Thèses sur le sujet « Body illusion »

People are generally quite good at adapting to changes in body shape and size because of the flexibility of the body representation. By means of bodily illusions, it is possible to experimentally induce updating of body representation and, thus, manipulate the sense of self. The main aim of this thesis is to investigate the sense of self through bodily illusions. Firstly, we investigated the relationship between the sense of ownership and self-localisation (Study 1). The results from this study are taken to suggest that the proprioceptive drift (i.e. a bias in the localisation of a given body part) is more likely triggered by and related to the visual capture of touch than it is a reliable measure of a shift in the sense of body ownership. In fact, our data show that the proprioceptive drift occurs not only in the absence of a shift in the sense of ownership, but even in the absence of a body-like object. Secondly, we investigated self-localisation of body parts by means of a novel illusion, the Disappearing Hand Trick. In particular, we explored the role of vision and proprioception (Study 2), as well as the role of attention and motor acts (Study 3), in locating one’s own hands when visual and proprioceptive information regarding the body are incongruent. Our data (Study 2) are in line with previous research, confirming a predominant role of vision over proprioception. In addition, they show that, after a certain amount of time, proprioception is weighted more heavily than vision. That is, our results demonstrate that the cortical proprioceptive representations can be updated even when there is no real need to do it (i.e. no movement is required). This might be seen as an evolutionarily convenient response to keep the body ready for a possible quick reaction. In Study 3, we ruled out the possibility that this effect was only driven by spatial attention being directed towards the side of the space where the hand was actually located. In fact, no difference in the localisation accuracy was found when the direction of spatial attention was manipulated. Finally, by asking the participants to reach across for their hidden right hand (Study 3), we confirmed that a motor act accelerates the reliance on proprioception, most likely by aligning the motor and perceptual coordinates in order to plan the movement. In the first three studies, a modification of the body representation was intentionally induced – namely, the purpose of the illusions was to change how the participants perceived their body. However, we wondered whether this same change might also occur at a more implicit level and how rapidly this may occur. We designed two different studies in which we tried to manipulate the participants’ perceived body size by providing incongruent information about the position of their limb (Study 4) or by showing the participants images of unrealistic bodies (Study 5). In Study 4 we showed that incongruent proprioceptive information coming from the same joint does not affect the perceived size of that body part, but does lead to a more accurate estimation of its position. On the other hand, the results of Study 5 would seem to suggest that body perception is more vulnerable to change in women than in men after exposure to same-sex ideal bodies. Taken together, these results suggest that, by manipulating the body representation, both explicitly, by means of a variety of bodily illusion, and even implicitly, by generating subtle incongruence between one’s own real body and how the body ‘should’ be, we were able to shed some light on the mechanisms behind the computation of body position and size, both of which are important elements for the definition of the self.

The feeling of owning a body part is often investigated by conducting and manipulating the rubber hand illusion, a three-way integration of vision, touch, and proprioception. In the last decade, more research on the role of interoception, the sense of the body's’ internal state, in the illusion has been made. One of the studied factors has been the affective touch, a caress-like, gentle, touch that is performed at a slow specific speed (1-10 cm/sec). Affective touch activates the C tactile afferents which send interoceptive signals to the brain, specifically the insula. The present systematic review investigated the role affective touch has on the strength of the rubber hand illusion. A range of electronic databases was searched for papers reporting research findings published in English before March 20, 2020. Twelve different articles were identified, but only five papers met the inclusion criteria. This thesis looked at the results from these five different studies and compared the effect of affective touch and discriminative, regular, touch have on the rubber hand illusion to see whether there is a significant difference. The results could not show a main effect of stroking velocity, site of stimulation, or social touch, which are components of affective touch. The results was based on four different measurements, the subjective experience of the illusion, pleasantness ratings, proprioceptive drift, and temperature difference in the skin. Opposed what was hypothesized, it could not be demonstrated that affective touch would induce a stronger rubber hand illusion than discriminative touch.

Embodiment is the experience of one's own body. It is often studied using the Rubber Hand Illusion (RHI). This illusion varies the consistency between visual, tactile and proprioceptive signals to elicit a change to embodiment. Changes to embodiment are typically measured using a single sensory outcome measure of proprioceptive drift, which is interpreted as a proxy measure of embodiment. This approach obscures the unique contribution of other modalities such as vision and touch. The work presented in this thesis uses a mixed method approach to investigate the unique contribution of visual, tactile and proprioceptive modalities within the multisensory process of embodiment. In study one, a qualitative analysis showed that when visual-tactile discrepancies were present in the RHI, participants described both body ownership and body extension type changes to embodiment, and changes to tactile perception. In study two, psychophysical measurements of the RHI showed changes to visual, tactile and proprioceptive aspects of embodiment, suggesting that embodiment in the RHI could be measured using multiple sensory outcomes. Studies three and four assessed the utility of measuring multiple sensory outcomes of the RHI, by exploring changes to embodiment following internal and external forms of body perception training. Study three showed that brief body scan meditation, as a form of internal body perception training, reduced the longevity of the visual sensory outcome of the RHI and that this reduction was negatively correlated with improvements in interoceptive sensitivity. Study four showed that learning about the body through anatomical dissection training, as a form of external body perception training, reduced the longevity of the visual sensory outcome measure and decreased interoceptive sensitivity, but only in medical students who were high in trait personal distress. Collectively, these findings suggest that aspects of the multisensory processes of embodiment can become specialised and identify some unique contributions of individual sensory modalities to embodiment. The proprioceptive sensory outcome appears to be stable over time but the visual sensory outcome is a longer-term change to embodiment, which is susceptible to interference from body perception training. In study five, confirmatory factor analysis was used to assess the psychometric properties of an embodiment change questionnaire measuring body ownership, body extension and perceived causality in the RHI. Factor scores from the questionnaire were correlated with visual and proprioceptive outcome measures of the RHI and measures of trait empathy. The results suggested factor scores had better convergent validity than the standard illusion score used in previous research. This work has improved subjective and perceptual measures of the RHI and specified ways that individual sensory modalities provide a unique contribution to embodiment. The methods developed have further applications for studying the multisensory process of embodiment and investigating embodiment in a number of clinical groups.

