Stress as a bodily response (physiological model)

Let’s get something straight right from the start.  The body’s reaction to stress is old fashioned.  In the modern World, in the vast majority of stress situations the body’s response to stress causes more harm than good.  However, in the olden days, before even Mrs Ashton, Mrs Wilson and I were born (though perhaps not Mr Dodd), like tens or hundreds of thousands of years ago, our present day response to stress would have been a lifesaver. 

Faced with danger such as a sabre tooth tiger or a warring tribe down the road then a sudden mobilisation of energy in the body was useful.  Consider the typical response to stress:

• Increased heart rate
• Increased blood pressure
• Relaxation of the lung’s bronchi (air channels widen)
• Release of glucose into the blood
• Dilation of pupils (letting more light into the eye)
• Slowing of digestion (allowing blood to flow to muscles, heart etc).

This is referred to as the 3fs response (fright: flight or fight) and serves a simple purpose.  It is pumping oxygen and glucose around the body providing energy to the areas where it’s most needed.  If the danger persists we can fight or we can turn and run.  If danger passes then very quickly the body can return to normal and primitive man can return to taking Dino for a walk!

BUT

Although our minds and behaviour have evolved since then (I speak for the majority of us here), our bodies and our biology have hardly evolved at all.  Today a typical stressor is likely to be examinations, bills, relationships, work etc.  However, our body does not distinguish between stressors, it reacts to them all in exactly the same way, i.e. the way it would have done thousands of years ago faced with life threatening stressors.  (This is why Selye called it the GENERAL adaptation response).  Exams therefore cause us to mobilise energy reserves, heart rate increase etc, as I’m sure you’ve noticed.  Unfortunately the response that was supposed to last seconds or minutes now lasts for the time of the exam stress, possibly weeks or months.  It now wears the body down and becomes a life threatener rather than a lifesaver.

The nervous system

I could bore you for hours here (as I’m sure some of you have noticed), but instead I’ll stick to the essentials. 

The Autonomic Nervous System (ANS).

This controls the functions that we have no conscious control over such as digestion, temperature and heart rate.  It can be split into two parts:

It’s obvious from this that the sympathetic nervous system is responsible for the stress response!  The Parasympathetic is left to return the body to normal when the threat has passed; it recharges the batteries for the next alert if you like.

The Hypothalamic-Pituitary–Adrenal Axis

Sounds complicated, lots of scientific words AND all joined up together.  It’s more straightforward than it seems.  I’ll assume that you’ve heard of the pituitary and adrenal glands, though the hypothalamus may be new to you. 

The important bits.

An area in the brain called the hypothalamus controls the body’s response to stress.  This is situated right next to the pituitary gland (sometimes referred to as the master gland because it controls the others) and both are located in the middle of the brain just behind the upper part of your nose!

In the stress response the Pituitary gland does two things. 

1. It sends nerve messages to the adrenal medulla (part of the adrenal gland)
2. It sends a chemical ACTH to the adrenal cortex (another part of the adrenal gland).

Note: a common measure of stress is skin conductance or Galvanic Skin Response (GSR).  This basically measure how moist your fingertips are.  The release of energy associated with stress causes sweating and increases the electrical conductivity of the skin.

That’s all there is to it.  The complicated bit done!!!

Research evidence

People without adrenal glands die when stressed unless they receive injections of cortisol (a steroid).  They have to be given training in avoiding or minimising stress!

Brady’s executive monkeys also supports the theory since the ‘executives’ died as a result of ulcers caused by long term disruption of digestion.  (See the key study later).

Remember that Brady’s study is flawed methodologically (in its methods) as well as being ethically very dubious.

Evaluation of the Physiological Model

This is clearly a very biological approach to stress.  It only considers events inside the body and sees stress as a purely physical response.  It does not consider differences between people, for example why one person’s stress is another person’s pleasure. 

Mason (1975) measured the levels of adrenaline produced by stressors in different people.  The same stressors produce different levels of adrenaline in different people depending on how they interpret the stress.  The physiological model does not consider people’s interpretations or perceptions of stress.
 

General Adaptation Syndrome

Selye, during his research on rats, noticed that their response to stress was always the same, regardless of the cause of the stress.  So whether the stress was caused by another male or by electric shocks to the feet, their response was indistinguishable.  This led Selye to conclude that there was just one response (General Adaptation Response) in rats and in other species including humans.  Selye further believed that a short-term response was harmless whereas a longer-term response could be dangerous.

Good points:

1.       Influential: it provided a basis for other theories and triggered lots of research into stress.

2.       Simple: the model is easy to understand, and its ideas and phrases are widely used by people studying stress.

Bad points

1.       Rats: Much of Selye’s work was based on rats.  There are two issues here

a.       Can we generalise the findings to humans?

b.       Ethical considerations since the rats died.

