تصمیم گیری ارگونومیک : یک چارچوب مفهومی از پیش زمینه هایی برای شاغلین با تجربه در مهندسی صنایع و ورزش درمانی

Ergonomists play an important role in preventing and controlling work-related injuries and illnesses, yet little is known about the decision-making processes that lead to their recommendations. This study (1) generated a data-grounded conceptual framework, based on schema theory, for ergonomic decision-making by experienced practitioners in the USA and (2) assessed the adequacy of that framework for describing the decision-making of ergonomics practitioners from backgrounds in industrial engineering (IE) and physical therapy (PT). A combination of qualitative and quantitative analyses, within and across 54 decision-making situations derived from in-depth interviews with 21 practitioners, indicated that a single framework adequately describes the decision-making of experienced practitioners from these backgrounds. Results indicate that demands of the practitioner environment and practitioner factors such as personality more strongly influence the decision-making of experienced ergonomics practitioners than does practitioner background in IE or PT.

Work-related musculoskeletal disorders (MSDs) comprise the largest group of occupational injuries and illnesses in the US and represent one-third of the injuries and illnesses reported to the US Bureau of Labor Statistics by employers (OSHA, 1999). While practitioners of ergonomics play an important role in recommending ways to prevent or control the occurrence of MSDs, little is known about how they make such recommendations in practice. Understanding the pragmatic, experience-based, decision-making processes of ergonomists can reveal the complexity of their solutions to MSDs. In addition, it can help determine whether current practices are consistent or at variance with ergonomics curricula. This study focused on the most prevalent and costly MSD, lower back disorders (LBDs) (NIOSH, 1997), in order to better understand the decision-making processes of ergonomics practitioners. Ergonomists’ backgrounds vary widely with respect to training and experience. This study explored how experienced practitioners from two professional backgrounds, industrial engineering (IE) and physical therapy (PT), make the decisions that result in their ergonomic recommendations. 1.1. Decision-making In ergonomics, there is a long history of studying decision-making within the contexts of information processing and problem-solving (Lehto, 1997). However, this literature includes few studies on how ergonomists themselves make decisions that result in their recommendations. A seminal study by Whysall et al. (2004) emphasizes the ergonomics consultancy process, highlighting the effectiveness with which recommendations are implemented. By applying qualitative methodology to the problem of preventing MSDs, they open up a new strategy for studying ergonomic decision-making in this area. However, decision-making research has focused primarily on models for choosing among decision alternatives (Lehto, 1997), and a need remains for studies that can illuminate the process by which alternatives are generated (Klein, 1993). The decision-making literature often separates into two main approaches: classical/traditional, in which the emphasis is on descriptive and prescriptive models (Orasanu and Connolly, 1993), and naturalistic, through which there has been an increasing emphasis over the past three decades on performance in real-world settings (Lipshitz, 1993). Studies on naturalistic decision-making suggest that the experience of the practitioner is an important factor (Connolly and Wagner, 1988; Zsambok, 1997), particularly in determining the decision-making strategy and schemata that a decision-maker brings to bear on a situation (Beach and Mitchell, 1987; Fiske and Taylor, 1984). 1.2. Schema theory This investigation was guided by the principles of schema theory, which states that people unconsciously organize and store information from previous experiences in an abstract form—called a “schema”—and later use their schemata to interpret and decide how to respond to input from new situations (Fiske and Linville, 1980). According to this theory, schemata enable the decision-maker to efficiently categorize a situation as a whole pattern (Federico, 1995). The activation of a generic schema is an automatic process that occurs as a person is exposed to a new situation (Rumelhart, 1984). Interaction with the situation leads to creation of an “instantiated schema” (i.e., a concrete, conscious pattern of concepts specific to the current situation) (Brewer and Nakamura, 1984). Researchers in the field of naturalistic decision-making generally conclude that real-world decision-making is strongly schema-driven (Klein, 1993; Marshall, 1995; Smith and Marshall, 1997). When members of a cultural group share experiences they form similar schemata, which in turn lead to similarities in their responses to future inputs (Strauss and Quinn, 1997). Conversely, people from different cultures may form contrasting perspectives that lead to differences in their schemata and responses to similar situations (Bostrom et al., 1994; Svenson, 1999). The different professional–cultural backgrounds (e.g., PT and IE) of ergonomists provide different sets of experiences which influence schemata for addressing workplace MSDs. These different schemata may, in turn, effect differences in practitioners’ decision-making processes. 1.3. Specific aims Our specific aims were to: (1) identify decision-making processes through which ergonomists arrive at recommendations for preventing and controlling LBDs in the workplace, and the conditions under which they carry out those processes; (2) identify elements of schemata that guide practitioners’ decision-making in this domain; (3) develop a conceptual framework for how schemata influence this decision-making; and (4) determine if a single conceptual framework adequately describes decision-making regardless of practitioner background in IE or PT.