Una grande varietà di input sensoriali dal mondo e dal corpo, sono continuamente integrati nel cervello al fine di creare rappresentazioni mentali sovramodali e coerenti del nostro stesso corpo. La plasticità è una caratteristica fondamentale di tali rappresentazioni, che consente costanti cambiamenti adattativi nelle funzioni mentali e nel comportamento. Anche le rappresentazioni corporee possono cambiare in base all'esperienza e, soprattutto, possono essere temporaneamente modificate mediante protocolli sperimentali. Nel presente lavoro, eravamo interessati a valutare la plasticità della percezione metrica del corpo e l'effetto di cambiamenti temporanei in essa sull'elaborazione delle informazioni corporee e spaziali. A tale scopo, sono stati utilizzati due illusioni corporee: la Mirror Box Illusion (MB) e la Full-Body Illusion (FBI). Il meccanismo principale che spiega l'efficacia di queste procedure sperimentali è il processo di incorporazione di una parte del corpo aliena. Nell'esperimento 1 abbiamo usato un paradigma visuo-tattile di FBI per valutarne la fattibilità e la replicabilità con corpi di dimensioni diverse. Abbiamo confermato che è possibile indurre e replicare nello stesso partecipante l'incorporazione verso manichini di dimensioni standard o più grandi. Nell'esperimento 2 e 3 abbiamo studiato la rappresentazione metrica della gamba e la sua malleabilità. Abbiamo quindi misurato l'effetto dell'FBI indotto da diverse dimensioni corporee, su un compito di valutazione della distanza percepita tra due tocchi applicati alla gamba del partecipante. Abbiamo scoperto che l'esperienza soggettiva di incorporazione è accompagnata da un cambiamento nella percezione della metrica del corpo che va di pari passo con la dimensione delle gambe incarnate. Poiché abbiamo confermato che, in soggetti sani, la rappresentazione metrica del corpo può essere modulata, abbiamo affrontato una domanda simile in pazienti con emiplegia. Nell'esperimento 4, usando un compito di bisezione del corpo abbiamo osservato che pazienti emiparetici mostrano una distorsione prossimale nella rappresentazione metrica dell'arto interessato. Abbiamo, inoltre, scoperto che la bisezione si sposta verso il punto medio reale dopo una sessione di trattamento con MB, rispetto a un trattamento di controllo senza specchio. Nell'esperimento 5 abbiamo trovato una modulazione simile della metrica corporea che, in un gruppo di pazienti affetti da aprassia ideomotoria trattati con una versione modificata della MB, era accompagnata da un miglioramento della programmazione dei piani motori. Negli esperimenti 6 e 7 ci siamo concentrati maggiormente sulla relazione tra metrica del corpo e rappresentazione dello spazio. In primo luogo, abbiamo testato l'ipotesi che una rappresentazione del corpo alterata influenzasse la percezione delle proprie attività motorie immaginate. I risultati hanno mostrato che i partecipanti immaginavano di camminare più velocemente dopo essere stati esposti a una FBI con gambe più lunghe. Inoltre, abbiamo scoperto che l'incorporazione illusoria di gambe più lunghe può influenzare la stima delle distanze allocentriche nello spazio extra-personale. L'incorporazione di gambe più lunghe, da un lato, ha, infatti, ridotto la distanza percepita in metri, dall'altro, ha prodotto un aumento del numero di passi che i partecipanti immaginavano di dover percorrere tra gli stessi punti di riferimento. In conclusione, abbiamo confermato che è possibile manipolare la rappresentazione metrica del corpo, mediante illusioni corporee e che ciò influenza la nostra capacità di stimare le distanze nel mondo esterno sia in termini di raggiungibilità che di stima allocentrica della distanza. Tale plasticità della rappresentazione corporea e dell'interazione spazio-corpo fornisce importanti indizi per la comprensione della rappresentazione corporea e della sua riabilitazione nei pazienti neurologici.
A large variety of sensory input from the world and the body, are continuously integrated in the brain in order to create supra-modal and coherent mental representations of our own body. Plasticity is a fundamental characteristic of the nervous systems, allowing constant adaptive changes in mental functions and behaviour. Thanks to this, even body representations can change according to experience and, crucially, they can be temporarily altered by means of experimental protocols. In the present work, we were interested in assessing the plasticity of the subjective metric of the body, and the effect of temporary changes in it on the processing of corporeal and spatial information. To this aim, two types of bodily illusion were used, i.e. the Mirror Box Illusion (MB) and the Full-Body Illusion (FBI), due to their known effects inducing strong modulations of body representation. The core mechanism accounting for the efficacy of these experimental procedures is likely to be the process of embodiment of an alien body part. In experiment 1 we used a visuotactile FBI-like paradigm to assess the feasibility and the replicability of the FBI for bodies of different sizes. Using this paradigm, we confirmed that it is possible to induce and replicate in the same participant, the embodiment towards mannequins of standard or bigger sizes. In experiment 2 and 3 we investigated body metric representation of the leg, and whether it can be plastically modulated by embodying mannequins of different sizes. To address this issue, we measured the effect of FBI induced by different body sizes, over a Body Distance Task (BDT), i.e. the assessment of the perceived distance between two touches applied to the participant’s leg. We found that the subjective experience of embodiment is also accompanied by a change in the perception of body metric that goes hand-in-hand with the current size of the embodied legs. Since we confirmed that, in healthy subjects, the metric representation of the body can be modulated, we addressed a similar question in patients with hemiplegia. In experiment 4, using a body bisection task we first observed that hemiparetic post-stroke patients show a proximal bias in the metric representation of their affected upper limb. Critically, we found that this bias shifts distally, towards the objective midpoint after a MB training session, compared to a control training without the mirror. In Experiment 5 we found a similar modulation of subjective body metric in a group of patients suffering from Ideomotor Apraxia, treated with a modified version of the MB setup, which was accompanied by an improvement in the programming of motor plans. In experiments 6 and 7 we focused more on the relationship between body metric and space representations. First, we tested the hypothesis that an altered body representation could modify the way in which individuals estimate their body affordances during a Motor Imagery Task. Our results showed that participants imagined walking faster after having been exposed to an illusion of longer legs. Furthermore, we found that the illusory embodiment of longer legs can affect the estimation of allocentric distances in extra-personal space. The embodiment of longer legs, on the one hand, reduced the perceived distance in meters, on the other hand, produced an enhancement of the number of steps that participants imagined they would have needed to walk between the same landmarks. In conclusion, we confirmed that it is possible to induce provisional modifications of the metric representation of the body, by means of body illusions. We showed that body representation is malleable to the point to shape our ability to estimate distances in the external world both in terms of reachability and allocentric distance estimation. Such plasticity of body representation and body-space interaction gives important clues for the understanding of body representation and its rehabilitation in neurological patients.

Body ownership can be studied via the rubber hand illusion (RHI), in which an artificial limb can be perceived as belonging to oneself. In the so-called moving RHI paradigm, both body ownership and sense of agency, induced by self-produced movements, can be investigated. The key question of this approach is whether movements generated by oneself increase the illusion of body ownership. Thus far, the results from moving RHI studies are inconsistent.This has led to uncertainty regarding the influences of the motor control mechanism on body ownership. Therefore, this study will present the first meta-analysis on moving RHI to estimate the illusory effectiveness induced by self-produced movements. A total of 23 experimental comparisons with 821 subjects were included in the meta-analysis. The results showed that the overall illusory effect induced by self-produced movements was superior toits control (e.g., asynchronous active movements) (Hedge’s g = 1.38, p < 0.001). However, due to dissimilarity in results between the studies, the sample size in the meta-analysis may not represent the general population. The subgroup analysis showed that studies using physical hands, such as wooden hands, yielded the largest effect compared to studies using a virtual projected hand or a video recorded image of the participant’s own hands. It can be speculated whether a three-dimensional hand with “realness” has an illusory advantage compared to hands presented in virtual or video image settings. Future studies need to apply aunified framework, particularly in experimental setups and measurements. This would obtain consistent results of the strength of the illusion within the moving RHI paradigm.

Following stroke, a patient may fail to report touch administered by another person but claim that s/he feels touch when it is self-administered. In Part One, the self-touch rubber hand paradigm was used to investigate different explanations for this phenomenon, termed self-touch enhancement. The most important finding was that patients reported touch based on feeling rather than by using proprioceptive information. Some patients have residual sensation that could be targeted in sensory rehabilitation. Part Two is a systematic investigation of the illusion of self-touch conducted with neurologically healthy participants. Participants used the right hand to administer touch to a prosthetic hand while the left (receptive) hand, positioned 15 cm from the prosthetic hand, received Examiner-administered touch. Proprioceptively perceived position of the administering and receptive hand was measured. Most participants experienced the single event of self-touch at the location of the receptive hand. Previous investigations have relied on measurement of only one hand and have concluded that participants experience self-touch at the location of the prosthetic hand. Our findings have implications for the role of ownership in this illusion. There is also a series of experiments in Part Two which test four potential constraints on the illusion of self-touch – violated expectations about the object that is administering touch, increased distance between the hands, alignment mismatch, and anatomical implausibility. For example, one study uses a novel paradigm to demonstrate that, although the subjective intensity of the illusion of self-touch is diminished by anatomical implausibility, most participants report the impossible experience of touching their left elbow with their own left index finger. Taken together, these experiments highlight the malleability of body representation, and provide a comprehensive framework for understanding the illusion of self-touch.

