Definitions of Abnormality

  • Created by: Bethany
  • Created on: 15-08-19 22:48

Definitions of Abnormality


Defines someone as abnormal if their behaviours are statistically rare or uncommon,

  • useful when a characteristic can be reliably measured/quantified,
  • uses a normal distribution- shows the proportions of people who share specific behaviours or characteristics,
  • the majority of people's scores cluster around the average and the further above or below it the fewer people there are who will achieve that score,
  • anyone outside the normal distribution is percieved as abnormal.

Link- Intellectual Disability Disorder (IDD) would be classed as abnormal. Although IQ scores in the general population form a normal distribution where the average is 100, only 2%  have a score below 70 so this is very rare and therefore abnormal.


 +Clear and easy to use.

  • easy to distinguish between normal and abnormal behaviour,
  • assessments of mental disorders include some kind of measurement of how severe symptoms are compared to the majority in society,
  • useful part of clinical assessment.

-Subjective judgement on where the cut off between normal and abnormal should be.

  • individuals might disagree on where this should be,
  • one clinician may see sleeping less than 80% of the population to be abnormal but another might say 90%,
  • cannot be used truly objectively when diagnosing disorders.

-Defines positive characteristics as abnormal.

  • unable to distinguish between desirable and undesirable characteristics,
  • very few people have an IQ over 150 (possibly regarded as a genius) and this definition would see this as abnormal,
  • should only identify those in need of diagnosis and treatment.

-Culturally biased.

  • behaviours statistically infrequent in one culture may be statistically quite frequent in another,
  • a symptom of schizophrenia is hearing voices which might be rare in some cultures but common in others,
  • a reliable definition should be consistent between cultures.


Defines someone as abnormal if they behave in way that is seen as unacceptable by the majority in society,

  • social norms are the accepted standards i behaviour in a society-how we are expected to behave,
  • social norms form the 'rules' of a society,
  • these rules can be written (explicit) and form laws or they can be unwritten (implicit) but generally accepted,
  • social norms allow for the regulation of normal social behaviour,
  • abnormality can be seen as someone who breaks these 'rules'- someone who demonstrates social deviance.

Link- Tourettes syndrome would be classed as abnormal by this definition because it can cause sudden outbursts which might break an implicit rule in society.


-Social norms change over time.

  • behaviours that are accpetable today might change in the future,
  • homosexuality was classed as a mental illness in America until as recently as 1973
  • a reliable definition should be realatively stable and consistent over time.

-Culturally biased.

  • behaviours acceptable in one culture may not be accpetable in another,
  • women in the Suri tribe in Ethiopia are required to wear lip plates and this would be seen as unacceptable in Western society,
  • a reliable definition should be consistent between cultures.

-Fails to distinguish between social deviance and


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