Russell L. Smith

Vigilance Research: Its Application To Industrial Problems1:

Review of the vigilance literature of the past two decades reveals that the results of most studies have questionable application to industrial inspection tasks for which they were, in part, designed to investigate. It is concluded that: (1) little or no evidence exists indicating that the oft-found decrement in the laboratory has a parallel in the industrial (or military) setting; (2) motivational variables may comprise the key to explaining the decrement and general law level of performance; (3) the decrement may be an artifact arising from a general failure of subjects to follow experimental instructions; and (4) many characteristics of inspection tasks bear little resemblance to those of vigilance tasks. These conclusions are supported by a body of evidence which can no longer be ignored by the serious investigator seeking to understand vigilance behavior and expecting to generalize his results. Redirection of vigilance research and greater experimental control are emphasized.

The Status of Maintainability Models: A Critical Review

Significant milestones in the development of maintainability assessment techniques are summarized. Maintainability models are critically reviewed in terms of general utility, ease of application, validity, and use of human engineering data. The capability of each model to be employed during various points in the system development cycle is evaluated with special consideration given to availability of model input data. Examples of potential model approaches are included. Survey results show continuing progress toward the potential development of efficient maintainability modeling techniques. However, increased effort is required to ensure the development of effective systems and to reduce maintenance costs. Emphasis is given to requirements for additional effort in (1) maintainability modeling early in the design process, (2) model validation, and (3) development of timely, valid input data.

Effects of Display Magnification, Proprioceptive Cues, Control Dynamics and Trajectory Characteristics on Compensatory Tracking Performance

An experiment was performed on the NOTS-UCLA heavy inertia tracking simulator to assess effects of display magnification, proprioceptive cues, displacement aiding, trajectory characteristics and trajectory direction on tracking performance. Particular attention was paid to interactions among these variables. The results showed that: (1) 5x magnification significantly decreased tracking error compared to tracking without magnification; (2) proprioceptive cues related to both azimuth and elevation significantly improved performance; (3) velocity plus displacement-aiding control dynamics (time constant = 0.1 sec) produced significantly lower error scores than unaided velocity control dynamics (time constant = 0.0 sec); (4) since no crossover tendencies were found, the effects of the varables appear to be independent.

Acquisition of Restore Time Data by Subjective Techniques

Abstract : The high costs of obtaining equipment repair time data by observational methods discourage acquisition of data for maintainability models. This state-of-affairs suggests the less costly alternative method of acquiring these data by subjective techniques. The study sought to explore this method by requesting experienced Air Force electronic technicians to provide repair time estimates on 23 electronic equipments. Validation work was not possible within the constraints of this study, but a series of analyses, including a comparison of the estimates with corresponding data in the Air Force AF 66-1 reporting system, suggested that the estimates may have practical validity. (Author)

Independent effects of error magnification and field of view on compensatory tracking performance

This experiment evaluated the independent effects of error magnification and field of view on compensatory tracking performance. Both display and optical magnification were investigated. In general, the results demonstrated that: (1) the facilitative effect on performance of display magnification was primarily due to the concomitant field of view reduction and not magnification per se; (2) optical magnification facilitated performance but subsequent display gain increases had no further affect; (3) regardless of visual mode employed, optimum performance levels on a complex trajectory converged at approximately the same field of view. In was suggested that increasing the optical gain or decreasing the field of view resulted in subjects reducing their reaction times to target movements. No evidence was found which indicated that magnification facilitated visual perception.