With the ability to feel through artificial limbs, users regain more function and increasingly see the prosthetics as parts of their own bodies. So, main focus of this project was dedicated to recuperating sensation by deception both in sighted and unsighted patients, started with illusionary experiments on healthy volunteers, brain signals were captured with medical EEG headsets during these tests to have a better understanding of how the brain works during body ownership illusions. EEG results suggest that gender difference exists in the perception of body transfer illusion. Visual input can be induced to trick the brain. Using the results, a new device has been designed (sound generator system-SGS) with the principal goal to find ways to include rich sensory feedback in prosthetic devices that would aid their incorporation of the user's body representation or schema. Studying the brain is fascinating; SGS tested and was found to have an adequate level of dexterity over course of one-month multiple times. After each try, the results were more tolerable than before that proved the idea that brain can learn and understand anything and can be manipulated temporary or lasting due to influences. Different methods used to validate the results, EEG acquisition, mapping subject brain function with EEG and finally interviewing participant after each attempt. Although the results of the illusion shows that when heat applies on rubber hand, subjects behave in similar manner as if their real hand was effected, but main question is still remains. How can the conditioning apply to daily life of amputees so that illusion become permanent? This is a rapidly developing field with advancements in technology and greater interdisciplinary integration of medicine, mechatronics and control engineering with the future looking to have permanent, low power consumption, highly functional devices with a greater intuitive almost natural feel using a variety of body signals including EMG, ultrasound, and Electrocorticography.

La distorsione della percezione della distanza tra due stimoli puntuali applicati sulla superfice della pelle di diverse regioni corporee è conosciuta come Illusione di Weber. Questa illusione è stata osservata, e verificata, in molti esperimenti in cui ai soggetti era chiesto di giudicare la distanza tra due stimoli applicati sulla superficie della pelle di differenti parti corporee. Da tali esperimenti si è dedotto che una stessa distanza tra gli stimoli è giudicata differentemente per diverse regioni corporee. Il concetto secondo cui la distanza sulla pelle è spesso percepita in maniera alterata è ampiamente condiviso, ma i meccanismi neurali che manovrano questa illusione sono, allo stesso tempo, ancora ampiamente sconosciuti. In particolare, non è ancora chiaro come sia interpretata la distanza tra due stimoli puntuali simultanei, e quali aree celebrali siano coinvolte in questa elaborazione. L’illusione di Weber può essere spiegata, in parte, considerando la differenza in termini di densità meccano-recettoriale delle differenti regioni corporee, e l’immagine distorta del nostro corpo che risiede nella Corteccia Primaria Somato-Sensoriale (homunculus). Tuttavia, questi meccanismi sembrano non sufficienti a spiegare il fenomeno osservato: infatti, secondo i risultati derivanti da 100 anni di sperimentazioni, le distorsioni effettive nel giudizio delle distanze sono molto più piccole rispetto alle distorsioni che la Corteccia Primaria suggerisce. In altre parole, l’illusione osservata negli esperimenti tattili è molto più piccola rispetto all’effetto prodotto dalla differente densità recettoriale che affligge le diverse parti del corpo, o dall’estensione corticale. Ciò, ha portato a ipotizzare che la percezione della distanza tattile richieda la presenza di un’ulteriore area celebrale, e di ulteriori meccanismi che operino allo scopo di ridimensionare – almeno parzialmente – le informazioni derivanti dalla corteccia primaria, in modo da mantenere una certa costanza nella percezione della distanza tattile lungo la superfice corporea. E’ stata così proposta la presenza di una sorta di “processo di ridimensionamento”, chiamato “Rescaling Process” che opera per ridurre questa illusione verso una percezione più verosimile. Il verificarsi di questo processo è sostenuto da molti ricercatori in ambito neuro scientifico; in particolare, dal Dr. Matthew Longo, neuro scienziato del Department of Psychological Sciences (Birkbeck University of London), le cui ricerche sulla percezione della distanza tattile e sulla rappresentazione corporea sembrano confermare questa ipotesi. Tuttavia, i meccanismi neurali, e i circuiti che stanno alla base di questo potenziale “Rescaling Process” sono ancora ampiamente sconosciuti. Lo scopo di questa tesi è stato quello di chiarire la possibile organizzazione della rete, e i meccanismi neurali che scatenano l’illusione di Weber e il “Rescaling Process”, usando un modello di rete neurale. La maggior parte del lavoro è stata svolta nel Dipartimento di Scienze Psicologiche della Birkbeck University of London, sotto la supervisione del Dott. M. Longo, il quale ha contribuito principalmente all’interpretazione dei risultati del modello, dando suggerimenti sull’elaborazione dei risultati in modo da ottenere un’informazione più chiara; inoltre egli ha fornito utili direttive per la validazione dei risultati durante l’implementazione di test statistici. Per replicare l’illusione di Weber ed il “Rescaling Proess”, la rete neurale è stata organizzata con due strati principali di neuroni corrispondenti a due differenti aree funzionali corticali: • Primo strato di neuroni (il quale dà il via ad una prima elaborazione degli stimoli esterni): questo strato può essere pensato come parte della Corteccia Primaria Somato-Sensoriale affetta da Magnificazione Corticale (homunculus). • Secondo strato di neuroni (successiva elaborazione delle informazioni provenienti dal primo strato): questo strato può rappresentare un’Area Corticale più elevata coinvolta nell’implementazione del “Rescaling Process”. Le reti neurali sono state costruite includendo connessioni sinaptiche all’interno di ogni strato (Sinapsi Laterali), e connessioni sinaptiche tra i due strati neurali (Sinapsi Feed-Forward), assumendo inoltre che l’attività di ogni neurone dipenda dal suo input attraverso una relazione sigmoidale statica, cosi come da una dinamica del primo ordine. In particolare, usando la struttura appena descritta, sono state implementate due differenti reti neurali, per due differenti regioni corporee (per esempio, Mano e Braccio), caratterizzate da differente risoluzione tattile e differente Magnificazione Corticale, in modo da replicare l’Illusione di Weber ed il “Rescaling Process”. Questi modelli possono aiutare a comprendere il meccanismo dell’illusione di Weber e dare così una possibile spiegazione al “Rescaling Process”. Inoltre, le reti neurali implementate forniscono un valido contributo per la comprensione della strategia adottata dal cervello nell’interpretazione della distanza sulla superficie della pelle. Oltre allo scopo di comprensione, tali modelli potrebbero essere impiegati altresì per formulare predizioni che potranno poi essere verificate in seguito, in vivo, su soggetti reali attraverso esperimenti di percezione tattile. E’ importante sottolineare che i modelli implementati sono da considerarsi prettamente come modelli funzionali e non intendono replicare dettagli fisiologici ed anatomici. I principali risultati ottenuti tramite questi modelli sono la riproduzione del fenomeno della “Weber’s Illusion” per due differenti regioni corporee, Mano e Braccio, come riportato nei tanti articoli riguardanti le illusioni tattili (per esempio “The perception of distance and location for dual tactile pressures” di Barry G. Green). L’illusione di Weber è stata registrata attraverso l’output delle reti neurali, e poi rappresentata graficamente, cercando di spiegare le ragioni di tali risultati.

La percezione unitaria della realtà è il risultato di un complesso processo d’integrazione delle informazioni provenienti dai differenti canali sensoriali. La capacità del sistema nervoso centrale di utilizzare sinergicamente queste molteplici sorgenti sensoriali è definita Integrazione Multisensoriale (Stein & Meredith, 1993). A causa della sua importanza sul comportamento, lo studio dei processi che la regolano è da tempo riconosciuto come un aspetto cruciale nell'ambito delle neuroscienze. Da questo punto di vista, un importante contributo può venire dallo confronto tra soggetti sani e soggetti con deficit cerebrali, al fine di chiarire quali aree cerebrali sono coinvolte, e per poter quindi far luce sui meccanismi neurali sottostanti. Un metodo utile di indagine sui fenomeni di interazione multisensoriale sfrutta le illusioni sensoriali, ovvero quelle situazioni in cui due stimoli di natura sensoriale differente vengono presentati più o meno in contemporanea, creando una falsa interpretazione dell'oggetto o dell'evento da cui provengono tali stimoli. Il presente lavoro esamina due forme di integrazione. La sound-induced flash illusion analizza l'integrazione audio-visiva (Shams et al., 2002): quando un singolo flash è accompagnato da molteplici segnali acustici (beep), il singolo flash è percepito come multiplo. L'aspetto interessante di questa illusione è che è stata riscontrata anche in soggetti patologici affetti da autismo (van der Smagt et al., 2007). Un secondo interessante fenomeno è quello delle body ownership illusions (BOIs), utili per indagare patologie quali la somatoparafrenia, in quanto i soggetti percepiscono oggetti non corporei come appartenenti al proprio corpo. I risultati raccolti hanno permesso la formulazione di alcuni modelli computazionali che possono essere testati con i dati esistenti. Il presente elaborato fa una panoramica sui modelli bayesiani, l'elettroencefalografia e, infine, le reti neurali, illustrando i risultati raggiunti.

