5.3.1 Overview of Work System Approach
5.3.1.1 Purpose and Characteristics of Work System Approach
The realizations of systems theory particularly were introduced into ergonomics via the work system approach. A work system is understood as an open, socio-technical system, which consists of elements.
Candidness is expressed by the fact that the system receives an input from its environment, which is transformed by purposeful cooperating of the system elements into an output, in order to fulfill the system purpose. Synonymously to the term of work system, the terms “man – machine system” and
“socio-technical system” are also used (Heeg, 1988).
The work system approach acts particularly as an analysis framework. It is conducive to systemic thinking, because it does not regard individual elements in isolation, but considers the various interde- pendences between the elements. Besides, the application of this analysis framework forces the ergono- mist to draw up a system limitation and, thus, make a clear problem definition.
Ergonomic literature refers to different concepts of work systems (e.g., Rohmert and Rutenfranz, 1975;
Karwowski, 1991; REFA, 1993; Hettinger and Wobbe, 1993; Luczak, 1998; Carayon and Smith, 2000;
Hendrick, 2001). These differ from each other regarding individual system components. Most of the system concepts have the following in common, humans in work systems change work pieces coming from the system environment in a purposeful way and dispense them into the system environment again. This happens with the help of working equipment and operating resources. Hereby, the work environment affects the working person.
In addition to this general work system approach, job order, and work task should be differentiated in accordance with Figure 5.5. In order to be able to execute an order, the work system receives different system inputs from its environment. Among these are work object, energy, and information. The infor- mation concerning the job order contains rules for the work process. This process determines the spatial arrangement and temporal sequence of cooperation between inputs, human, and techniques and is designated as working method. The information about the job order is interpreted by the working person. The person takes over the job order as a task in a redefined form. In accordance with the task, the work object is converted to a nominal condition by activities of the working person with the help of the working equipment and operating resources. Energies are converted and information is produced so that the essential output of a work system consists of a changed work piece, as well as infor- mation and energy. During the process of transformation of inputs to outputs the physical environ- mental influences affect humans. These are known as the work environment.
The term “work system” is widely interpreted in the literature, that is, parts of an individual workplace can be constituted as a work system like a whole enterprise (Luczak, 1998). Zu¨lch (1992) differentiates between work systems on a macro- and micro-level. Micro-work systems refer on the one hand to indi- vidual jobs and on the other hand to working methods. The macro-level of a work system corresponds with the level of working groups. On this level the work organization and the technical process are regarded.
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The differentiation between job order and work task provides a first reference point for the fact that the system purpose is dependent on the point of view on the work system. From the systems environment point of view, the main purpose of a work system consists of purposeful handling of job orders. Work systems are regarded by their environment under purpose-rational and economic criteria. From the point of view of a human who is working in the system, the purpose of the work system is the realization of personal motives. On the one hand, his work accounts for the assurance of his subsistence via the payment. On the other hand, the purpose of the system can be seen as an interesting and varied task.
5.3.1.2 Goals of Work System Design and the Idea of Man in Ergonomics
Basic goal of work system design is the optimization of the entire work system. In the sense of the main objective of ergonomics work systems are to be suitably arranged for both human and economical pur- poses. Thereby, economy is determined by the best possible proportion of inputs (e.g., raw materials, energy) to outputs (e.g., finished products, service). Human abilities and technical conditions are to be adjusted, in order to arrange work systems to be suitable for humans. Ergonomics is based on the assumption that rationalization and humanization goals work complementary to each other. On the one hand, humane conditions of work lead to effectiveness (in the sense of result reaching) and efficiency (in the sense of small resources inputs). On the other hand, effectiveness and efficiency form an import- ant basis, in order to be able to create humane conditions of work. The consideration of the “resources coworker,” the “human factors,” has become more important. A one-sided pursuit of one or another goal clearly leads to suboptimal results.
Ergonomics considers the technology, the organization, and the personnel in the context of human work. In doing so, ergonomics distinguishes itself from predominantly human being-referred disciplines by including technical aspects into the working process. On the other hand, a differentiation takes place
work piece
working equipment / operating resources
working person task
input output
material information
energy material
information energy (changed) work environment
job order
acting on
acting on
feedback feedback
work result
FIGURE 5.5 Overview of work system approach.
