aqa  Definitions of abnormality, including deviation from social norms, failure to function adequately, statistical infrequency and deviation from ideal mental health.

Abnormal psychology is the study of people who are ‘atypical’ in society. Since the term atypical is subjective, psychologists have come up with definitions of abnormality.

There are four main definitions of abnormality are:

  • Deviation from Social Norms
  • Failure to Function Adequately
  • Statistical Infrequency
  • Deviation from Ideal Mental Health

Deviation from Social Norms

Each culture has behaviours that are expected of people and deemed to be ‘normal’. These may be explicit social norms (i.e. laws for behaviour, which, if broken, result in punishment by a justice system) or implicit social norms (unwritten standard of behaviour, which, if broken, may result in being looked down on by others). An example of an explicit social norm is stealing. An implicit social norm may be not standing too close to someone when conversing with them.

Limitations of this definition:

  • Firstly, social norms differ from culture to culture. What is deemed normal in one culture, may not be in another. For example, in Afro-caribbean societies speaking to dead relatives is normal, but this behaviour may be viewed as a sign of abnormality in the UK, for example.
  • Additionally, cultural norms are often time-specific. For example, homosexuality was a criminal act in the UK (i.e. breaking an explicit social norm) until 1967.
  • Social norms also depend on context. Screaming and shouting in public may be a sign of abnormality if it occurred in the middle of a shopping centre, but what about at a football match?
  • Eccentric behaviours may not necessarily be indicative of abnormality, for example streaking at a football match.
  • Criminal behaviours may not always be indicative of an abnormality that requires treatment, for example tax fraud.

Failure to Function Adequately


According to this definition a person is abnormal if they are unable to cope with the demands of day-to-day life, such as looking after themselves and holding down a job and social relationships. The Global Assessment Functioning Scale (GAFS) is used by psychologists to determine whether this is the case (see link).

Here is an example of someone scoring 40/100 on the GAFS: “Some impairment in reality testing or communication (e.g., speech is at times illogical, obscure, or irrelevant) OR major impairment in several areas, such as work or school, family relations, judgment, thinking, or mood (e.g., depressed man avoids friends, neglects family, and is unable to work; child frequently beats up younger children, is defiant at home, and is failing at school). ” (Source)

Limitations of this definition:

  • It can be very subjective. How can an external person judge how well someone is coping? Especially if they are not with that person 24/7 or qualified to judge. Should the patient decide themselves?
  • Abnormality does not always stop the person from functioning and so abnormality may be missed. They may appear fine to to others, i.e. hold down a job and relationships, but actually be experiencing inner distress which they hide.
  • Cultural Relativism: High levels of stress may be normal in some cultures, for example in Eastern America. It is not necessarily an indication that the person is failing to function adequately. Differences in individuals’ circadian rhythms may mean that some people struggle to function early in the morning, as their body clock is naturally shifted towards being a ‘night owl’.
  • Many people engage in negative/harmful behaviours that affect their functioning, but we don’t necessarily see as being abnormal. For example drinking alcohol socially, which affects functioning, or high risk sports, which carry an extremely high risk of injury.

Statistical Infrequency

Using this definition of abnormality, behaviour that is statistical infrequent is deemed to be abnormal. Usually this would be defined as any behaviour that falls beyond two standard deviations from the norm, thus occurring in only a small number of the population. For example, if a person’s IQ is significantly low, statistically, they are deemed to be abnormal.

Limitations of this definition:

  • Not all rare behaviour is negative. For example, having an extremely high IQ would not necessarily be deemed to be abnormal, despite being rare.
  • Culture plays an important part in this definition. If someone has emigrated and their behaviour is statistically infrequent in the new culture, they may be falsely labelled as abnormal.
  • There is also an arbitrary cut-off point. Whilst the upside of this is that the definition can be used objectively, it also means that someone who falls just inside the cut-off point would not receive treatment when maybe they need it. Should someone with an IQ of 69 be deemed abnormal, when someone with an IQ of 7 is not?
  • Some abnormalities are not statistically infrequent. For example, 1 in 5 people in America will suffer from Depression at some point in their lifetime. According to this definition they are not abnormal (and should thus not receive treatment?!)

Deviation from Ideal Mental Health


In 1958 Jahoda proposed 6 criteria for Ideal Mental Health:

  1. Positive view of the self
  2. Resistance to Stress
  3. Autonomy and independence
  4. Accurate perception of reality
  5. Positive friendships and relationships
  6. Environmental mastery – able to meet the varying demands of day-to-day situations.

According to Jahoda, each of these criteria must be met for a person to be fully healthy/normal.

Limitations of this definition:

  • One clear limitation is that it is very difficult to meet all of these criteria all of the time, which would thus indicate that many people are abnormal much of the time!
  • These definitions may also be ethnocentric, having been devised in the West. For example, autonomy and independence is only valued in individualistic societies. In collectivist cultures, group cohesion is valued above these, thus a disproportionate number of people from other cultures would be deemed abnormal under this definition.
  • Whilst being resistant to stress is beneficial for individuals, experiencing stress may not always be bad. For example, some people may perform better in sports, when acting or when public speaking if under a degree of stress.


Go Further

  • There is an interesting TV documentary called “How Mad Are You?” made by the BBC.
  • “Is there a definitive line that divides crazy from sane? With a hair-raising delivery, Jon Ronson, author of The Psychopath Test, illuminates the grey areas between the two.”