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SESSION V: DISCUSSION CHAIRMAN- Brig. Gen. Victor A. Byrnes, USAF (MC) PANEL DISCUSSION C. L. Crouch, Illuminating Engineering Society and Illuminating Engineering Research Institute Jack W. Gethard, Applied Physics Laboratory, The John Hopkins University Robert H. Brown, U. S. Naval Research Laboratory GENERAL DISCUSSION Speakers as noted 197

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SESSION V: DISCUSSION Panel Discussion C. L. Crouch: The organizers of this program are to be congratulated upon fulfilling one of the important functions of the Vision Committee, that is bring- ing representatives of many disciplines together for discussions of common problems. Each specialist in his own field goes home with concepts from others, and we derive something uniquely better from the cross-~ertilization of dis- ciplines. We better appreciate, now, some of the problems of the illumination of radar and sonar displays. In much simpler form, we have these problems in our ordinary practice of illumination when we must see things involving areas of high brightness and low brightness. We constantly have a change of adaptation and, perhaps, overstimulation in the form of glare, so that when we try to see things, we can ~ Or Fir ~ r ~ ~ 1 ~ ~ not. vve nave formulated these pro olems as being very definitely concerned with transitional adaptation. In the Illuminating Engineering Research Institute, we are proposing to study this phase intensively in the near future to find out what goes on as we look here and there, and how effectively we do see a normal interior. What is the sequence of eye positions in looking about from place to place as we carry on our activity? If we know the sequence, and if we know the limitations of seeing in each particular position, then we can really begin to design in terms of all the factors involved. This was brought out very well in the discussion of formulating in terms of total design' of all factors involved, and then intelligent- ly proceeding to develop answers to the problem, perhaps through actual model study. I especially appreciated this viewpoint of considering the difficulties of looking from a high-brightness to a low-brightness area. J. W. Gethard: I have no idea how ill Paul Fitts is (Ed: Dr. Fitts was scheduled to be on the Panel, but was taken ill and could not attend the sym- posium), but in many respects he may be the lucky one, since he doesn't have the problem of trying to draw together such a diverse program as this. The 20-odd papers pose a staggering problem of integration. The Vision Committee has certainly been given a new look in many respects. Whether this new look will be pleasing to all is a matter which those who have attended the sessions and managed to sit through all of them will have to decide for themselves. There has been something for everyone, including, perhaps, a certain amount of disappointment for a few. I say this despite my appreciation of the difficulty of putting together a talk with slides and getting up before a group of people to present it. I think that yesterday's program (Ed: Sessions I and II) was rather dis- appointing except for some of the scientfic papers. I believe that the absence of more salt and pepper in the form of scientific papers has been felt as a loss by a number of the attendees. In my opinion, no new material was presented yesterday that was very exciting, and certainly there was nothing presented in a form that the Vision Committee could get its teeth into. In the past' it -198-

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has been the policy of various groups' chiefly the military, to bring before the Vision Committee certain problems that it would like to see studied by the Committee. These were usually problems with challenging visual require- ments. Yesterday' however, I heard no such problems presented. Instead a group of operational requirements were paraded before us that looked to me at least 15 years old. The only new operational requirement that I remember, and I may remember this for some time, is the requirement for "anchoring per- sonnel in the environment." I don't know quite what the Vision Committee could do about a problem of this kind. It has been pleasing to learn of the suc- cess of the blue-lighting venture of some years back, and it also has been most interesting to hear a review of the possibilities of spot lighting for working en- vironment. Nevertheless, I recall no new general methods or even specific methods that were presented. Today's session picked up considerably and the papers were better. While there were a few disappointing features, there was a great deal of improvement in today's program (Ed: Sessions III and IV). I had hoped to hear during the Symposium something about noise and visibility, especially with regard to serious electronic countermeasure problems that the military are facing; some- thing about new display techniques; something about the possibility of compar- ing the visibility function on cathode-ray tubes when the eyes are pitted against automatic detecting devices; and something about the problem of comparing visibility with detectability two quite different things, I think. In general we have heard something about each one of these. The only one that was not mentioned at all was the problem of comparing the eye with automatic de- tectors. Automatic detecting systems certainly are coming along; unless the eye is to be put out of business7 someone will need to make a careful evaluation of the eye as a detector, as compared with the machine. This may fall in the classified area, however, and I rather suspect it does. I think perhaps the Vision Committee needs a new working group on visual displays. It had one once, around 1948-1949, I think. It was dissolved, primarily because it didn't do very much work. Perhaps the reason why it didn't is still to be seen, in part' even in today's proceedings; that is, we do not yet have a fundamental statement of what the visual display problems really are. Until a thorough-going analysis of the display problem is made, it is rather difficult to see precisely what such a working group of the Committee would do. I think the first thing that should be done is this: we should have a group evaluate the classified material in much the same way as the Committee as a whole was able to evaluate the unclassified material during the last two days. I think, however, it would be a mistake to bring together the entire body of the Vision Committee to make this evaluation, as was done here. :!Rather7 I believe that a small working group should gather together the material, filter it, evaluate it, and present it to the Committee in a discussion of perhaps not more than an hour's length. From the Committee's standpoint of getting at the basic problems, I think the meat of yesterday afternoon's program could have been presented in an hour's discussion and perhaps, in some respects, would have been pre- sented better than it was by the individual discussants. Essentially, what the - 199

