Sciences cognitives | EPFL Graph Search

thumb|283x283px|Les six disciplines scientifiques constituant les sciences cognitives et leurs liens interdisciplinaires, par l'un des pères fondateurs du domaine, G. A. Miller. Les traits pleins symbolisent les disciplines entre lesquelles existaient déjà des liens scientifiques à la naissance des sciences cognitives ; en pointillés, les disciplines entre lesquelles des interfaces se sont développées depuis lors. Les sciences cognitives constituent une discipline scientifique ayant pour objet la description, l'explication, et le cas échéant la simulation des mécanismes de la pensée humaine, animale ou artificielle, et plus généralement de tout système complexe de traitement de l'information capable d'acquérir, conserver, utiliser et transmettre des connaissances. Les sciences cognitives reposent sur l'étude et la modélisation de phénomènes aussi divers que la perception, l'intelligence, le langage, la mémoire, l'attention, le raisonnement, les émotions, l'esprit ou même la conscienc

Context effects on probability estimation

Wei-Hsiang Lin

Many decisions rely on how we evaluate potential outcomes and estimate their corresponding probabilities of occurrence. Outcome evaluation is subjective because it requires consulting internal preferences and is sensitive to context. In contrast, probability estimation requires extracting statistics from the environment and therefore imposes unique challenges to the decision maker. Here, we show that probability estimation, like outcome evaluation, is subject to context effects that bias probability estimates away from other events present in the same context. However, unlike valuation, these context effects appeared to be scaled by estimated uncertainty, which is largest at intermediate probabilities. Blood-oxygen-level-dependent (BOLD) imaging showed that patterns of multivoxel activity in the dorsal anterior cingulate cortex (dACC), ventromedial prefrontal cortex (VMPFC), and intraparietal sulcus (IPS) predicted individual differences in context effects on probability estimates. These results establish VMPFC as the neurocomputational substrate shared between valuation and probability estimation and highlight the additional involvement of dACC and IPS that can be uniquely attributed to probability estimation. Because probability estimation is a required component of computational accounts from sensory inference to higher cognition, the context effects found here may affect a wide array of cognitive computations.

PUBLIC LIBRARY SCIENCE2020

Preventing Breaks in Embodiment in Immersive Virtual Reality

Thibault Serge Mario Porssut

Virtual reality (VR) is immersive not only because of visual integration, but because we can act and perform in a virtual environment (VE). Beyond the mere fact that a VR system provides images computed directly from the users' viewpoint in stereoscopy, it can also provide a natural way to interact within the VE using the entire body. Full-body motion capture allows the user's movement to be mapped to a virtual body. Such a mapping may let users feel in control of (sense of agency), own (sense of body ownership) and locate themselves inside this virtual body (sense of self-location), thus leading them to feel embodied in this virtual body whenever these conditions are met (sense of embodiment (SoE)). Hence the integration of a full body avatar in VR is essential, as it brings even more; experiencing being someone else, train to recover mobility or having superhuman abilities. Most importantly, the avatar mediates the virtual nature of the VE to make it seamless for the user. Thus, this thesis focuses on helping the users execute complex movements in VR by applying a distortion to their movements. However, such a distortion is efficient only if users, when assisted, do not experience a break in embodiment (BiE), i.e., do not abruptly lose their sense of embodiment. Moreover, the way the virtual body is perceived is not consistent between users and some users might accept or reject a virtual body more easily than others. Therefore, this thesis explores how to prevent a BiE while distorting users' movement and adapting the VR experience to each individual. To this end, we designed a system combining brain-computer interface and machine learning to detect when users experience a BiE, compute users' preferences, and adapt the VR application's parameters. We first identified the user`s threshold for perceiving a movement distortion in some critical contexts, such as articular limits. We designed a new distortion to help users execute a complex movement. We introduced a method based on machine learning to find users' preferences when using our new distortion. We also established a link between the brain's error monitoring mechanism and the cognitive process of embodiment. This link exposed a new implicit EEG marker indicating when users experience a BiE. Finally, we designed a system to calibrate the distortion implicitly based on users' preferences with all these elements. This system first consists of detecting a BiE during a continuous movement thanks to state-of-the-art brain-computer interface algorithms. Our machine learning method then computes users' preferences, and the distortion is adapted dynamically. This original approach demonstrates the use of an implicit feedback loop to help users while preventing any BiE. Our framework opens an exciting perspective for personalized and self-adapting embodiment systems.

EPFL2021

Neural Mechanisms of the Embodied Self

Ravi Tej Sai Giridhar Tadi

What is it like to have a body? The unitary experience of the self and the body accompanied by unambiguous self-location and egocentric visuo-spatial perspective are essential aspects of the embodied self. They play a vital role for dynamic whole body human perception and interactions in our daily lives and help distinguish our body from others and the environment. In the current thesis, we used an amalgam of virtual reality techniques and cognitive neuroscience methods in combination with electrical neuroimaging to investigate multisensory, sensorimotor, and cognitive processes involved in mental own body imagery, visuo-spatial perspective taking, the feeling of ownership and agency and their contribution to different aspects of the bodily self and bodily processing.

EPFL2011

Preventing Breaks in Embodiment in Immersive Virtual Reality

Thibault Serge Mario Porssut

EPFL2021