Assumptions of the biological model of abnormality
1. The biological model is based on the assumption that abnormal behaviour has a
physiological cause. In this respect mental disorders are just like any other illness
and this is why this model is often referred to as the medical model. Mental
illness can be caused by genes, biochemistry, neurophysiology and infection.
2. Genetic inheritance is an important cause of all human behaviour including
abnormal behaviour. Studies of identical (M.Z.) twins have revealed a very high
concordance rate for conditions such as schizophrenia – if one twin has
schizophrenia the likelihood that the other will also get it is nearly 50%. Genes
also determine levels of hormones and other chemicals that influence behaviour.
Assumptions of the psychodynamic model
1. Freud believed that the cause of abnormal behaviour was in the unconscious mind
and related to unresolved conflicts of childhood – especially those experiences in
the first three psychosexual stages. During these stages the child may become
fixated due to over or under indulgence of needs and these fixations may lead to
abnormal (and normal) behaviours in later life.
2. Conflicts between the three parts of the personality – id, ego and super-ego –
create anxiety. The ego attempts to deal with these anxieties with a variety of
defence mechanisms – many of which can be the cause of abnormal behaviour.
For example the repression of feeling of anxiety causing feelings or memories. If
not dealt with these repressed feelings can cause problem behaviour.
Assumptions of the behavioural model
1. All behaviour is learned through the principles of classical conditioning
(association) and operant conditioning (reinforcement). Abnormal behaviour is
learned in the same way and so can be unlearned and replaced with more
2. Behaviourists believe that the basic units of learning will be the same in animals
and humans. Units of learning will be greater in number and complexity in higher
animals and humans but the same basic laws that link stimulus and response will
be the same. This justifies the use of animals in experimentation – Skinner,
Pavlov etc experimented on rats, pigeons and dogs – as results can be generalised
Assumptions of the cognitive model
1. Cognitive psychologists believe that thinking directs all behaviour and that
abnormal behaviour is caused by faulty thought processes. These thought
processes may include faulty assumptions about the self – very common in
depression to have self defeating thoughts. They may also focus on the outside
world – for example in the case of phobias when threats from external objects or
events are over exaggerated
2. The cognitive approach is different from all the others in that it sees the individual
as having control. Although they may need some help, the person is able to
control how they think. Cognitive therapy focuses on helping the person to accept
this control and begin to have rational and self enhancing thoughts.