La kinesthésie chez l’Homme repose sur le traitement des multiples informations sensorielles générées au cours de l’action. Notre démarche expérimentale vise à évaluer l’apport respectif des sensibilités proprioceptive musculaire, tactile et visuelle à la perception des mouvements du corps. Utilisant des leurres sensoriels capables de créer des illusions kinesthésiques, nous recherchons, lors d'approches psychophysiques et en neuroimagerie, les règles et aires cérébrales impliquées dans la fusion multisensorielle. Ce travail confirme que chacune des trois modalités véhicule des informations pertinentes pour le système nerveux central (SNC), qui se combinent différemment selon la vitesse du mouvement et les modalités en présence. Tact et vision véhiculent des informations cinématiques redondantes, complémentaires de la proprioception, relatives aux mouvements du corps dans son environnement. Elles semblent plus fiables pour coder des mouvements lents (Blanchard et al., 2011, 2013). L'IRMf met en lumière un réseau de convergence hétéromodal de perception d’un mouvement de la main et confirme que les régions pariéto-cérebello-insulaires sont le siège de processus d'intégration supramodaux. En combinant trois signaux sensoriels différents, ce travail fournit la preuve originale de leur intégration à différents niveaux du SNC, des aires primaires, jusqu’aux aires supérieures du traitement de l’information. Rappelant le modèle de "Modality Appropriateness" de Welch & Warren (1986), nos résultats soutiennent l'idée d'une pondération des entrées, optimisant la kinesthésie, en fonction de leur relative pertinence à coder un évènement donné
Human kinesthesia is based on the processing of a great amount of sensory information available during action. To assess the respective contribution of muscle proprioception, vision and touch of self-movement perception, our experimental approach relies on sensory lures likely to generate illusory sensations of movement. In psychophysics and functional neuroimaging (fMRI) experimental setting, we try to better understand how and where this "multisensory fusion" occurs. This work confirms that each modality conveys kinesthetic information relevant for the central nervous system (CNS), is combined in a non-equivalent way according to the velocity of encoded movement and sensory modalities involved. Tact and vision seem to provide redundant cinematic information about body movements relatively to environment, complementary to muscle proprioceptive signals and seem to be more reliable for coding small velocities (Blanchard et al., 2011, 2013). Our neuroimaging results highlight a heteromodal network involved during kinesthesia and confirms that a supramodal insulo-cerebello-parietal region is the substrate for trisensory integration processing. By combining three kinesthetic signals from different sensory origins, this work provides evidence of integration at different levels of the CNS. Recalling the "Modality Appropriateness" model of Welch & Warren (1986), our results also support the idea of a weighted integration of sensory inputs, which would optimize kinesthesia, based on their relative relevance to encode a given event

Our bodies are arguably one of the most intimate things we will ever know. But the comfort of our own physical boundaries can be altered in various ways. In this analysis, we will look at how vision contributes to the sense of owning a body by analysing six abnormal conditions: the rubber hand illusion, phantom limbs, somatoparaphrenia, the body-swap illusion, out-of-body experiences, and heautoscopy. Examinations of these experimental or pathological conditions has granted a greater understanding of body-ownership. It was discovered that vision plays different modulatory roles, being more intricately involved in full-body ownership than in part-body ownership. Vision appears to be highly connected to self-location and first-person perspective, which both are contributing factors in projecting the sense of ownership to an external location. In part-body ownership, however, vision can be overruled by other senses, such as proprioception. Though it is still able to contribute to the illusion of projecting ownership and proprioceptive displacement to a rubber hand.

In the last decade, research on visual perception of the human body remarkably increased, especially following the discovery of the Extrastriate Body Area, an occipito-temporal region selectively involved in body-processing (Downing et al., 2001). However, an intriguing issue is to what extent a specific kind of body representation in the brain is devoted to the knowledge of the bodily self. Research on the visual recognition of the self-body, in particular, is still scarce, especially if compared to the extensive body of research devoted to the recognition of self-face. In the present thesis, a systematic investigation of unexplored aspects of self-body and self-face recognition is presented, with particular focus on the one side, on the possible neural correlates, and on the other, on the variables of personality that may play a role in these cognitive functions. Recent work in neuroscience indicates a superiority in the visual processing of one’s own than other people’s body-parts (Frassinetti et al., 2008). Specifically, subjects show higher accuracy when asked to match pictures depicting their own compared to unfamiliar body-parts, the so-called “self advantage”. It remains to be established, however, which cortical regions are involved in this phenomenon. To this aim, in experiments reported in Chapter 2 the causal role of cortical regions specifically involved in body-parts processing (i.e., the right Extrastriate Body Area) and in self-face recognition (i.e., the right Inferior Parietal Lobule) was investigated by means of Transcranial Magnetic Stimulation. The results did not allow definitive conclusions regarding the role of the cortical areas under investigation for self body-parts recognition; nonetheless, behavioural data seem to suggest that the self-recognition ability is not as universal as generally believed. In particular, the strength of the “self advantage” showed a large degree of variability across participants. Therefore, the contribution presented in Chapter 3 was aimed at finding some possible determinants that modulate the self-body advantage. Namely, it was examined whether the self-body recognition ability is modulated by implicit and explicit self-esteem, relying upon studies linking the physical self and self-esteem. Two studies were conducted using paradigms assessing covert (Experiment 3) or overt (Experiment 4) self-body recognition (i.e., the matching-to-sample used in previous studies and a new-developed paradigm of overt recognition). Results revealed that the self-body recognition ability is qualified by individual differences in self-esteem, and especially implicit self-esteem, measured with the Implicit Association Test, a widely used procedure for measuring strengths of automatic associations between concepts (Greenwald et al., 1998). Moreover, considering the two studies together, only the implicit self-esteem showed incremental validity in predicting the ability to recognize self body-parts. The results are discussed in terms of the role of individual differences such as implicit self-esteem for cognitive functions such as self-body recognition. Finally, a study (Experiment 5) was conducted to better address whether self-esteem and other personality traits with strong interpersonal value (i.e., empathy) also correlate with the strength and stability of self-representation. Self-face representation was recently found to be less stable than believed in the past (Tsakiris, 2008). Our findings reveal that higher level of implicit self-esteem correspond to lower susceptibility to the “enfacement” illusion, measured in terms of incorporation of other people’s facial features in the self-face representation following synchronous visuo-tactile stimulation in a mirror-like setting. Moreover, the Perspective Taking component of empathy was found to correlate with the introspective experience of the illusion. All in all, the present contribution bridges recent research in the cognitive neurosciences and social cognition and points toward a complex interplay among cognitive and personality factors in the domain of self-recognition.

