Models of Abnormality

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These seek to explain how psychological disorders develop.  Broadly speaking with mental disorders explanations can be split into two types:

Biological or medical explanations:  These see psychological illnesses as similar to physical illnesses in that they have a physical cause.  Psychiatrists tackle mental illness from this perspective.

Psychological explanations:  These adopt the view that psychological illnesses have their root cause in the mind and seek to explain them using a variety of different psychological theories, some of which we have come across before.  The main psychological approaches are:


  1. Their main assumptions about psychological illness
  2. The way they seek to explain psychological illness
  3. An evaluation of the model
  4. Treatments suggested by the model
  5. Ethical implications of the model

Behaviourist Cognitive Humanistic

Each has its own unique perspective and we shall consider each in more detail later. For each explanation, medical and psychological we shall consider:

It is worth mentioning that no one model offers a perfect explanation of any disorder and that often a combination of theories offers the best way forward.  Until recently the medical model has been dominant but psychological models are being used more and more.  In a clinical setting the psychiatrist would normally employ the medical approach whereas the clinical psychologist would adopt one of the psychological methods.


Medical model (also referred to as biological)

1.  Assumptions

  • Psychological illnesses have a physical cause (genetic, chemical, anatomical etc.)
  • Treatment of psychological illness will require a physical intervention (surgery or drug treatment for example).

The medical model believes that psychological illness can be caused by one of the following physical causes:

2. Explanations


Put simply, mental illness is inherited from parents.  This could be shown if there is a tendency for an illness to run in the family or if a particular gene can be identified as being responsible for the disorder. 

Usual methods of study include family, twin or adoption studies that look for links between individuals with a similar genetic make up.  However, this is psychology, and nothing is ever that simple!  At best what we can say is there appears to be a genetic predisposition in some people to develop a particular disorder.  For example if one twin has schizophrenia there is on average about a 42% chance that their identical brother or sister will also develop the disorder.  This obviously suggests that schizophrenia is not 100% genetic, but it also suggests that there is a genetic element to it.


The brain relies on various chemicals to help it communicate, these are called neurotransmitters.  Examples include adrenalin, serotonin and dopamine.  Perhaps an imbalance in these chemicals can lead to psychological disorders.  We know that LSD can cause similar symptoms to being schizophrenic and we know that LSD is chemically similar to the brain chemical dopamine. 

Dopamine hypothesis of schizophrenia

It appears that the schizophrenic brain is overly sensitive to this neurotransmitter so as a result messages get passed on that would be blocked out in a ‘normal’ brain.  Drugs such as


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