2.       Simplistic: GAS only considers the body’s response to stress, (physiological model).  As Psychologists we know that stress is not that simple.  It does not consider individual differences such as personality (hardiness, type A or B) or other factors such as culture and gender.

Note: criticisms of the GAS is a common exam question!

Stress and Physical illness

Stress can cause ill health in a number of ways:

It is also vital to mention that many of these effects could be attributable to habits taken up by stressed people.  Much of the evidence outlined below is correlational so does not imply cause and effect!!!  More on this later.

Coronary heart disease (CHD)

CHD is caused by a narrowing of the arteries supplying blood to the heart caused by a build up of fats in the vessels (similar to the furring up of hot water pipes).  There are two types:

·         Angina: in which blood flow is restricted.  This results in chest pains particularly following exercise.

·         Myocardial infarction: in which blood flow to part of the heart is completely blocked and can result in death.

Causes of CHD

Gender (men are far more susceptible), age (guess!), cholesterol, high blood pressure, smoking, genetics, diabetes…

Stress and CHD

Studies have suggested a link between negative life events, such as divorce, and CHD and stress at work and higher incidence of CHD, particularly in men.  Occupational factors tend to include lack of control, low job satisfaction and monotony.

As pointed out in the table above there is a clear physiological link between stress and CHD.  The 3Fs response has the following adverse effects on the circulatory system:

·         Constriction of the arteries increasing blood pressure.

·         Increased blood flow wearing down the arteries

·         Release of fats into the bloodstream increasing the risk of blockage (artherosclerosis).

Type A behaviour and CHD

We will return to this study when we look at individual differences in the stress response.

Stress and Stomach ulcers     

The University of Plymouth has an excellent section on this study and the follow ups.  See link:

http://salmon.psy.plym.ac.uk/year1/psy128coping_with_stress/psy128coping_with_stress.htm

Other research:

Weiner et al (1957) examined the gastric secretions of army recruits!  (What would you like to do when you grow up?).  They found that after 4 months of stressful training 14% of those who produce a lot of stomach acid developed ulcers, whereas none of those who produce little acid developed them.  From this they concluded:

1.       there may be a link between stress and ulcers

2.       stress could not be the only cause since 86% of over-secretors did not develop ulcers.

Stress and the immune system

We have already seen that during times of stress the adrenal cortex produces steroids (called corticosteroids since they’re produced by the adrenal cortex).  These stop the body producing lymphocytes (white blood cells) that attack foreign bodies such as viruses, in the bloodstream.

Research evidence

There’s lots of it.  Choose the ones you prefer or think you’re most likely to remember.  Kiecolt-Glaser et al (1984) is a good one to use as key study.  Note: it’s Janice Kiecolt-Glaser so refer to her as ‘she.’

Other studies

·     Riley (1981) placed mice on a turntable at 45 rpm; (they must be single mice.  I’ll try this ‘joke’ again and see if you get it this year!).  This induced stress and decreased their number of lymphocytes.

·     Kimzey (1975) found that American astronauts who had just gone through the stress of re-entry had a lower white blood cell count.

·     Sweeney (1995) took biopsies from the arms of volunteers.  It was found that participants who were stressed by caring for elderly relatives took longer to heal.  Think of the practical implications of this for people recovering from major surgery!

·     Cohen et al (1991) carried out an impressive study on 394 participants.  They each had their stress index measured using a questionnaire that also took into account their ability to cope and their feelings about their stress.  They were then given nasal drops that infected them with cold viruses.  When tested by doctors there was a direct correlation between their stress index and the probability that they developed a cold.

Stress and cancer

The link is by no means proven, but there is some evidence.

·      Jacobs & Charles (1980) found that children who had developed cancer have often been exposed to above average levels of stress in the previous year.

·      Visintainer et al (1983) injected cancerous cells into animals.  Those that were then stressed were less able to fight the cancer.

·      Tache et al (1979) found that cancer is more likely in single, separated or divorced people.  This was put down to lack of social support in reducing the effects of stress.

·      Levy (1993) believed that immune suppression might again be to blame.  It is thought that the immune system produces chemicals that fight cancer.  As with CHD it may be behaviours associated with stress, such as smoking, that cause cancer, not the stress itself.

Indirect affects of stress on health.

It is essential that this be considered in any part c question on stress and physical health as it will guarantee AO2 marks.