La présente étude porte sur l’anthropologie et la politique de Spinoza. Il s’agit précisément de montrer en quoi, la réflexion spinoziste sur l’homme se donne particulièrement à lire à travers les concepts d’ « individu », de « corps » et d’« affects ». Au cours de notre analyse, nous montrons que ces concepts occupent une place de choix chez l’auteur de l’Éthique pour deux raisons : d’une part, c’est par eux, que le philosophe déploie son analyse des rapports psychophysiques de l’individu humain. En effet, selon lui, le corps humain étant une réalité « en acte », il est nécessairement affecté par d’autres corps. Or, en tant qu’il est aussi l’objet de l’idée (l’esprit), rien n’affecte ou ne modifie sa puissance, sans qu’il ne soit perçu par l’esprit humain. Et, l’« affect » n’est tout autre que cette modification de la puissance corporelle et sa perception par l’esprit. Autrement dit, l’affect peut se définir comme la conscience simultanée que l’individu humain a de son propre corps, par l’entremise de la perception des altérations de la puissance d’agir de ce dernier (les sciences contemporaines, telles que la neurobiologie, la psychologie, la médecine, et bien d’autres, corroborent les thèses de Spinoza à ce propos). C’est en insistant sur la simultanéité des rapports psychophysiques, donc sur l’absence d’interaction du corps et de l’esprit, que Spinoza se démarque de Descartes. D’autre part, à travers les mêmes concepts (de « corps » et d’« affects »), Spinoza permet aussi de penser la constitution d’un autre genre de corps ; un corps né de l’union des individus humains, à savoir : le corps politique. Les affects sont, non seulement au fondement de la constitution de ce corps, mais ils sont aussi ce qui permet de réguler les affaires humaines. C’est en ce sens que Spinoza nous amène à concevoir le corps politique, non pas comme une rupture - contrairement à ce que soutenait Hobbes - mais comme une continuité de l’état de nature. Le mérite de l’anthropologie spinoziste est de montrer qu’autant la nature humaine ne peut se concevoir sans affects, autant aucune réflexion politique ne peut avoir de valeur de vérité sans la prise en compte de ces mêmes affects
The Dissertation is a study of Spinoza’s anthropology and politics. It shows how Spinoza’s reflection on man can be read with an emphasis on the concepts of “individual”, “body” and “affects”. These concepts have a prominent place for the author of Ethics for two reasons: 1) they are central to his analysis of the mind body relation. Because, according to him the human body, for being a reality “in action”, is necessarily affected by other bodies. 2) However, as it is also the object of an idea (mind), nothing affects or modifies its power, without it is being perceived by the human mind. And the affect is the very modification of physical power and its perception by the mind. In other words, the affect can be defined as simultaneous consciousness that the human individual has from its own body by means of perception of the changes of his power to act (the contemporary sciences, such as the neurobiology, the psychology, the medicine, and many others, may confirm the theses of Spinoza). Our study pays attention to the simultaneity of the affections of the body and the ideas of these affections in the mind, and to the lack of interaction of body and mind that characterizes Spinoza’s philosophy and makes the difference with Descartes’ conception. It is important to emphasize that Spinoza with the same concepts of “individual”, “body” and “affects”, also allows us to think of the constitution of another kind of body the political body. The affects are not only on the foundation of the constitution of this body, but they are also what allowed to regulate human affairs. It is in this sense that Spinoza leads us to conceive the body politics, not as a breakage - unlike Hobbes - but as a continuation of the state of nature. Spinoza’s anthropology is powerful, because it proves that human nature cannot be conceived without affects, as well as no political thinking can have a value without considering the affects

In the last decade, neuroscience and psychology alike have paid increasing attention to the study of affective touch, which refers to the emotional and motivational facets of tactile sensation. Some aspects of affective touch have been linked to a neurophysiologically specialised system, namely the C tactile (CT) system. While the role of this system for affiliation, social bonding and communication of emotions have been investigated, less is known about the potential role of affective touch in the awareness of the body as our own, i.e. as belonging to our psychological 'self'. This thesis attempted to contribute to the knowledge on affective touch and its relation to body awareness, by exploring the potential role of this modality to the way we perceive and make sense of our body as our own. Specifically, this work aimed to advance the current state of knowledge by investigating: 1) the effect of affective touch on the sense of body ownership, which is a fundamental aspect of body awareness; 2) the relation between interoceptive modalities, originating both internally (i.e. cardiac awareness) and peripherally (i.e. affective touch), and exteroception in body awareness; 3) the effect of intranasal oxytocin on the perception of affective touch and bodily awareness; 4) the perception and social modulation of affective touch in psychiatric patients who show difficulties in body awareness, namely patients with Anorexia Nervosa, and 5) the modulating role of self-other distinction and of self-other relation in the perception of affective touch and body awareness. In a first experiment (N = 52) the rubber hand illusion paradigm was used to investigate the role played by CT-optimal, affective touch in the sense of body ownership. The results showed that slow, pleasant touch enhanced the experience of embodiment in comparison to faster, neutral touch, suggesting that affective touch might uniquely contribute to the sense of body ownership. The following study (N = 75), used a similar methodology to test whether interoceptive sensitivity as measured by a heartbeat counting task would modulate the extent to which affective touch influences the multisensory process taking place during the rubber hand illusion. The results could not confirm a systematic relation between interoceptive sensitivity and the perception of affective touch, nor its influence on body ownership. The next study (N = 41) included a double-blind, placebo-controlled, randomised, cross-over design testing the effect of intranasal oxytocin on the perception of affective touch and body ownership, as measured by means of the rubber hand illusion. There was no evidence supporting the hypothesis that intranasal oxytocin could influence the CT system as tested in this study. The next study (N = 55) applied some of the above methodologies to investigate the perception of CT-optimal touch in patients with anorexia nervosa and its emotional modulation by top-down factors. The results confirmed the hypothesis that people with anorexia nervosa show a reduced perception of affective touch compared to healthy controls, but its perception was not influenced by top-down affective modulation, in the sense that both patients and healthy controls perceived touch as more pleasant when presented concurrently with positive facial expressions compared to neutral and negative faces. Finally, the last two studies (N = 76 and 35 healthy volunteers, respectively) focused on the relationship between affective touch and body awareness in the context of social cognition. These studies used both online and offline social modulation paradigms to investigate the role of self-other distinction and of self-other relation in the perception of affective touch. The results showed that positive top-down social information can enhance the perceived pleasure of tactile stimulation. Taken together, these studies point to the central role of affective touch in body awareness and social cognition. Finally, they also pave the way for future studies examining the role of disruptions of the CT system in the development of neuropsychiatric impairments of body awareness and social cognition.

The definition of the body is uncertain within contemporary culture. This ‘body’ in question is ‘characterised’ by the pervasive and ubiquitous images of our visual culture, where mass media and advanced visual technology have created a highly simulated world. In this simulated world, the body is doubled. In this exegesis, I attempt to explore what the body means in contemporary visual culture by questioning and examining body image and its impact on our ideas of the body. I draw upon Baudrillard’s notion of ‘ hyper-reality’ and have applied it to the body image. This has resulted in my statement that contemporary (body) images in their own right, exterminating the original (body). From this, the notion of ‘the body in hyper-reality’ was formed and became a key concept for this exploration. In my visual practice, I conceived the idea of juxtaposing the contemporary body image with the classical statue through making an analogy between Baudrillard’s critique of contemporary images and early Christianity’s prohibition of the graven image. By combining the idea with my previous research tool of ‘critical illusion/ambiguity’ (a strategy where illusion or ambiguity is systematically arranged to draw the viewer’s attention and lead them to mediating on a certain issue), I conjured up a strategic device called ‘tactical disguise’ where contemporary body images merge into classical sculptures, pretending to be them. Through this process of disguising, I attempt to place the contemporary body images in the theatrical past, attaining a critical distance, at the same time drawing out discourses arising from the ironic juxtaposition of the two. Centreing upon this key strategy, my visual practice explored issue such as celebrity culture and idolatry, mass media and voyeurism, the ideal body, surveillance culture, simulation and the body, body image as commodity by experimenting with different types of body image as the subject for statues: images of famous, anonymous, ordinary or simulated bodies. An attempt to evoke the notion of the body in hyper-reality through visual practice was crystallised in the work, In search of Russell Crowe. In this work, the sculptural object’s interplay with other mediums such as video, performance, and photographs, brought an experimental aspect to the work, increasing the coherence and impact of my studio practice. This at the same time opened up a potential derived from the expansion of medium employed.
Thesis (Professional Doctorate)
Doctor of Visual Arts (DVA)
Queensland College of Art
Full Text

