definition of abnormality (1)

• Statistical infrequency


  Any relatively usual behaviour or characteristic can be thought of as ‘normal’, and any behaviour that is unusual is ‘abnormal’.
• Normal distribution


  In any human characteristic, the majority of people's scores will cluster around the average, and that the further we go above or below that average, the fewer people will attain that score
• Normal distribution of IQ


  • Average IQ is set at 100
  • Most people (680) have a score (IQ) in the range from 85 to 115
  • Only 2% of people have a score below 70
• Intellectual disability disorder (IDD)

  Diagnosis for individuals scoring below 70 on IQ tests, which is very unusual or abnormal
• This statistical approach ( statistical infrequency) comes into its own when we are dealing with characteristics that can be reliably measured, for example intelligence
• Strength of statistical infrequency


  • is it’s usefulness

  • SI is used in clinical practice, as part of formal diagnosis and a way to assess severity of an individual's symptoms.

  • e.g. diagnosis of intellectual disability disorder requires an 1Q of below 7o (bottom 2%.).

  Beck depression inventory. A score of 30+ (top 5% of respondents) is widely interpreted as indicating severe depression.

  • shows that the value of the statistical infrequency criterion is useful in diagnostic and assessment processes.
• Limitation of statistical infrequency 


  • infrequent characteristics can be positive as well as negative.

  • For every person with an IQ below 70 there is another with an IQ above 130. Yet we would not think of someone as abnormal for having a high IQ.

  • This examples show that being unusual at one end of a psychological spectrum does not necessarily make someone abnormal.

  • This means that SI is not sufficient as the sole basis for defining abnormality.
• Deviation from social norms


  When a person behaves in a way that is different from how we expect people to behave
• Groups of people (hence 'social')

  • Choose to define behaviour as abnormal on the basis that it offends their sense of what is acceptable or the norm
  • Making a collective judgement as a society about what is right
• Norms are specific to the culture we live in


  may be different for each generation and every culture, so theres relatively few behaviours that would be considered ‘universally‘ abnormal on the basis that they breach social norms.
• Homosexuality


  • considered abnormal in our culture in the past
  • continues to be viewed as abnormal (and illegal) in some cultures (e.g. in April 2019, Brunei introduced new laws that make sex between men an offence punishable by stoning to death.
• Antisocial personality disorder, (psychopathy)


  A person who is impulsive, aggressive, and irresponsible.
• Symptom of antisocial personality disorder


  Absence of prosocial internal standards, associated with failure to conform to lawful and culturally normative ethical behaviour
• Psychopathic behaviour


  Considered abnormal in a very wide range of cultures, because it doesn’t conform to our moral standards.
• strength of deviation from social norms


  • is its usefulness.

  • used in clinical practice.

  • e.g. key defining characteristic of antisocial personality disorder is the failure to conform to culturally normal ethical behaviour i.e. recklessness, aggression, violating the rights of others and deceitfulness.

  • These signs of the disorder are all deviations from social norms which plays a part in the diagnosis of schizoptypal personality disorder.

  • shows that the deviation from social norms criterion has value in psychiatry.
• Limitation of deviation from social norms


  • Variability between social norms in different cultures and situations.

  • person from one cultural group may label someone from another group as abnormal using their standards rather than the person's standards.

  • For example, the experience of hearing voices is the norm in some cultures but would be seen as a sign of abnormality in the UK.

  • difficult to judge deviation from social norms across different situations and cultures.