Ronan Boulic

Related publications (176)

Cybersickness assessment framework(CSAF): An Open Source Repository for Standardized Cybersickness Experiments

Ronan Boulic, Nana Tian, Adriano Viegas Milani

Studies of cybersickness (CS) often require a significant invest- ment in creating the primary VR environment and other experiment- related features. In addition, minor differences in VR content in independent studies may lead to opposite results. This motivates us to introduce a standardized CS assessment framework to facilitate the development of CS-related experiments. This paper describes the concept of the framework, the current progress of the technical implementation, and future goals

IEEE2023

EEG signature of breaks in embodiment in VR

Olaf Blanke, Ronan Boulic, Ricardo Andres Chavarriaga Lozano, Bruno Herbelin, Fumiaki Iwane

The brain mechanism of embodiment in a virtual body has grown a scientific interest recently, with a particular focus on providing optimal virtual reality (VR) experiences. Disruptions from an embodied state to a less- or non-embodied state, denominated Breaks in Embodiment (BiE), are however rarely studied despite their importance for designing interactions in VR. Here we use electroencephalography (EEG) to monitor the brain’s reaction to a BiE, and investigate how this reaction depends on previous embodiment conditions. The experimental protocol consisted of two sequential steps; an induction step where participants were either embodied or non-embodied in an avatar, and a monitoring step where, in some cases, participants saw the avatar’s hand move while their hand remained still. Our results show the occurrence of error-related potentials linked to observation of the BiE event in the monitoring step. Importantly, this EEG signature shows amplified potentials following the non-embodied condition, which is indicative of an accumulation of errors across steps. These results provide neurophysiological indications on how progressive disruptions impact the expectation of embodiment for a virtual body.

2023

EGG Objective characterization of cybersickness symptoms towards navigation axis

Khalil Haroun Achache, Ali Raed Ben Mustapha, Ronan Boulic, Nana Tian

The current study sought to objectively evaluate cybersickness by utilizing Electrogastrogram (EGG) physiological data in relation to three different navigation axes: Translational movement along the longitudinal and lateral axes, and rotation along the vertical Yaw axis. EGG was employed as it has been clinically identified as a valuable tool for capturing dysfunction in the stomach. This resulted in a 2x2x2 factorial design. Results from both subjective and objective measurements (N=26, F=10) indicate that rotation along the Yaw axis is the primary factor influencing cybersickness. Additionally, it was found that individuals who are not susceptible to cybersickness do not exhibit any dominant factors. In summary, through the analysis of EGG data, several key physi- ological indicators of individual susceptibility to cybersickness were identified. The findings suggest that there is a positive correlation between the mean dominant frequency and the tachygastria ratio with individual susceptibility, while the normalgastria and normal- tachy ratio were found to be negatively correlated with individual susceptibility

IEEE2023

A review of cybersickness in head‐mounted displays: raising attention to individual susceptibility

Ronan Boulic, Nana Tian

Cybersickness still poses a significant challenge to the widespread usage of virtual reality, leading to different levels of dis- comfort and potentially breaking the immersive experience. Researchers have attempted to discover the possible fundamental causes of cybersickness for years. Despite the longstanding interest in the research field, inconsistent results have been drawn on the contributing factors and solutions to combating cybersickness. Moreover, little attention has been paid to individual susceptibility. A consolidated explanation remains under development, requiring more empirical studies with robust and reproducible methodologies. This review presents an integrated survey connecting the findings from previous review papers and the state of the art involving empirical studies and participants. A literature review is then presented, focusing on the practical studies of different contributing factors, the pros and cons of measurements, profiles of cybersickness, and solutions to reduce this phenomenon. Our findings suggest a lack of considerations regarding user susceptibility and gender balance in between groups studies. In addition, incongruities among empirical findings raised concerns. We conclude by suggesting points of insights for future empirical investigations.

2022

Changing Finger Movement Perception: Influence of Active Haptics on Visual Dominance

Loën Boban, Ronan Boulic, Bruno Herbelin

The perception of one’s own body is a complex mechanism that can be disturbed by conflicting sensory information and lead to illusory (mis-) perceptions. Prominent models of multisensory integration propose that sensory streams are integrated according to their reliability by approximating Bayesian inference. As such, when considering self-attribution of seen motor actions, previous works argue in favor of visual dominance over other sensations, and internal cues. In the present work, we use virtual reality and a haptic glove to investigate the influence of an active haptic feedback on one’s visual and agency judgments over a performed finger action under experimentally manipulated visual and haptic feedbacks. Data overall confirm that vision dominates for agency judgment in conditions of multisensory conflict. Interestingly, we also show that participants’ visual judgment over their finger action is sensitive to multisensory conflicts (vision, proprioception, motor afferent signals, and haptic perception), thus bringing an important nuance to the widely accepted view on a general visual dominance.

