This is the final report detailing the research conducted during a three-year project funded by the HP Laboratories External Research Program (1997-2000) in collaboration with the Department of Computer Science, University of Bristol, UK. The project's initial goals were centred on the investigation of human factors issues related to interacting with distributed computer graphics worlds in real-time over a network. These objectives were extended and focused on fidelity metrics for computer graphics simulations displayed on Head Mounted Displays. Theories from cognitive psychology were employed to devise these metrics which were, subsequently, validated by formally designed experiments involving human judgements of spatial memory awareness states. Notes: Katerina Mania, Dept of Informatics, University of Sussex, Falmer, Brighton, BN1 9QT UK 27 Pages