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The Hypercard-UNIX electronic mail system (HUES) was programmed using Hypercard version 1.2.5 on a Macintosh computer system. HUES was created as a user-friendly way for U.S. Army Human Engineering Laboratory (HEL) employees to transfer electronic mail, as well as files of various types and formats, to anyone connected to the Internet. (Note: The Internet is a collection of many networks that service universities, private industry, and the Department of Defense.) The system is essentially an interface or shell, which receives information from another computer system (in this case, a UNIX system) and displays the information in a format that allows easier user interaction with the UNIX system. The system receives information from another computer by using a group of transmission control protocol/Internet protocol (TCP/IP) code resources developed by Apple Computer, Inc., for use with Hypercard and Macintosh computer systems. This transfer of information allows users to take advantage of the Macintosh's point-and-click user interface to perform desired procedures, instead of having to type UNIX commands. The system was designed to be expandable, with two different means of establishing a connection to a host computer (i.e., modem or TCP/IP). The system also allows direct manipulation of UNIX files, (i.e., deleting, viewing) and the option of directly sending UNIX commands.

An experiment was conducted to examine the effects of display resolution and target range on the ability of soldiers to identify tanks presented on a display monitor. Subjects learned to identify 24 images consisting of four tanks at three orientations and at two ranges. Subjects then identified targets using five levels of resolution produced by low-pass spatially filtering the images. The modulation transfer function area (MTFA) metric was calculated to be 9.1, 4.8, 3.6, 2.4, and 1.3 for the five levels of resolution. Subjects' visual capabilities were tested using the Contrast Sensitivity Function (CSF) Test; however, individual differences in the CSF did not correlate with target identification performance. Results indicated that target identification performance depended on the interaction of display resolution and target range. With near targets, loss of resolution had little effect on the percentage of targets identified or the response times until MTFA fell below 2.4, whereas with distant targets, loss of resolution always degraded performance. These results indicate that operators of indirect viewing devices do not require high resolution images as long as the targets are large and high contrast.

Research indicates that traditional measures fail to rate hazard from intense impulses accurately. This failure may be due to increased complexities in the ear's response at such high sound pressure levels. Therefore, to gain insight into the problem, we have been developing a mathematical model of the ear that reproduces the response of the ear from free field pressures to basilar membrane displacements and calculates hazard there (modeled as mechanical stress). This model is conformal with the structure of the ear and includes the spectral tuning of the external and middle ears, a non-linear stapes, and a changing susceptibility along the cochlear partition. The model can be used to calculate a hazard index for virtually any impulse and although work is still continuing on the development of the model, it is thus far able to explain the hearing loss data better than any other system. If the model were incorporated into an integrated circuit/meter, it would have the virtues of being complex enough to rate hazard accurately, be simple to use, and because it is theoretically based, be useful in suggesting design changes for impulse- producing sources as well as more effective designs for hearing protectors. hazard rating, spectrum, impulse noise, impulse noise, noise hazard.

A computer-controlled system was developed which provides the capability to generate processed dynamic imagery for human factors research. Processing of the video may involve any operation such as enhancing, degrading, or adding overlays. This system may also be used during experimental trials to perform data collection and score subject responses. The system is comprised of several components: a computer, an image processor, two lapse video cassette recorders, and a custom built VCR control circuit. When possible, processing is performed as the video is being displayed to a subject. When processing complexity is too great, the video is processed before experimentation. The input to the system is imagery on a video tape. The imagery is processed frame by frame and the results are stored on the output video tape. Processing appears to be performed in real time when this resultant tape is played at the regular speed. The flexibility and cost effectiveness of the system make it an ideal developmental tool, test-bed, and simulator for the processing of dynamic visual imagery. The hardware software for implementing the system are discussed in detail. Image processing, Computer graphics, Dynamic imagery, Video systems, Visual imagery, Human factors, Real time.

This report describes the C functions and FORTRAN subroutines involved in the communications between the aviation tactical operations center (AVTOC), air defense tactical operations center (ADTOC), and helicopter nodes for the U.S. Army Human Engineering Laboratory (HEL) counter-air program demonstration. It uses transmission control protocol/internet protocol (TCP/IP) as the communications protocol, and it is written under the virtual address extension/virtual memory system (VAX/VMS) and UNIX operating systems in a manned, interactive simulation. The software design consists of ten C programmer written functions and one FORTRAN programmer written subroutine. The functions and subroutine are explained in detail and a listing of source codes is included in the appendices.

The theoretical basis for the use of spectrum in rating hazard is well established for sound intensities most often encountered in the workplace. The frequency-selective transmission characteristics of the conductive mechanisms of the external and middle ears, coupled with the generally broad and gently sloped spectra of noise in the workplace, promote energy transmission in the midrange so that some measure of energy there should do well at ranking hazard. However, at sound pressures above 130 dB, often exceeded by impulsive sounds such as gunfire, the picture is much more complex. Conductive non- linearities in the middle ear can act to reduce the energy transmitted to the cochlea, protecting the ear and allowing it to resist damage. At the same time, however, the mechanisms of loss operating within the cochlea become very sensitive to amplitude so that relatively small quantities of energy can do permanent damage. These mechanisms are not well characterized in the frequency domain; consequently, spectrum is likely to have marginal utility in rating hazard for really intense sounds. hazard rating, spectrum, impulse noise, noise hazard.

