Stress Studies

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  • Stress Studies
    • Cohen (1991)
      • A study into the relationship between stress and the immune system
        • Gave participants a nasal spray containing either a common cold virus or a harmless salt solution
          • All participants filled in a stress questionnaire where they reported the number of stressful events experienced in the previous year, their ability to cope and the number of negative feelings such as anger and depression. They were given a stress index score based on this
            • Almost all of the virus infected patients showed signs of infection, but only a third actually developed a cold. The third that developed a cold tended to have a higher stress score
              • Therefore Cohen found a positive correlation between high stress scores and the development of a common cold virus
      • Strengths
        • High ecological validity
      • Weaknesses
        • Correlational study so cause and effect cannot be assumed
        • Stress index score is based on responses to a questionnaire. Participants answers may be inaccurate, they may lack insight or may give socially desirable answers
        • Participants ability to cope is a subjective measure
        • Exposing participants to a cold virus is ethically questionable
    • Kiecolt-Glaser et Al (1984)
      • A study into the relationship between stress and the immune system
        • Conducted a natural experiment using 75 medical students who were about to take their final exams
          • Their blood was sampled twice, one month before the exams and on the day of their exams
            • The number of T cells was measured as indicators of immune functioning. Students also filled in questionnaires on both occasions, which measured psychiatric symptoms, loneliness and life events
              • T cell activity declined between the lower stress and high stress conditions. Thus the findings confirm the assumption that stress is associated with reduced immune functioning
      • Strengths
        • The experiment utilises a real life experience of stress which increases it's external validity
        • The measure of immune function (the number of T cells) is objective and so cannot be biased or subjectively interpreted by the investigator
      • Weaknesses
        • It is a natural experiment, so the IV is not under the control of the experimenter. Other factors could have affected the results
        • The study uses medical students who are a very specific group. This limits the extent to which these results can be generalised
    • Holmes and Rahe (1967)
      • Developed the Social Readjustment Rating Scale (SRRS)
        • Examined 5000 patient records and made a list of 43 life events that preceded their illness. Next, they asked 400 participants to rate each life event in terms of the amount of readjustment it of lifestyle they thought it produced
          • They assigned a random value of 500 to marriage and asked participants to rate the other events in relation to it, asking 'how much readjustment would this event require from the average person?'
            • From this, they developed the SRRS. Scores from each participant were averaged and divided by 10 to give a life change unit score (LCU) for each event
              • Using the SRRS, they asked different participants to indicate which of the life events had happened to them over the past year. A life event score was calculated by adding up the value of each event
                • They found a relationship between high SRRS scores for events ocuring in the preceding year and the likelihood of physical illness in the following year.
                  • Findings from numerous studies using the SRRS have shown that a person who had experienced events totalling more than 300 life change units over a period of a year was more at risk for a wide range of mental and physical illnesses including heart attack, anxiety, depression and asthma
        • Strengths
          • The research triggered a great deal of other research
          • It is a quick and easy measure of life change and the correlation between high SRRS score and illness is reliable
        • Weaknesses
          • The SRRS tends to mix together too many different kinds of events which will not effect everyone in the same way
          • The data used to establish the SRRS was collected retrospectively and may not be reliable
          • It does not take into accound individual differences. Some people may have vulnerable personalities and different events may affect people in different ways
          • It is not a complete list - some life changes are missing
    • Rahe et Al (1970)
      • Used the SRRS to measure correlation between life changes and the onset of illness
        • Investigated 2500 male US naval personnel over a period of 6 months
          • Participants were asked to say how many of the life events they had experienced in the past 6 months. A total LCU score was calculated for each participant
            • A health record was also kept of each participant during the six month tour of duty, after which they calculated the correlation between total LCU's and incidence of illness
              • They found a significant positive correlation of +0.118 between total LCU score and illness
      • Strengths
        • The findings from the study support other research that suggests that life events do have an association with stress related health breakdown
      • Weaknesses
        • The correlation they found is weak. It is significant because of the sample size being so large but it suggests there may be other factors affecting health
        • This is a correlational study so cause and effect cannot be established
        • The sample only included male US navy personnel; therefore it was both ethnocentric and andocentric. This reduces the validity of the study and makes it difficult to generalise to other populations
        • The study does not take into account any individual differences that may be involved in reactions to stress. Some people may react more because of things like personality, social support network,age, lifestyle ect
    • DeLongis et Al (1982)
      • Devised the hassles scale. The original form had 117 items, although shorter versions have been constructed for specific groups
        • Some research suggests that the negative effects of daily hassles can be offset by daily uplifts. The uplifts scale has 135 items that cheer people up
          • DeLongis et Al gave 100 middle aged adults 4 scales to complete once a month for a year
            • 1. Hassles Scale  2. Uplifts Scale  3. Life events questionnaire 4. Health status questionnaire
              • They found that there was a significant correlation between hassles scores and ill health but no significant correlation between uplifts score and health
                • Comparing hassles scores with life events score, they found that although both showed significant correlations with health status, the correlation for hassles score was greater
      • Weaknesses
        • Correlational research so cannot infer cause and effect
        • Self report measures can lack validity because; people may interpret items on the scale in different ways, people may not tell the truth as the may show 'social desirability bias' and they may not accurately recall all the hassles they experienced
    • Johansson et Al (1978)
      • Studied the effects of workload stress and lack of control in a Swedish sawmill
        • Two groups of workers at a Swedish sawmill were identified
          • The first was a group of 14 'finishers' whose job was at the end of the production line. They worked in a noisy environment , isolated from other people. Their work was repetitive but highly skilled
            • The speed at which they worked was determined by the production line, so they had little control over their speed of work. They job was also highly responsible. Their productivity determined to pay of everyone in the factory. If they made mistakes and the wood was spoiled, pay would be reduced
              • They were compared to a group of 10 cleaners whose work was more varied, they worked at their own pace and had more social contact.
