Proceedings of the Human Factors and Ergonomics Society Annual Meeting

Power boat operators' visual characteristics were recorded with a corneal reflection eye movement system in order to determine their foveal fixations. Data were collected while three (3) subjects performed three (3) different types of navigation tasks at three (3) velocities in two (2) boating environments.

Results indicate that boaters scanned a significantly larger area to the right of the vessel during a limited access water condition than during an open water condition. More fixations to the right of the boat during a limited access water condition may be related to the fact that their cockpit station is on this side of the vessel. A significant velocity-navigation task interaction was observed for the duration parameters. It has been speculated that this effect was due to a speed/accuracy trade-off. During a channel task with increased velocities, the durations increased. McDowell (1975) related similar increases in automobile drivers' durations to processing information more accurately. The decrease in durations, which the boaters exhibited during compass and visual reference tasks, may be related to an increased information processing rate.

Corrective lenses are normally prescribed to correct the refractive errors of the eyes to give good visual acuity at distance (6 m). When presbyopia is present, a convex lens addition (bifocal power) may be included as part of the near correction to move the near focussing point back into the normal reading range (36 to 46 cm). The advantages gained by these corrections may be minimal, or even detrimental, to visual acuity at the intermediate range. A study was undertaken to determine the functional visual acuity of presbyopic individuals at the intermediate visual range with and without the best near and best distant vision corrections.

Review of the literature concerning the relationship of biorhythm theory to human error accidents indicates there is much inconsistency. This study attempted to resolve some of the existing variability through careful selection and statistical analysis of a driver-error subject population. Fatalities involving 506 U.S. Naval off-duty personnel were examined. Birth dates were compared with accident dates to determine if the differences between observed and expected accident frequencies were significant. No chi-square values were found to be statistically significant at the .05 level. It was concluded that biorhythm is not a useful accident prevention aid. Inconsistency in human error research will continue to be reported until experimenters more precisely define birth and accident times and combine this information with more rigidly designed research methodology.

Biological rhythms in physical, emotional and intellectual states in humans are discussed. Both popular and scientific views of biorhythms are given and compared. The popular view is found to be inconsistent with scientifically-collected data. Data on real biological cycles and examples of individual biorhythms are given. The significance of accepting and using biorhythmic phenomena is briefly discussed.

Independent groups of male college student volunteers were exposed in a standard seated posture to one of 5 conditions of vertical (Z-axis) harmonic oscillation for two hours or until vomiting. A control condition, sinusoidal motion at 0.17 Hz with a root mean square acceleration of 0.13 g, served as the basis of comparison with the remaining four conditions, which were generated by the sum of two sinusoids, namely, the fundamental at 0.17 Hz plus the second (0.33 Hz) or third (0.50 Hz) harmonic. The experimental conditions differed either in the phase relationship or the relative acceleration level of the added harmonic. The predicted motion sickness incidence (MSI) was calculated for each sinusoid alone from a previously derived mathematical model and compared with the obtained MSIs. While the overall differences may have been due to chance, certain motion combinations provoked unexpectedly high MSI. No simple relationship between predicted MSI for single-frequency motion and the obtained complex-motion MSIs emerged from this study. Until further data are forthcoming, guidelines for motion sickness prevention based on the presumption of independence of action of component frequencies in a complex motion must be interpreted with caution.

This study was conducted to determine the differential effects on women's psychomotor performance of wearing cold weather clothing designed for them vs. cold weather clothing designed for men. Twenty women performed a battery of tasks under each of 10 clothing conditions. The tasks were divided into the following categories: (1) body flexibility, (2) rate of movement, (3) psychomotor coordination, and (4) manual dexterity. The results indicate that certain features of women's cold weather clothing, particularly fit, contribute to higher performance levels than those attained with men's clothes.

The mining industry has been correctly regarded for many years as an extremely dangerous one. In addition to the many hazards inherent in the mining environment itself, miners have had to cope with poorly designed equipment and jobs, inadequate training, and inept supervision. Recent efforts of the U.S. Bureau of Mines and a number of contractors have brought current technology to bear toward the solution of these problems.

