Robert C. Williges

Manipulating the response criterion in visual monitoring.

Forty-eight subjects were required to detect long-duration brightness changes (signals) and ignore short-duration changes (nonsignals) occurring on an electroluminescent panel during a 60-min. monitoring session. Signal-to-nonsignal ratios (constant 1/9, changing 1/9 to 1/1, or constant 1/1) and signal detectability (0.3 or 0.6 sec. difference between signal and nonsignal duration) were combined factorially in a between-subject design. The changing signal-to-nonsignal ratio resulted in an intermediate level of signals correctly detected. The classical decrease in percent of signals detected over time occurred in the constant 1/9 ratio condition under both levels of signal detectability. Signal detection theory analyses were restricted to low detectable signals. A marked increase in β over the monitoring session occurred in the constant 1/9 ratio condition, whereas β remained low and relatively constant in the other signal-to-nonsignal ratio conditions. Both the limitations of a decision-theory interpretation and the implications of using changing signal-to-nonsignal ratios for manipulating the observers effective response criterion were discussed.

Response Surface Methodology Central-Composite Design Modifications for Human Performance Research

Selected response surface methodology (RSM) designs that are viable alternatives in human performance research are discussed. Two major RSM designs that are variations of the basic, blocked, central-composite design have been selected for consideration: (1) central-composite designs with multiple observations at only the center point, and (2) central-composite designs with multiple observations at each experimental point. Designs of the latter type are further categorized as: (a) designs which collapse data across all observations at the same experimental point; (b) between-subjects designs in which no subject is observed more than once, and observations at each experimental point may be multiple and unequal or multiple and equal; and (c) within-subject designs in which each subject is observed only once at each experimental point. The ramifications of these designs are discussed in terms of various criteria such as rotatability, orthogonal blocking, and estimates of error.

Motion Relationships in Aircraft Attitude and Guidance Displays: A Flight Experiment

Sixteen nonpilot Naval ROTC students were tested on tasks involving conflicting visual and vestibular cues while flying with each of four basic aircraft attitude presentations (moving horizon, moving airplane, frequency-separated, and kinalog) in a Beechcraft C-45H airplane. Flight-director versions of each display presenting either compensatory or pursuit steering guidance were also compared on a command flight path tracking task involving random heading changes. For all attitude presentations, pursuit tracking was superior to compensatory tracking and the order of merit of the four attitude presentations in flight casts doubt upon the validity of previous simulator experiments. It was concluded that the principle of display frequency separation provides at least equivalent pilot steering performance to that obtained with the conventional moving horizon format, while the anticipatory cues it affords tends to reduce the incidence of control reversals under circumstances of subliminal angular acceleration by providing initial direction-of-motion compatibility.

The Transition of Experienced Pilots to a Frequency-Separated Aircraft Attitude Display

Independent groups of eight professional pilots each were given one flight in a Link GAT-2 simulator and one flight in a Beechcraft C-45H using, respectively, the moving horizon, moving airplane, and frequency-separated attitude displays. The flight tasks performed by the subjects included recovery from unknown attitudes, disturbed attitude tracking, and completion of an area navigation course. Data collected in the C-45H aircraft demonstrated superior performance of both the frequency-separated and moving horizon displays when compared to the moving airplane display during unknown attitude recoveries. The frequency-separated display was superior to all others during disturbed attitude tracking. It was concluded that the flight performance of experienced pilots during their initial transition to a frequency-separated flight attitude presentation is at least comparable, and for some tasks superior, to their flight performance with the conventional moving horizon presentation.

Applying Response Surface Methodology to Problems of Target Acquisition

To specify mans target acquisition capabilities and limitations, many equipment and situational variables as well as their interactions must be considered simultaneously. Response surface methodology (RSM), originally developed for use in the chemical industry, provides an experimental technique for collecting data on many quantitative variables at once in order to develop a multiple regression polynomial equation which describes the functional relationship between a performance score and the experimental variables. This equation, in turn, can be used to predict target acquisition performance. Besides the mathematical advantages of RSM, the technique provides the human factors engineer with the additional advantages of economy in data collection, flexibility in experimental approach, and efficiency in controlling undesirable fluctuations.