In June 1990, the U.S. Army Human Engineering Laboratory (HEL) conducted a preliminary evaluation of a prototype computer device called the tactical computerized interactive display (TACID). The objective of this preliminary investigation was to identify human factors evaluation issues related to the TACID liquid crystal display (LCD) and message software. A practical method of user interface evaluation (Johnson, Clegg, & Ravden, 1989) was used to evaluate the TACID. During Phase 1 of the evaluation, a system designer evaluated the TACID display and software using checklists from DOD- HDBK-761 (DoD, 1985). Four HEL researchers, who were taught to use the TACID, noted the general readability of the LCD display as well as human factors problems associated with the software. During Phase 2 of the study, the performance of 27 West Virginia Army National Guardsmen was recorded on video tape as they performed relatively simple military communications tasks using the TACID. Finally, during Phase 3, the operators were asked to complete questionnaires about the TACID training they had received and their operational experience with the device. In most cases, the software used on the TACID was consistent with DOD-HBK-761 (DoD, 1985). The subjects had no problems reading the LCD display, and they only had a few problems with Battlefield digital message processing, Digital text editing, Flat panel computer display, Human- computer interaction (HCI).

Innovative software techniques to advance methods of analysis in eye movement research have not kept pace with the development of hardware for collecting the samples of eye position (Scinto & Barnette, 1986). Eye fixation and duration have been the primary measures focused upon to glean knowledge of subjects' performance while engaged in cognitive visual tasks. Program cluster was developed as a means of investigating the dynamics of target examination characteristics that did not lend themselves to traditional eye movement analysis methods. The development of this tool proved to be a valuable means of assessing visual activity at a micro level as compared to the gross measures of distribution of visual attention in various areas of the visual field. This report describes the history surrounding the development of program cluster as an analysis tool, the source of input required for its execution, the mechanics of the execution as an interactive process, the program's products of visual displays and data file output, and potential application of such a tool for analysis of visual activity. clusters target discrimination eye movements visual attention fixations visual examination.

This study is to determine whether greater minimum spacing is required between push buttons for gloved operation than for bare-handed operation. Seventy-two undergraduate students served as subjects in groups of 12, one group for each of the six hand-wear conditions. The six hand-wear conditions consisted of one bare-handed group and five glove groups. Each of these five groups wore one of the following glove types: a butyl and cotton glove assembly, a butyl and nomex glove assembly, a leather and wool glove assembly, a fire-fighting glove, or a thin vinyl glove. Subjects performed two button-pushing tasks. One task was self paced, allowing subjects to determine response times. The other task was machine paced, allowing subjects decreasing amounts of time to respond. Subjects performed these tasks on three different panels containing nine buttons each. The three panels varied by spacing between the buttons. One panel contained buttons 13 mm apart, another 19 mm apart, and another 25 mm apart. Results from the self-paced task indicate that subjects responded faster on the 13-mm and 19-mm panels than on the 25-mm panel. This suggests that the 13-mm spacing is adequate for speed of operation for gloved operators. Error data and machine-paced time data neither support nor contradict this result. Results also indicate that subjects with larger hands tend to score faster times with more errors in the machine-paced task. This effect does not seem to be because of gender differences.

An evaluation of the psychological stress experienced by Special Forces (SF) candidates during the 3-week Special Forces Selection and Evaluation Course was conducted in January 1991 by the U.S. Army Human Engineering Laboratory (HEL). The HEL stress battery was used to assess the psychological stress responses of the candidates seven times representing anticipated times of high and relatively low stress. Periods of higher and lower stress were tracked using the measures in the stress battery. Candidates showed higher stress levels at the start of the course and at times of high physical and mental demand and showed lower levels at times of lower demand. The highest stress levels, however, were associated with the final day when their outcome in the course was revealed. Over all seven times during the course, those who were ultimately selected for SF training displayed lower stress responses than those who were not selected. When the stress responses were compared with those previously collected for men in other stress situations, the candidates' stress levels were found to be in the low to moderate ranges. The selected candidates displayed levels more in the low range and those who were not selected displayed levels more in the moderate range. The highest stress displayed by both groups (moderate to high range) occurred when they were waiting to hear their course outcomes. The findings contributed to the validation of HEL stress assessment methodologies.

The objectives of the experiment described in the paper were the determination of the effects of nonuniformities on operator performance and perception, and the validation of current recommended standards. Subjects performed two tasks in the presence of nonuniformities: an objective visual search task and a subjective magnitude-estimation task for the determination of perceived uniformity. The results indicated that the nonuniformities did not appreciably affect search performance, and that current recommendations are appropriate, although the magnitude-estimation task results indicated that the subjects were sensitive to the nonuniformities. The subject impressions of perceived uniformity results follow the contrast threshold function of the visual system. display luminance nonuniformity, perceived uniformity, visual displays.

