Physiological Psychology: Stress
APFCC Key Studies
Independent Variable: The manipulated variable; the variable that is changed on purpose in an experiment.
Dependant Variable: The responding variable; the variable that may change as a result of a change in the independent variable.
Kiecolt-Glaser et al
Aims:
- To discover a link between stress and reduce immune function.
- They aimed to establish a difference between conditions of high and low stress.
- They also wanted to see whether other factors such as psychiatric symptoms, loneliness and life events were associated with immune function.
Procedure:
- A total of 75 first year medical students, it was a self selected sample.
- This was a natural experiment because the independent variable, (the level of stress due to the imminence of exams) was naturally occurring.
- A blood sample was taken a month before their exams (a low stress condition) and also on the first day of their final exams (a high stress condition).
- The measurement of natural killer cells and T cells was taken as indicators of immune function (the dependant variable).
- On both occasions, the students were given a questionnaire measuring psychiatric symptoms, loneliness and life events.
Findings:
- Natural killer and T cell activity declined between the low-stress and high stress conditions. Thus, the assumption was correct.
- The questionnaires revealed that immune system responses were particularly suppressed in participants who reported that they were experiencing psychiatric symptoms, loneliness, or stressful life events.