Aircraft Simulator Motion and the Order of Merit of Flight Attitude and Steering Guidance Displays

Twenty-four nonpilot, volunteer subjects were tested on three flight tasks while flying four basic aircraft attitude presentations (moving horizon, moving airplane, frequency-separated, and kinalog) in a light twin-engine aircraft simulator providing three types of motion cues (no motion, standard GAT-2 motion, and washout motion). The flight tasks involved conflicting visual and vestibular cues and included disturbed attitude tracking, command flight path tracking in both pursuit and compensatory modes, and a series of recovery trials from discrete unknown attitudes. To provide a basis for comparison, the present simulator study closely replicated the procedures used in the Roscoe and Williges (1975) flight experiment. The frequency-separated display yielded performances at least equivalent and in some cases superior to those obtained with the conventional moving horizon display. Either type of simulator motion resulted in better disturbed attitude tracking performance than no motion, and washout motion provided stereotypic control responses in recovery from unknown attitudes most closely corresponding to those obtained in flight. It was concluded that care must be used in generalizing simulator results to flight performance when no physical motion cues or inappropriate ones are present in the simulator.

Synthetic Flight Training Revisited

Critical issues in the development and use of synthetic flight trainers are reviewed. Degree of simulation and fidelity of simulation are discussed as key design considerations. Problems in measurement of original learning, transfer, and retention are presented. Both transfer effectiveness and cost effectiveness are described as critical factors in the evaluation of flight trainers. Recent training innovations, such as automatically adaptive training, computer-assisted instruction, cross-adaptive measurement of residual attention, computer graphics, incremental transfer effectiveness measurement, and response surface methodology, are discussed as potential techniques for improving synthetic flight training. It is concluded that broader application of simulation is necessary to meet the new demands of pilot training, certification, and currency assurance in air transportation.

Software Interfaces for Aviation Systems

Publisher Summary As aviation systems become more computer dependent, the emphasis on user-oriented software design must increase to improve user acceptance, system efficiency, and safety. Human factors considerations in the design of computer-based aviation systems must address both the issues and the process of software interface design. These interfaces must incorporate fundamental principles and guidelines of the human–computer dialogue design that are tailored to the specific functions performed by pilots, controllers, and others who interact with computer-based aviation systems. Software functions that are relevant for the design of aviation systems include data entry, data display, data management, action control, feedback and user guidance, error management, data protection, language, and communication between users. In parallel with the development of human factors design guidelines and tools to use them, the software design process itself needs to be considered. The concept of layering software into computation and HCI components is central to the design of software for aviation systems. The design process for computational software for aviation systems must provide for software maintenance and must address the complexities of real-time operation, concurrency, and fault tolerance. HCI software must take into consideration the capabilities and limitations of the pilots and controllers who will use it, and iterative redesign is key to successful HCI software for computer-based aviation systems.

Simulator Motion as a Factor in Flight-Director Display Evaluation.

The results of research conducted in ground-based flight simulators must be interpreted with care in view of the potential effects of differences between the simulated and actual flight environments. A study comparing various flight-director displays in a moving-base simulator was replicated without motion. Significantly different results occurred as a function of the presence or absence of motion. Implications of these results raise doubt concerning the validity of findings from simulator experiments in which whole-body acceleration cues might be a factor.

Transfer Assessment Using a Between-Subjects Central-Composite Design

Transfer of training from a pursuit rotor to an epicycloid pursuit rotor was assessed by means of a response surface methodology (RSM) central-composite design. Number of training trials, time between training trials, and tracking speed of the training task were combined in a three-factor, RSM central-composite design. Multiple-regression prediction equations relating these three independent variables to trials to criterion on the epicycloid pursuit rotor were calculated for both an unreplicated and replicated RSM design. A representative first-order response surface was plotted for the replicated design. The results are discussed in terms of necessary RSM central-composite design modifications and the overall applicability of using RSM in transfer of training research.