A contract-enhancement algorithm is described which avoids the flat noisy appearance often produced by histogram equalization. This algorithm is based on the intensity-dependent spatial summation (IDS) model purported by Cornsweet and Yellott. The model's initial intent was to demonstrate its ability to replicate certain effects in human vision. Its implementation as an image- enhancement routine has predominantly emphasized its ability to enhance edges in imagery. The model has been modified to produce enhancement not only at edges but throughout the entire image profile. As a comparison to histogram equalization, which collapses some quantilization levels in the process of expanding others, the algorithm largely preserves the original brightness gradations as it expands them. Thus, the shape-from-shading cues so important to the perception of form and contour are preserved. Also, this technique, in most cases, enhance high frequency noise to a far lesser extent than does histogram equalization.

Experiments were conducted to assess human performance measures of the perceptibility of tracked vehicle designs as viewed through a simulated sensor system. Subjects were trained to identify silhouettes of 4 tracked and 4 wheeled military vehicles. Each targets was embedded in one of 12 levels of white noise, that is, the signal-to-noise ratio. Subjects' identification responses were analyzed to produce 3 SNRs for each target at which were barely detectable, recognizable as to target type, or identification as a specific target. Analyses of the data indicated that the relative perceptibility of each target depended largely upon the number of features that it shared in common with other targets in the expected target set. Another experiment explored whether eye movement behavior could determine which target silhouette features appeared to be most critical to target discrimination. The forced choice responses of 22 subjects from the first experiment were analyzed to determine for each individual the specific SNR for detection, recognition, and identification for each of the 8 targets. Results indicated that the pattern of visual attention for the Bradley differed from the other tracked vehicles. There also did not appear to be any systematic match between strategies that subjects indicated they were using to identify targets and where they might have actually looked. These results were interpreted to mean that the pattern of visual attention is perceptually driven, whereas target identification per se is a cognitive function.

This study was conducted to investigate the effects of display failures and rotation of dot-matrix symbols on visual search and recognition performance. The type of display failure (cell, horizontal line, vertical line), failure mode (On, failures matched the symbols; Off, failures matched the background), percentage of cells failed (0,1,2,3,4%), and rotation angle (0 deg, 70 deg, 105 deg) were the variables examined. Results showed that displays that exhibit On cell failures greater than 1% significantly affect search time performance. Cell failures degrade performance more than line failures. Search time and accuracy are best when symbols are oriented upright. The effects of display failures and rotation angle on search time were found to be independent. Implications for display design and suggestions for quantifying the distortion caused by rotation are discussed.

This research supported the Advanced Combat Rifle field test and the Human Engineering Laboratory (HEL) stress program by evaluating competition as a methodology for producing a known level of stress in soldiers. The subjects in this field experiment were volunteer infantrymen from the 82nd Airborne Division and the 101st Airborne Division (Air Assault). During the 2 competition weeks, 10 soldiers from each division participated; during the control week, 20 soldiers form the 82nd Airborne division served as subjects. The subjects fired M855 ball ammunition loaded into 30-round magazines from M16A2 rifles equipped with Crane Naval Weapons Support Center No. 1 muzzle devices. Each subject fired two different target scenarios during the record-fire days, one scenario in semiautomatic mode and one in burst mode. Each scenario consisted of 36 target presentation events. Events involved presenting one, two, or three targets for 1.5, 3, or 5 seconds at 50, 100, 200, or 300 meters. The stress created by competition was assessed by comparing the psychological and physiological responses of the soldiers firing competitively with the responses of soldiers firing during noncompetitive, control conditions, and with the responses obtained from subjects in other stress protocols.

A TOW Accuracy Study was conducted in 1989 comparing TOW gunners' hit probabilities during mock battle conditions at the National Training Center (NTC), Fort Irwin, California, and during modified range conditions at Fort Hood, Texas. Since some observers have speculated that greater stress at NTC could adversely affect hit probabilities, an evaluation of stress experienced during the conditions created at the two sites was conducted. Psychological data obtained at the two sites were compared with each other and with similarly obtained referent data for protocols involving surgical stress, examination stress, competition stress, and control conditions. It was concluded that the two sites were about equally stressful and, based on comparison with the referent findings, that the stress experienced was of a moderate level. Because the test plan did not control for test site order, the possible effects on performance that were because of test site factors could not be assessed. Implications of confounding order with test site were discussed and recommendations were offered for appropriate experimental designs for determining the possible effects of stress on hit probabilities.

The results of a recent experiment concerning the effects of training on the performance of subjects using the automatic speech recognizer are reported. Over a 5-day period, 20 military enlisted grade male subjects were trained and tested in using a connected speech (speaker-dependent) machine automatic speech recognizer in a self-paced task controlling a generic tactical display by voice command. Experimental results show that a majority of the subjects had little difficulty with the automatic speech recognizer and that for these subjects training produced only a slight improvement in recognizer performance. These subjects performed at a high machine recognition rate. However, during the first session, a large minority (35%) of the subjects had difficulty training their speech to be machine recognizable. These subjects required at least two training sessions to perform the task at their best ability, and even after they were trained, their performance never reached the performance level of other subjects.

