Definitions of abnormality: statistical deviation and deviation from social norms
Key terms
- Statistical deviation: occurs when an individual has a less common characteristic, for
example, being more depressed or less intelligent than most of the population
- Deviation from social norms: concerns behaviour that is different from the accepted
standards of behaviour in a community or society
Statistical deviation
According to the statistical deviation definition, any relatively usual behaviour or characteristics
can be thought of as ‘normal’ and any behaviour that is different to this is ‘abnormal’
- This is what is meant by statistical deviation
- For example, we can say that at any one time only a small number of people will have
an irrational fear of buttons
Example: IQ and intellectual disability disorder
The statistical approach comes into its own when we are dealing with characteristics that can be
reliably measured, for example intelligence
- In any human characteristic, the majority of scores will cluster around the average and
the further we go above or below that average, the fewer people will attain that score
- This is called the normal distribution
The average IQ is set at 100 and most people (68%) have an IQ in the range between 85 and
115
- Only 2% of people have a score below 70
- Those individuals scoring below 70 are very unusual or ‘abnormal’ and are liable
to receive a diagnosis of a psychological disorder - intellectual disability disorder
(which used to be known as mental retardation)
Evaluation of the statistical deviation definition
Key terms
- Statistical deviation: occurs when an individual has a less common characteristic, for
example, being more depressed or less intelligent than most of the population
- Deviation from social norms: concerns behaviour that is different from the accepted
standards of behaviour in a community or society
Statistical deviation
According to the statistical deviation definition, any relatively usual behaviour or characteristics
can be thought of as ‘normal’ and any behaviour that is different to this is ‘abnormal’
- This is what is meant by statistical deviation
- For example, we can say that at any one time only a small number of people will have
an irrational fear of buttons
Example: IQ and intellectual disability disorder
The statistical approach comes into its own when we are dealing with characteristics that can be
reliably measured, for example intelligence
- In any human characteristic, the majority of scores will cluster around the average and
the further we go above or below that average, the fewer people will attain that score
- This is called the normal distribution
The average IQ is set at 100 and most people (68%) have an IQ in the range between 85 and
115
- Only 2% of people have a score below 70
- Those individuals scoring below 70 are very unusual or ‘abnormal’ and are liable
to receive a diagnosis of a psychological disorder - intellectual disability disorder
(which used to be known as mental retardation)
Evaluation of the statistical deviation definition