This study examines the interaction between portraits by the exponent of French colourist painting Nicolas de Largillierre (1656–1745) and elite spectatorship in the early eighteenth century as enactment of the idea of painting as an art of pleasing the eye. As developed in the theory of art of Roger de Piles (1635–1709), the idea of painting as an art of pleasing the eye coexisted with the classicist view, which in turn emphasised the potential of painting to communicate discursive meanings and hence to engage the mind. The idea of painting as an art of pleasing the eye was associated with a taste that valued the pictorial effects of painting and related to the ideal of honnêteté, which expanded on the art of pleasing in polite society by means of external appearances as a sign of social distinction. The aim of the study is to explore how portraits by Nicolas de Largillierre address the spectator and how such paintings might have come to have meaning for spectators in the early eighteenth century. To do this, the study takes a performative approach and defines meaning as a product of the interplay of pictorial effects and spectatorial response, progressing from the initial encounter throughout the sustained exploration of the paintings. Building on close analyses of selected paintings and readings of texts that bear on issues of pictorial imitation, spectatorship and social interaction, the study brings into focus the interplay of cognitive and sensory activities, including verbal articulation and bodily movement, which come into play in the production of meanings through the act of spectatorial experience. The study also emphasises the interplay of the mimetic and the material aspects of the paintings as an important bearer of meanings and identifies several interrelated sites of tension in which the pictorial effectiveness of the portraits resides. The study concludes by suggesting that to infer such meanings, the spectator should be prepared to respond to the address of the paintings actively, by engaging the mind, the senses and the body. Such an interpretation of the interaction between portrait paintings and spectators proposes a complex view of the ways in which artistic and spectatorial practices in the early eighteenth century might have interacted to create meanings while reproducing at the same time social and aesthetic conventions and ideals, such as the art of pleasing the eye.

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The amount of pain we feel is not always directly related to the amount of damage our body suffers. In fact, research over the last decade has shown that the experience of pain is strongly linked with how we feel about our body, including its shape and how much we like it. Chronic pain is associated with a distorted mental representation of the body, which can have a significant impact on everyday live. Evidence suggests that multisensory illusions can modulate pain and can lead to changes in body perception. However, the factors that may contribute to previously observed analgesic effects remain unclear. This thesis aimed to systematically asses the effects of these illusions on pain and body representation in both healthy individuals and individuals with chronic pain. First, this thesis aimed to investigate the effects of multisensory illusions on body representation, sense of body ownership, and pain in healthy individuals. Chapter 2 found that multisensory illusions can alter perceived body shape, body satisfaction, without losing ownership. Chapter 3 examined whether distorting the size and shape of the virtual hand could modulate pain in healthy participants. No evidence was found for this, which could indicate that pain is not necessarily affected by virtual body ownership over a distorted hand. Having established that multisensory illusions can alter body perception and the affective experience of the body, the second aim of this thesis was to investigate the effect of multisensory illusions on body representation, body ownership, and pain in individuals with hand osteoarthritis (HOA). Chapter 4 investigated whether people with HOA performed differently on a hand laterality motor task to investigate whether people with HOA present with a disruption of the working body schema. Though no evidence was found for a general impairment on this task, the findings suggested that performance on the task was mediated by the presence of pain. Chapter 5 investigated effects of multisensory illusions on pain and pain sensitivity in individuals with HOA. The results demonstrated that viewing the body could modulate pain; and affected body representation, body ownership, and agency. Chapter 6 examined the effects of multisensory illusions on subjective and objective aspects of body perception in people with HOA of the hands, compared to healthy controls. Though no evidence was found for an analgesic effect of the illusion, results showed that participants with HOA have a disturbed experience of the size of their hand compared to healthy controls. Furthermore, the results suggest that individuals with HOA may have an abnormally high body dissatisfaction that cannot readily be altered by multisensory illusions. This thesis found mixed support for the analgesic effects of multisensory illusions on pain in HOA and concludes that the specific context in which pain occurs is important. It also highlights the many perceptual and cognitive factors that may contribute to the modulation of pain. The findings imply that future work should focus on interventions that are more portable and accessible for home use, and focus on developing research around the effects of repeated and prolonged exposure to multisensory illusions on pain, body image disturbances and body dissatisfaction.

Cette thèse propose de discuter la conception du crime comme un acte de survie face à la résurgence d’hallucinations sensorielles. Les sujets criminels témoignent du sentiment d’être dépossédés de leur corps, de ne plus contrôler leurs actes, décrivent des vécus de pénétration, d’explosion, de mutilation, de démantèlement : une menace terrifiante s’incarne par la dégénérescence de la sensorialité. L’hallucination ne parvient pas ici à se formaliser et emprunte directement la voie du corps. Le sujet a alors recours à l’acte pour externaliser ces vécus sensoriels persécuteurs, enkystés dans un morceau de corps, et pour tenter de trouver une amorce de symbolisation primaire. Au cours de la prise en charge individuelle ou groupale de ces patients, il s’agit donc d’écouter les manifestations hallucinatoires qui tendent à se loger dans leurs corps, pour qu’adviennent leurs mises en sens, au sein des enjeux transféro-contre-transférentiels. La thèse analyse ainsi l’aménagement d’un dispositif thérapeutique, créé pour permettre une appropriation subjective des terreurs qui ont contraint ces sujets à se placer comme hors de la scène du crime. Dans le cadre d’une pratique thérapeutique en centre de détention, un groupe à médiation corporelle et picturale est proposé aux patients incarcérés, afin de privilégier l’expression du langage sensori-moteur. La médiation corporelle fonctionne comme un attracteur des vécus catastrophiques sous-jacents aux hallucinations sensorielles, et leur partage sensori-affectivo-moteur permet l’apparition d’une scène psychique groupale. Par la mise en mouvement du corps du sujet en groupe, la sensori-motricité se trouve réunifiée aux autres modalités sensorielles. La médiation picturale s’offre alors comme un écran du rêve sur lequel sont projetés, puis représentés, les éprouvés corporels du sujet en groupe, et potentialise ainsi le déploiement de l’hallucinatoire onirique
This thesis discusses the concept of crime as an act of survival in the face of a resurgence of sensory hallucinations. Criminal subjects describe a feeling of being dispossessed of their bodies, of no longer having any control over their actions, of experiencing penetration, explosion, mutilation and dismantling : a terrifying threat made real by the degeneration of the senses. In such cases, the hallucination fails to take form and uses the body directly. The subject then resorts to the act in order to externalise these tormenting sensory experiences, encysted in part of the body, and try to trigger primary symbolisation. In individual or group therapy sessions with these patients, the aim is therefore to listen to the hallucinatory manifestations embedded in the body, so that their meaning can emerge through transference and countertransference. Hence, we analyse a therapeutic solution created to enable the subjective appropriation of the terrors that led these subjects to situate themselves outside the crime scene. As part of therapeutic work in a detention centre, patients are invited to take part in a corporal and pictorial mediation group to encourage the expression of sensori-motor language. Corporal mediation acts as a magnet for catastrophic experiences underlying sensory hallucinations, and sharing them in a sensory-affective-motor manner enables the appearance of a group psychological scene. Through movement of the subject's body within the group, sensori-motricity is reunited with the other sensory forms. Pictorial mediation then acts as a dream screen onto which are projected, then represented, the subject's corporal experiences within the group, thereby rendering dreamlike hallucination possible

碩士
台南應用科技大學
美術研究所
101
I expound the creation of human body as the main shaft in this thesis. The human body has been the theme of artistic creation all the time. No matter the painting creation or the expression form, both of them were performed by the artists frequently in Western art history. By reviewing the development of art under the influence of different eras and culture, I realize that the combination of painting creation and inherent spirit is the result of the era that individual was in, traces of memory and inner emotion interwove together. I found the original intention of my creation in the thesis, and I tried to search a fantastic balance by denying and identifying myself constantly. And what this text should probe into is creator''s own consciousness of human body, I consider it as a kind of technique of expression with the human body in creator''s eyes. I ought to know what the relationship of the theme expression and myself is to distinguish between myself and these works. Aiming at the process of my creation, I faced all sorts of difficulties, bottleneck and every single record along the process. I could analyze the idea of my creation clearly through the study of my thesis, and furthermore construct the subject consciousness of the creator. It’s written down in the thesis that how I identified myself in the creation among the contradiction of research, difficulties and panics. It’d explain why creator considered human body as the theme of self- expression.