The purpose of the present investigation was to initiate the development of a standardized methodology for use in conducting human factors evaluations of trucks and similar vehicles within the context of operational field tests. The methodology focuses on the assessment of users' (drivers') judgments of the vehicles being evaluated and allows for the differential weighting of individual human factors characteristics. The methodology is presented, including recommended statistical analysis procedures. The key to the methodology is the Human Factors Vehicular Evaluation Instrument which is an interview form containing eighty-five human factors characteristics relevant to vehicle design and operation. Data is presented from the initial utilization of the methodology in an operational field test.

The maximum capability of weak females to actuate manual brake systems and power brake systems with power failure depends upon a number of variables. The following variables will be discussed and preliminary conclusions made on their quantitative effect: percentile of population to be covered, sex, age, force within a trial, repeated trials, left vs right foot, static vs moving vehicle, location of pedal to driver and seat, and preferred seat location.

Using many assumptions and skimpy data, a 5% USA female, seated in a properly adjusted seat, for a panic stop will exert about 215 N in a moving, full-size USA vehicle with power brake failure.

In Experiment I a total of 30 subjects used the device to scan bar code patterns of varying position, orientation and width. The strongest main effects on the dependent variable, proportion of labels scanned in error, were observed for the independent variable, label width. Label widths of 0.1 inch produced error rates of 58.2 percent compared to error rates of 29.6 percent and 24.8 percent for 0.2 inch and 0.3 inch width labels, respectively. Experiment II examined learning effects and showed that label scanning accuracy leveled off after scanning 400 to 500 labels.

The purpose of this paper is to examine some of the problems presented by the wearing of a helmet in the sensing of information necessary for safe operation of a motorcycle. The paper is organized into three major areas. One area is concerned with a laboratory study of simulated motorcycle operation and the sensing of sirens and horns of motor vehicles at various distances for subjects wearing helmets and subjects who served as control that wore no helmets. The second study reported is a parallel to the laboratory study but it was conducted in an outdoor setting. The third area considered is a biomechanical analysis of the head and neck of a motorcyclist who sustains a blow to the head in an accident.

The independent variables investigated in the two studies of auditory sensing were the type of helmet worn, the type of auditory information being presented to the subject, and the direction from which the auditory signal was presented to the subject. A motorcycle helmet with a full face shield and one without a full face shield were compared with a control level of a subject wearing no helmet. A warning siren and a motor vehicle horn were the two types of auditory signals presented to the subjects. The four directions of presentation of the auditory signal were front, rear, left and right.

Both of these tests of the ability of the motorcyclist to detect the two auditory signals indicated that the helmet did significantly attenuate the signal and that the emergency vehicle siren or horn would have to be dangerously close to the cyclist before it could be heard as compared to the cyclist under the same conditions who was not wearing a helmet.

The alleged problem of motorcycle helmets producing injuries to the cervical spine in certain types of impact situations was analyzed from a biomechanical standpoint. Some helmet designs were found to be capable of producing an injury to the neck for certain crash configurations between the helmet and a solid object. Suggestions are presented for modification of helmet design to significantly reduce the injury potential of the helmet for this type of injury, while at the same time protect the head from other types of injury.

Because of the limited dynamic range of most display devices, potentially available sensor information may not be optimally displayed for use by an operator. Generally, some portions of a scene will be dark while others will be very bright, and it is often difficult to obtain an acceptable value of video gain. A gain setting which provides good contrast in the darker portions of the image results in saturation of the display and a loss of detail in the light portions of the scene. Local Area Brightness and Gain Control (LABGC) is an image processing algorithm designed to increase contrast in local areas of the display without causing saturation in other areas, thereby providing greater displayed detail. It is a contrast enhancement technique that automatically adjusts display brightness and gain in an effort to retain the maximum sensor video dynamic range while operating within the constraints of a limited dynamic range display device.