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Vision Committee needs to know, I think, and what at least I was unable to find out after two days, is precisely how the Committee can assist the military in the visual displays area. Perhaps Dr. Brown has some ideas how this can be done. Finally, I would like to put in a good word for the speakers who described some of the new developments in the display field. These new techniques and the results that are anticipated will add greatly to the uses of visual displays employing cathode-ray tubes. R. H. Brown: Mr. Crouch and Dr. GeLhard have stated, very clearly, their summaries of the symposium, and they have covered the ground quite well. I would like to touch on a few points. May I thank the committee which organized the program for the symposium. I would also like to thank the speak- ers who, on relatively short notice, prepared their talks, submitted abstracts, and in many cases had manuscripts ready. Let me touch briefly on the sessions of yesterday, which seemed to me to be confronted with some critical problems in the general area of visual dis- plays. Since World War II, a major development in the use of radar and sonar displays has been low-level lighting, which allows men to do other things than look at radar scopes. At the same time, the introduction of low-level lighting, whether broad-band-blue or localized lighting with extensive use of sheet polar- izers and spotlighting, does introduce new problems. If one looks at some of the new-classical literature, say Human Factors in Undersea Warfare or other sys- tematic summaries, one finds most of the discussion directed toward relatively high light levels. And it seems to me that data are needed for some of the lighting problems which were taken up yesterday. There was a difficulty in terminology, both yesterday and today. I was confused, for instance, by the use of "blue-foot-lamberts." I was also confused by the use of the term "signal-to-noise ratio." In one case, it was used in refer- ence to luminance; in another case, it was used in reference to the inputs for a radar indicator or system. This question may be related to the adequacy of a lighting system. One may evaluate it in terms of the luminance on the cathode- day tube, or one may evaluate it in terms of signals to the indicator or system. Surely there seems to be a need for a working group on visual displays which could report annually to the Committee on Vision. General Discussion Knoll: This morning I made the suggestion that perhaps there was an area here where some of the contrast data could be applied. Since then several people have pointed out to me some of the difficulties which at the time I didn't appre- ciate. Difficulties, for example, such as the fact that on a radar display the background luminance is not uniform. A second objection to trying to apply these data is that, particularly in the PPI presentation, luminance varies con- tinually for a given point on the scope presentation. Certainly these are diffi- culties which are not insurmountable. A serious attempt should be made, per- haps beginning with a static presentation of some sort, to see if the data can be applied, and can be applied with some degree of accuracy. Then perhaps it 200

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would be another step to go on to non-uniform backgrounds which vary not only in a spatial sense' but also in a temporal sense. It seems to me incredible that one will have to go through each of these different types of CRT presenta- tions, systematically running a number of subjects through to attempt to get some data in this way. If the luminance characteristics of cathode-ray tubes could be made available, perhaps the Committee on Vision could translate these into visibility data. Gebhard: With respect to what Dr. Knoll said, I think it's quite true that a great deal can be done along the lines of making the calculations he has in- dicated; and as a matter of fact, I think C. T. Morgan said as much in a pub- lication in which he attemped to summarize the work that had been done by Hopkins on radar displays some years back. There has arisen in recent years, however, much concern about what happens when the display contains noise, especially noise of differing characteristics. Such noise, I think, tends to make difficult the kinds of calculations that could be made quite easily on relatively noise-free scopes, although there may be ways of getting around this analytical- ly. This is a good example of the sort of thing that could profitably be taken up in a working group on displays. Ballard: I would like to ask our stormy petrel panel member a question. He remarked that some of the things we heard yesterday were old, and in- deed I remember hearing about the broad-band-blue system for quite a few years. Of course it was highly classified back in the early days; as a matter of fact, the color blue just missed being made secret at Wright Field at one time, as I recall! But seriously, even though some of these things have been known for some time, I'd like to ask Dr. GeLhard whether he thinks it is still worth while pulling them together in one place, as has been done at this sym- posium, and more particularly, whether it is worth publishing the proceedings including all of these papers, so that in one book, which you can hold in your hand, you can see the broad picture of the radar display problem, including both the old and the new, as we have seen it these past two days. Gebhard: Emphatically yes, in answer to Dr. Ballard's question. I per- sonally would prefer to hold a book in my hand and sit in a comfortable chair picking out those portions I wanted to read than sit on these hard seats for two days to accomplish the same results. I can only repeat that some of the ma- terial doubtless could have been boiled down some of it probably would be thrown out, I think, by an editor. Perhaps this should have been the way to handle the Symposium I don't know. Talk after the fact, of course, is very easy. It's much more fun being a stormy petrel than being a program chair- man, and much easier. Miles: It has been a special pleasure to attend this symposium of the Vision Committee after having been absent from the United States for three years. There are one or two points I would like to call attention to. I think it Arise to begin studying acuity and such problems in association with the move- ments of the eyes. Pursuit movements' saccadic, and compensatory eye move 201