In contending that sections of Western society seek to conform to the myth of the perfect body image, reconstructing the exterior so much that we no longer recognize our true selves, I am making a statement that goes against the classical beliefs of the anatomically perfect human form. In doing this I question society’s devotion to ideas associated with the beautiful. Two decisive eras, the Classical and the Hellenistic altered the perception of the human form to the present day. I have directed my attention to artists who broke the constraints of these classical traditions of what was conventionally considered beautiful. Some who have challenged the myth of beautiful perfection are Antony Gormley, Janine Antoni, Shelley Wilson, Ron Mueck, Egon Schiele and Duane Hanson. Their work invoke preoccupations with ordinary and emotional themes relating to body image: teenagers suffering from eating disorders, suppressed issues of cosmetic surgery, habitual themes of isolation, mortality and doctrines on the mundane in suburban culture. These impact on my art visually and conceptually. In my artwork I am endeavoring to personify physical alteration: the multiple transformations that some undergo to be noticed in the crowd; how effortless it becomes to alter physical appearance and begin again. The material I use is latex with its resemblance to skin and so visually compatible to the concept I am endeavoring to impart: the constant physical alteration in an attempt to be accepted. Hyper-real body parts bought together in an installation present themes of relentless change, volume and satisfaction or discomfort with outward appearance. Body image and image of the body is all encompassing and unavoidable and will always be a part of our lives. It has become inherent in contemporary culture. The project illustrates the consequences of adhering to the classical archetype of perfection: the chronic reshaping of our physical exterior. It is narrated through my own experience in submitting to this dogma; the relentless struggle with my physical appearance and the reconstructions I have undergone in an attempt to be noticed.

碩士
東方設計學院
文化創意設計研究所
99
The statement of the study explores the theories and ideas of body painting, based on my own experiences of creation, the feminine awakening and introspection of gender awareness ideology, the art theories and the understanding of body aesthetic practice. Meanwhile, by the insight of creative practice and theories including discerning, clearness, understanding and realization, it suggests the meaning and values of creative action. The general and theoretical study of beauty of artistic works and the exploration of its methods and contents have been changing with the current of time. It also has the different interpretations because of races, beliefs and cultural differences, especially applied on design fields widely and blending into life art. The author, combining body lines with painting skills, creates the multi-style work of body painting. Furthermore, the thinking characteristics of being a female, the awakening of sexual consciousness and the realization of the inner-minded conversation to past life provide the important factors for my works. For a long time, the author has been spontaneously applying the theories of abstract on drawing lines in order to capture the spirit of my life. It has similar process with expressionism which seeks to express emotional experience and the search of spiritual reality. Therefore, it not only constructs the drawing space of creation, but also represents the realistic appearance. In terms of the subject of body painting, the author adopts feminine interpretations of sexes, physiological meaning and unconsciousness in surrealistic painting style to sketch the totems and symbols. At the same time, body painting on female body curves taking on prolific space differs from plat drawing. The existence and interlocking of reality and illusion show the reality of creation. That also expresses the reality of the author’s emotional illusive mind and manifests the beauty of body and feminine spirits. It forms my own creative style and IV thoughtfulness of the body style aesthetics. In the study, the author can realize the creative energy that originates my own penetration of inner sensation and the expression of my life emotions. The reative sequence of ideas contains the spiritually real philosophy of expressionism and the illusive world of surrealism. By the creative practice, the author brings up the self-contemplation to clarify the reality and illusion of my own existence and judges the creative meaning and values as well. In the future, the author expects to break through the life energy and to review my own introspection and action.

The simultaneous application of interlaced innocuous warm and cool stimuli (a thermal grill stimulus, TGS) can elicit sensations of burning heat (the Thermal Grill Illusion, TGI). The TGS is thought to alter the central interactions between somatosensory sub-modalities (i.e. cold-inhibition of pain). Previous psychophysical findings point to body site differences in perceptual thermal thresholds. The primary objective of this study was to evaluate whether, using the same TGS, a TGI can be elicited at body sites other than the upper extremity. The present findings indicate that the TGI can be induced at the palm, back, calf, and foot. Pain and unpleasantness in response to the TGS were more frequent and intense following stimulation of the palm and back than the calf and foot. Lower cold pain thresholds were associated with lower pain intensity ratings in response to the TGS. These two findings may reflect differences in central integrative processes.

碩士
國立臺灣體育運動大學
體育舞蹈學系碩士班
103
This thesis examines the graduation production “Life Is a Dreamlike Illusion” and expounds on reviewing the production process and on the interpretations of dance. The main goal is to extensively discusses the dance movement, the interpreting methods, and the participation experiences of the three dances that the author performed - “I am Liao, Wan-Lin”, “The Girls at Play “, and “Lost Paradise”. The first chapter, “Introduction”, is an account of the author’s return to dance performance after reconsideration, which resulted in the motivation and the purpose of the graduation production. The second chapter, “Performance Form and Literature Review”, is a literature review on the development of modern dance, on the process of searching proper training and body symbols, and on the performance theories of role interpretation and performance, such as those of Hsing-Chien Kao and Constantin Stanislavsky. The third chapter, “Production Process and Content”, is a narrative on the process of the production and a brief introduction on the content of the dances. The fourth chapter, “The Analyses and Interpretations of Dancing Body”, examines the rehearsal process, the challenges encountered, and the author’s reflections on her dancing body. The final chapter, "Conclusion", is a summary of the improvements and the changes that the author has gained from this production “Life Is Only an Illusion” in the hope of sharing her experience with dancers who are on the same journey.

Virtual Reality (VR) is an important tool for researchers of many different fields, from cognitive neuroscience to social psychology. The present work will explore the use of VR, and in particular of immersive virtual reality (IVR), in the study of some key aspects of our bodily self and bodily related behaviour and perception. In the first part of the present work we will discuss the combined used of IVR and full body illusion (FBI) in the study of body image distortion (BID) in anorexia nervosa (AN). The first chapter will serve as a general introduction to AN and its most prominent clinical characteristics, as well as introducing some key concepts like the malleability of the bodily-self through multisensory bodily illusions and a brief overview of a series of studies that applied both IVR and embodiment illusions to manipulate participants’ body representation. The second chapter will present a study in which we used the embodiment illusion of different sized avatars to characterize and reduce both the perceptual (body overestimation) and cognitive-emotional (body dissatisfaction) components of BID in AN. For this study we built personalized avatars for each participants (healthy controls (HC) and AN patients) and applied synchronous and asynchronous interpersonal multisensory stimulation (IMS) to three different virtual bodies (the perceived one, a +15% fatter one and a -15% thinner one). The different components of BID were measured by asking participants to choose the body that best resembled their real and ideal body before and after the embodiment illusion was induced. The results of this study showed a higher body dissatisfaction in AN patients, who also reported stronger negative emotions after being exposed to the largest avatar. However, the embodiment procedure did not affect BID in AN patients. Based on the results of the previous study, in the study presented in the third chapter we decided to shift our focus from somatorepresentation, i.e. the explicit representation of the body which comprise both cognitive and emotional components of body image, to somatoperception, i.e. the implicit representation of the body which comprise both body perception and body schema. In this study we applied a FBI over an underweight (BMI = 15) and normal weight (BMI = 19) avatar and measured the effect of the embodiment illusion on participants’ (AN and HC) body perception and body schema estimations. To measure body perception, we asked participants to estimate the width of their hips while their vision was blocked, whereas for the body schema estimation participants had to estimate the minimum door’s aperture width in order to pass through it inside an IVR scenario. The results showed that AN patients reported an overestimation in both body perception and body schema estimations. Furthermore, in AN patients we saw a change in the body schema estimation accordingly to the size of the embodied avatar, thus showing a higher bodily self-plasticity compared to HC. In the fourth chapter of the present work we will go over the results of the two aforementioned studies and will briefly discuss some possible future directions. Finally, the last two chapters of the thesis will present two research projects that will respectively utilize IVR and the embodiment illusion for the study of individual dishonest behaviour in digital interactions (chapter 5) and for the modulation of acute and chronic pain (chapter 6). As the COVID-19 pandemic deeply affected the work on both these studies, these two final chapters will only present a general introduction and the methods/technical implementation for both research projects.