Our finding that a single conceptual framework adequately represents decision-making of both IEs and PTs may be an indication that other personal factors in combination with situation factors are more important than professional background, at least among experienced practitioners of ergonomics. In particular, the data suggest that practitioner adaptation to workplace demands through experience strongly influences the formation of practitioners’ instantiated schemata and subsequent decision-making behavior. While the schema concepts in the framework are broadly applicable to and consistent with the practice of ergonomics for the prevention and control of LBDs in the workplace, the data grounding the concepts’ dimensions challenges stereotypes about the way ergonomics is practiced in the real world. Consider, e.g., the way our data on breadth of focus challenge the image the profession holds of itself, as a field which takes a systems-oriented, macro-approach to solving problems (Helander, 1997). Based on this image, it would seem surprising that 68% of group-scope stories were aligned at the micro-end of the breadth of focus continuum. Within these group-scope stories only three instances emerged in which practitioners indicated any effort to expand their focus from the target jobs to encompass macro-level factors. Those who made such efforts expressed frustration that the client thwarted their attempts to provide a broader perspective on the problem and its potential solutions. This suggests that situation factors (e.g., a client organization's narrow view of ergonomics, view of LBDs as routine problems not warranting in-depth analysis, or lack of willingness to allow the practitioner access to macro-level information) may impact this phenomenon. In addition, practitioner factors (e.g., personality, life development, need to make a living) may affect to what degree a practitioner opposes a client's resistance to expanding the focus from micro to macro. This study found no substantial difference in the distribution of stories from IEs and PTs along the breadth of focus continuum, even when stories on individual- and group-scope situations were analyzed separately. Another stereotype challenged by the data is “hierarchy of controls”, which incorporates a common philosophy that engineering controls are preferable to administrative controls, and that administrative controls are considered only when engineering controls are not feasible or cannot completely eliminate exposure to risk factors (Konz and Johnson, 2000; Putz-Anderson, 1988). On the surface, participant decision-making does seem consistent with this philosophy. However, while no participants indicated an a priori preference for administrative over engineering controls, the data include a substantial portion of stories in which both IEs and PTs gave stronger consideration to administrative recommendations than would be expected under strict adherence to the hierarchy of controls. For instance, in 43% of stories, participants make a point of considering both engineering and administrative alternatives equally before making their recommendations. An explanation suggested by the data is that practitioners perceive LBDs to be a problem whose cause is multifactorial, and which therefore requires comprehensive control. This explanation challenges the philosophy of hierarchy of controls, suggesting that its emphasis on physical risk factors for LBD may be too narrow for real-world applications in the health and safety arena. Of course, the homogeneity seen across practitioner subgroups may stem from the selection of experienced ergonomics practitioners for this study; perhaps among novices more stereotypical patterns might be evident. Based on the literature, one might expect experienced practitioners of ergonomics to consider psychological and psychosocial risks among both the individual and work/workplace factors when addressing LBDs in the workplace (Carayon et al., 1999; Kalimo and Lindstrom, 1997; Marras, 2000; Moon and Sauter, 1996; National Research Council, 1999). However, our data on “range of risk factors” contradict this expectation somewhat. For example, in 76% of stories practitioners considered only the physical and physiological demands of target jobs rather than a broader range of work/workplace risk factors. This finding was similar for IEs and PTs, and held true even when stories on individual- and group-scope situations were analyzed separately. This is consistent with the predominance of stories in which practitioners took a “micro” focus, and further challenges the image that the ergonomics profession takes a systems-oriented, macro-approach to solving problems. Support for the influence of personality on the formation of instantiated schemata and subsequent decision-making behavior can be found in the literature on schema theory (Markus, 1977; Markus, 1983; Strauman, 1994; Wiginton, 1999). Interestingly, the personality characteristics illuminated by our study correspond to the Five Factor Model, a dominant model of personality traits: “openness to experience, conscientiousness, extroversion, agreeableness, and neuroticism” (Ewen, 1998; McCrae and Costa, 1996 and McCrae and Costa, 1997; McCrae and John, 1992). For example (see Table 3), practitioners’ ability to work with people corresponds to the “extroversion” and “agreeableness” factors of the Five Factor Model; confidence in self corresponds to “neuroticism”; tendency to look beyond the obvious corresponds to “openness”, and creativity corresponds to “conscientiousness” and “openness”. Further research is needed to evaluate the relevance of practitioner personality to the practice of ergonomics. As with all studies using retrospective accounts of past events, biased recall is a potential limitation (Carroll and Johnson, 1990). To mitigate the concern that participant reporting may be less than accurate, we emphasized recent examples (Ericsson and Simon, 1984) and asked interview questions in ways that supported participants’ recall (Bradburn et al., 1987). In future studies, this potential limitation could be minimized by including direct observations of practitioners in decision-making situations. While this study employed follow-up interviews to enhance the interpretative validity of the framework, future studies could expand the degree to which this technique of “member checking” is used (Lincoln and Guba, 1985; Pyrczak, 1999). Although generalizability of our study is limited to situations involving LBD and experienced practitioners from backgrounds in IE or PT, it has strong explanatory power for situations similar to those represented by the practitioners and practice situations that we included. The conceptual framework generated herein has direct applicability for ergonomics practice. For example, the results: (1) indicate areas in which some norms of practice are incomplete or are at variance with how real-world practitioners actually solve problems in practice, (2) link situation contexts with practitioner decision-making processes, and (3) bring to light the importance of practitioner factors including personality, life development, and perception of one's role in the field of ergonomics. Faculty involved in the educational preparation of ergonomics practitioners may draw upon this framework to link curricula with practice, particularly in the areas of in problem-solving and professional judgment.