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The purpose of this paper is to explore human environmental factors which appear to be directly related to one's decision to participate or not to participate in sport and physical recreation. More specifically, the paper is focused upon certain factors within the child's sports environment which have been shown to influence his attraction to or avoidance of sports participation. Three major behavioral determinants (role models, expectancies, and reinforcements) are examined and discussed. An attempt was made to obtain some information on the question of why, when given an equal opportunity, some children will participate in sport, while others will not.

This paper provides the background for the following papers with respect to the general purposes and objectives of the conference of which those papers were a part. The basic point of departure of the conference was the measurement of performance that could be considered to be relevant to the requirements placed on the human operator by operational systems. The primary points for consideration related to practical research design requirements such as validity and reliability.

This paper describes methods presently being used by the Research Staff of New York University to evaluate the important parameters of human body segments: mass, volume, center of mass and mass moment of inertia. Previous studies in the field are reviewed with regard to data obtained and subjects used in the investigations. Sources of difficulty in the proper solution are discussed in order to formulate the best procedure, followed by a description of the techniques now being employed. The paper concludes with a look into future applications of body segment parameter data.

This paper summarizes the discussion elicited by the preceding papers. Subsequent to the conference, the tape recordings of the discussion were perused and a series of statements were identified as representing possible points of agreement on the issues considered. These statements were evaluated by 15 people who participated in the conference on a semantic differential scale (agree vs. disagree). The most important conclusions relate to the criterion problem, task taxonomies, the reliability of measures, and the role of face validity in the design of research apparatus.

This paper considers social interaction within sports, and offers a number of theoretical constructs which might be utilized in the analysis of the athlete-coach relationship. These constructs are to some extent interdisciplinary, and range from a social-systems framework to a social-action perspective.

Motor performance calls into play a number of complex physiological and biological systems. An understanding of the function and behavior of such systems is necessary if motor performance is to be properly analyzed and helpful if it is to be improved. The concepts of systems and control theory offer a powerful (though sometimes not fully exploited) methodological technique for achieving such an understanding. This paper discusses some of the elementary concepts of systems theory as applied to motor performance and presents qualitative discussions of its usefulness in that field.

The reporting of sports injuries has been generally inconsistent with modern epidemiological principles. Because of the approach to recording the incidence, nature, and severity of sports injuries, it is very difficult to assess statistically the risk factors of individual activities. Without this knowledge, one cannot isolate the many variables, both overt and covert, which contribute to injurious situations. Recommended practices are included within the paper.

This paper explores the problem of the adequacy of personnel performance testing on a current Ballistic Missile Test Program. It advances the thesis that criteria for judgment of technical worth must consider program/system requirements and cost-effectiveness. Examples of three categories of human performance testing on the Minuteman Ballastic Missile Program are described.

One of the most important problems in the design and/or operation of a computer utility is to obtain dynamical characteristics that are acceptable and convenient to the on-line user. This paper is concerned with the problems of access to the computer utility, response time and its effect upon conversational use of the computer, and the effects of load on the system. Primary attention is placed upon response time; rather than a single measure, a set of response times should be measured in a given computer utility, in correspondence to the different types of operations requested. It is assumed that the psychological value of short response time stems from a subjective cost measure of the user's own time, largely influenced by the value of concurrent tasks being postponed. A measure of cost (to the individual and/or his organization) of the time-on-line required to perform a task might thus be derived. More subtle is the problem of the user's acceptability of given response times. This acceptability is a function of the service requested (e.g., length of computation), and variability with respect to expectations due both to uncertainty in the user's estimation and to variations in the response time originated by variable loads on the system. An effort should be made by computer-utility designers to include dynamic characteristics (such as prediction of loads and their effects) among their design specifications.

In a previous communication we reported data supporting the recommendation that a red road traffic signal should have an intensity of 200 cd for optimum recognition from 100 m when the signal is seen against a very bright sky (104cd/m2). This confirmed the earlier result of Boisson and Pagès. The present paper extends the data to include (a) the effect of signal size on optimum signal intensity for a practical range of angular diameters (4.1 to 16.5 min of arc), and (b) the effect of background luminance for a range of luminances of 1.5 ft-L to 2250 ft-L. The results show that optimum signal intensity is independent of signal size and that spatial summation by the visual system is complete. However the same data demonstrate a failure of spatial summation when a conventional threshold criterion (probability of seeing the signal 0.5) is used. It is shown that smaller signals will be more effective than larger ones of the same intensity if their intensity is less than optimum. Optimum signal intensity is shown to be a linear function of background luminances greater than 10 ft-L. A graph relating optimum signal intensity to signalling range for various background luminances summarises the experimental data.

