Human Factors: The Journal of the Human Factors and Ergonomics Society

The system design trade study process was investigated to determine the feasibility of including human resources data. First, 61 completed trade studies from aeronautical, missile, and command and control systems were analyzed to determine the characteristics of trade studies. Then, four simulated trade studies containing engineering and human resources data and representing flight control and avionics subsystems were constructed for experimental use. Seventy-two experienced design engineers performed the simulated trade studies.

It was found that engineers can and do use human resources data in system design trade studies. Personnel costs and quantities are assigned more weight than skill types, skill levels, and availability of personnel. A detailed presentation of human resources data is given more weight than a condensed presentation. Four major sources of variability in trade study results were found. These are: choice of parameters, weighting factors for the parameters, methods of normalizing the parametric data, and methods of combining parametric data and weighting factors. Standardization of trade study methods is recommended to help overcome this variability.

This study was performed in two phases. The first phase concentrated on the influence of avionic design and technical training factors on student performance. The second phase dealt with the impact of design and personnel factors on the performance of technicians in operational Air Force units. Avionic components were scaled on a variety of design characteristics, and data were collected on the task time and error performance of students and technicians performing a functional checkout maintenance task on the components. Personnel data were also obtained on each subject. Multiple-regression equations were then developed to predict task performance from design characteristics and personnel measures. The multiple R's for students were 0.90 for time and 0.82 for errors. The multiple R's for technicians ranged from 0.60 to 0.88, depending on the type of maintenance and criterion measure used; all R's were significant at the p < .001 level.

A survey was conducted within the Navy's research and development community to obtain information on user-perceived needs for human performance and personnel resource data to support system development efforts. Findings were to be used to develop guidelines for planning and developing a human resources data store system. Twenty-two activities were contacted: eighteen Navy activities and four industrial firms. Thirty-seven separate interview sessions were held involving 48 respondents.

Principal data store guidelines identified concerned data validity and generalizability, retrievability, a priority need for design trade-off decision data, and a data format responsive to users with either behavioral or engineering backgrounds. Sixteen types of data were identified as required by system planners/managers, human factors specialists, and design engineers. Twenty guidelines were developed on data presentation formats and supporting information. The sets of guidelines may be used to develop a conceptual framework for a general data bank system which would identify and relate users, types of data, potential data sources, and program priorities.

The modern organization structure — whether in the public or private sector — is composed of a highly unpredictable resource: people. They enter the organization at different points and bring to it an almost infinite variety of skills. The staffing of an organizational entity, therefore, contains many uncertainties. To reduce the effect of these uncertainties, the authors have developed a sophisticated human resources forecasting system using computer-based modeling and simulation techniques. This model was designed and developed for use in a large branch banking system operating statewide. It is, however, applicable for use in other industries having different organizational structures. The Manpower Planning Quotas model (MPQ) is a tool which permits management to experiment with alternative staffing policies to achieve an optimum level of qualified personnel.

The question of how to obtain a specified quantity of satisfactory manpower inputs for a given time period is a problem which confronts almost any personnel decisionmaker. The staffing model proposed in this paper defines selection, training, and any selection/training combination as being alternative staffing strategies which are available for coping with an organization's manpower requirement problems. Very few personnel decisionmakers, however, approach such problems with any appreciable knowledge of the relative costs associated with different alternative input strategies and of the costs of different misclassification errors which can result.

The staffing model described here incorporates cost and utility considerations and suggests that the relative costs of alternative staffing strategies are amenable to systematic analysis. The model specifies the probability estimates for success and failure in both selection and training, the direct costs for each, and the potential costs which result from errors of misclassification. Then, an expression and rationale for determining the minimum total cost associated with various combinations of selection and training strategies are presented.

To date there has been no cohesive examination of the interrelationship between new technology and manpower resources. Most studies have reflected the disciplinary bias of economists or technologists. Economists have stressed supply and demand factors and the role of new technology on increase in productivity. Technologists have stressed the deterministic effects of new technology.