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towards economic-technical disciplines, which exclusively aims at the optimization of the work result.
Therefore, the requirement of ergonomics must proceed from a human conception, which regards humans, on the one hand, as a performance generator in work systems and, on the other hand, as a complex nature whose needs are to be considered during the work system design. Complexity results from the various, inter-individual performance rates and motives of humans, which can change depend- ing on the situation and the course of time.
5.3.1.3 Limitations of the Application of Work System Approach
Even if the work system approach can be applied in principle to different levels — from a single execution via the work place and the entire enterprise to interplant cooperation — the level of workplaces is emphasized. Hereby, the workplace is understood as the spatial range in a work system in which the work task is performed by an employee. This focus on the level of the workplace in the application of the work system approach may be connected above all to the fact that the system approach was developed in a time, which was influenced by industrial mass production and high division of labor. Accordingly, work systems were arranged in such a way that an individual working person had to execute simple, short-cyclic, and repetitive activities. The work was determined to a great extent by working methods specified in the job order and by technology. Ergonomic efforts for the improvement of labor situation for industrial workers with the help of humane design of workplaces came to the fore.
Today, however, industrial manufacturing is characterized by a high variety of products and variants.
Mass production was replaced gradually by a series production with small- and middle-sized batches in many industries. Work organization was also developed further because of these changed requirements.
Thus, decentralized team and process-orientated work systems, which regulate themselves exceedingly and are flexible to react to changing requirements can be found in many enterprises. The borderlines of work systems are shifted because of the implementation of teamwork. Groups do not only realize executive tasks, but also tasks of regularization, preservation, and optimization within the work system. Rules are no longer set only by the environment of a work system, but are also the result of group-dynamic processes. A control of work systems at group level is carried out increasingly today through target agreements between groups and supervisor.
Moreover, the importance of the service sector in the western industrial nations increases. Services are characterized by the integration of the customers or of a factor, which are imported by the last- mentioned. The work system approach is to be modified to the extent that the “work object” in accordance with the work system conception outlined earlier can also concern a subject, in this case, the customer.
During the following description of the individual elements of a work system the changes in the general conditions are considered.
5.3.2 Elements of a Work System 5.3.2.1 Working Person
Referring to the working person, several dimensions of human work capacity can be distinguished theor- etically, even if it is difficult to account for the differentiation in dimensions in a metrological way con- cerning the concrete application. These dimensions are called, on the one hand, ability and, on the other hand, willingness to perform. In regards to ability the characteristics, which cause the achievement structure of a working person are considered physiologically as achievement capacity of the organs and/or organ systems and psychologically as achievement potential of psychological functions and/or appropriate com- ponents. Willingness to perform is determined physiologically by the excitation level of organs and/or organ systems in the psychological sense by achievement attitudes and motives such as needs, interests, intentions, or convictions. Components of the willingness to perform are, thus, a necessary condition, in order to utilize the existing potential of abilities. This means that only people who are physiologically above a certain exci- tation level (e.g., muscle tonus) and those who are additionally motivated (psychological dimension) can achieve the performance level, which they are enabled to achieve due to their physiological and psychological characteristics.
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The characteristics of a person who has the ability to perform is influenced by four categories. These are the constitution-, disposition-, qualification-, and adaptation characteristics (Figure 5.6). Constitution characteristics are unchangeable ratios in the life cycle of humans. Among these characteristics are gender, somatotype, and ethnical origin. Disposition characteristics are variable, however, the working person has no direct influence on this. Disposition characteristics cover the age, body weight, the state of health, and the intelligence of a working person. Beyond that, the biorhythm belongs to the disposition characteristics. This means that the human efficiency in the course of a day is subject to fluctuations. The entirety of all knowledge, skills, and experiences of a working person are understood as qualification characteristics, which a working person must have for carrying out activities at the workplace. Charac- teristics, which affect the human ability and are changeable at short notice are called adaptation charac- teristics. Adaptation characteristics refer to the fatigue and recovery, as well as the strain of a working person. With the beginning of an activity numerous physical and psychological conversion procedures start, whereby humans adapt increasingly to the workload caused by the activity. Manual labor, for example, leads to a rise of the heart rate and the muscle blood circulation, in order to be able to meet the demanded achievement. The realization became generally accepted that an optimal achievement of working humans is only ensured in the long term, if the fatigue caused by the work stays within limits.
