PSYA2 Biological Psychology: Stress (Part 1)

1) Stress as an external stimulus in the environment that produces a stress response (e.g exams)

2) Stress as a response or reaction to environmental events, specifically the psychological/physiological response to stressors (e.g fear/anxiety)

3) Stress as a transaction between an individual response and their environment; the percieved demands of the environment and their percieved ability to cope. (e.g events are only stressful if a person percieves it as a stressor)

This is the immediate response to a stressor

1) The hypothalamus activates the sympathetic branch of the ANS to prepare for "flight or fight"

2) This stimulates the adrenal medulla to release adrenaline and noradrenaline into the blood stream.
These increase arousal; heart rate + blood pressure + blood sugar + perspiration increase, muscles tense, digestion is slowed etc.  

This kicks in more slowly after prolonged exposure to the stressor

1) The hypothalamus releases corticotrophic-releasing hormone 

2) This stimulates the pituitary gland to release ACTH

3) The adrenal cortex then releases cortisol

4) This stimulates the liver to release glucose to provide energy

If the stressor goes away;

5) The parasympathetic branch of the ANS is activated which reverses these reactions and brings the body back to normal

If the stressor persists, we may become ill - e.g high levels of cortisol may weaken the immune system, prolonged levels of adrenaline can increase cholesterol which is linked to heart disease.

Aim:- To test what effects stress had on the immune system by testing whether stressed people where more likely to get the comman cold.

Procedures:- Cohen gave participants a nasal spray filled with either the comman cold virus or a harmless salt solution. All participants filled out a stress questionaire where they reported: stressful events in the last year, their ability to cope, number of negative feelings e.g anger/depression. Participants were given a stress index score based on this.

Findings:- Almost all virus infected participants showed signs of infection but only 1/3 developed a cold - this 1/3 tended to have a higher stress score. Cohen found a positive correlation between high stress scores and development of a comman cold.
Conclusions:- The study suggests that stress can affect our immune system's ability to protect against illness. The participants with higher stress scores being more likely to develop a cold suggests that thier immune system could have been effected by stress

Evaluations:- 
- This is a correlational study, we cannot assume cause and effect
- High ecological validity, based on real life stressors
- Questionaire and stress index score based from them are very subjective, may be inaccurate + subject to demand characteristic (social desirability)
- Ethical issue: participants gave consent but, giving them the comman cold virus is ethically questionable 

Aims:- To establish a link between stress and reduced immune functioning.~

Procedures:- natural experiment using 75 medical students. The participants blood was sampled one before their final exams (lower stress condition) and on the first day of their final exams (high stress condition) The number of T cells was measured as indicator of immune functioning (high number indicated better immune functioning). Participants filled out questionnaires which measured psychiatric symptoms, loneliness and life evnts on both occasions.

Findings:- T cell activity declined between the lower stress and higher stress conditions. The questionnaires showed that immune response was particulary low in participants who reported that they were also experiencing psychiatric symptoms, loneliness or stressful life events

Conclusions:- The findings confirm the assumption

Evaluation:-
- Natural experiment, the IV is not under control of the experimenter. Extraneous variables might have had an effect
- Valid method of measuring immune functioning, T cell activity is objective and can't be misinterperated
- External validity as it makes use of a real life situation
- Lack of population validity: small sample of very specific group (medical students) 

Life Changes - infrequent but major events in life that you have to adapt and adjust to, and are therefore stressful. These events can often cause long term stress.
e.g divorce, death of a partner

Daily Hassles - frequent but minor events that arise in the course of a normal day. These do not cause a great deal of stress but over time can have the effect of a long term stressor.
e.g travel problems, disagreement with friends/partner

Aims:- Holmes and Rahe developed the Social Readjustment Rating Scale (SRRS) to find out if there was a relationship between life events and illness, as a result of their observations as medical doctors of patients who experienced several life events before becoming ill.

Procedures:- Examined 5000 patient records and made a list of 43 life events that preceded illness. Asked 100 participants to rate each life event in terms of how much readjustment it produced, using a randomly assigned value of 500 to marriage and rating the other events in relation to it. Scores from the participants were then averaged and divided by 10 to give a Life Change Unit (LCU) for each event.
They asked different participants to indicate which of the 43 life events they had experienced in the past year. A life events score was calculated by adding up the LCUs of the events.

Findings:- a relationship bewteen high SRRS scores for events in the past year and the likelihood of experiencing some sort of physical illness the following year.

Conclusions:- Studies using SRRS scale show that a person who has experienced more than 300 LCUs over a period of a year are more at risk of mental and physical illness.