This experiment is one of a series of studies about visual task performance with dot-matrix displays. In this study, the variables of matrix size and symbol rotation are evaluated for their effects on visual search time for familiar alphanumerics as well as for dot-matrix-formed U.S. Army symbols. The results show that increasing the size of the matrix from 7 x 9 to 9 x 11 or even to 11 x 15 dots significantly improves performance for alphanumerics as well as Army symbols, particularly for the more difficult and confusable symbols. Search accuracy improves in much the same manner as search time does.

Two models of text comprehension, a process model proposed by Kintsch and van Dijk (1978) and a causal model proposed by Trabasso and Sperry (1985), were tested in two experiments with eight procedural texts. In Experiment 1, 24 female college students rated the importance of propositions, idea units, and sentences to the overall procedure described in the texts on a 7-point scale. In Experiment 2, 16 female college students recalled each of the eight texts immediately after reading it. Predictors derived from the models were used to predict the ratings and the recall in multiple regression analyses. The results showed that the amount of variance accounted for by the predictors varied from text to text. In general, for the ratings and recall, the causal model accounted for more variance than the process model did. For the process model, level within the hierarchy accounted for the most various and for the causal model, the causal chain factor accounted for the most variance. The models were not as powerful as in previous research with narrative texts perhaps because these models do not take into account the cognitive representation involved in doing the task described by a procedural text.

When dot-matrix characters are rotated, as may be in a moving map display, their dot-matrix patterns are distorted and their legibility is thus affected. In this experiment, 16 subjects performed a random search task in which they were asked to look for a target in a random character pattern. The independent variables were (a) the direction (clockwise or counterclockwise), (b) the angle of stimulus image rotation, and (c) the target character's distance from the center of the screen, which was also the center of rotation. The dependent variables were response time and response correctness. Significant effects were found for the angle of rotation, the target character's distance from the center, and the target character. The results indicate that (a) no angle-dependent mechanism is involved in performing this task and the angle of rotation influences recognition mainly through the distortion of dot-matrix patterns; (b) the target character's radial distance from the center of the screen is the determining factor for search time, while the x and y coordinates of the target contributed to dot-matrix pattern distortion; and (c) the target characters interacted differently with the angle and distance factors to determine the extent of distortion and their legibility. Means to quantify the extent of distortion are discussed and the direction for future research is suggested.

This research is the second in a series of experiments undertaken to develop optimum design criteria for matrix-addressable displays. This study examined the effects of character size, luminance modulation, font, and polarity on both contextual task (reading) performance and performance in a random search task. The random search task consisted of locating a target letter or numerical within one of nine sectors on the display. Only upper case alphabetic characters and the numerals 0 through 9 were used. Using a font (3) by modulation (3) by polarity (2) by character size (3) within-subjects factorial design, only the main effects of character size, font, and polarity were found to be significant. There were no significant interactions. Post hoc analyses indicated that response speed increased as character size increased from a 7 x 9 matrix, to a 9 x 11 matrix, to an 11 x 15 matrix. Post hoc analyses revealed that response times were longest with the maximum dot font, but did not significantly differ between the Huddleston and Lincoln/MITRE fonts. Additional post hoc comparisons indicated that negative contrast (dark characters on a light background) produced significantly faster response times than did positive contrast (light characters on a dark background).

This document describes a body of research conducted for the purpose of improving the performance of automatic speech recognition (ASR) systems in noisy, stressful environments. To accomplish this, several avenues of basic research were investigated. First, novel techniques for noise reduction were developed. Second, three novel robust recognition systems were developed. One of these techniques relied on noise removal, another on linear least squares system identification, and the third on robust distance measures. Third, methods for characterizing stressed speech parametrically were developed. Among the descriptors used were various prosodic features, spectral features, and glottal excitation characteristics. Fourth, methods were developed that were shown to improve ASR performance in noisy or stressed conditions.

Recoilless weapons commonly release a great deal of energy rearward in the immediate vicinity of the crew. If such weapons are fired from within structures, there is concern that in addition to the acoustic hazard to the ear or other organs, there might be hazard associated with flying debris or even structural collapse. Two studies were conducted to evaluate such hazards by remotely firing a total of 24 rounds from the 90 mm recoilless rifle, LAW, TOW, and DRAGON weapons systems from within enclosures (Price, 1978; Shank & Garinther, 1975). The structures, selected from available buildings, were made of various materials (reinforced concrete, masonry, sandbags, and wood) and ranged in volume from 14 cubic m to 161 cubic m with venting areas from 2.9 square m to 11 square m. Data included pressure histories, motion pictures of the structures and small objects placed in the room, and physiological data from 32 goats (tissue/organ system damage) and 8 cats (hearing loss measures). At the firer's locations, peak pressures ranged from 178 to 189 dB and B-durations ranged from 28 to 376 msec. Although the firings commonly produced some structural damage, none of the firings caused structural collapse or induced tissue damage to non-auditory organs. Ear drum rupture did occur in 5 goats and the cat ears exposed with no hearing protection did show permanent hearing losses. Of the cat ears exposed with hearing protection (EAR plugs), only one showed a permanent loss., Published in Scandinavian Audiology Supplementum, v34 p39-48 1991.