碩士
國立交通大學
傳播研究所
107
women-body-consuming and popular culture influece feminism by the perspective of postmodernism? (2) What’s the connection between “the women body-building discourse” and “the confident women discourse” ? What kind of effect will this kind of image impact the existed dual-gender? (3) Can we expect “the women body-building discourse” to become a liberation for women, or is it just a new type of shackel? To answer these, this article first discuss the relationship between ‘agent’, ‘social ctructures’, and ‘the right for defining bodies”. According to Bourdieu’s argument, agent and structures are two sides of one coins, which is undevidable─that is, social structures are both structuring structures and structured structures─both of them are striving for the right to define bodies. In accordance with, the hyper-realistic and illusion of popular culture played an inevitable role in disputing the symbolic value. Hence, postmodernism view popular culture have the power to de-construct and re-construct the “realistic”. Accordingly, this article view “the women body-buildig discourse” have strong ties with “the confident women discourse”, and they exist side by side and play a part together, to become part of the doxa. Nevertheless, whether it is a liberation or a new shackle? Researches are disputing this issue continually, and have all kinds of optimistic and pessimistic opinions. But to this article, the greatest contribution of this phenomenon is to point out “what is women’s body, actually?”. As to this, people might reconsider the right of existed dual-gender frame, and the new possibility of women. In addition, it’s more important to rethink how to diversify the main stream and be ourselves within the few-standard doxa.

Poczucie własności ciała – bezpośrednie i natychmiastowe wrażenie, że dane ciało lub jego określona część należy do danej osoby – jest konstytuowane na bieżąco w wyniku procesów łączenia informacji z różnych zmysłów, przede wszystkim wzrokowych, dotykowych i proprioceptywnych. W związku z tym, dzięki wykorzystaniu precyzyjnej stymulacji multisensorycznej, możliwe jest jego iluzoryczne przeniesienie na przedmiot zewnętrzny. Przykładowo, podczas iluzji gumowej ręki (IGR) badany obserwuje gumową atrapę, głaskaną pędzelkiem w zsynchronizowany i zgodny przestrzennie sposób z pozostającą poza polem widzenia ręką prawdziwą. W efekcie pojawia się przekonujące wrażenie, że dotyk płynie z gumowej ręki, a ona sama jest częścią ciała danej osoby. Wykorzystując paradygmat badawczy IGR, prezentowany projekt stara się określić zależności między własnościami sygnałów wzrokowych, dotykowych i proprioceptywnych a wrażeniami posiadania ciała powstającymi w wyniku ich integracji. Celem pracy jest weryfikacja i rozbudowa istniejących modeli wnioskowania przyczynowego, według których sugestywność IGR zależy od stopnia czasoprzestrzennej zbieżności sygnałów, ich precyzji oraz indywidualnej skłonności do ich łączenia. W ramach projektu zaproponowano i empirycznie przetestowano własną koncepcję teoretyczną, wskazującą na kluczową rolę dwóch pomijanych dotychczas w literaturze czynników – czasoprzestrzennej złożoności informacji dotykowej oraz siły uprzedniego powiązania sygnałów. Uzyskane wyniki wskazują, że poczucie własności jest wyznaczane głównie przez strukturalną korelację sygnałów wzrokowo-dotykowych – zastosowanie spójnej, czasoprzestrzennie złożonej stymulacji znosi osłabiający iluzję wpływ rozbieżności wzrokowo-proprioceptywnych oszacowań położenia ręki. Zwiększenie dystansu dzielącego ręce prowadzi do zmniejszenia siły IGR tylko w przypadku braku lub uproszczonej stymulacji dotykowej. Indywidualna precyzja proprioceptywna, mierzona z wykorzystaniem zarówno aktywnego odtwarzania pozycji ręki, jak i pasywnej detekcji pozycji kątowej stawu łokciowego, nie ma wpływu na zaobserwowane efekty. Uzyskane wyniki wskazują na drugorzędną rolę propriocepcji w kształtowaniu się poczucia własności, rozszerzając współczesne rozumienie procesów atrybucji ciała. Prezentowany projekt może mieć również istotne implikacje praktyczne dla programów rehabilitacyjnych wykorzystujących technologię wirtualnej rzeczywistości.
Body ownership – a distinct and immediate experience of one’s body or its particular part as belonging to oneself – is being constituted on an ongoing basis by the integration of signals from multiple sensory modalities, primarily visual, tactile, and proprioceptive. Therefore, application of precise multisensory stimulation enables illusory transfer of body ownership to an external object. In the rubber hand illusion (RHI), participants observe a rubber dummy being stroked synchronously and in a spatially congruent manner with their visually occluded hand. The procedure induces a vivid impression that tactile sensations arise from the rubber hand that is a part of one’s body. Using the RHI paradigm, the present project aims to uncover the interactions between properties of visual, tactile, and proprioceptive signals and body ownership feelings emerging from their integration. The project attempts to verify and develop extant causal inference models which propose that RHI vividness depends on the degree to which sensory signals are spatiotemporally congruent, their precision, and individual propensity to combine them. A novel theoretical proposal, consisting of a hypothesis that two hitherto overlooked factors – spatiotemporal tactile complexity and the strength of prior relatedness of signals – play a key role, was put forward and empirically tested in the course of the project. The results demonstrate that body ownership is primarily determined by the structural correlation of visuo-tactile signals – application of spatiotemporally complex stimulation subverts the illusion-diminishing effect of divergence between visual and proprioceptive estimates of the hand’s location. Increased distance between hands leads to attenuation of RHI strength only when tactile information is absent or simplified. Individual proprioceptive precision, operationalized either as performance in active arm position reproduction or as performance in passive elbow joint’s angular position detection task, does not modulate observed effects. Obtained results suggest that proprioception may have a subsidiary role in determining body ownership feelings and thus extend contemporary understanding of body attribution processes. The project may also have significant practical implications for the rehabilitation programmes drawing upon virtual reality technology.

碩士
國立臺灣師範大學
美術學系在職進修碩士班
96
Abstract Keywords: reality, illusion, body, scenery The style of “Traveling around the edge of reality and illusion” has long been the author’s direction of creation. The present study aimed to describe the image of “body scenery”. There are countless bodies in the surface of this world. The author tried to point out the images of body from the natural scenery and to survey them from the aspect of cosmology. The body was regarded as a tiny universe which was explored the mutual relation to the giant universe. The author came back to her inner self to re-monitor herself so as to create art works in the most sincere manner. For ages, the author had been traveling constantly to seek the real freedom and release out of the fixed mode. Then, the author figured out fondly what she had been looking for was lingering about between reality and illusion. There were six chapters involved in the present study, each of which was summarized as follows: in the first chapter, the author indicated the motive and purpose of the present study as well as the research scale and method. The development of the topics, “traveling around the edge of reality and illusion” and “body scenery” were also precisely described in this chapter. The second chapter explained the support of the main thesis, which is based on creation theories. It started with reality and imagination, explored philosophically by traveling around illusion, and indicated the illusion shown in the virtual and real image in Asian and western cultures and in art. In the third chapter, the author treated, according to her own creation theory, the effect of the reality of mind thinking, the image of body scenery, the illusion of nature and female body and the philosophy of drawing creation on individual drawing. The forth chapter talked about the content and style of the author’s creation as well as the media and skills of her main creation. The fifth chapter was to read the works by analyzing and reading the illustrations with the paintings. The readers can realize the author’s reasons and intention while creating every single work. Finally, in the sixth chapter, the author reviewed the research process and gave suggestions for future studies.