Tej Tadi

Video ergo sum: Manipulating bodily self-consciousness

Humans normally experience the conscious self as localized within their bodily borders. This spatial unity may break down in certain neurological conditions such as out-of-body experiences, leading to a striking disturbance of bodily self-consciousness. On the basis of these clinical data, we designed an experiment that uses conflicting visual-somatosensory input in virtual reality to disrupt the spatial unity between the self and the body. We found that during multisensory conflict, participants felt as if a virtual body seen in front of them was their own body and mislocalized themselves toward the virtual body, to a position outside their bodily borders. Our results indicate that spatial unity and bodily self-consciousness can be studied experimentally and are based on multisensory and cognitive processing of bodily information.

The limits of agency in walking humans

An important principle of human ethics is that individuals are not responsible for actions performed when unconscious. Recent research found that the generation of an action and the building of a conscious experience of that action (agency) are distinct processes and crucial mechanisms for self-consciousness. Yet, previous agency studies have focussed on actions of a finger or hand. Here, we investigate how agents consciously monitor actions of the entire body in space during locomotion. This was motivated by previous work revealing that (1) a fundamental aspect of self-consciousness concerns a single and coherent representation of the entire spatially situated body and (2) clinical instances of human behaviour without consciousness occur in rare neurological conditions such as sleepwalking or epileptic nocturnal wandering. Merging techniques from virtual reality, full-body tracking, and cognitive science of conscious action monitoring, we report experimental data about consciousness during locomotion in healthy participants. We find that agents consciously monitor the location of their entire body and its locomotion only with low precision and report that while precision remains low it can be systematically modulated in several experimental conditions. This shows that conscious action monitoring in locomoting agents can be studied in a fine-grained manner. We argue that the study of the mechanisms of agency for a persons full body may help to refine our scientific criteria of self-hood and discuss sleepwalking and related conditions as alterations in neural systems encoding motor awareness in walking humans.

Quantifying Effects of Exposure to the Third and First-Person Perspectives in Virtual-Reality-Based Training

In the recent years, usage of the third-person perspective (3PP) in virtual training methods has become increasingly viable and despite the growing interest in virtual reality and graphics underlying third-person perspective usage, not many studies have systematically looked at the dynamics and differences between the third and first-person perspectives (1PPs). The current study was designed to quantify the differences between the effects induced by training participants to the third-person and first-person perspectives in a ball catching task. Our results show that for a certain trajectory of the stimulus, the performance of the participants post3PP training is similar to their performance postnormal perspective training. Performance post1PP training varies significantly from both 3PP and the normal perspective.

Neurogoggles for Multimodal Augmented Reality

We present a neurogoggles system that offers truly immersive augmented and virtual reality with unique biofeedback based on brain and bodily signals. The system consists of a wearable head-mounted display that integrates two stereoscopic color cameras for video-through experience, a depth sensor for object tracking, an inertial sensor for head tracking and electrophysiological measurements for brain and bodily signals. The system is designed to ensure low-latency synchronization across all functional modules, which is a key element for multimodal real-time data analysis. We showcase this technology with an immersive experience combining multimodal data and artistic digital content using Kudan augmented reality engine. In this experience, the user is presented with an interactive world behind a brain image wall poster, which reacts to users brain state.

The Architectonic Experience of Body and Space in Augmented Interiors

The environment shapes our experience of space in constant interaction with the body. Architectonic interiors amplify the perception of space through the bodily senses; an effect also known as embodiment. The interaction of the bodily senses with the space surrounding the body can be tested experimentally through the manipulation of multisensory stimulation and measured via a range of behaviors related to bodily self-consciousness. Many studies have used Virtual Reality to show that visuotactile conflicts mediated via a virtual body or avatar can disrupt the unified subjective experience of the body and self. In the full-body illusion paradigm, participants feel as if the avatar was their body (ownership, self-identification) and they shift their center of awareness toward the position of the avatar (self-location). However, the influence of non-bodily spatial cues around the body on embodiment remains unclear, and data about the impact of architectonic space on human perception and self-conscious states are sparse. We placed participants into a Virtual Reality arena, where large and narrow virtual interiors were displayed with and without an avatar. We then applied synchronous or asynchronous visuotactile strokes to the back of the participants and avatar, or, to the front wall of the void interiors. During conditions of illusory self-identification with the avatar, participants reported sensations of containment, drift, and touch with the architectonic environment. The absence of the avatar suppressed such feelings, yet, in the large space, we found an effect of continuity between the physical and the virtual interior depending on the full-body illusion. We discuss subjective feelings evoked by architecture and compare the full-body illusion in augmented interiors to architectonic embodiment. A relevant outcome of this study is the potential to dissociate the egocentric, first-person view from the physical point of view through augmented architectonic space.

Brain activity underlying third person and first person perspective training in virtual environments

Over the years, different approaches have been explored to build effective learning methods in virtual reality but the design of effective 3D manipulation techniques still remains an important research problem. To this end, it is important to quantify behavioral and brain mechanisms underlying the geometrical mappings of the body with the environment and external objects, both within the virtual environments (VE), the real world and relative to each other. The successful mapping of such interactions entails the study of fundamental components of these interactions, such as the origin of the visuo-spatial perspective (1PP, 3PP) and how they contribute to the users performance in the virtual environments. Here, we report data using a novel set-up exposing participants - during free navigation - with a scene view from either 3PP or the habitual first-person perspective (1PP).