Theoretical Models on the Relationship Between Stressful Situations and Strains
These models specify the configuration of workplace factors that are associated with strains—that is, stress reactions. Major models include the person-environment fit theory (Harrison, 1978), job demand-job control model (Karasek, 1979), the vitamin model (Warr, 1987) and the effort-reward imbalance model (Siegrist, 1996).
Person-Environment Fit Theory
Person-environment (P-E) fit theory assumes that stress occurs because of an incongruity between the individual and the
environment (for an overview, cf. Edwards, 1998; Harrison 1978). Thus, it is neither the person nor the situation alone that causes stress experiences and strains. There are two types of incongruity between an individual and the environment The first type refers to the fit between the demands of the environment and the abilities and competencies of the persons The second type refers to the fit between the needs of the person and supplies from the environment.
At the conceptual level, P-E fit theory differentiates between the objective and the subjective person as well as between the objective and the subjective environment (Harrison, 1978). Objective person and objective environment refer to the individual needs, abilities, and competencies and to environmental supplies and demands as they actually exist—that is, independent of the person's perceptions. Subjective person and subjective environment refer to the individual's perceptions. Therefore, fit can refer to the congruence between (a) objective environment and objective person, (b) subjective environment and subjective person, (c) subjective and objective environment (i.e., contact with reality) and (d) subjective and objective person (i.e., accuracy of self-assessment).
The theory argues that the objective person and environment affect the subjective person and environment and that incongruity between the subjective environment and the subjective person produces strain. Strain increases as demands exceed abilities and as needs exceed supplies. When abilities exceed demands, strain may increase, decrease, or remain stable. Similarly, when supplies exceed needs, strain may increase, decrease, or remain stable. The exact picture of the relationships depends of the content and importance of the dimension in question.
In a classic study, French, Caplan, and Harrison (1982) explicitly tested P-E fit theory. Indeed, P-E misfit was associated with psychological, physical, and biological strains. Subsequent studies on P-E fit resulted in similar findings and identified a needs-supplies incongruity as the strongest predictor of strain (Edwards, 1991). However, many of these studies have been criticized for methodological shortcomings, particularly the operationalization of P-E fit as a difference score (Edwards, 1995). More recent studies—most of them published after 1990—overcame these problems by examining three-dimensional relationships of the person and environment with strain measures. These studies partially confirmed the basic assumption of P-E lit theory—that is, that strain increases as fit between the person and his or her work environment decreases (Edwards, 1996; Edwards & Harrison, 1993). These studies also pointed to complex patterns including curvilinear relationships; taken together, the studies do provide some empirical support for the P-E fit model. However,
longitudinal studies are still missing. Therefore, a final conclusion about this model would be premature.
job Demand-Job Control Model
The job demand-job control model differentiates between two basic dimensions of work place factors—namely Job demands and job decision latitude (Karasek, 1979). Job demands are the workload demands put on the individual. Job decision latitude refers to the employee's decision authority and his or her skill discretion. Karasek combined the two dimensions of job demands and job decision latitude in a two-by-two matrix of jobs: jobs low on demands and low on decision latitude (passive jobs), jobs low on demands and high on decision latitude (low-strain jobs), jobs high on demands and low on decision latitude (high-strain jobs) and jobs high on demands and high on decision latitude (active jobs).
^ With respect to stress reactions, Karasek (1979) states that the combination of high demands and low decision latitude in the high-strain jobs is most detrimental for people's health and well-being. The combination of high demands and high decision latitude in the active jobs, however, are assumed to produce little harm for the individual. Stated differently, the model basically assumes that high decision latitude attenuates the negative effects of high demands.
During the past two decades, the job demand-job control model stimulated a large amount of empirical research. There
• is substantial (although not unequivocal) support for the model. We discuss findings from this research in more detail later in this chapter. A theoretical critique is given by Kasl (1996).
Warr (1987) proposed a vitamin model to specify the relationships between stressors and employee health and well-being. The vitamin model claims nonlinear relationships develop between work characteristics and individual outcomes. Drawing an analogy to the effects of vitamins on the human body, Warr assumes that there are two types of work characteristics. First, some features of the work situation have a constant effect on the individual—that is, they have an effect that increases up to acertain point, but then any added increase of the level of this w°nt characteristic does not have any further effects (neither kneficial nor detrimental effects). Warr likens these effects to
^acteristics to vitamin C. Examples are salary, safety, and
S1gnificance. For example, people need the vitamin of
salar>' "P to a certain point. Therefore, people's well-being in-
•es with having more income; at a certain level, however,
- uihonal salary increase will not have any further increase
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of people's well-being. Second, other work features have a curvilinear relationship between the level of this work characteristic and well-being. Warr likens these to the vitamin D, which is positive to a certain dose, but then every further increase has a negative effect. Examples of these work features are job autonomy, social support, and skill utilization. For example, a low degree of job autonomy is detrimental to well-being. Therefore, up to a certain level, job autonomy increases well-being. If job autonomy is further increased, job autonomy becomes negative because people are overwhelmed with the responsibilities that job autonomy implies.
In terms of stress, this model implies that a specific amount of job autonomy, job demands, social support, skill utilization, skill variety, and task feedback is beneficial for the individual, but a very high level of these job characteristics creates a stressful situation. In contrast, high levels of salary, safety, and task significance do not show this detrimental effect.
Empirical studies on the vitamin model are still rare, and support for the curvilinear relationships between workplace factors and strain variables is mixed. Some studies did not find any significant curvilinear relationship (e.g., Parkes, 1991), whereas others gave support to the vitamin model (e.g., de Jonge & Schaufeli, 1998; Wan-, 1990). Warr found curvilinear relationships between job demands and several strain measures such as job-related anxiety, job-related depression, and low job satisfaction; a curvilinear relationship was also found between autonomy and job satisfaction. De Jonge and Schaufeli (1998) found evidence for curvilinear relationships between job demands, job autonomy, and social support on the one hand and employee well-being on the other hand.
Effort-Reward Imbalance Model
A variant of a P-E fit model is Siegrist's (1996) effort-reward imbalance model. Basically, the effort-reward imbalance model assumes that a lack of reciprocity between costs and rewards are experienced as stressful and result in strains. More specifically, the model states that the degree to which an individual's efforts at work are rewarded or not is crucial for that person's health and well-being. Effort may be the response to both extrinsic and intrinsic demands. Extrinsic demands refer to obligations and demands inherent in the situation. Intrinsic demands result from a high need for control or approval. Rewards comprise money, esteem, and status control, such as job stability, status consistency, and career advancement. In essence, the model assumes that situations in which high efforts do not correspond to high rewards result in emotional distress situations—particularly high autonomic arousal.
A number of studies showed that a combination of high effort and low reward predicted self-reported health
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complaints, cardiovascular risk factors, and manifestations of coronary heart disease (Bosma, Peter, Siegrist, & Marmot, 1998; de Jonge, Bosma, Peter, & Siegrist, 2000; Peter, Geissler, & Siegrist, 1998; for a summary cf. Siegrist, 1998). Most interesting is that a longitudinal study with blue-collar workers showed that experiencing an effort-reward imbalance was associated with 6.15 times the risk of developing coronary heart disease 6.5 years later (Siegrist, Peter, Junge, Cremer, & Seidel, 1990; cf. also the similar results by Bosma et al., 1998).