Virtual Reality (VR) is finding its way into many domains, including healthcare. Therapists greatly benefit from having any scenario in VR at their disposal for exposure therapy. However, adapting the VR environment to the needs of the patient is time-consuming. Therefore, an intelligent decision support system that takes context information into account would be a big improvement for personalised VR therapy. In this paper, a semantic ontology is presented for modelling relevant concepts and relations in the context of anxiety therapy in VR. The necessary knowledge was collected through workshops with therapists, this resulted in a layered ontology. Furthermore, semantic reasoning through logical rules enables deduction of interesting high-level knowledge from low-level data. The presented ontology is a starting point for further research on intelligent adaptation algorithms for personalised VR exposure therapy. CCS CONCEPTS • Theory of computation → Semantics and reasoning; • Information systems → Expert systems; • General and reference → Design.

Computer interfaces have been diversifying: from mobile and wearable technologies to the human body as an interface. Moreover, new sensing possibilities have allowed input to interfaces to go beyond the traditional mouse-and keyboard. This has resulted in a shift from manifest to latent interactions, where interactions between the human and the computer are becoming less visible. Currently, there is no framework available that fully captures the complexity of the multidimensional, multimodal, often latent interactions with these constantly shifting interfaces. In this manuscript, the Human-Computer-Context Interaction (HCCI) framework is proposed. This framework defines 5 relevant interaction levels to be considered during user research in all stages of the new product development process in order to optimize user experience. More specifically, the interaction context is defined in terms of user-object, user-user, usercontent, user-platform and user-context interactions. The HCCI framework serves as a concrete tool to use in a new product development process by HCI researchers, designers, and developers and aims to be technology independent and future-proof. This framework is a preliminary suggestion to be matched against other innovation development projects and needs to be further validated.

The development of immersive technologies has brought with it the need to redefine the concept of quality of experience (QoE). Studies have explored QoE in virtual reality (VR) by adopting a top-down approach-these are solely based on existing frameworks and theory, and complemented with novel technical considerations. It can be argued that any QoE framework derived in this manner is limited, as its scope is fixed even prior to any data gathering process. To this end, the current study proposes a bottom-up approach, involving the user in the formulation of a broader QoE model. The repertory grid technique (RGT) was used to analyse and group 360 attributes, listed by participants as criteria they used in judging the quality of a VR experience. The advantage of RGT is that it has a holistic approach towards the interpretation of the user's experience combined with the precision of quantitative analysis. The study resulted in a QoE model that consists of three main groups of attributes (i.e., user, content, and system). Furthermore, the analysis showed that participants listed attributes related to their experience and appraisal of VR, and to the content that they viewed. In contrast, very few system-related attributes were mentioned. Finally, the current study discussed the RGT methodology-and user-driven approaches in general-as a complementary research approach to create a comprehensive and practical QoE model.

Straight cuts are a storytelling tool that is used to direct the viewer's attention towards the main events of the plot. This research evaluated the effect of frequency of straight cuts that are controlled by the system (rather than by the viewer) on the viewer's experience of VR (i.e., presence, narrative immersion, sense of agency, simulator sickness, and enjoyment). We used both quantitative and qualitative methods to examine the viewer's experience and understanding of a one-minute long VR movie in three versions (i.e., 15 cuts/minute; 8 cuts/minute; no cuts). The study illustrates that sense of agency, enjoyment, and understanding of the story are influenced by the frequency of straight cuts. Also, straight cuts focus viewers on events in the story, which in turn helps them understand the plot better. However, we need a balanced frequency of cuts to preserve the sense of agency of users. Finally, the study highlights that the viewers' experience is a result of an interplay between narrative immersion, sense of agency, and presence.

Virtual reality exposure therapy (VRET) has been widely acknowledged as an effective alternative for in vivo exposure therapy (iVET). So far, previous research focused on long- and short-term effectiveness and comparisons to iVET, whereas the impact of design choices is understudied. Hence, the present study focuses on the effectiveness of several types of anxiety cues for the manipulation of anxiety. More specifically, five interoceptive cues (i.e., “fake” bodily sensations for tunnel vision, light flickering, heartbeat audio, blurred vision, and dizziness) and a physical cue (i.e., heat stimulation) are implemented in the VRET design of a within-subjects experiment with people who have claustrophobic and panic tendencies (N = 24). Results show that adding interoceptive cues significantly increased reported levels of anxiety, independent of the type of interoceptive cue. However, introducing a physical cue in VRET can also be effective but has no real added value when combined. Studies focusing on the design of anxiety cues can be valuable in understanding the effectiveness of VRET.

In this paper we assess the impact of head movement on user's visual acuity and their quality perception of impaired images. There are physical limitations on the amount of visual information a person can perceive and physical limitations regarding the speed at which our body, and as a consequence our head, can explore a scene. In these limitations lie fundamental solutions for the communication of multimedia systems. As such, subjects were asked to evaluate the perceptual quality of static images presented on a TV screen while their head was in a dynamic (moving) state. The idea is potentially applicable to virtual reality applications and therefore, we also measured the image quality perception of each subject on a head mounted display. Experiments show the significant decrease in visual acuity and quality perception when the user's head is not static, and give an indication on how much the quality can be reduced without the user noticing any impairments.