                • Both groups' stress levels were measured by testing the amount of adrenaline and noradrenaline in their urine. Also medical records were checked to look at the number of illnesses suffered and the number of days off work through illness
                  • The finishers had higher stress levels than the cleaners. They had higher blood pressure, a higher rate of stomach and intestinal disorders and reported suffering more headaches. They had more days off work due to illness
                    • Urine samples showed they had higher levels of adrenaline and noradrenaline in their urine on work days than on rest days. When the management changed the organisation of the factory so that pay was not determined by productivity, their stress levels dropped significantly
      • Strength
        • The study uses a real life situation, so has high ecological valitidy and the findings can be related to real life
      • Weaknesses
        • Some important variables e.g. individual differences were not controlled in this study
        • There are demand characteristics - participants may feel better because somebody is paying attention to their needs
        • The study cannot exclude other variables that may affected the results
    • Marmot et Al (1977)
      • Investigated the relationship between job control and stress-related illness
        • A sample of 10,308 civil servants aged 35-55 were investigated in a longitudinal study over three years using questionnaires and observation
          • Job control was measured through both a self report questionnaire and by independent assessments of the work environment by personnel managers. Job control was assessed on two occasions, three years apart. Records were also kept of stress-related illness. The correlation between job control and sress-related illness was worked our
            • Participants with low job control were 4 times more likely to die of a heart attack than those with high job control. They were also more likely to suffer from other stress related disorders such as cancers, strokes, and gastrointestinal disorders
              • These findings were consistent on both occasions that job control was measured and the association was still significant after other factors, such as employment grade, negative attitude to work, social support etc were taken into account
                • Job control was found to be negatively correlated with high stress as indicated by the number of stress related illnesses
      • Weaknesses
        • The questions may give cues as to the aim of the research, so participants may experience demand characteristics
        • Participants may show social desirability bias
        • Participants may lack insight
        • This is a correlational study, so cause and effect cannot be inferred
    • Friedman and Rosenman (1959)
      • Type A and Type B Personality
        • Friedman and Rosenman worked as cardiologists and noticed that patients with coronary heart disease (CHD) often shared similar personality characteristics. They wanted to investigate whether there was an association between these personality characteristics and stress related illness
          • A self-selected sample of 3200 Californian men aged between 39 and 59 years was used. This was a longitudinal study, as the participants were health at the onset in 1960 and were assessed over a period of eight and a half years
            • Part one of the study included structured interviews and observations, which assessed personality type and current health status. From the personality assessment participants were classified as having a type A or type B personality
              • Type A personalities are impatient, hostile, competitive, workaholics, irritated by even small delays, time conscious and multi-taskers
                • Type B personalities are patient, relaxed and easy going
                  • Part two of the study was the follow up eight years later when the incidence of CHD was recorded. A correlational analysis was carried out to test the association between Type A/B behaviour and CHD
                    • 257 participants had developed CHD during the eight and a half years, 70% of which had been classed as type A. This was still the case when other factors such as blood pressure, smoking, obesity known to be associated with heart disease were taken into account
                      • The correlation was +0.3 which is a relatively low correlation. Friedman and Rosenman concluded that the type A behaviour pattern increases the individuals experience of stres, which increases the vulnerability to CHD
                        • The high levels of stress hormones suggest that they do experience more stress than type B's. The release of the hormone cortisol from the adrenal gland tends to raise the fat content of the blood
      • Weaknesses
        • Type A behaviour includes a number of characteristics and is too broad a definition to be useful
        • This ia a correlation analysis so cause and effect cannot be established
        • Although some aspects of lifestyle were controlled, there may have been other variables that could have affected vulnerability to heart disease
      • Strengths
        • Personality types were identified by structured questionnaires rather than the less reliable self reporting
        • As it measures real life variables, this study has greater external validity
    • Kobassa and Maddi (1979)
      • Hardiness
        • The study was carried out in a large US public utility company that had become concerned about the high levels of stress experienced by it's personnel due to promotions due to promotions and demotions as a result of widespread restructuring
          • The study was a longitudinal one and began with all 837 of the company executives and participants
            • Kobassa used a modified version of the SRRS to measure stress. The scale was improved by adding 15 stressors identified by a group of executives as common to their lives. The additional items were weighted for seriousness by the same group
              • To assess an illness, an illness rating scale was used. This included 118 illnesses, rater for seriousness by doctors. Two questionnaires were posted out to all 837 participants and were to be answered for the previous 3 years
                • About three months later the same participants wer asked to complete a number of questionnaires to assess personality
                  • Tow groups were identified from the original sample; 100 executives who had high stress scores and high illness scores and 100 executive who had high stress scores but low illness scores
                    • Using the personality tests, she identified differences between the samples. The executives who, despite high stress levels did not become ill scored higher on three personality characteristics;
                      • Control -  A person with high perceived control has the feeling of being able to strongly influence events in their own lives
                        • Commitment -High commitment means high involvement in and appreciation of self, family, work and society
                          • Challenge - A person high in challenge thinks of change as an exciting opportunity instead of something to be feared
                            • These characteristics became knwon as the hardy prsonality
      • Weaknesses
        • Much of the data is retrospective and based on self-report, which may not be reliable
        • Hardiness, stress and illness were assessed by using questionnaires which can be problematic as they are subjective and therfore may be biased

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