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1. The effect of stress on the immune system; a natural experiment Kiecolt-Glaser et al (1984) (Read about this study in Cardwell) Aim: To see if exam stress reduces…
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  • 1. The effect of stress on the immune system; a natural experiment Kiecolt-Glaser et al (1984) (Read about this study in Cardwell) Aim: To see if exam stress reduces functioning of the immune system. Procedure: 75 medical students were used in this natural experiment. Blood samples were taken one month before examinations (low stress) and during examinations (high stress). T cell lymphocyte activity in the blood was measured. Students completed questionnaires to assess the amount of life stresses being experienced. Results: Conclusions: N.B. This study looks at the effects of short-term stress (exams last for a short time only)
  • 2. Some questions on the study 1 Define what is meant by natural experiment? 2 What is the independent variable in this study? 3 What is the dependent variable in this study. Evaluation of the study 1 Natural experiments are high in ecological validity. Explain why this study is ecologically valid. The stress (exams) was a real life stress, not an artificial one (such as being threatened with an electric shock in a laboratory). 2 With natural experiments it is not possible to establish cause and effect. In this case we cannot be sure that the reduction in T cell activity was due to the exams. Why? There might have been other changes happening at the same time as the exams that caused the reduction in T cell activity. E.g. 3 Explain why measuring the amount of T cell activity is a good way of measuring the effects of stress. It is objective, measurable using accurate scientific tests. Students cannot fake their T cell activity levels. 4 What is wrong with the sample used in this study? They are all medical students. The result cannot be generalised to other groups in society. 5 This study did not assess illness. It may be that changes to the immune system are so small that they have no significant effect on health. If you have time read (and make notes) from the ‘Further Analysis’ section.
  • 3. Some questions on the study 1 Define what is meant by natural experiment? 2 What is the independent variable in this study? 3 What is the dependent variable in this study. Evaluation of the study 1 Natural experiments are high in ecological validity. Explain why this study is ecologically valid. 2 With natural experiments it is not possible to establish cause and effect. In this case we cannot be sure that the reduction in T cell activity was due to the exams. Why? 3 Explain why measuring the amount of T cell activity is a good way of measuring the effects of stress. 4 What is wrong with the sample used in this study? 5 This study did not assess illness. It may be that changes to the immune system are so small that they have no significant effect on health. If you have time read (and make notes) from the ‘Further Analysis’ section.
  • Lecf Rac

    Jul 23, 2017
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