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This is the second biennial interim report for the study titled The Effect of a Monocular Helmet-Mounted Display on Aircrew Health: A Cohort Study of Apache AH Mk 1 Pilots. The principal aim of this occupational health study is to determine if the use of the monocular Integrated Helmet and Display Sighting System (IHADSS) helmet-mounted display (HM...
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... eyes are held in place by three pairs of muscles that constantly balance the pull of the others. These muscles work together to move the eyes in unison, which allow the eyes to track moving objects. Binocular vision is a consequence of the separation of the eyes, which results in two views of the scene. To prevent double vision (diplopia), the eye uses a movement called "vergence." The eyes turn to direct the images directly onto the retina. The brain fuses these two images into one. When both eyes fail to point to the same location in space, a condition known as heterotropia or strabismus exist. The condition is diagnosed using the unilateral cover test; the subject fixates on a point in space and one eye is covered. If the uncovered eye refixates to the point, this indicates the eye was not aligned. In cases of strabismus, individuals will see double or suppress the image of one eye; in either adaptation stereopsis will not exist. Both eyes are checked using the unilateral cover test. If neither eye refixates when the opposite eye is covered, strabismus is not present and the subject is considered orthotropic. Covering one of the eyes and noting the change in the line of sight of the covered eye can test eye muscle balance. If both eyes accurately point toward the target when each eye is covered separately, this normal muscle condition is called orthophoria (Figure 18). If the line of sight departs from the target object, a condition known as heterophoria exists. Such departure can be either lateral or vertical in nature. If the line of sight of the covered eye laterally departs such as to turn outward, a condition called exophoria is present; if the line of sight of the covered eye laterally departs such as to turn inward a condition called esophoria is present (Figure 18). If the line of sight of either covered eye vertically departs from normal vergence, such that one line of sight is directed above the plane of the other, a condition called hyperphoria is present (Figure 19) (Borish, ...
Citations
... Urban areas are expected to be the future battlefield and combat in urban areas cannot be avoided." Unfortunately, although the everexpanding role of urban ground operations is clear, the available scientific and technology literature for NVGs is predominantly focused on the aviation community (e.g., [18][19][20][21][22][23]). In turn, the existing human performance research may not translate well into close-combat operations given the key differences in behavioral demands. ...
As early as the Vietnam War, the United States Military has employed various forms of night vision goggles (NVGs) to enhance warfighter capability under low light conditions. In recent years, the most common form of NVGs used by US ground forces has been the binocular or “dual tube” variety, such as the AN/PVS-15 and AN/PVS-31A. Compared to binocular NVGs, modern panoramic night vision goggles (PNVG), such as the GPNVG-18, provide potential benefits by more than doubling the field of view. This capability could be particularly useful in urban environments and specifically during room-clearing operations. However, previous human performance studies with NVGs have largely focused on aviation operations rather than ground forces undertaking a close-combat mission set. Combined with the emerging technology of the PNVG, and the lack of live fire during testing, there is little empirical evidence about the relative human performance benefits of having a wider field of view during close-combat operations. The current investigation addressed this issue by examining how wider peripheral vision impacted the process of dynamic room entries. Using highly trained military operators, live ammunition, and three separate live-fire room-clearing scenarios, we examined performance differences between the current technology in binocular and panoramic NVGs. Our results suggest that soldiers cleared rooms significantly faster when using PNVG than when using binocular NVGs. The largest benefit occurred for engaging targets placed in the extreme corners of rooms. Applications and trade-offs are discussed along with the need for increased human performance studies addressing close combat under NVGs.
... An initial report describing the study's protocol, methodology, development and initial execution phase was published in November 2001 as USAARL Report No. 2002-04 (Hiatt et al., xxiv 2002a). The first interim (two-year) report was published in September 2004 as USAARL Report No. 2004-18 (Rash et al., 2004; a second interim (4-year) report for the period of January 2000 to December 2004 was published in December 2009 as USAARL Report 2010-09 (Rash et al., 2010) and presented at the Aerospace Medical Association in May 2008 (Adams et al., 2008); a 6-year study review was presented at the 2009 SPIE Head-and Helmet-Mounted Displays XIV Conference, Orlando, FL, and published in the conference proceedings (SPIE, Proceedings Vol. 7326 [Hiatt et al., 2009]). ...