Three general classes of image enhancement techniques for synthetic aperture radar (SAR) video were investigated through non-real-time computer simulation. The general categories were 1) monochromatic adaptive gray shade transformations, 2) pseudocolor encoding, and 3) feature analytic methods. The class of feature analytic techniques was found to have the greatest potential for improving the operational utility of SAR imagery.

The maximum entropy spectrum (MES), a sampled data power spectrum estimator, is applied to the enhancement of imagery obtained by synthetic array radar (SAR) imaging systems. MES offers better frequency resolution than conventional Fourier transform methods for certain signal classes. Since azimuth ground resolution in SAR systems is obtained by doppler frequency measurement of the radar return, the method is capable of enhancing the resolution of SAR maps. The principal signal requirement is adequate signal-to-noise ratio. The maximum entropy method has been tested using data obtained by the Hughes FLAMR radar system. The super-resolution capabilities of the method are demonstrated using FLAMR images of corner reflector arrays.

A radar target acquisition research study was conducted to access the effects of two levels of 13 radar sensor, display, and mission parameters on operator tactical target acquisition. A saturated fractional-factorial screening design was employed to examine these parameters. Data analysis computed ETA² values for main and second-order effects for the variables tested. Ranking of the research parameters in terms of importance to system design revealed four variables (radar coverage, radar resolution/multiple looks, display resolution, and display size) accounted for 50 percent of the target acquisition probability variance.

A number of mathematical models of target acquisition have been developed to predict the performance of electro-optical sensor systems. None of these models, however, adequately treat the influence of the background scene on operator tactical target detection and recognition. Most assume a uniform background of some average luminance: a situation that is unlikely to occur in any realistic mission. The failure to include the influence of backgrounds of varying complexity may result in erroneous predictions of performance that are highly optimistic. The reported research was directed toward the issues of background scene complexity. The data are interpreted as evidence for a two-component model of target search and detection.

A study was conducted to determine the effects of illumination, velocity and knowledge of results on distance judgment accuracy in simulated night NOE flight. Twenty subjects were randomly divided into KOR and NK groups and then shown a part task, video tape simulation of NOE flight which contained 45 target presentations. The subject's task was to approach the obstacle on a collision course until he reached his minimum safe breakaway distance, then make an avoidance response with his simulated control stick. Illumination, velocity and feedback conditions were varied while measuring the accuracy of response in terms of mean error distances from the analytically determined breakaway point. The results indicated that reductions in illumination, given that the object is visible at all, had no significant effect on distance judgment while both feedback and reduced velocity produced improved accuracy. The results were interpreted in terms of their interactions and then translated to operational suggestions concerning training for NOE pilots.

The emphasis on aviator workload has been of primary concern to the US Army aviation community since the incorporation of low altitude terrain flight techniques into the helicopter tactics repertory. Since navigation has been a particularly acute problem at low altitudes, this project examined the visual workload of the navigator/copilot during terrain flight (nap-of-the-earth, contour and low level) in a UH-1H helicopter. Visual performance was measured via a modified NAC Eye Mark Recorder used in conjunction with a LO-CAM high speed camera. This technique provided the means to objectively record and analyze the navigator's visual performance through the examination of: (1) visual time inside the cockpit on flight and engine instruments, (2) time inside the cockpit on the map or other navigation aids, and (3) time outside the cockpit in various windscreen sectors.

A visual free time task (Strother, 1973) was utilized to determine the amount of visual time the navigator had available, during flight over the prescribed course, for a nonflight related task. The data indicate that the navigator's normal workload was demanding; the visual free time task was utilized only 3% of the total time. The data also indicate that the duty of navigating required 92.2% of the copilot's total visual time while the engine and flight instruments were utilized only 4% of the time. These data are discussed in relation to the copilot's specified duties.

A pursuit tracking task in three-dimensional space was studied in order to assess the impact of depth perception on human operator performance in manual control. Performance scores and frequency response data were collected and analyzed for three modes of display as defined by the angular relationship between the human operator's line-of-sight and the line segment representing the tracking error. When depth perception had to be completely relied upon, a significant decrement in performance occurred and was accompanied by the introduction of phase lags in the human operator's response.