Although virtual reality (VR) has many applications, only few studies have investigated user acceptance of this type of immersive technology. We propose an extended version of the Technology Acceptance Model (TAM) that addresses some aspects of VR. Our model includes variables from the TAM, user experience, variables specific to VR, and variables relating to user characteristics. This model was tested with 89 users who performed an aeronautical assembly task in VR. Results suggest that intention to use VR is positively influenced by perceived usefulness and negatively influenced by cybersickness. Hedonic quality-stimulation and personal innovativeness are predictors of perceived usefulness. Perceived ease of use does not have a significant impact on intention to use and it is only influenced by pragmatic quality. These findings have a number of implications regarding user acceptance of VR.

The commercialization of Head-Mounted Displays (HMDs) aimed at the general public has led several videogame and virtual reality companies to offer new modes for continuous travel, in addition to commonly implemented instantaneous travel modes such as the Teleporting metaphor. These new modes include the ArmSwinger metaphor, seen as “more natural.” Yet unlike Teleporting mode, ArmSwinger mode has so far not been studied. Our study was designed to fill this gap, by comparing the effects of these two travel modes implemented on an HTC Vive in terms of performance and user comfort. We collected two measures of performance (effectiveness and efficiency) and three measures of user comfort (cybersickness, user experience, and cognitive load). Results showed that (1) no significant difference was found in completion time between ArmSwinger mode and Teleporting mode, even if ArmSwinger mode seems more effective; (2) ArmSwinger mode caused more cybersickness than Teleporting mode in terms of nausea; (3) ArmSwinger mode produced a more negative user experience than the Teleporting mode in relation to appealingness qualities; and (4) ArmSwinger mode created a higher cognitive load than Teleporting mode in relation to the physical demand, effort, and frustration dimensions.

Over the past decade, many studies have examined the potential benefits of educational virtual environments (EVEs), either by comparing them with other media or by assessing the effects of their features on learning. Paradoxically, very few of them have explored the effects of stereoscopic versus nonstereoscopic displays on learning and/or the subjective experience provided in an EVE. Our study was designed to fill this gap, by comparing the effects of these two virtual reality modes in an interactive mechanics learning task. We collected measures of task effectiveness (success/failure and completion time), learning outcomes and subjective experience (user experience, flow, and immersion). Results showed that (1) users were more successful in the learning tasks in the stereoscopic condition, and (2) perceived affective quality, flow, and immersion were better in this condition.

Imagine you are facing a mirror, seeing at the same time both your real body and a virtual display of your brain in activity and perfectly superimposed to your real image “inside your real skull”. In this paper, we introduce a novel augmented reality paradigm called “Mind-Mirror” which enables the experience of seeing “through your own head”, visualizing your brain “in action and in situ”. Our approach relies on the use of a semi-transparent mirror positioned in front of a computer screen. A virtual brain is displayed on screen and automatically follows the head movements using an optical face-tracking system. The brain activity is extracted and processed in real-time with the help of an electroencephalography cap (EEG) worn by the user. A rear view is also proposed thanks to an additional webcam recording the rear of the user's head. The use of EEG classification techniques enables to test a Neurofeedback scenario in which the user can train and progressively learn how to control different mental states, such as “concentrated” versus “relaxed”. The results of a user study comparing a standard visualization used in Neurofeedback to our approach showed that the Mind-Mirror could be successfully used and that the participants have particularly appreciated its innovation and originality. We believe that, in addition to applications in Neurofeedback and Brain-Computer Interfaces, the Mind-Mirror could also be used as a novel visualization tool for education, training or entertainment applications.

The exchange of avatars, i.e. the actual fact of changing once avatar with another one, is a promising trend in multi-actor virtual environments. It provides new opportunities for users, such as controlling a different avatar for a specific action, retrieving knowledge belonging to a particular avatar, solving conflicts and deadlocks situations or even helping another user. Virtual Environments for Training are especially affected by this trend as a specific role derived from a scenario is usually assigned to a unique avatar. Despite the increasing use of avatar exchange, users' perception and understanding of this mechanism have not been studied. In this paper, we propose two complementary user-centered evaluations that aim at comparing several representations for the exchange of avatars; these are termed exchange metaphors. Our first experiment focuses on the perception of an exchange by a user who is not involved in the exchange, and the second experiment analyzes the perception of an exchange triggered by the user. Results show that the use of visual feedback globally aids better understanding of the exchange mechanism in both cases. Our first experiment suggests, however, that visual feedback is less efficient than a simple popup notification in terms of task duration. In addition, the second experiment shows that much simpler metaphors with no visual effect are generally preferred because of their efficiency.

Brain-Computer Interfaces (BCI) introduce a novel way of interacting with real and virtual environments by directly exploiting cerebral activity. However in most setups using a BCI, the user is explicitly asked to remain as motionless as possible, since muscular activity is commonly admitted to add noise and artifacts in brain electrical signals. Thus, as for today, people have been rarely let using other classical input devices such as mice or joysticks simultaneously to a BCI-based interaction. In this paper, we present an experimental study on the influence of manipulating an input device such as a standard computer mouse on the performance of a BCI system. We have designed a 2-class BCI which relies on Alpha brainwaves to discriminate between focused versus relaxed mental activities. The study uses a simple virtual environment inspired by the well-known Pac-Man videogame and based on BCI and mouse controls. The control of mental activity enables to eat pellets in a simple 2D virtual maze. Different levels of motor activity achieved with the mouse are progressively introduced in the gameplay: 1) no motor activity (control condition), 2) a semi-automatic motor activity, and 3) a highly-demanding motor activity. As expected the BCI performance was found to slightly decrease in presence of motor activity. However, we found that the BCI could still be successfully used in all conditions, and that relaxed versus focused mental activities could still be significantly discriminated even in presence of a highly-demanding mouse manipulation. These promising results pave the way to future experimental studies with more complex mental and motor activities, but also to novel 3D interaction paradigms that could mix BCI and other input devices for virtual reality and videogame applications.