What we've learned about Presence in Virtual Environments


Frederick P. Brooks, Jr.

Department of Computer Science

University of North Carolina



Abstract:  The UNC-Chapel Hill Effective Virtual Environments project, funded partly by the ONR Virte program, and partly by NIH, has undertaken to study the properties and parameters of virtual environments quantitatively and experimentally.


First, we had to develop an objective, valid, reliable, and sensitive measure of effectiveness.  We adapted an environment from Slater, et  al, at University College London, that corresponds to a  stress-producing real environment. Meehan showed that change in heart rate as one transitions from a low-stress VE into a high-stress one is a suitable surrogate for presence and a measure of effectiveness.


So far we (that is, the graduate students of Mary Whitton and me) have established or confirmed that:


1.  Walking-in-place makes a more effective VE interaction mode than flying, and there is strong evidence that real walking is better yet. [Usoh]


2.  Wider field of view produces both to better sense of presence and better performance in spatial tasks. [Arthur]


3.  Provision of even primitive passive haptic cues enhances presence and enhances maze-learning performance. [Insko]


4.  Natural interaction with real objects (as opposed to virtual models) improves performance in a manual spatial arrangement task. It does not seem to enhance presence. [Lok]


5.  Users walking in both HMD and cave VEs can be imperceptibly rotated so that their virtual travel domains are substantially larger than the real tracked areas.  [Razzaque]



6.  End-to-end system latency really matters for HMD systems, even at quite good latencies.  To be precise, presence is significantly enhanced in an immersive VE  with 50 ms delays over that same system with 90 ms delays. [Razzaque and Meehan]


7.  A pilot study showed little difference in presence between users in a VE with complex geometry, exposed to a visually faithful VE, a VE of limited visual fidelity, and a VE with arbitrary texturing and no illumination. [Zimmons]





Brief Biography:


Fred Brooks is Kenan Professor of Computer Science at the University of North Carolina at Chapel Hill.  He has a B.A. in physics from Duke and S.M. and Ph.D. in computer science at Harvard under Howard Aiken.


He joined IBM upon graduation and was one of the architects of the IBM Stretch and Harvest computers.  From 1961-65 he was Corporate Project Manager for the System/360, including development of the System/360 computer family hardware, and the Operating System/360 software.  For this work he shared the 1985 National Medal of Technology with Bob Evans and Erich Bloch.


He joined UNC in 1964, where he founded the Department of Computer Science and chaired it for its first 20 years.  His research has been in computer architecture, software engineering, and interactive 3-D computer graphics ("virtual reality"). His best-known book is The Mythical Man-Month: Essays on Software Engineering  (1975, 1995); his latest is Blaauw and Brooks, Computer Architecture: Concepts and Evolution, (1997).


Dr. Brooks has served on the National Science Board and the Defense Science Board.  He is a member of the National Academy of Engineering, National Academy of Sciences, the Royal Academy of Engineering (UK), the Royal Netherlands Academy of Arts and Sciences, and the American Academy of Arts and Sciences.  His career work has been recognized by the A.M. Turing Award of the Association for Computing  Machinery, the Bower Science Award of the Franklin Institute,  and the John von Neumann Medal of the Institute of Electrical and Electronic Engineers.


He became a Christian at age 31.  He and Mrs. Brooks are faculty advisors for a graduate-student chapter of InterVarsity Christian Fellowship.