In today's society, our cognition is constantly influenced by information intake, attention switching, and task interruptions. Together with the collected data sets, this thesis paves the way for methodical and technical tools that integrate workload-awareness as a factor for context-aware systems. Previous interfaces were limited in their ability to utilize cognitive workload for user interaction. Finally, we present our vision of future workload-aware interfaces. In the end, we present applications that regulate cognitive workload in home and work setting, investigate how cognitive workload can be visualized to the user, and show how cognitive workload measurements can be used to predict the efficiency of information intake through reading interfaces. We show that electroencephalography and eye tracking are reliable modalities to assess mental workload during user interface operation. We provide evidence that the human brain and eye gaze are sensitive to fluctuations in cognitive resting states. We then investigate different physiological sensing modalities to enable suitable real-time assessments of cognitive workload. Subsequently, we investigate suitable feedback modalities in a user-centric design process which are desirable for cognitive assistance. We predict that recent developments in physiological sensing will increasingly create user interfaces that are aware of the user's cognitive capacities, hence able to intervene when high or low states of cognitive workload are detected. This temporarily mobilizes additional resources to deal with the workload at the cost of accelerated mental exhaustion.

The human body expresses the use of cognitive resources through physiological responses when confronted with a plethora of cognitive workload. This increases the difficulty of a given task, adding to the existing workload and leading to compromised cognitive performances. Our findings can be used to design experiences based on shifts of perception.

Statistical analysis of the empirical results shows the existence of a perspective continuum in VR. In a study, we explore users' attitudes, experiences and perceptions while controlling a virtual character from the two known perspectives. This flexibility of perspectives broadens the design space of VR experiences through deliberately manipulating perception. A perspective continuum enables adapting and manipulating the sense of agency and involvement in the virtual world. We introduce the notion of a perspective continuum in VR, which is technically related to the camera position and conceptually to how users perceive their environment in VR. Yet, Virtual Reality (VR) allows for flexibility in choosing perspectives. Traditionally, FPP and TPP perspectives are seen as distinct concepts. Modern games make creative use of First-and Third-person perspectives (FPP and TPP) to allow the player to explore virtual worlds. In all other cases, a first-person perspective is still better suited for navigation tasks, regardless of representation. Our results show that only when a third-person perspective is coupled with a realistic representation, a similar sense of embodiment and spatial awareness is felt. For each perspective, we also compare three different levels of realism for users' representation, specifically a stylized abstract avatar, a mesh-based generic human, and a real-time point-cloud rendering of the users' own body. In this paper, we investigate, through a user evaluation, how these perspectives affect task performance and embodiment, focusing on navigation tasks, namely walking while avoiding obstacles. However, due to its unnaturality, we argue that a third-person perspective is not as effective or convenient as a first-person view for task execution in VR. On the other hand, recent user studies show a penchant towards a third-person view of one's own body to seemingly improve spatial awareness. Indeed, researchers have shown that users' feeling of presence and spatial awareness are highly influenced by their virtual representations, and that self-embodied representations (avatars) of their anatomy can make the experience more engaging.

This can make self-awareness problematic. They do this by totally occluding the physical world, including users' bodies. Head-Mounted Displays are useful to place users in virtual reality (VR).

Third person the visitor walkthrough