Causes and Sources of Stress
Biological theories
a) Cannon's Fight or Flight response
Walter Cannon (1871-1945)
Walter Cannon (1914) described the
basic physiological process which goes
on when we are confronted with a
stressor. When being chased by a
tiger or by the police with a water
cannon (stressor), the body needs to
give quick energy to the muscles either
to run away (flight) or defend oneself
(fight). So the body produces a stress
response by pumping out lots of
adrenaline, and other hormones.
Water cannon
A little biology. The fight or flight response activates both the autonomic nervous system and the
endocrine system. Between them they stop some functions of the body and activate others. So the
digestion system is turned off, the bowels evacuate themselves and the immune system closes
down. On the other hand the heart rate, blood sugar levels and perspiration all increase.
When the stressful situation passes, the body returns to equilibrium, but if stress is prolonged it
does not, and the result can be raised blood pressure, cardiovascular problems and
atherosclerosis.
b) Selye's General Adaptation Syndrome
A similar physiological approach is taken by Hans Selye (1907-82, right). He
observed in animals (rats mostly) a process which they all went through in
response to a prolonged stressor no matter what that stressor was. It is
important to note that the stressor need not be the physical threat that
Cannon described, it could equally be a bad employer, a nagging husband,
unemployment, poverty etc.
According to Selye the stress process always went through three stages:
Alarm stage
Resistance
Exhaustion
The presence of
the stressor is
registered
The flight or fight response takes
place. This deals with the stress in
the short term
If the stressor is still there, the body has lost the
ability to deal with it. The body has become
exhausted. At this stage stress-related illness may
occur
Psychological theories:
a) Cognitive Appraisal Theory (Lazarus 1970s)
The cognitive approach looks at meanings and perceptions. Arnold Lazarus developed CAT which
is similar to HBM (see lifestyle section) where the person evaluates a stressor and then
evaluates their own ability to cope with it.
Stressor
External
event

Primary Appraisal
Is the event a threat?
If so, how threatening?
YES

Secondary Appraisal
Are coping resources
sufficient to cope with
the threat?
NO

Stress
Stress results in bio,
cog, emotional and
behavioural responses.
Lazarus follows Rotter’s work on locus of control. Someone with a high level of self-efficacy and a
strong internal LOC will feel less stress than someone with low self efficacy and an external LOC.
b) Personality Explanations
Friedman & Rosenman (1974) claimed that there were two basic personality types.Type A got
easily stressed whereas Type B was more relaxed and laid back. Type A were more likely to lead a
lifestyle that led to coronary heart disease (CHD).
Type A individuals tended to be ambitious, competitive, easily angered, time-conscious, wanting
recognition, and demanding of perfection in both themselves and others. Type B individuals tended
to be relaxed, easy-going and not driven to achieve perfection.
Are You Type A?
For each question rate yourself from 0-10, where 0 = not at all and 10 = very much indeed
1 Do you finish people’s sentences for them?
2 Do you often try to do more than one thing at a time?
3 Do you gesture and swear a lot while talking?
4 Do you find it hard to sit with nothing to do?
5 Do you need to win in games and sport, even when playing with children?
6 Do you hate waiting in queues?
7 Do you get impatient watching others carry out a task?
Key Study: Friedman & Rosenman (1974)
Aim: To investigate a link between personality and CHD.
Procedure
Longitudinal study
Questionnaire (similar to above) with Likert scale
3000+ San Francisco males aged 39-59
Some interviewed and all given Likert scale type
questionnaires (see above)
Followed up 8 years later – to check CHD rates.
Findings: 8 years later 257 had CHD, 70% of these were type A.
Conclusion: Personality type and CHD are related. Of all the Type A behaviour patterns, hostility is
the most closely linked.
Evaluation
a) Holistic v reductionist
All the theories tend to be reductionist (bio, perception, personality). It might be better to unite the
three into what is called the ‘diathesis-stress response’, where stress is seen as an interaction
between genes (a biological predisposition to heart disease) and psychology (the perception and
personality of the individual). The diathesis is the biology and stress the psychology.
b) Reliability and validity
Selye’s work on rats may not be generalisable to humans. F&R are reliable but not valid as asking
attitudes about situations, not investigating the behaviour in the situation itself.
c) Individual differences
The biological explanation of stress fails to show a strong correlation between stress and illness.
Also the F&R level of CHD is not very high. It has been repeated many times, but the correlation,
while positive, is never very strong (eg +0.33) - so relationship is only moderate. This suggests that
individual differences are important, ie why one person experiences stress-related illness and not
another. However, Lazarus’ cognitive model can explain individual differences.
e) Ignores social factors
The psychological explanations ignore the social dimension. Although exams are seen as stressful
in a negative way, marriage and childbirth are seen as positive, yet they both cause great change
to a person’s life. This is a similar evaluation to the health belief model and theory of planned
behaviour in earlier topics.