The Combat Service Support Division of the U.S. Army Human Engineering Laboratory conducted a series of field trials uploading ammunition onto a surrogate of the Army's latest generation of tactical transport, the Palletized Loading System (PLS), a 15-ton payload capacity truck equipped with a demountable flatrack instead of a conventional fixed bed. Twelve recent graduates from the advanced individual training course for ammunition handlers (military occupational speciality 55B) were tasked to load and secure PLS flatracks, both grounded and on board PLS trucks, with pallets of ammunition. Two types of typical high usage ammunition were chosen, 155mm artillery projectiles and 105mm tank cartridges for armored units. Each of the ammunition types was further subdivided as uniform loads where the flatracks are loaded with identical pallets of one commodity and Unit Configured Loads (UCLs), a mix of projectiles and propellant charges for the artillery loads, and a mix of 105mm cartridges and small arms ammunition for the armor loads. The experimental results and subsequent comparative statistical analysis showed that (a) loading and securing grounded flatracks was faster than loading on board trucks and (b) armor ammunition loads took less time than artillery ammunition loads. There were no differences in the total times for UCL versus uniform loads; however, the time to secure an artillery UCL was greater than for the uniform load, probably because a more difficult tie-down routine with more tie-down straps was being used.

This document describes a research plan which will lead to the development of a model that relates speech communication to performance. The experiments to be conducted answer questions about the effect of spoken message set complexity on operational performance. A message set has been defined as the set of all possible response-triggering messages within the boundaries imposed by the situation or setting. First-year and long-term objectives are presented. An experimental paradigm, independent and dependent variables, subject populations, and other details of the experiment are described. Operational definitions of the independent variables are presented. Additionally, a tentative research plan for continued studies is proposed.

Little research has been conducted about human performance in symbol search of cartographic images on matrix-addressable displays. Alphanumeric studies have researched failures and polarity on such displays but not using cartographic images. Two studies were conducted which required subjects to search for symbols on cartographic images under various conditions of failure, polarity, and background clutter. Response time and accuracy were measured. Generally, high clutter impeded performance more than low clutter, and negative contrast produced slightly better performance than positive contrast. Horizontal line failures affected search ability more than vertical line or cell failures did, particularly when the failures were in the on mode rather than the off mode. Further, it was discovered that while previous alphanumeric studies found effects at 3% failures or greater, effects were observed for the present studies at 2% or greater, apparently because of the presence of map information on the display. Recommendations for cartographic display design and future research are discussed.

Reading and visual search speed and accuracy were used to evaluate the effects of simulated line and cell failures on a visual display. Five experimental variables (failure type CELL, VERTICAL LINE, AND HORIZONTAL LINE), PERCENT FAILURE 0%, 4%, 8&, OR 12% CELLS FAILED, display polarity LIGHT CHARACTERS ON DARK BACKGROUND OR DARK CHARACTERS ON LIGHT BACKGROUND, mode of failure FAILURES MATCH THE SYMBOLS OR FAILURES MATCH THE BACKGROUND, and matrix size 7 X 9, 9 X 11, OR 11 X 15 DOTS) significantly affected performance of both the reading and search tasks. Additionally, many of the interactions among these variables were significant. The experimental results indicate that as the percentage of failures increased, performance systematically decreased. For failure levels of less than 4%, little effect on performance was found. Performance increased as the size of characters increased. A 30% improvement in search time and a 7% improvement in reading time was obtained by using dot- matrix sizes larger than 7 x 9 pixels. In general, dark symbols presented on a light background (negative contrast) were read and searched for more quickly than light symbols presented on a dark background (positive contrast).

This study was conducted to quantify, as a function of speech intelligibility, the performance achieved by 30 normal hearing tank crews when conducting gunnery scenarios in an armor simulator. A scenario consisted of 10 missions. Four targets (tank, truck, helicopter, and troops) appeared during each mission, and it was the commander's task to instruct the gunner to shoot at the appropriate target with the appropriate weapon. The speech intelligibility (SI) measure used was the modified rhyme test (MRT). Performance measures (for each scenario) were recorded at nominal SI levels of 100%, 75%, 50%, 25% and 0%. Specific measures used to evaluate performance as a function of SI were categorized as follows: (1) Mission time -- Time to identify the target, Time to fire upon the target, Time to kill the target, and Time to accomplish the mission. (2) Mission completion -- Percent of targets identified, and Percent of targets killed; (3) Mission errors -- Percent of crew killed, Percent of times wrong target was killed, and Percent of communication errors; (4) Gunner accuracy -- Number of rounds required to kill a target; Aiming error. This report provides results from these performance measures and quantified the changes in armor gunnery performance as a function speech intelligibility. Keywords: Voice communications; Intercommunication systems.