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meets constitute factors that are implicated in visual performance. We have long neglected adequate study of them. New insights in this area may prove useful. I have a problem in my mind, suggested by our program, though perhaps this isn't a good time to take it up for full discussion. We are presenting patterns and constellations of colors and lines on these scopes for the purpose of giving men information for use in operating the machines. We expect them to read the information symbolized on the scope. I remember that in studies of the process of reading by photographic recording of eye fixations and saccadic movements, it is very easy to distinguish a reading record of a man who knows mathematics when he is reading material that includes mathematical formulas from a record made by a non-mathematical reader. It is the same way for a man who knows chemistry and is reading an article that includes chemical formulas. The men who know these technical subjects spend about five times as long on such formulas as do the men who don't really understand them. It is the general rule that for every item in the formula one fixation is required, or at least used. A formula that contains half a dozen items usually gives a record show- ing the eye fixating back and forth, not always progressing left to right, and continuing this attentive behaviour for one or more seconds. One or two five- letter words in context usually requires less than the perceptual span of a . . ^. . simple fixation. When we are presenting live material on the scopes for resolution and information of operators we may underestimate the time that they are going to require in visual fixations to get the information. If it is regular information, symbolized by a square as different from a circle, it may perhaps be read very fast. But if it's new information I would predict that if our eyes continue to work as they do in the process of reading technical printed matter: the man who really wants the information even though he's able to interpret it quite quickly and know its meaning, will tend to make successive fixations on various bits of that information. Brynes: Thank you7 Dr. Miles, I can't refrain from remarking at this point what a pleasure it is to have Dr. Miles back with us. He is one of the deans of the Vision Committee. When I first came with this Committee many years ago he was a member of the Committee and one large part of its backbone; he's recently spent three years in Turkey; he's now back in this country, up at the U. S. Naval Medical Research Laboratory in New London; and we're certainly delighted to have him here at this meeting. Crouch: In reference to Dr. Knoll's comments I am wondering if some of the instrumentation which we are developing at I.E.R.I. might not be helpful. We find that you cannot apply, in the ordinary work tasks, the theoretical con- trast data because of the variations which occur in the background and in the configuration of the detail. For instance, pencil writing is non-uniform and varies from point to point. We have developed a contrast threshold meter which "floods" the task or the detail with an increasing overlaying brightness to thres- hold, inserting at the same time an absorption in proportion to the flooding -202

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action which keeps the adaptation level constant at all times. Then we come to threshold by decreasing the contrast to threshold. With this instrument we are able to evaluate much more precisely than by estimating from taking various minute measurements of the detail and its background and trying to determine variations of contrast. We can get threshold very quickly. The visual task evaluator, which you heard Dr. H. R. Blackwell mention yesterday morning' is now in rather large sizes but will be miniaturized for use in the field in portable size. Using this visual task evaluator' any complex configuration can ~ ~ ~ 1 ~ be rectucect to its thresho~ct. one ot the earliest forms of this was used by Dr. L. A. Jones of the Eastman Kodak Company in the first World W ar' In the measurement of the effectiveness of camouflage. Illuminating Engineering Institute research is producing several other in- struments. For the problems of various brightnesses in the field of view. Dr. Glenn Fry is developing for interior lighting engineers a portable disability glare meter which can be set on a tripod for measuring in any position the dis- ability glare present. Dr. S. K. Guth has already developed a meter which measures discomfort glare under similar circumstances. With this group of . ~ three Instruments we propose to evaluate any particular situation, interior as well as exterior. Byrnes: Thank you, Mr. Crouch. Is there any further discussion? If not, I have one comment, namely, that in almost all of the papers concerning capabilities of individuals, particularly on radar scopes, the subjects were in- telligent, well motivated, untired, unbored subjects. The results with these people are not totally comparable to the results obtained when a subject be- comes tired and bored and "wants out." I would like to suggest that some of these studies be carried to a point that will determine what factors retain their importance when these other conditions come into play, because there may be a difference. This is the only comment I have to make on the symposium other than .1 ~.1 J ~ to Inane tne program committee and Dr. Brown and our distinguished panel for their participation, as well of course as the individuals who presented the papers. I would also like to thank the members of the Committee who acted as chairmen: Dr. Imus, Dr. Graham, and Colonels Gersoni-and Hill. And one last piece of gratitude: This is my last meeting as Chairman of the Vision Com ~ _ ~ ~ ~ ~ r .~ . ~ ~ __: Settee and 1 want to thank all of you for the support you nave given me curing the several years that it has been my pleasure to serve as your Chairman. It has been one of the really fine experiences of my life. Thank you very much. 203-

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