This article synthesizes theories and findings from behavioral and social science and the field of management, as well as from economics and technology, within the framework of systems science. In sequence, the article discusses: the sociotechnical system environment in which the interaction between new technology and manpower resources takes place; the measurement of technological change; how technological change affects manpower; the prediction of skill and manpower requirements; and electronics-based computer-communications technology. The needs for advances in theory and methodology are argued. The elements of a systems theory are sketched, and the value of the systems dynamics approach to modeling and computer simulation is emphasized.

Forty student drivers received various amounts of driving simulator and film-only pretraining to determine the transfer effectiveness of open-loop simulation using passive instructors in a driver education program. To measure the effects of previous driving experience, the simulator performance of eight licensed drivers was compared to the student drivers. Early in simulation, licensed drivers exhibited reliably better steering performance than the 6-hr. simulation pretraining students, but the reverse was true late in simulation. Six hr. of pretraining yielded significantly better transfer in terms of overall automobile driving performance on a McGlade Road Test than 3 hr. of pretraining regardless of whether the pretraining included instructional films alone or films used in conjunction with simulators. A component analysis of the first hour of driving performance revealed that the 6-hr. pretraining groups were superior to the 3-hr. group on a procedures dimension. In addition, the film-only pretraining groups were superior to the simulator groups in terms of a steering dimension during the first hour of transfer. Implications of these results are discussed in terms of improving simulators used in driver education.

Two experiments are described in which the effect of nontargets in positions immediately adjacent to the target (target surround) on visual search times was examined under two background conditions. The target in the first experiment had a higher luminance than the background elements; in the second experiment the target was a “double-dot”, i.e., two background elements immediately adjacent. The backgrounds used were statistically generated using the parameter probability of transition (P_t) from the state “dot to no dot” to determine presence or absence of nontargets in the display matrix. When P_t=0.5, a random background was generated and when P_t = 0.25, a constrained background was produced. Constrained backgrounds are those in which some grouping is imposed on the elements of the background.

For both background conditions, mean search times increased sigmoidally as a function of the number of nontargets in the target surround. Search times were longer for unconstrained than for constrained backgrounds. A search strategy is suggested which would produce these results; further experiments are suggested to test the validity and generality of these concepts in visual search experiments.

The effect of scapular restriction on the manual work space of 20 subjects was studied. The three-dimensional method to determine work space is presented. The work spaces of the extremity when unrestricted and when restricted by a shoulder harness are compared. The restriction of scapular movement reduced the work space volume by 54%. Less difference was found in the volumes of the restricted and unrestricted work spaces at the extreme anterior and posterior areas of the work space. Volume differences were greatest in the intervals immediately in front of the body. The work space was decreased in the areas above shoulder level due to restriction of the scapula. The lower regions of the work space, over the knees, showed minimal differences due to restriction. There were also changes in the bimanual work space when one scapula was restricted.

A Coriolis test on the USAFSAM biaxial stimulator was administered to 131 pilots. Two groups of pilots (“rested” and “fatigued”) were tested twice. Some of the pilots in each group got motion sickness during the initial test period. A two-parameter analog, measuring the rates of decay and sensitivity coefficients of vertical nystagmic responses, was used to compare the effects of fatigue and induced motion sickness on the nystagmic responses induced by Coriolis accelerations.

Fatigue, in terms of moderate sleep deprivation of 24 to 30 hr., had significant deleterious effects on the vestibulo-ocular responses. Fatigue and induced motion sickness, simultaneously occurring, showed further deterioration of the vestibular system when compared with the nystagmic responses of rested and nonsick pilots. Such results indicate that fatigue and induced motion sickness make flying even more hazardous.

A simple (one-channel) or a complex (three-channel) vigilance task was administered with or without threat of shock to a large group of flight students. It was found that a larger absolute decrement was obtained in the complex task, but the relative decrements were equivalent for both. One-channel monitoring was better overall than three-channel monitoring in the non-stressed condition. Stressed subjects performed better than nonstressed, and this enhancement was greater for three-channel monitoring.