Evaluation:-
- Individual differences, some people may have more vulnerable personalities and become ill due to that rather then the events. Events also affect people differently and may explain the weak correlation found.
- The SRRS muddles too many different kinds of events which effect everyone differently.
- SRRS data was collected retrospectively
-SRRS is a quick/easy measure & the relationship is reliable even though it is weak, & inspired further research 

Aims:- to measure the correlation between life changes and onset of illness

Procedures:- investigated 2500 US male navel personnel over 6 months. Participants were questioned on how many life event s they had experienced over the last 6 months and an LCU score was calculated for each participant. A health record was kept for each participant during a 6 month tour of duty. A correlation between LCUs and incedients of illness was then correlated.

Findings:- Rahe found a significant positive correlation of +0.118 between total LCU score and illness. The association was significant.

Conclusions:- as total LCUs increase, so does the incidence of illness.

Evaluation:- 
- The correlation found is weak, suggests there may be other factors.
- Fairly large sample size
- Correlational study so can't assume cause and effect
- Limited population validity due to ethnocentric (all American) and andocentric (all male) sample of a very specific type of person (Naval personnel) 
- Does not take into account individual differences, e.g lifestyle, age, social support network
- Supporting research (e.g Stone et al.) suggests that life events do have a small but significant association with stress-related illness. 

- DeLongis devised the Hasseles Scale. Orignal had 117 items, although shorted versions have been made for specific groups (e.g students; having boring teachers, unfriendly classmates) 

- Some research suggests that daily hassles can be ofset by positive everyday experiences called daily uplifts, e.g recieving praise, getting on well with your partner, feeling healthy. The Uplifts Scake was devised with 135 items that cheer people up.

Procedures:- DeLongis 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 questionnaire

Findings:- Significant correlation between Hassles score and ill health but no significant correlation between Uplifts score and health. Comparing Hassles score with Life Events score, they found both had significant correlation with health but the correlation between Hassles score and health was greater.

Evaluation:-
- Correlational research so cannot infer cause and effect
- self report measures are subject to demand characteristics; participants might interperet things different, social desireability bias
- Retrospective date might not be reliable. 

Aims:- to study the effect of workload stress and lack of job control

Procedures:- natural experiment using independant measures design. One group of workers at a Swedish sawmill was the 14 "finishers" who worked at the end of the production line. They worked in a noisy environment & were isolated from other people. They had very repetitive but highly skilled work and the pace at which they worked was detirmined by the production line, so they had little control over speed of work. Their productivity determined the pay of everyone at the factory. The other group was 10 cleaners. They had more varied work at their own pace and more social contact.
Both groups stress hormone level (adrenaline and noradrenaline) was tested through unrine samples on work and rest days. Medical records were also checked to see illnesses suffered and number of days off work.

Findings:- The finishers had higher stress levels than the cleaners, including: higher blood pressure, higher rate of stomach and intestinal disorder (e.g ulcers), more reports of headaches, more days off work due to illness. They had higher levels of stress hormones than the cleaners and had higher levels of stress hormones on work days to rest days. When managers changed the system so that they were not responsible for everyone's pay, their stress levels dropped significantly

Conclusions:- This study shows a correlation between workload stress and illness. There could be several factors (low job control, high responsibility, level of skill, lack of social support) however the change in the stress levels after change in the system of pay suggests that was a factor

Evaluation:-
- You can't isolate which variable(s) was causing the stress
- Some important variables were not controlled in this study (e.g those exhibiting Type A behaviour were more attracted to the finishers jobs)
- Highly realistic & ecologically valid, can relate to real life
- Cannot exclude extraneous variables (e.g low pay which leads to poor financial situation, leading to stress)
- Subject to demand characteristics; the participants might have felt better and less stressed because someone was paying attention to their needs.  

Aims:- ivestigate the relationship between job control and stress-related illness

Procedures:- Sample of 10,308 civil servants (67% male, 33% female) aged 35-55 were investigated in a longitudinal study over 3 years using questionnaires and observation. Job control was measured through self-report questionnaires and independant assessments of the work environment by personnel managers. Job control was assessed on two occasions that were 3 years apart. The correlation between job control and stress was worked out.

Findings:- Participants with low job control were 4X more likely to die of a heart attack then those with high job control, more likely to suffer from stres related disorders e.g cancers, strokes, gastrointestinal disorders. Findings were consistant on both occasions and still significant when other factors (e.g social support, job demands, employment grade, attitude to work, risk factors for CHD) had been removed. 

Conclusions:- Low job control is negitively correlated with high stress

Evaluation:-
- subject to demand characteristics; trying to "help" the researcher, social desirability bias
- Correlational study so cannot infer cause and effect
- Other variables not taken into account initially
- Longitudinal research is subject to attrition.
- Observer effect and/or observer bias