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

A model of a man-machine-environment complex is presented in which it is shown that each man-machine system defines for itself an operational environment from within the ecosphere. It is pointed out that this model has application to all design for human use, and to operation of man-machine systems. Its specific application to recreation is shown in relation to three areas—considerations of system safety in recreation; responsibilities and liabilities of manufacturers of recreational equipment; and responsibilities of researchers, human factors engineers, and those who supply manufacturers with operational design data. It is argued that safety management requires an epidemiological rather than a therapeutic or piecemeal approach, and that until safety is considered systematically as an objective in the design and operation of a man-machine-environment complex, recreational or otherwise, we cannot attain the optimal.

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.

An epidemiological study of a closed population of 2071 skiers investigated the effects of method of skill acquisition and type of release binding on accident rates.

The population was observed for an entire skiing season. Accidents numbering 221 were generated by the population. Distributions within the population of age, sex, skill level, years of experience, marital status, and type of binding used were obtained prior to the start of the season. Exposure to risk was obtained at the end of the season.

Injury data included measures of severity, location of injury (upper vs. lower extremity), ski patrol involvement, binding release or not, and overall and lower-extremity injury rates.

Conclusions drawn are: (1) lessons as presently structured are not contributing to ski safety and, in fact, are associated with high accident rates; (2) bindings that have more than two release modes (up at the heel laterally at the toe, roll about longitudinal axis, etc.) have lower accident rates than those with only two release modes; (3) cable bindings are categorically dangerous by every accident variable available; and (4) a significant sex by binding-type interaction exists that has important implications for both female skiers and binding designers.

This paper is concerned with the development of a standardized dynamic evaluation process which will be applicable to specialized power consumer vehicles on which the operator rides. The standardized process will be suitable for evaluation of vehicles with specialized functions such as boats, lawnmowers, snowmobiles, all-terrain vehicles, golf carts, industrial vehicles, and farm equipment.

The proposed method differs from existing practices, which are usually limited to employing static human engineering standards in vehicle design and testing, and generally give inadequate consideration to dynamic operating influences. The authors believe that the vehicle should be considered not only as a dynamic man-machine system, but as a dynamic man-machine system operating within a variety of dynamic environments. Only by such complete analysis will adequate safety be assured.

Central to the many problems inherent in the design and use of snowmobiles is their rapid increase in popularity as sporting and recreational vehicles during the past decade. The major problems-damage and injury-producing accidents, noise pollution, damage to private property, and detrimental effects on natural ecology—are described and analyzed. Examples are given that typify the current state-of-the-art investigations of the problem areas. It is noted that such studies, both scientific and engineering, have dealt only in piecemeal fashion with some of the most widely acknowledged problems.

The paper examines the existing need for a system-oriented program of research designed to provide data for a wide range of system design standards capable of assuring the survival of this form of recreation.

The paper briefly discusses the perception of velocity and prediction of motion as processes involved in the performance of fast-ball game skills. Two experiments utilizing a motion-prediction paradigm, in which the subject was allowed to view a moving tennis ball cross the display and disappear from view, are reported. The subject was required to estimate when the ball would reach a target set on the extended motion track. The experiments examined the effects of viewing distance, prediction distance, and stimulus velocity upon the accuracy and variability of performance. The first experiment found that both prediction distance and stimulus velocity were significant variables, their additive effects showing a linear relationship between prediction time and both constant and variable errors. The second experiment demonstrated that these linear relationships were replicable phenomena and that motion prediction became more accurate when subjects were given knowledge of results and allowed to practice the task.

A linear-positioning task was learned over 1, 3, or 10 practice trials under high feedback (HFB-augmented position cues) or low feedback (LFB—no positional cue augmentation). Subjects' abilities to sustain accurate performance without IF and to appraise the magnitude and direction of errors were examined during 10 further test trials. Absolute errors were least after 10 practices with HFB, as predicted by closed-loop theory. However, HFB apparently caused performance inferior to LFB when only one practice trial was permitted.

Skill in estimating distances is essential for professional athletes as well as many nonathletes. How this skill can be acquired was considered by the authors in an experimental study. Three factors (target size, target distance, and the use of instruments) were investigated using a factorial design with repeated measures. The instruments consisted of two portable range finders employing different principles: coincident image and stadiametric ranging. Both instruments are commercially available. Those were compared with the performance of the naked eye. Sixteen subjects each made 12 range estimates; subjects were not given performance feedback following trials.

No significant differences were found between performances using either instrument or the unaided eye. Subjects, on the average, made more accurate estimates with the stadiametric instruments for both targets at both distances. The unaided eye was consistently least accurate. Subjects preferred the coincident image device over the stadiametric one. Recommendations were made for a training technique that would utilize the latter device and immediate feedback to train athletes in distance-judging skills. In general, it was found that training would be most parsimonious if subjects alternated between the stadiametric device and the unaided eye.

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 human performance characteristics of pitching and batting within the context of baseball game situations are examined to determine their influence on the batter' decision to swing or not at a pitched ball. Signal detection theory techniques are used on generated data to show how the probability of the batter swinging at a “strike” and leaving a “ball” could be optimized. Applications of this approach to game situations and areas for future research are discussed.

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.

Scholarly writings on the causes and effects of play, recreation, and leisure from Aristotle' Ethics to the most contemporary articulation on Leisure and the Quality of Life have been of a philosophical, speculative, and logical nature. But there has been little effort devoted to empirically validating or systematically researching what motivates people to become involved in certain forms of leisure and what are the effectsof participation in these activities.

The purpose of the present paper is three-fold: (1) to propose an applied intersystem congruence model of play; (2) to discuss some empirical evidence which offers preliminary evidence for the intersystem congruence model of play; and (3) to suggest some problems for further consideration.

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.