Stress is associated with all manner of bad habits, for example smoking, drinking alcohol to excess, poor diet due to lack of time, lack of exercise for the same reason, lack of sleep etc…  All of these are likely to have an adverse effect on a person’s health so could cause some of the ill-effects attributed to stress per se.

Cohen & Williamson (1991) found that people who are stressed tend to smoke more, take less exercise, drink more alcohol and sleep less than others.  All of these habits can lead to ill health. 

Wills (1985) found that stressed teenagers were more likely to start smoking.  Similarly, Carey et al (1993) found that adults who had given up smoking were more likely to take it up again when stressed.

Brown (1991) found that life events were more likely to cause students to seek medical advice if the students were low in physical fitness, as compared to students high in physical fitness.

Conclusion

It may not be stress itself that causes ill health but the behaviours that stressed people tend to engage in.

b. Sources of Stress

This section can loosely be split into two sections:

• “Causes of stress” (or stressors as they are known), such as life events, hassles, occupational stress etc.
• “Individual differences in the stress response” looks at factors that may effect how we cope with stress such as personality, culture and gender.

Causes of stress

1. Life events (Social Readjustment Rating Scale: SRRS)

Holmes and Rahe were two hospital doctors who noticed that many of the patients that they visited on their rounds had suffered life events causing disruption to their lives in the previous year.  They decided to construct a questionnaire to examine the possible link between life changing events and physical ill-health. 

1. They examined the medical records of over 5000 patients
2. They compiled a list of 43 life events
3. They rated these in order of the time it would take to get your life back to some semblance of normality following the event
4. They gave ‘marriage’ an arbitrary score of 500 and got others to rate the other events in comparison to this.  They averaged out the scores and divided them by 10, so in the final scale ‘marriage’ has a score of 50.
5. The scale starts at 100 LCUs (Life Change Units) for ‘death of a spouse and ends with 11 LCUs for ‘minor violation of the law.’

The scale was tested on different groups of people to determine its relevance.  Patients would add up the score for each life event and this would be their total LCU.  They believed that a score of over 300 meant an 80% chance of developing a serious physical illness in the following year. 

Evaluation of the SRRS

Individual differences: the life events in the list will have different meaning and cause different amounts of disruption to different people.  For example the effects of divorce will depend on how long the couple have been married, whether or not children are involved, whether the person is escaping a violent partner etc…

Cause and effect: the scale implies a correlation between stress and ill-health, however, as I’m sure you must have realised by now correlations do not prove cause and effect.  All manner of other reasons could be used to explain the link.  Ill-health could be causing the stress, or the life events.  For example a heart attack could cause loss of job, major changes in standard of living resulting in break up of marriage etc. 

Positive life events: Martin (1989) found no correlation between positive life events such as ‘outstanding personal achievement’ and ill-health.

There are other problems as you would have found when you did the test, such as not relevant to people your age and does not consider other forms of stress such as hassles.  However, it is unlikely that you would be expected to mention more than two.

On a positive note: the SRRS was the first of its type and inspired many others to follow and devise more relevant and useful tests.  The scale is rarely used in serious psychological research today.

Use of the SRRS

Rahe et al (1970) tested 2500 naval personnel on board 3 ships just before they set sail.  During their six months tour of duty the sailors kept health records.  A correlation of 0.118 was found between LCUs and ill-health.  This is relatively low; however, because of the size of the sample (2500) it is statistically significant.

2. Hassles and Uplifts

Generally our everyday feeling of being stressed can probably be attributed more to minor, irritating problems than to the rarer major life events.  Some research has found that hassles have a greater correlation with ill-health than do the seemingly more serious life events.

Examples of hassles and uplifts (Kanner et al 1981)

Evaluation of this study

Many of the earlier problems still exist:

1. There are still many examples of stressor not considered such as so called chronic stressors such as poverty, poor housing, overcrowding in inner cities etc.
2. Individual differences are still not considered.  We all perceive and react to stress differently, some people seemingly being able to cope better than others, and again these are not considered.
3. Cause and effect.  Yet again the study is a correlation so does not prove that the stress is causing the illnesses.  For example just before a cold we may feel more hassled, but this could be because the virus is already having its effect, leaving us tired and less able to cope with everyday events.  That is the illness is actually causing the hassle!

3. Occupational stress

This is a favourite topic for examination questions as well as being an important issue for workers around the World.  Recently stress has overtaken the common cold as the main reason for absence from work.

Causes of stress in the workplace:

Work overload

Breslow and Buell (1960) found that employees working more than 48 hours a week were twice as likely to develop CHD than those working 40 hours a week.

However, it is probably the perception of long hours that is more important than the number of hours per se.

Environmental factors

These include any aspect of the working environment that is likely to cause stress; most obvious examples include noise, temperature, vibration, lighting and overcrowding.