... NVGs have been in use for more than 20 years in aviation, military and civilian applications, ground operations on vehicle and on foot, law enforcement, and even the aiding of people with night blindness (Berson, Mehaffey, & Rabin, 1974;Hoover, 1983;Verona, 1985;Verona & Rash, 1989;Wiley, Glick, & Holly, 1983). The widespread use of NVGs is evident in more recent reports (e.g., Adam, 2004;Gore & Hughes, 2008;Rash et al., 2009;Shender, Ostrander, & White, 2009;Squair, 2007), indicating the widening use of this technology for various purposes in diverse domains. ...
... Even in poor weather that degrades lighting conditions (e.g., overcast skies eliminating starlight and moonlight), NVGs can operate by taking advantage of human-made illumination. The most common use of NVGs is with flying aircraft, particularly, rotary wing, for a variety of missions (e.g., Adam, 2004;Brickner, 1989;Cho, Clark, & Rupert, 1995;Negrette, 1998;Rash et al., 2009). The use of NVGs with fixed-wing aircraft, including fast jets, has also increased in recent years (e.g., Gore & Hughes, 2008;Shender et al., 2009;Squair, 2007). ...
... This means that even for a FOV of 30° to 40°, some of the resolution afforded by NVGs is not being used for tasks requiring high acuity. However, decreased FOV afforded by NVGs has been implicated in disorientation (Dolezal, 1982;Johnson, 2004aJohnson, , 2004bRash et al., 2009, Ruffner, Antonio, Joralmon, & Martin, 2004Salazar et al., 2003). The "extra" FOV is essential for providing peripheral vision information critical for orientation and SA (Task, 1992), as will be discussed later. ...
The technology underlying night vision goggles (NVGs) enhances human ability to operate in dark and low-light conditions. However, NVG-aided vision is limited relative to daylight human vision and may entail risks. This review focuses on NVGs with image intensifier technology and explores the impact of their use on human performance. The review covers technology and device characteristics (image quality and field of view), physical configuration (ocular configuration, NVG weight, and forward center of gravity), and contextual and environmental factors (mission and task aspects, lighting, weather, and terrain). The key human factors in NVG use are visual and cognitive performance (visual acuity and contrast sensitivity, stereopsis and depth perception, distance and size estimation, spatial orientation, and situation awareness), and physical and physiological aspects (neck strain and injuries, and headaches). Understanding technology and contextual factors and their influence on human factors is critical to improving performance and safety with NVGs. Technology and device improvements, along with appropriate mission planning and training, play a critical role in aided night vision performance.
With proliferation of mobile devices that provide ubiqui-tous access to information, the question arises of how dis-tracting processing information in social settings can be, especially during face-to-face conversations. However, rel-evant information presented at opportune moments may help enhance conversation quality. In this paper, we study how much information users can consume during a conver-sation and what information delivery mode, via audio or visual aids, helps them effectively conceal the fact that they are receiving information. We observe that users can inter-nalize more information while still disguising this fact the best when information is delivered visually in batches (mul-tiple pieces of information at a time) and perform better on both dimensions if information is delivered while they are not speaking. Interestingly, participants qualitatively did not prefer this mode as being the easiest to use, preferring modes that displayed one piece of information at a time.
A collaborative occupational health study has been undertaken by Headquarters Army Aviation, Middle Wallop, UK, and the U.S. Army Aeromedical Research Laboratory, Fort Rucker, Alabama, to determine if the use of the Integrated Helmet and Display Sighting System (IHADSS) monocular helmet-mounted display (HMD) in the Apache AH Mk 1 attack helicopter has any long-term (10-year) effect on visual performance. The test methodology consists primarily of a detailed questionnaire and an annual battery of vision tests selected to capture changes in visual performance of Apache aviators over their flight career (with an emphasis on binocular visual function). Pilots using binocular night vision goggles serve as controls and undergo the same methodology. Currently, at the midpoint of the study, with the exception of a possible colour discrimination effect, there are no data indicating that the long-term use of the IHADSS monocular HMD results in negative effects on vision.
In the early 1980s the U.S. Army fielded the first integrated helmet-mounted display (HMD) for use in the AH-64 Apache helicopter. To reduce head-supported weight and minimize center-of-mass offsets, a monocular optical design was selected. Although early design concerns of binocular rivalry and the Pulfrich phenomenon never materialized, user surveys have documented persistent reports of visual complaints and illusions in peacetime training flights. However, a recent evaluation conducted under battle conditions in Operation Iraqi Freedom found statistically lower reports of complaints and illusions. While these reported problems are short-term, questions have been raised regarding potential long-term physiological effects resulting from long-term use of this monocular display. A 10-year longitudinal study, currently underway in the U.K., has been implemented to definitively answer the question of whether long-term exposure produces any degradation in binocular visual function.