In this report, the fundamental theoretical and applied principles are outlined, which have been cited to justify the relative benefits of object displays, the representation of several quantitative variables as features of single geometric objects. In particular, the proximity compatibility principle is described, which asserts that object displays will facilitate information integration tasks but will disrupt tasks that require focused attention on the individual dimensions of the object. Finally, an experiment is described contrasting three displays: a monochrome object, a multicolor object, and a separated bar graph display. Subjects were required to either integrate or focus attention on one of three sources of displayed information in an aircraft stall judgment task. Evaluation of the monochrome object revealed superior integration performance but degraded focused attention performance relative to the bar graph display, thus illustrating the proximity compatibility principle. The multicolored object, in contrast, emerged as a display concept that could potentially support accurate integration and focused attention performance, highlighting the role of emergent features and color coding, and suggesting some modifications of the proximity compatibility principle. The results are discussed in terms of their theoretical and practical application to multi- element interface design. (kr)

This report describes research that was performed at the University of Illinois Aviation Research Laboratory. This research examined how the human operator's ability to integrate multiple channels of information is influenced by stress and by display formatting which brings channels of information closer. In a series of experiments, it was concluded that information integration is facilitated by combining formation channels into a single object display and by the use of common color. These manipulations do not necessarily facilitate dual task performance or focused attention. Some important distinctions in the creation of object displays are also described. It was also concluded that the use of common perceptual modalities (all visual) or spatial proximity does not enhance information integration ability relative to dual task performance. The use of a single hand to perform two integrated response actions can facilitate performance, particularly if one action is continuous and the other is discrete. In some studies, the effects of mild stressors were imposed to enhance benefits associated with multi-task auditory displays and to enhance the benefits of object displays. (jes)

The traditional univariate analysis of the repeated measures design is obtained by treating subjects and their associated interactions as random effects. This analysis requires that certain variances and covariances of the dependent variable at various combinations of within-subject factors are equal. Instability of the variance and covariance components may mask significant effects and may compel the researcher to use a less powerful multivariate technique. The number of subjects required in the multivariate approach is a function of the number of dependent variables and levels of the within-subject factors. Thus, the researcher may be forced to use a conservative degree-of-freedom adjustment instead, which may mask significant results if subject availability is limited.

This document comprises a bibliography about tracking and related literature, with corresponding documentation in the form of indexed author and subject listings. Indexing was performed to enhance its utility as a reference. Topical subjects were distinguished after a review of citations revealed repeated mention. Generally, tracking is divided into compensatory tracking (such as driving a car while keeping the vehicle within the boundaries of the road) or pursuit tracking (such as aiming a gun at a moving target while keeping the gun sight directly on the target). This search was partly performed through computer inquiries using the National Technical Information Service's DIALOG information Retrieval Service, and the PSYCINFO service of the American Psychological Association. Sources were also manually extracted, including journal articles, Government and private sector reports, conference proceedings, and books. In some instances, direct contact was made with author(s). (rwj)

Recent events have increased interest in the ranges at which the helicopter crewman can be expected to detect and/or identify a target. Studies of air-to-ground target detection identification have all concluded with essentially the same results; a stationary, passive, noncamouflaged military ordnance type of target can be detected by an observer in a slow speed, 60 knots, low flying, less than 300 feet, helicopter at maximum ranges up to 2000 meters but cannot be reliably identified at ranges greater than 1000 meters.

This document is a review of the individual performances of the skilled aviators who participated in the US Army Human Engineering Laboratory Target Acquisition, Camouflage Application and Identification Friend or Foe tests and the Modern Army Selected Systems Evaluation Test, Evaluation, and Review Cobra/Tow Follow-On Evaluation. It highlights the individual performance differences in target detection and identification slant range and time and in eye fixations and scanning behavior against stationary and moving, camouflaged and uncamouflaged armor.

This report examines the effects of pictorial, abstract, and arbitrary shape coding on symbol perception and discrimination. This investigation also explored effects of varied or double border, regular or reverse screen, and augmentation coding. Perceptibility was assessed by measuring the time to detect a symbol's presence, recognize its coded affiliation, and identify its coded system type. Correct response times were analyzed with separate nested one-factor analyses of variance, and errors were analyzed with both confusion matrices and chi-square test. Discriminability was assessed by recording errors made while determining if sequentially presented symbols were identical. Errors were analyzed with both confusion matrixes and chi-square test. Correct detection and recognition times did not differ significantly; identification times did, however. Matrix analyses of discrimination errors showed that confusions resulted from the same factors that caused both recognition and identification errors. Chi-square tests indicated the scheme coded with varied or double borders and abstract shapes had a significantly greater number of discrimination errors than the one coded with regular or reverse screening and pictorial shapes, which had more than the one coded with augmentations and arbitrary shapes. Exit survey results confirmed earlier findings.

Because of the increased importance of conserving aircraft instrument-panel space, vertical-scale instrument displays are being given greater consideration. In an effort to identify any potential problems associated with vertical-scale instrument displays, a human-factors evaluation was performed on the production prototype of the vertical-scale instrument display for the OV-1D. Some of the factors considered in the investigation include light distribution, spectral analysis, impact on dark adaptation, high- ambient conditions, and night-vision-goggle compatibility. Recommendations have been made with respect to the light distribution and marking sizes.

