Deviation from Statistical Norms Explanation
Anything infrequent is abnormal.
Anyone whose behaviour differs from the norm is called 'abnormal'.
When a score gets far away from the average it is abnormal.
Normal distribution curve 95.4% of scores are either side of the mean.
Any score outside that percentage would be considered statistically infrequent and therefore abnormal.
Very low IQ scores are considered abnormal and may be given extra help in society.
In statistical terms they are likely to fall in the bottom two standard deviation bands e.g. an IQ of 70 or below.
Deviation from Statistical Norms Evaluation
One score may not be enough to define someone as abnormal. It may be necessary to look at more than one measure i.e. not just IQ. Therefore it can't be applied to real life as there are aspects of people that can't be measured, and so they can't be fully classed as abnormal.
Having a single cut off present's difficulties. Who decides where that line lies? If 70 is the cut off for IQ how can we justifie someone with 69 being abnormal whereas someone with 70 is normal. This means that a person with an IQ of 70 can be denied help that someone with an IQ of 69 can get. That person may need that help but is denied it because statistically they aren't abnormal.
People with very high IQ scores, aren't considered normal, as they fall outside of the middle range, we woudn't however call them abnormal in the sense of being mentally ill. This means that people below normal are seen as ill and in need of help, but people above the normal statistical range are glorified.
Deviation from Social Norms Explanation
Any unusual social behaviour is abnormal e.g. wearing nightclose in the street, talking to yourself or hearing voices.
Unusual behvaiour is statistically infrequent, is expected as people generally conform to social norms.
However behaviour might be quite frequent in society , though against social norms, so the social norms rather than statistical infrequency is the focus here e.g. feeling depressed, not being able to get dressed or go our the house.
What is classed as normal behaviour depends on the culture you belong to, the context you are in and can vary over time e.g. wearing a chicken suit for an advertising company is normal, but to ho shopping in one is abnormal. Also, 100 years ago an unmarried woman who got pregnant outside of marriage was sent to an institution.
Deviation from Social Norms Evaluation
There may need to be several examples of anti-social behaviour before we are willing to label someone as abnormal. Perhaps wearing nightclothes and singing in the street suggests abnormality rather than just wearing nightclothes which you might do in an emergency. This is because one display of an abnormal trait may be a one off or something that isn't done frequently. The rest of a persons personality may be considered normal and so there needs to be multiple traints that are abnormal in order to be classed as infrequent in society.
There are cultural differences in social norms, so measuring abnormality by means of such norms which are not fixed, is not likely to be useful. This is because different cultures may live in.
This definition explains why different cultures can have different ideas about what is abnor,aland so is generalisable.
We tend to think of abnormality as involving odd behaviour so this definition allows someone who is very intelligent not to be seen as abnormal.