This paper describes and gives the basis for a Display Evaluative Index (DEI) technique, a calculational method for deriving a figure of merit of the effectiveness of displays of a particular equipment to transfer information to the operator and for the operator to act on that information and perform the appropriate control action. Reliability, validity, and discriminating power results are reported to be satisfactory.

This paper discusses the rationale for analysis and definition of flight crew training requirements. Using the Instructional System Approach, the concept of flight crew performance from a management aspect is presented together with methods for determining detailed flight crew training requirements.

This paper presents an analysis of swimming motion with specific attention given to the flutter kick, the breast-stroke kick, and the breast stroke. The analysis is completely theoretical. It employs a mathematical model of the human body consisting of frustrums of elliptical cones. Dynamical equations are written for this model including both viscous and inertia forces. These equations are then applied with approximated swimming strokes and solved numerically using a digital computer. The procedure is to specify the input of the swimming motion. The computer solution then provides the output displacement, velocity, and rotation or body roll of the swimmer.

This paper is concerned with the important visual variables that determine image quality on computer-controlled CRT displays. A strategy is developed that leads to general conclusions about each variable even though most of these variables interact. For each variable considered, the recommended range of values is determined on the basis of experimental evidence and is compared with the values presently used on displays. Where discrepancies between these two exist, alternative solutions are mentioned. Conclusions are(i) presently used values of display luminance, chromaticity (color), and resolution are adequate; (ii) several displays flicker; (iii) characters are large enough but may be marginal in terms of number of elements; (iv) luminance contrast is not adequate.

This paper describes a quick economical method for determining the maximum range at which camouflaged targets can be detected. The method produces results which agree within 10% of those obtained by conventional psychophysical methods.

Human factors scientists often work closely with operations analysts in the investigation of social, business and man-machine systems within viable operational organizations. The human factors approach to such operational concept studies should be commensurate with that of the operations research worker. One approach to such methodology is described in this paper as is a description of field data sources available to the Army.

The advent of computer time sharing poses an extraordinary challenge to human factors research during the next decade. Before time sharing, two facts combined to de-emphasize the importance of human factors considerations in the design of computer systems: (1) the cost of the computer's time was exorbitantly high relative to the cost of users' time, and (2) the users constituted a select, highly skilled and highly motivated group of specialists. Two of the promises of time sharing, however, are (1) a drastic reduction in the cost of computer time to the individual user, and (2) the large scale availability of computer facilities to individuals untrained in any areas of computer technology. Human factors considerations then become important both for economic and psychological reasons. This paper briefly notes what a few of these considerations are.

This paper is an evaluative review of the literature concerning the locations of the centers of gravity of the human body and body segments. Data from several sources are compared and the methods and limitations discussed. It is shown that the selection of source and the manner of applying center of gravity data will depend on (1) the accuracy required, (2) anthropometric characteristics of the population under study, and (3) equipment and body positions anticipated.

The purpose of this paper is: (1) To review the rationale of measuring operator workload in terms of auxiliary, or secondary task performance scores; (2) To summarize the important characteristics of suitable loading tasks; (3) To describe several loading tasks which have been used or which are potentially useful; and(4) To suggest the development of a set of standardized tasks which would be useful in obtaining more nearly comparable measures over a wide range of primary tasks.

An effort was made to locate representative data on human activities in complex operational systems. Very little operational data were found which were suitable for our purposes. Therefore, this requirement was compromised and activity data from tests and paper and pencil analyses were used. These data were then classified by two raters according to an adopted taxonomy. It was generally concluded that where activity data have been gathered under operational conditions, they have been useful to design engineers, human factors specialists and systems analysts. It is further noted, however, that additional effort must be devoted to the development of better methods for obtaining data and corresponding criteria of human performance under operational conditions. A discussion of the taxonomy and other techniques indicated that collection of activity data should be feasible under operational conditions. In addition it is suggested that increased standardization and use of operational definition in the development of these techniques might result in improvement of their general applicability.