Speech recognition technology could be especially advantageous to single-crewmember helicopters like the Light Helicopter Family (LHX). Before speech recognition can be considered a viable technology for helicopters, several issues remain to be resolved. One of these is changes in the voice that occur as a result of stress, noise, and vibration. This paper reports the results of an investigation conducted to determine the effect of vibration-induced changes in the voice on the accuracy of a speech recognition system. A series of flight tests were conducted using 12 participants and 8 different flight maneuvers. Data were collected with the participants speaking 50 phonetically balanced words into the speech recognizer while seated in the copilot's seat of a UH-1H helicopter during each of the 8 flight maneuvers. The results indicate that speech recognition system accuracy is not affected by helicopter vibration.

Noise produced by track-laying vehicles causes hearing loss, interferes with speech communication and provides aural detectability to the enemy. The purpose of this program is to develop noise reduction concepts and to develop the technology necessary to produce a lightweight, track-laying vehicle of the M113 family that has a sound pressure level of 100 dB(A). The earlier phases of this study rank ordered the major noise sources of the M113A1 armored Personnel Carrier, developed a preliminary mathematical model of the track and suspension, developed a high compliance prototype idler that provides over 15 DB(A) of idler dependent noise reduction, and developed an experimental compliant sprocket. Initial work was done to allow analytical prediction of changes in interior noise due to hull structure changes. The present study developed an experimental isolated roadarm assembly. The goal of 95 dB(A) for roadarm-induced noise along was closely approached. Noise-to-force transfer function measurements were made on this assembly mounted in an M113A1.

The advantages of electrical less-lethal weapons are discussed along with the general less-lethal weapon evaluation model. The basic electrical parameters of voltage, current, power and frequency are discussed. General data is developed relative to the physiological responses. A parameter termed as no- let-go current is considered and data values are presented to provide limits for both desirable and undesirable usage effects. These effects are discussed in some detail and related to application for a 50 kilogram man. Information required for utilization with the general less-lethal weapons evaluation model is assembled where feasible. Finally, two existing electrical less-lethal weapons are briefly discussed and their prime characteristics noted.

The AT-4 is a man-portable, 84-mm antiarmor weapon designed by the FFV Co. of Sweden who is represented in the United States by Honeywell Corp. This AT-4 evaluation was conducted in two parts. The first part addressed its durability, ruggedness, and compatibility with the marine rifleman's fighting load. This took place on the USAHEL (US Army Human Engineering Laboratory) cross-country and mobility/portability course. The second part examines the time it took marines to prepare the weapon for firing, and the frequency and type of errors they made during the preparation. Recommendations are made to improve the ruggedness, durability, and operational suitability of the AT-4. The AT-4 was found to be a rugged weapon that is fast and easy to prepare for firing. It was enthusiastically endorsed by the Marine test participants even though it is significantly larger and heavier than the lightweight antiarmor weapon (M72A1) with which they were familiar. Originator-supplied keywords include: Antitank weapons, Recoilless rifle, and Infantry weapons.

A literature review was conducted to examine helicopter external vision requirements and related visual display characteristics. Several articles are summarized in annotated bibliography format. A subsequent discussion section addresses the information contained in those articles as well as relevant information contained in other documents. Suggestions are made for future research. Keywords: Bibliographies; Rotary wing aircraft; External Vision; Field of view; Helmet-mounted display; Panel-mounted display; Resolution; Vision; Literature survey.

An investigation of the portability of medium antitank weapons was conducted at the request of the US Army Infantry School for the Improved Medium Antiarmor Assault Weapon (IMAAW) program. The purpose was to review and summarize the existing data base, to complete a man-portability matrix, and to provide guidance on the weight limitations for an IMAAW. The review of the data base supported the previously stated position of the US Army Human Engineering Laboratory (USAHEL) that Dragon is at or near the weight limit of portability for the infantryman. Conclusions were that the IMAAW gunner should be a dedicated gunner and should carry equipment reflecting that role. The IMAWW should weight no more than 30 pounds, if it is to be carried by one infantryman. If the weight of the IMAAW exceeds 30 pounds, the weapon should be crew-served. The man-portability matrix could not be completed because it was concluded that predictions of energy expenditure should not be used to evaluate portability.

U.S. Army Human Engineering Laboratory (HEL) Standard S-1-63C (September 1972) was the first design standard for noise in which all previous conflicts between U.S. Army medical guidelines and materiel design criteria were resolved. Its lineal descendent, MIL-STD-1474(MI) (March 1973), was the first design standard for noise in which all Army review activities concurred. This report treats the historical background of Army noise standards, the bases for the noise-limit provisions of MIL-STD-1474(MI), and considerations underlying the specified noise measurement procedures. Appendixes credit the many personnel involved, and an extensive list of references is provided.