Most of the determinants mentioned for the ability are mutually dependent on each other, for example, somatotype and body weight, age and experience, skills and strain. Differences between people or changes within a person, however, do not have to lead inevitably to differences in the achieve- ment. Measurable effects on the achievement cannot be determined due to the existence of mutual com- pensation mechanisms.
Constitution characteristics are solely influenced by the selection of personnel. Disposition character- istics can also be affected by other measures. Specifications of some characteristics can be changed within a limited range also through measures of work system design. For example, realizations of the influence of biorhythm on the human ability effect the shift work models. Qualification characteristics can be
FIGURE 5.6 Individual determinants of human performance (From Luczak, H., 1989, Wesen Menschlicher Leistung. In: Institut fu¨r angewandte. Arbeitswissenschaft (ed.): Arbeitsgestaltung in Produktion und Verwaltung.
Cologne: Bachem, pp. 39 – 60, With Permission).
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determined by both, a purposeful selection of personnel and by measures of the work system design and personnel development. For example, the introduction of a continuous improvement process (CIP) can lead to the fact that employees exchange knowledge and experiences during operational problem solving, causing the qualification level within the CIP-team to increase. Adaptation characteristics are not or only indirectly affected in their developments by a selection of personnel. Measures of the work system design can exert influence on variables at short notice such as strain and fatigue. For example, organizational rules of recovery periods can help to avoid an excessive demand and a possible harm to working persons.
The willingness to perform, the work motivation of a person, results from the reciprocal effects between personal motives of the working person and the motivation potential of the work. Neither the motives nor the motivation potential of the work alone are sufficient, in order to explain the devel- opment of work motivation. The motivation potential of work results from the expectations of employees to be able to achieve their motives. For example, motivation potentials regarding achievement, power, and integration can be differentiated from each other, since motivation potential always refers to specific motives (Kleinbeck, 1996). A work situation with a high achievement-related motivation potential is, for example, characterized by establishing a range of decision and activity for employees in which a complete and in their view important task with adequate difficulty can be worked on. Motivation potential regarding power always contains work activities, whenever the work activity is implemented by several employees simultaneously and the task makes it necessary that a person (e.g., guidance person) affects other people in the sense of achieving a certain goal. High motivation potential regarding integration exhibit work activities, which give many opportunities to the working person to achieve social contacts and maintain them. If motivation potentials are highly developed, these do not lead inevitably to a high motivation. Motivation potentials are regarded, therefore, as a condition of work motivation. For example, if a work system is spatially arranged in such a way that it permits interactions between working persons, this leads to a high motivation for the employees with a strong integration motive.
For people with low integration motive, however, the possibility of exchanging itself with colleagues does not lead to increased motivation.
5.3.2.2 Job Order and Work Task
The objective job order — or in the sense of a recognized obligation leading to a self-identified order — usually would be redefined by the employee in the form of a task. A distinction between job order and work task appears essential, as employees rarely adopt job orders accurately or how they are intended, but follow their own subjective interpretation of the job order (Hackman, 1969; Hacker, 1995). In Hackman’s (1969) perception, the job order — termed by him as “objective task input” — con- sists of “stimulus materials” and instructions. Regarding instructions, there is a differentiation between
“instructions about goals” and “instructions about operations.” Mostly orders consist of a combination of goals and rules concerning the work method, that is, “Minimize the wavering in the tone you hear (instructions about goals) by adjusting the four knobs on this panel (instructions about operations).”
“Stimuli are the actual physical materials with which subjects work.” “Think about this picture and tell me what it means” is an example of an objective task input, which is conveyed by stimulus materials.
