Research carried out by Kiecolt-Glaser et al (1984) showed that the immune system is weakened with stress. She carried out a natural experiment on 75 medical students and asked them to complete a questionnaire to find out how stressed they were. She then took one blood test, and a second one later on during the students exam week and measured the level of natural killer cells present in the blood. She found that during the exam week when the students were most stressed, their immune system had weakened due to a decrease in the number of natural killer cells.
However, although this piece of research is valuable in that it shows the relationship between stress and the immune system, it was carried out only on medical students therefore it is difficult to generalise the results on other students and the general population. Also, the results show a correlation therefore we cannot determine cause and effect because it doesn’t tell us whether stress cause the decrease in the immune system or whether this decrease caused the stress. On the other hand this study has a high ecological validity because it was a natural experiment and has high mundane realism because the task (exams. i.e. naturally occurring) was realistic.
In addition to this research carried out by Evans et al (1994) also helps us to see the relationship between stress and the immune system as it looks at the effects of both chronic and acute stress. He asked students to give a talk to give a talk to each other which created a period of acute stress and measured their sigA levels. Afterwards he measured their sigA levels during exams week (chronic stress). He found that acute stress enhances the immune system due to a higher level of sigA found, but during a period of chronic stress their sigA levels had decreased suggesting a weakened immune system.
A positive of this research is…