Shaping Interaction in Virtual Reality Experiences for Access, Agency and Effects

Virtual Reality (VR) is now widely used across domains including entertainment, training, education, and healthcare, although its underlying concepts have also been explored in fields such as art and literature. Its value lies in its ability to reproduce physical-world locations, create environments that cannot be directly experienced in the physical world, represent phenomena that are otherwise inaccessible, and enable users to act and behave in ways that may not be possible outside immersive environments. In this sense, VR is not only a technological medium, but also a means of investigating how human perception, action, and experience are shaped within immersive environments. Interaction is a central aspect of VR, enabling users to influence and modify virtual environments in real time. However, the relationship between users and virtual environments is reciprocal: while users act upon the environment, they are also influenced by the environment and by the ways in which they interact with it. Existing definitions and approaches to interaction often emphasize its technological dimension, focusing on how users modify or control the virtual environment, while giving less attention to how interaction may shape users perceptions, experiences, and behavioral outcomes. This thesis approaches interaction within a broader conceptual framework based on two complementary perspectives. On the one hand, interaction is considered a technological component that enables users to modify the virtual environment through specific actions. On the other hand, it is considered an enabling condition for subjective responses and behavioral outcomes. Within this framework, interaction is examined in relation to three interconnected dimensions: access, concerning who can access and participate in the experience; agency, concerning what users can do within the virtual environment; and effects, concerning what the experience may foster in users. Building on this framework, the thesis addresses two broader questions: how VR experiences can be designed to enable access and participation for users with diverse needs, and what role interaction plays in experiential training scenarios, particularly in fostering learning, familiarization, and awareness. These questions define two main research themes: accessibilityoriented interaction design and the role of interaction in experiential training. They are investigated through a set of projects employing complementary qualitative and quantitative methods. The studies presented in this thesis show how interaction and action within virtual environments can contribute to a range of outcomes, including learning, emotional responses, familiarization, and awareness. The findings further illustrate how interaction can influence not only what users are able to do within a virtual environment, but also how they experience and respond to it. Across applications ranging from accessibility-oriented interaction design to experiential training and climate-change awareness, the thesis therefore conceptualizes immersive application design as the design of a reciprocal relationship between users and virtual environments. Within this relationship, interaction functions as a mechanism through which VR can enable access, agency, and effects