Although people can cope reasonably well with noise it does appear to cause some impairment in performance, particularly if the noise is unpredictable.  Glass et al got 60 participants to complete cognitive tasks such as word searches under one of four conditions:

The researchers concluded that we can adapt to high noise levels but this is more difficult if the noise is not constant or is unpredictable.

The stress of overcrowding has been studied in other species particularly rats where it has lead to bizarre behaviours such as parents eating their offspring.  Freedman et al (1975) found a correlation between high density living conditions such as inner cities, and admissions to psychiatric hospitals.  Yet again this is a correlation so does not prove c_____ and e_____.  Perhaps you could think of some other reasons, other than overcrowding to explain why inhabitants of inner cities are more likely to be diagnosed with mental illness.  Clues perhaps in the next topic!

Role ambiguity

To some extent we all play roles, particularly in the work situation.  You may have noticed that some teachers behave very differently out of work when playing a different role!  Role ambiguity is likely to occur when a person is unsure of their precise responsibilities within an organisation and has been reported as a major source of stress by 35% of workers in the USA. 

Role conflict

This is a common form of stressor and arises when the job requires you to behave in a way that is at odds with your own desires or beliefs.  For example working overtime may be at odds with your role as parent.  Similarly someone in middle management may find it difficult to balance the needs of their superiors for higher output with the needs of their staff for a shorter working week.

There are other forms of workplace stress including burnout, repetitive work, isolation, lack of control etc.; some of these are addressed by the key study of Johansson et al (1978)

1. Civil Servants

Marmot et al (1997) began with the hypothesis that control was negatively correlated with stress-related illness; that is as control decreases the level of illness increases.

Over 10,000 civil servants were investigated over a period of three years.  Researchers assessed the level of job control by self report questionnaires and by assessments by personnel managers and this was then compared to levels of stress related illness. 

They found that workers with less control were four times more likely to die of heart attack than their colleagues with more control.  In addition they were more likely to suffer from other stress related illnesses such as cancers, ulcers, stomach disorders and strokes.  Even when other possible contributory factors such as diet, smoking, social support etc. had been taken into account the additional risk remained!

The conclusion was obvious, that lack of control seemed to be associated with illness and they recommended that employers gave their staff more autonomy and control.

Criticisms of this study:

Since the method is correlational it can only be said that there appears to be an association between low control and stress-related illness.  It cannot be assumed that low control is causing illness!   It could be that workers with poor health are less likely to achieve the higher grades where control is greater.  This would explain the findings just as well.

Workers filled in self-report questionnaires which are notoriously inaccurate and prone to participant reactivity (see notes on research methods).  Basically, if the workers suss what the researchers are looking to find they may answer questions accordingly.  Similarly the personnel managers assessing people’s jobs may do the same!

2. Sawmill

Johansson et al studied a small group of workers in a large sawmill.  Their job was ‘finishers’, i.e. they were the final link on a conveyer belt system.  The rate at which they worked determined the output of the mill so their job was very responsible. 

Sources of stress included: responsibility for the mill’s output, responsibility for the pay of other employees (since pay was linked to productivity), working in isolation, so didn’t have others to share problems with, little control (since they worked on a conveyor belt), highly skilled but repetitive work.

The researchers’ measured their stress hormones (adrenaline and noradrenaline) and patterns of illness. 

Findings:  They had much higher levels of stress than other workers in the mill and, presumably as a result, had more stress related illnesses and days off work.

Conclusion:  The researchers recommended that the finishers should move to a salary structure (i.e. pay not based upon output) and should be allowed to rotate jobs with other workers.

Individual Differences in the stress response

We will look at individual differences in detail in the next topic, but you have had a brief introduction to them in attachments (Ainsworth in case you’d forgotten).  Individual differences, as the title suggests looks at ways in which we differ from one another, rather than the ways in which we are similar.  Generally we could differ because of personality, gender, social class, ethnicity, age, genes, life experiences etc.  In terms of our response to stress we’ll concentrate on:

• Personality and behaviour (Type A or B and Hardiness)
• Gender (There appears to be a difference in our biological response to stress)
• Culture (Why do some ethnic groups seem to be less stressed?)

Personality and behaviour

A famous longitudinal study carried out by Friedman & Rosenman (1974).  The researchers had earlier identified two basic behaviour types:

Being a bit of a saddo, I think of these things in terms of Eastenders’ characters, for example Phil Mitchell (type A) and Patrick, (Paul’s dad, (type B).  Perhaps you can think of your own to help you remember the characteristic traits of each.

Type A behaviour and CHD (See earlier notes for fuller details)