost half of the intervention studies (42%) provided therapeutic approaches combining more than one perceptual task, or sensory-motor tasks together with perceptual strategies, thus it was difficult to estimate the relative effectiveness of each single therapeutic component.

Conclusions: To our knowledge, this is the first attempt to systematically map and summarize this research area in the field of musculoskeletal disorders and rheumatic diseases. Although methodological limitations limit the validity of the evidence obtained, some strategies of assessment tested and therapeutic strategies proposed represent useful starting points for future research. This review highlights preliminary evidence, strengths, and limitations of the literature published about the research questions, identifying key points that remain opened to be addressed, and make suggestions for future research studies. Body representation, as well as pain perception and treatment, can be better understood if an enlarged perspective including body and space perception is considered.