The US Army Human Engineering Laboratory assessed possible degradation in the performance of missile repair persons while wearing NBC protective clothing. Nine male soldiers, just graduated from the Advanced Individual Training Course in Missile Repair, were required to perform repair tasks in three replications. Two repair tasks were chosen; one considered non- difficult whose activities concentrated on procedural diagnostics and fault isolation; the second considered difficult, required manipulating small machine parts and hand tools requiring fine eye-hand coordination. The experimental results and subsequent comparative statistical analysis showed no degradation in performance of the easier procedures and diagnostic task. The time to complete the more difficult task was degraded (increased) on the average of 45% in MOPP 4 with a definite contribution to degradation attributed to the mask/hood and the protective gloves by themselves. A significant improvement attributed to learning from the first to the second presentation was found, but not from the second to the third presentation. The participants' degree of learning was neither enhanced nor held back while in protective clothing as compared to working in the duty uniform.

The restraint system for door gunners in a UH-60 Black Hawk helicopter is equipped with tether straps that allow them to stand up from jump seats to engage targets while still being secured to the aircraft. This freedom of motion has resulted in the restraint system being inadvertently released by the buckle contacting the M60-D machine gun and the aircraft structure. This report evaluates modifications to the restraint system handle to prevent inadvertent releases. Keywords: Aviator's restraint system; Seat belts; MOPP (mission-Oriented Protective Posture).

Field tests conducted to obtain descriptions and comparisons, and evaluate tactical usefulness of antitank systems firing signatures. Two standard issue systems (the M72 LAW rocket and the M67 recoilless rifle), a proposed 81mm recoilless rifle system with two types of propellants, and a proposed 79mm rocket system with two types of propellants were fired in pairs. Five enlisted men served as downrange observers and judged the firing signatures and returned simulated counterfire. The reported tactical usefulness of signature components depended on the contrast ratio such that high contrast ratio for a component resulted in greater usefulness. Although all the candidate systems produced larger signatures than the LAW, the larger signatures did not prove to be tactically dramatically detrimental in terms of decreased post-firing survivability of the systems.

A field evaluation was conducted of a sight rib designed by the author to improve the pointing qualities of the M16A1 and M16A2 rifles. The sight rib is an integral part of a new upper handguard and bridges the space between the front sight assembly and the carrying handle. It is parallel to the rifle bore and creates a strong visual cue as to where the barrel is pointing. Past firing tests have indicated that such a cue would improve a shooter's ability to hit targets quickly when there is insufficient time to aim properly. Twenty seven combat arms riflemen participated in the evaluation. They fired at pop up E silhouettes emplaced in a fan at both 30 and 75 meters. The targets were presented for 2 and 3.5 seconds. Both range and exposure time were varied randomly. The test participants fired with both standard and sight rib equipped M16A1 rifles using both aimed fire and pointed fire techniques. Time to fire and hit or miss data were gathered for each target presentation so that the data could be graphed too show cumulative percent targets hit as a function of time. The results indicated that the sight rib on the M16A1 rifle significantly improved the soldier's ability to hit a target when the target is exposed briefly or the shooter fires quickly. Originator-supplied keywords include: M16/A1 Rifle, Small Arms, Quickfire, Sight Rib, Infantry Rifle, Pointed Rifle, Rifle Evaluation, Human Factors Engineering, Rifle Aiming Performance, Soldier Firing Performance.

A field test was conducted to evaluate pilotage-navigation performance using a forward-looking infrared (FLIR) night-vision system. Two types of displays (helmet-mounted and panel-mounted) were used, each with three fields of view (FOV) (narrow, 15 deg vertical x 20 deg horizontal; medium, 30 deg vertical x 40 deg horizontal; wide, 45 deg vertical x 60 deg horizontal). The results indicate that the wide FOV is more effective than either of the narrower FOV's. The future TADS system is proposed to have a horizontal FOV on the order of 40 deg; the authors believe this will present serious problems in conducting pilotage navigation. The implications of these results are discussed.

Cockpit lighting in U. S. Army helicopters was investigated for compatibility with use of night-vision goggles, AN/PVS-5. Instrument-lighting systems in existing Army helicopters, e.g., eyebrow lighting, post lighting, are not suitable for use with night-vision goggles. A comparatively simple flood- lighting system can provide suitable lighting in the cockpit of existing helicopters for reading instruments with night-vision goggles. The most suitable instrument-lighting system for use with the goggles is integral instrument lighting; however, indicator lights need to be modified so they are compatible with the goggles. Methods were investigated for instantaneously refocusing the goggles inside the cockpit. Luminance levels compatible for use with night- vision goggles are stated in photometric terms.

The report contains a compilation of data from a review of the available literature on the subject of cockpit lighting. The purpose of this review is to pinpoint areas where sufficient results have been obtained to prevent the repetition of similar studies. It is also the intent of the report to point out areas where future research is needed before improvements in current lighting systems can be made. The major areas of discussion are red versus white, major cockpit lighting problems, auxiliary lighting, glare reduction, luminance levels and legibility, and future considerations. Within each section, conclusions and recommendations have been made based on the information presented.