From: Martine Wedlake Subject: HUMAN-FACTORS: Pyschological Effects of latents in VE's Date: Thu, 10 Apr 1997 10:25:36 -0700 Message-ID: <334D2290.2EB3@informix.com> Organization: INFORMIX Software, Inc. My formal background is a mixture of hardware and software, but precious little human factors (and psychology). I'm interested in getting some pointers regarding the psychological effects of latency in virtual world representations. As I understand it, simulator sickness results (at least partly) from the display lag between when a user moves his/her head to when the updated image is displayed. However, in distributed VR another form of lag is caused by the delay of the virtual object's update reaching the user's host machine. This has the visual effect of "freeze framing" specific objects within the virtual environment, but does not affect the display lag. I'm looking for studies that show the psychological effects of lags induced within the environment as would be expected in a distributed VR system? The studies I've read indicate that the virtual environment becomes unusable if the display lag grows over about 60-80ms; is there an analagous statement that can be made for virtual environment lag? One other question: while the literature I've seen indicates that raw refresh rate is important for improving the user's tracking ability, it seems to me that it really ought to be related to the radial error not display lag. Regardless of how fast the subject moves his/her head, the display lag should be short enough to ensure that the radial delay is kept within x degrees. Have you seen studies that define what this radial error should be kept to? A SWAG would be about 10 degrees. Is this a fair characterisation? Thank you very much for your time! -- Later, Martine Martine Wedlake