The paper develops a methodological approach to the sizing of man-machine systems which is predicated upon the efficiency of conversion of available system energy into useful goal directed work. Systems are generically categorized into two classes as a function of their energy replacement characteristics. Four classes of energy conversion efficiency degradations are delineated which can adversely affect system capability, reliability, and cost. The effects of alterations in operator performance characteristics upon system design are detailed in terms of engineering changes, and suggestions are advanced as to the nature of the future research necessary to obtain maximum cost effectiveness in future systems.

It was discovered during recent explorations in various industries that many hours were wasted in irregularly recurring pauses. This paper outlines an experiment which attempted to regularize these unofficial pauses and to test whether fixed rest pauses could be introduced to reduce fatigue and improve quality and operatives' job satisfaction, without loss of production and earnings. This openly acknowledged the operatives' social need for communication. “Compensatory relaxation allowances” were therefore given as actual rest of 10 minutes at the end of each hour. Four 15-minute breaks at longer intervals were also tried. Interviews were held at three different stages to assess the effect of the experiment on the operatives' attitudes toward the job, colleagues, supervisors, etc. Improvement in production and its quality and in earnings was found at the end of the experiment, and the more frequent and shorter break of 10 minutes was unanimously preferred.

Quantitative knowledge of the mechanical and structural characteristics of human tissue and its analytical interpretation are of considerable clinical significance. The paper presents typical results in relation to two tissues of the body: skin and rib cartilage. As regards the former, the tension necessary to produce blanching is discussed on the basis of measurements taken during operations, while in respect of the latter self-locked stresses evaluated in the laboratory on post-mortem material are presented.

Application of strength data to human engineering problems is often hampered by ambiguities of both terminology and data. This paper attempts to point out some of the problems. After defining “strength” and clarifying related terms, mechanical, physiological, and statistical implications of strength testing are discussed. It becomes obvious that strength data are fully relevant to human engineering problems only if the operator must exert maximal static muscle force; if submaximal forces are required, the applicability of strength data is very limited. Research is needed to establish relations between human static force capacity and the abilities to perform maximal or submaximal dynamic work. At present there is little evidence that static force data accurately predict dynamic performance.

This paper describes the application of a deterministic theory for characterizing or modeling the dynamics of a human operator in a manual control system. Linear time-varying, nonlinear time-varying, and non-linear constant-coefficient models are obtained by applying the theory to tracking data taken for one- and two-axis tasks with various displays. The accuracy and fidelity of these advanced models are explored in detail. Also, new information about time variability and nonlinearity of the human operator, obtained by studying the models and the manual control system signals, is presented.

This paper examines the effect of the complexity of the post-detection response demands on subsequent monitoring performance at two rates of target presentation. Three conditions requiring differentially complex post-detection responses were compared with a baseline condition in which no post-detection demands were made (save the simple detection-indicating response). The results indicated that two of the three complex conditions were accompanied by significantly less decrement in performance than that found in the baseline condition. The third was not significantly different from the baseline condition. “Arousal theory” could account for the results on the basis that there exists an optimal level of cortical arousal stemming from sensory variation provided by a task. If this hypothetical level is not reached or exceeded, a decrement in performance is to be expected. No clear answer was provided regarding an interaction between effects attributable to signal rate with effects attributable to response complexity.

This paper describes some of the folk norms or so-called “rules of thumb” that governed the making of tools and implements up to middle of the nineteenth century. These norms were established on the bases of intuition or through a long process of development by trial and error. In many instances dimensions arrived at on the basis of these norms have agreed with those established as optimal by means of biomechanical analysis.

This paper reports a new technique for evaluating industrial designs, based on electromyographic recordings of the muscles involved in carrying out the intended task. A hybrid computer circuit quantifies total muscular effort expended in performing the industrial task and the design that optimizes this measure is selected. The methodology has been shown to be effective in evaluating effort associated with static as well as dynamic tasks and therefore can be applied in a multitude of situations. Evaluation of the shape and size of a torque-wrench handle illustrates how the technique may be used in selecting an optimal design.