Stimulus Theories and Research
Remaining consistent with the usage of the term ‘stress’ described in physics, some investigators have focused on stress as a stimulus. Most notable among researchers employing this approach were Holmes and Rahe (1967). These investigators devised a list of major life events known as the Social Readjustment Rating Scale. Intuitively selecting ‘death of a spouse’ as the barometer of the most stressful life event, this instrument consisted of 43 items measuring distinct life changes that were self-reported over a specified period of time, typically one year.
Each item was assigned what Holmes and Rahe called a Life Change Unit score based upon the item’s relative severity with reference to ‘death of a spouse.’ Research employing the Social Readjustment Rating Scale has demonstrated an association between the number of significant stressful life events and incidence of a number of psychological disorders and medical diseases (Brown and Harris, 1989; Horowitz et al.,1977).
Elliott and Eisendorfer (1982), also focusing on stimulus characteristics, differentiated the various types of stressors that provoked challenges to bodily homeostasis. For example, they believed that acute or limited stressors, like a single surgery, elicited quite different stress responses than chronic stressors like job strain. Chronic stressors could also be categorized as enduring or intermittent. Being married to a nonsupportive spouse would be enduring, but having a sexual dysfunction would presumably be intermittent.
Finally, they also discussed what were called ‘stressor sequences.’ Stressor sequences represented prolonged stressors that contained multiple and often different types of challenges to the individual. Divorce, for example, typically involved a prolonged sequence of stressful life events that presented different sorts of challenges to the individuals as they occurred (for example, separation, learning your spouse is getting remarried, working out child custody arrangements, loneliness, loss of joint friends, etc.).
According to these stimulus theories, the distinct types of stimuli led to unique and predictable patterns of stress responses.
Other researchers have focused more on daily stressors than the major life events that were proposed by Holmes and Rahe (1967).
These daily stressors or ‘hassles’ have included events like arguments with co-workers, dealing with traffic congestion, and receiving irritating phone calls. Some research has found that the effect of these daily hassles on health outcomes is more problematic than the effect of major life events on health outcomes (Brantley and Jones, 1993; Delongis et al., 1982).
Although research examining stress as a stimulus using self-report checklists has provided valuable evidence linking stress to various disease endpoints, many problems have been identified with this methodology. Foremost among these is the limited content of items contained in these inventories, the confounding of items on stress and health questionnaires, the questionable methods employed for assigning weights in scaling life events, and the generally low reliability and validity of the instruments themselves (Zimmerman, 1983).
In an effort to deal with the problems associated with self-report inventories typically employed in this type of research, some investigators have adopted alternate methods of assessing stressors that people encounter on a daily basis. For example, Wethington, Brown, and Kessler (1995) suggest that personal interview strategies for assessing stress do a better job of capturing unique stressful situations that influence individuals than standardized checklists.
The constellation of unique family dynamics, financial strain, and spiritual struggles that accompany a patient encountering a transplant procedure, for example, represents a stressful situation that is not easily captured on a self-report checklist.
In this situation, it is clear that an interview assessment strategy may capture the degree of stress more richly. Interview-based strategies of assessment are much more labor intensive, however, and unlikely to be used in large epidemiologic trials. Additionally, Lepore (1995b) recommends the use of observational assessment methods or securing information from significant other informants to complement either selfreport or interview-based methods of assessing stressors.
Basically, the more consistent the information obtained from multiple sources, the greater confidence researchers can have in their assessment of stress.