Cohen et al investigated the role of life stress on a person’s vulnerability to the common cold. He gave his participants questionnaires to fill out on the number of stressful left events they had encountered in the previous year and asked them to rate their level of negative emotion and degrees of stress. From this he then created a “stress index”. The participants were exposed with the common cold and after 7 days the number of participants that had developed the common cold were recorded. It was found that 82% of participants became infected and the chance of developing a cold was significantly correlated with the stress index. This study shows that there is a relationship between stress and illness, and that life stress and negative emotions may affect our immune systems adversely.
However, one limitation of the study is that it only shows a correlation and not the cause. As Cohen didn’t directly cause the participants stress, it isn’t possible to determine whether high levels of stress actually do affect the functioning of the immune system negatively. It is possible that those who didn’t contract a cold may’ve had stronger immune systems than those who did and as a result, individual differences may affect the results.
A strength of the study is that Cohen had very good ethical considerations while undertaking his research. His participants were fully informed about the procedure of the study and that they would be infected with a cold as them knowing wouldn’t affect his results in anyway. This means that his participants were able to give fully informed consent.
Cohen’s findings are backed up by a study done by Kiecolt-Glazer in which he studied the effects of important exams on the functioning of the immune system. 75 medical students had blood samples taken 1 month before their exams where stress would be quite low and another during the exams when stress would’ve been much higher. It...