READING 17
Negative Life Events, Perceived Stress, Negative Affect, and Susceptibility to the Common Cold by Cohen, Tyrrell, & Smith (1993)
Please refer to the printed reader, Readings in Social Psychology 3/e, for the text of this article.
Overview
Until recently, the medical community did not know if psychological factors such as stress could “get into” the body’s immune system. As the exciting research presented in Chapter 14 (Health) reflects, however, health researchers today working in the field of psychoneuroimmunology (psycho for mind, neuro for nervous system, and immunology for the immune system) find that stress produces a wide range of disabling effects on the body—including an increased risk of chronic back pain, upper respiratory infections, arthritis, and some forms of cancer. This range of effects suggests that stress may weaken the immune system—the first line of defense against illness. Does this mean that people who are under stress are more likely to get sick? To answer this question, Sheldon Cohen and others (1993) paid volunteers to spend nine days and nights in a medical experiment, where they reported on life stress and then received randomized exposure to a common cold virus. The question: Were those suffering high levels of stress more likely to catch the cold than those with lower levels of stress? As you read this innovative study, ask yourself: Would you have agreed to participate in it? What are the health implications of the results?
Critical Thinking Questions
1. As has been demonstrated throughout your textbook, there are numerous ways to operationally define a variable in a study. What are three specific ways in which Cohen and colleagues measure illness in the present research?
2. How is the design of this study different from one in which researchers interview 400 people about their level of stress and number of colds in the past year? What are the differences in the nature of the conclusions one could draw from that type of study as opposed to the present study?
3. The authors report that they “control” for a variety of variables including age, gender, allergic status, weight, and number of roommates. What does it mean to control for these variables? Why would researchers measure a series of variables that were not directly related to the focus of the study?
4. How would you summarize the major findings of this study regarding the relationship between stress and illness?
5. Cohen et al. discuss differences between the effects of negative life events and the effects of perceived stress. What are these differences? Why are they important?
6. How could you use the present findings in your own life? That is, what implications do these findings have for your own attempts to avoid illness? What attributional or coping styles would be most helpful in these attempts?
Answers to Critical Thinking Questions
1. The researchers used several operational definitions to assess illness. First, they checked for biological evidence of infection by examining nasal secretions for presence of a virus. Second, they took a blood sample from participants, which were checked for evidence of viral-specific antibody production. A third way of assessing illness was through subjective ratings on a scale ranging from 0 (“no cold”) to 4 (severe cold). The researchers obtained self-ratings on this measure, and also had a clinician rate each participant. Additional measures included in this study were body temperature and mucus weight.
2. The hypothetical study described in this question—in which participants’ self-reported stress levels are compared to self-reported illness frequency—would be a correlational study. Such an investigation could reveal that there is a relationship between stress and illness, but it would not allow for any causal conclusions regarding this relationship. A positive correlation could indicate, for instance, that stress causes illness, but it could also indicate that illness leads to stress. For that matter, a third variable such as socioeconomic status could cause both illness and stress. The Cohen et al. study is more controlled in that the researchers exposed participants to a virus and then observed the extent to which stress predicted their susceptibility to illness after the virus exposure. Though not a true experiment, since stress level was measured and not manipulated, the controlled nature of this study allows for some causal conclusions regarding the influence of stress on susceptibility to infection.
3. Participants enter any study with a wide range of individual differences, including age, gender, self-esteem, education, and other tendencies and preferences. In a true experiment, researchers randomly assign participants to condition so that the different groups are rendered equivalent on these and all other dimensions. The present study is not an experiment, however, and participants have been selected, not assigned to conditions. In order to draw conclusions regarding the influence of stress on illness, the researchers need to take into consideration a variety of pre-existing differences among participants. By measuring these individual differences, they can conduct a statistical analysis that “controls” for them and isolates the specific influence of stress on illness. Had Cohen et al. not measured these variables, they would not have been able to rule them out as potential influences on participant illness.
4. The major finding of this study is that participants with higher levels of stress were more susceptible to illness than participants with lower levels of stress. More specifically, participants reporting high levels of stress were more likely to be diagnosed with a cold than participants with low stress. Participants with high stress were also more likely to exhibit biological indications of infection than participants with low stress. In addition, participants reporting more than three stressful life events averaged a higher post-exposure body temperature than participants reporting fewer than three stressful life events.
5. Cohen et al. report that negative life events were associated with greater rates of illness, and specifically with an increase in symptoms after infection. Perceived stress was also related to illness, but this relationship was due mostly to an increased risk of infection. According to the authors, this is a critical difference. Specifically, effects on infection rates likely result from the relationship between stress and the immune system, or between stress and the ability of one’s tissues to block a virus. This is consistent with the effect of perceived stress in this study. Illness, however, presumably results from the body’s response to infection, including the release of histamines that lead to physical symptoms. This seems to be the effect of negative life events in this study. Interestingly, though both negative life events and perceived stress are associated with an increased susceptibility to illness in this study, the reasons for these relationships appear to differ.
6. One clear-cut implication of these findings is that an effective way to avoid illness is to cut down on one’s level of stress. There may be many ways of accomplishing this goal, from behavior modifications to changes in one’s cognitive tendencies. One way to deal with stress is through problem-focused coping, in which you try to resolve the problem or situation that is causing stress. Another strategy is emotion-focused coping, in which you do not intervene to change the stress-inducing situation, but rather alter the way in which you think about it. In terms of attribution, research has demonstrated that internal, global, stable attributions for negative life events increase susceptibility to depression, and they may also make stress more likely. On the other hand, external, specific, unstable attributions for negative events may help a person to avoid stress.
Links For Further Investigation
The present research makes a strong case for the causal relationship between stress and illness. The medical community has also taken notice of this relationship, and you can read about ways to prevent stress and recognize its physical symptoms on WebMD at Additional details regarding stress-related disorders and symptoms, as well as a stress-prevention help guide, can be found at
For a less scientific take on stress, see This site provides a free test that asks the questions, “What’s your stress style?” and “How do you handle stress?”