During the instructions about goals, realizations from the theory of goal setting should be considered (Locke and Latham, 1990; Kleinbeck, 1996). These show that from goals, a performance-enhancing effect can proceed. Thus, on the one hand, ambitious goals and, on the other hand, specific, preferable quan- tified goals lead to a higher performance than low set and nonspecific, qualitatively formulated goals as, for example, “do your best” or “work at a moderate pace.” A condition for these positive effects on the performance is, however, the fact that a working person assesses a given or declared goal as realistic (Locke and Latham, 1990). The extent to which the goals affect the performance, additionally, depends on variables like the goal commitment and feedback. The goal commitment expresses how willing employees are to commit themselves to a certain goal or how high the resistance is to give up the goal or to downgrade the emphasis of the goal. The higher the goal commitment is, the larger the action intensity and perseverance and, thus, the achievement. A possibility of strengthening the goal commit- ment and increasing the associated performance exists in setting monetary incentives (Kleinbeck, 1996).
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Thus, coworkers pursue goals whose reaching or reaching degree has effects on their payment substan- tially more consistently than goals, which are not coupled to their payment. Thus, the probability of achieving the objectives rises. Feedbacks, which give information to the employees about the goal reach- ing degree during the work process positively influence the effects of goal setting on performance. Due to the knowledge about existing discrepancies between the goal and the current performance level, the employee can increase action intensity and duration and, thus, eliminate these discrepancies (Locke and Latham, 1990).
The valid rules of the work process (instructions about operations) are also called work methods. A work method usually applies to all people who are active in a work system. By work manner the individ- ual execution of the work method is understood (REFA, 1993). If the work method is given and the dis- persion of the individual work manner is small, then a high method level is referred to. The method level is affected, on the one hand, by the level of organization of a work system and, on the other hand, by the abilities and skills of the employees. These two influencing variables depend again on the repeating fre- quency of job orders. A high method level — usual in line and mass production — offers only small interpretation clearance to the employee concerning the redefinition of the job order. Beyond that, the factors including the comprehensibility and acceptance of the job order, typical expectations and values of the working person, and existing experiences with considerably similar orders affect the rede- finition process (Hackman, 1969).
Work tasks can be differentiated into primary and secondary tasks. “Each system or sub-system has, however, at any given time, one task which may be defined as its primary task — the task which it is created to perform” (Rice, 1958). Value generating activities are a direct result of a primary task. They create value for the internal and external customers. The processing of secondary tasks is not directly valuable, however, it forms a condition for fulfilling the primary task and achieving the goals of a work system (e.g., annual cost reduction around 3%). Secondary tasks can be separated into tasks of system regularization, preservation, and optimization (Miller and Rice, 1967; Antoni, 1996). The tasks of system regularization include, for example, the job order planning and production control. Typical tasks of system preservation are preventive maintenance and repair related to the technical subsystem of a work system. With reference to the social subsystem, consisting of the employees, for example, train- ing measures can be added to the tasks of system preservation. Among tasks of system optimization is, for example, the implementing of the CIP in a work system. The detailed fixing of the boundaries cannot be made solely by formal rules set by the enterprise, as the work system, on the one hand, is subject to changes in the time response (e.g., coworker turnover) and the environment of the work system, on the other hand, changes its demands (e.g., due to changed customer’s requests) on the system. According to the theory of social systems (Section 5.2.5), the fixing of the boundaries rather takes place by the work system itself. Creating boundaries between system and environment is an achievement, which generates the system partially itself. Even if processes creating the boundaries do not take place consciously in every case, the creating of the boundaries can be interpreted as another secondary task. The subject of this task clarifies whether certain activities are to be implemented in the work system or its environment (e.g., a work system, which is preliminary in the process). Furthermore, the work system and its environment (e.g., other work systems, supervisor) have to clarify how certain tasks have to be fulfilled. This clarifying process, thereby, primarily refers to those activities, which were not specified clearly by organizational rules or the work method.
The type and range of the primary and secondary tasks determine the range for decision and activity of employees in a work system. Range for decision and activity makes an individual and collective self-regularization possible and forms a condition for the increase in work motivation of the employees.
5.3.2.3 Work Object and/or Recipient of Services (Subject)
The purposeful change of the work object is regarded (on the point of view of the system environment), as a rule, as the main objective of the work system. Regarding a work system in a production plant, the work object is changed by manufacturing methods as, for example, metal forming, cutting, and coating.
Concerning service enterprises — as aforementioned — the “work object” can be the customer who
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