From: John Wann Subject: Re: HUMAN-FACTORS: Children, VR, and home entertainment Date: Thu, 21 Nov 1996 13:28:09 +0000 Message-ID: Marc Bernatchez replied to my suggestion that he was making "unwise" statements on HMD safety. Marc relied: > >I must disagree with this statement. I don't "give the media fuel" to >exaggerate the implications a HMD could have on people. > The statements you make in the "interview" document you publicised: (http://www.imaginative.com/VResources/vr_revs/vr_revs1.html#The hardware corner) are highly speculative and are very strong** so I won't repeat them here. BUT you don't have any data to support your claims, so in my view they are certainly "unwise" ** Your own words were "I'm using severe sentences here as you see but the situation is severe" > >Also, have you done any testing of these issues on young kids in the 8-15 >years old range? If so, I would like to read your papers. To my knowledge >(that has much limits I freely admit), I don't know of any such reports. > No this data has not been collected and as I have outlined previously on this list there are ethical issues blocking the research in this area. But note that: (i) We are the only group that has published optometric data on the effects of HMDs that you discuss. (ii) Within our group we also work directly on child vision (but not in HMDs). I am not stating that there isn't a potential problem, but your statement of it is speculative and this isn't the way for the science to progress. When you've collected data, or literature-researched what effect repeated heterophoria / have on this age range, then you should have the basis for a clear scientific statement on this issue. >>Marc also suggests that some HMD companies have jumped on the bandwagon, >>without worrying about human-factors. > >As I said, let's not generalize. Many companies are going the right way with >this. The generalisation was in your "interview" - name me (in private) a single HMD company with a market share that you think is being irresponsible? - I think you are doing the HMD manufacturers a disservice. >When I see a 20 arc minutes per pixel HMD being in use, no >matter for what, I just can't say "everything is fine"....let's just say >that 20 for >this reference is like being blind (or almost) Sure we would all like higher resolution displays AND 120deg FoV, but this is not realistic in terms of the present state of the base technology. The important point, however, is to considered the human factors aspects: i) The reference to "legally blind" is one that goes back to an early (1991-92) statement based on equivalent Snellen acuities. Yes current HMDs are very poor at presenting clear Snellen-type text, but many visualisation tasks involve large, coloured geometric shapes/surfaces that may be in motion - the Snellen metric is not appropriate in this case. The "legally blind" statement is pretty meaningless unless you want to use the HMD purely as a text display with small font sizes. ii) Even if the display does render you "legally blind" when reading text, that doesn't mean it "make you blind". Prolonged viewing of a low resolution display is not desirable because they provide a poor accommodative (focal) stimulus, but here we are confusing "resolution" and "spatial frequencies". Pixelly displays can have high spatial frequencies (pixel edges) to drive accommodation (focus), its only when they are blurred that you have a display with only low-spatial frequencies that is difficult to focus upon. iii) In our past papers we have raise the issue of accommodation-vergence conflicts (which Marc re-states in his web-pages). BUT this problem will become GREATER as screen resolution improves - so low resolution screens may have an unintended advantage in reducing the AC/A and CA/C conflict. >John, could you make some of your past papers electronically available >on-line? One big problem for many people is the lack of time to look >for/order paper material over normal post etc. I'd sure like to read your >documents. > We have been switching to a new web-site and we will try and upload these at some stage, but to emphasize my point - I think it is dangerous to make authoritative pronouncements on a health and safety issue when it seems you haven't, as yet, read the papers that present hard data on the topic. John W ********************************************************* Dr John P. Wann < J.P.Wann@rdg.ac.uk> ********************************************************** Action Research Laboratory: Development, Rehabilitation, Immersive Virtual Environments (Wann, Mon-Williams, Langaas, Smyth , Swapp ) Supported by: Action Research; EPSRC: European Commission ARL - DRIVE Department of Psychology University of Reading PO Box 238, Reading RG6 6AL, UK +44 1734 318532 Fx +44 1734 316604 ***********************************************************