Now You’re Thinking with Portals: Investigating Episodic Memory and Locomotion with Redirected Walking in Impossible Spaces

Natural walking locomotion in virtual reality (VR) allows intuitive movement through a virtual environment (VE), lower rates of simulator sickness, and increased immersion. However, it is limited by available play-space. Impossible spaces are VEs that use self-overlapping geometry to imitate larger play-spaces within a smaller area. Understanding how users interact with impossible spaces requires understanding how they perceive and remember VEs. However, it is unknown how impossible spaces impact users’ memory. An experiment was conducted comparing 32 participants’ memory from two conditions: natural walking in an impossible space and joystick movement in a similar non-impossible space. Participants were given up to 20 min to explore a virtual museum and were not instructed on what to remember. The experience was designed to allow participants to freely explore the VE at their own pace, allowing engagement duration to vary naturally. No significant differences were found between conditions for object or spatial memory; however, participants in the natural walking condition spent more time in the environment, revisited more areas, and were more confident identifying objects not encountered in the VE. This suggests natural walking in impossible spaces may be a viable alternative to traditional locomotion techniques.