2022

Reaching articular limits can negatively impact embodiment in virtual reality

Olaf Blanke, Ronan Boulic, Bruno Herbelin

Providing Virtual Reality(VR) users with a 3D representation of their body complements the experience of immersion and presence in the virtual world with the experience of being physically located and more personally involved. A full-body avatar representation is known to induce a Sense of Embodiment (SoE) for this virtual body, which is associated with improvements in task performance, motivation and motor learning. Recent experimental research on embodiment provides useful guidelines, indicating the extent of discrepancy tolerated by users and, conversely, the limits and disruptive events that lead to a break in embodiment (BiE). Based on previous works on the limit of agency under movement distortion, this paper describes, studies and analyses the impact of a very common yet overlooked embodiment limitation linked to articular limits when performing a reaching movement. We demonstrate that perceiving the articular limit when fully extending the arm provides users with an additional internal proprioceptive feedback which, if not matched in the avatar’s movement, leads to the disruptive realization of an incorrect posture mapping. This study complements previous works on self-contact and visuo-haptic conflicts and emphasizes the risk of disrupting the SoE when distorting users’ movements or using a poorly-calibrated avatar.

2022

Adapting Virtual Embodiment through Reinforcement Learning

Olaf Blanke, Ronan Boulic, Bruno Herbelin, Yawen Hou

In Virtual Reality, having a virtual body opens a wide range of possibilities as the participant's avatar can appear to be quite different from oneself for the sake of the targeted application (e.g. for perspective-taking). In addition, the system can partially manipulate the displayed avatar movement through some distortion to make the overall experience more enjoyable and effective (e.g. training, exercising, rehabilitation). Despite its potential, an excessive distortion may become noticeable and break the feeling of being embodied into the avatar. Past researches have shown that individuals have a relatively high tolerance to movement distortions and a great variability of individual sensitivities to distortions. In this paper, we propose a method taking advantage of Reinforcement Learning (RL) to efficiently identify the magnitude of the maximum distortion that does not get noticed by an individual (further noted the detection threshold). We show through a controlled experiment with subjects that the RL method finds a more robust detection threshold compared to the adaptive staircase method, i.e. it is more able to prevent subjects from detecting the distortion when its amplitude is equal or below the threshold. Finally, the associated majority voting system makes the RL method able to handle more noise within the forced choices input than adaptive staircase. This last feature is essential for future use with physiological signals as these latter are even more susceptible to noise. It would then allow to calibrate embodiment individually to increase the effectiveness of the proposed interactions.

2021

On the Importance of Providing a Tangible Haptic Response for Training Cardiopulmonary Resuscitation in Virtual Reality

Ronan Boulic, Mathias Guy Delahaye, Bruno Herbelin

The current approach to train Cardiopulmonary Resuscitation (CPR) is to employ a mannequin device replicating the physical properties of a real human head and torso. This aims to ensure a correct transfer of the cardiac massage location, amplitude and frequency in a real situation. However, this type of training does not replicate the stress that may be elicited in the presence of a real victim ; this may result in reduced CPR performances or even errors. Virtual Reality (VR) may alleviate this lack by adding visual immersion with a Head-Mounted Display (HMD) so that the trainee is cut from the potential distractions of the real surrounding and can fully engage in a more faithful training scenario. However, one must ensure in the first place that using this technology maintains the quality of the CPR. Hence, we have conducted an experimental study to evaluate the potential of visual immersion in such a training context (limited to the cardiac massage). One important requirement was to ensure a correct hand tracking while executing the standard CPR two-hands pose. In the present paper we describe first how we assessed a simple approach using two HTC-Vive trackers. Results show that the proposed minimal setup based on a single hand tracking is validated for frequency and, with correction, for amplitude. Then, to assess the quality of the training, we performed an evaluation study considering the following two factors: Haptic feedback with the mannequin device (with/out) and Real-time Performance feedback (with/out) in the HMD. We observed that the visually immersive experience proposed in this paper delivers a sufficient level of spatial presence, involvement and agency. Integrating the real CPR mannequin in VR has a significantly positive impact on the massage performance quality whereas displaying the real-time performance in the virtual environment tends to be only useful for the frequency when no mannequin is used.

The Eurographics Association2021

Does scaling player size skew one’s ability to correctly evaluate object sizes in a virtual environment?

Ronan Boulic, Mathias Guy Delahaye, Bruno Herbelin

This paper presents the results of a study performed in order to evaluate whether a navigation technique, based on scaling the user’s avatar, impacts the user’s ability to correctly assess the size of virtual objects in a virtual environment. This study was realized during the CERN Open Days with data from 177 participants over eighteen years old. It allowed us to observe well-established phenomena, such as the impact of gender on susceptibility to motionsickness, as well as original results associated with scaling factor and avatar embodiment. We observed that the user is more prone to overestimate object sizes from the Virtual Environment when provided with an avatar, while scaling the Inter-Pupillary Distance according to the scale of the user contributes to a reduction in the overestimation of object sizes within the Virtual Environment.

Association for Computing Machinery2020

Exploring Blink-Rate Behaviors for Cybersickness Detection in VR

Ronan Boulic, Nana Tian

Cybersickness continues to be one of the main barriers for mainstream adoption of Virtual Reality (VR). Despite the wealth of research available on this topic, it is still an unsolved problem. This paper explores the potential influence of cybersickness over the course of a VR experience on player Blink-Rate. This investigation was conducted on the same VR task with two diverging control schemes with a low or high risk of inducing cybersickness. A total of 34 participant data was collected from two separate playing sessions. Although no significant differences were observed, sick individuals showed to have a higher blink-rate frequency over the course of the VR experience while non-sick individuals presented a more stable blink-rate frequency.

IEEE2020