Thesis defence : Marion GIROUX

Kinaesthesia is the conscious perception of the movements of different parts of one's own body in space. It results from the integration of multiple sensory signals such as visual, proprioceptive, or tactile signals. Multisensory integration would depend on three congruencies : temporal, spatial and semantic congruencies. For the integration to be optimal, the different sensory signals should occur at the same time, at the same place and be semantically associated. The main objective of this work was to study the sensory integration mechanisms involved in kinaesthesia using artificial signals. To this end, we investigated the extent to which artificial sensory signals could take part in kinaesthesia depending on their degree of congruency with natural signals, thus generating situations that could not be produced with natural signals alone.We adapted the mirror paradigm to virtual reality, substituting the natural visual signals (i.e., the arm reflection in the mirror) with artificial signals (i.e., avatar’s arms). This implementation of the mirror paradigm in virtual reality allowed us to manipulate different degrees of semantic incongruency (morphological dissimilarity between avatar and real body) or spatial incongruency (perspective from which the avatar is seen) between visual stimuli coming from the avatar and non-visual stimuli (especially proprioceptive) coming from the participant's body. Overall, our results showed that semantic or spatial incongruencies did not prevent the contribution (and thus the integration) of visual information from the avatar to the kinaesthetic percept, even when the level of incongruency was high (e.g., avatar's arms represented by three dots; third-person perspective). However, this contribution was reduced as the level of incongruency increased, with visual information having less weight in the kinaesthetic (multisensory) percept as incongruency increased (Articles 1-3).In this work we also explored the hypothesis that only visual signals coming from the participant's own body or from any embodied object could be considered for kinaesthetic purposes. This hypothesis is partially validated by a cross-sectional analysis of the results of the five experiments in Articles 2, 3, and 4, showing a positive relationship between the level of embodiment of the avatar and the intensity of kinaesthetic illusions as assessed by subjective measures of speed and duration of illusions. However, the dedicated study (Article 4), aimed at experimentally manipulating the level of avatar embodiment, did not provide evidence for such a link.Finally, we also tested whether an auditory stimulus generated by sonification of movements could contribute to kinaesthesia, in the absence of vision. In this study (Article 5), auditory information previously associated with movements was not effective in generating illusions of movement.Overall, the results obtained demonstrated the contribution of artificial visual stimuli to kinaesthesia. Moreover, they indicate that this contribution varies according to the degree of semantic and spatial congruency between artificial and natural stimuli.

Encadrants :
- Directeur de thèse : Michel GUERRAZ - Michel.Guerrazuniv-smb.fr (Michel[dot]Guerraz[at]univ-smb[dot]fr)
- Codirecteur : Christian GRAFF - christian.graffuniv-grenoble-alpes.fr (christian[dot]graff[at]univ-grenoble-alpes[dot]fr)
- Co-encadrant : Julien BARRA -julien.barrauniv-smb.fr (ulien[dot]barra[at]univ-smb[dot]fr)

Mots-clés de la thèse : Kinesthésie, Proprioception,  Sonification du mouvement, Audition, Vision, Réalité virtuelle,