Why definitions matter

In this topic, AQA wants you to understand four ways psychologists have tried to decide whether a person's behaviour or experience should be seen as a mental health concern:

• deviation from ideal mental health
• deviation from social/cultural norms
• failure to function adequately
• statistical infrequency

These are not four separate disorders. They are four definitions, or decision rules. Each one draws the boundary between "typical" and "concerning" in a different place.

The word abnormality appears in older AQA papers and many textbooks. The updated 2025 specification uses the broader phrase definitions in the field of mental health, but the four definitions are the familiar AQA content. In exam answers, it is fine to write about "abnormality" where the question uses that term, but keep the tone precise and non-stigmatising.

AO1 - knowledge: Know what each definition means and the specialist terms attached to it.

AO2 - application: Be able to spot which definition is being shown in a stem. For example, "only 1 in 1000 people" points towards statistical infrequency; "cannot get to work or maintain hygiene" points towards failure to function adequately.

AO3 - evaluation: Be ready to explain why each definition is useful but incomplete. A strong answer does not just say "it has limitations"; it explains the exact problem with that definition.

Deviation from ideal mental health

This definition works like a comparison with physical health. Just as a physical illness might be identified by the absence of healthy functioning, poor mental health can be identified by the absence of psychological wellbeing.

The key theorist is Marie Jahoda (1958), who described criteria for positive mental health. AQA mark schemes often credit examples such as:

• a positive attitude towards the self
• self-actualisation, meaning working towards one's potential
• autonomy, meaning independence and self-direction
• integration/resistance to stress, meaning psychological balance under pressure
• accurate perception of reality
• environmental mastery, meaning being able to adapt to everyday demands

AO1 - what to say: A person may be considered to show poor mental health if they lack several of these criteria. The more criteria that are absent, the more serious the concern may be.

AO2 - applying it: Dave avoids mirrors, believes all his friends secretly think badly of him, cannot concentrate at work and feels constantly anxious. The ideal mental health definition could be applied because Dave lacks a positive attitude towards the self, may have an inaccurate perception of reality, is not coping well with stress and is struggling to reach his potential at work.

AO3 - evaluation: A strength is that this definition focuses on positive mental health rather than only listing symptoms. It encourages psychologists to ask what wellbeing should look like, not just what illness looks like.

However, the definition sets a demanding standard. Many people lack one or more ideal criteria at times, especially during exams, bereavement or major life changes, without necessarily having a mental disorder. It can also be culturally biased: autonomy and self-actualisation may be valued strongly in individualist cultures, whereas collectivist cultures may place more emphasis on family obligation or community harmony. That makes "ideal" mental health less universal than it first appears.

Deviation from social and cultural norms

A social norm is an expected way of behaving in a group. Examples include queuing, wearing appropriate clothes for a setting, speaking at an expected volume, or respecting personal space. These are not usually written laws, but people notice when someone breaks them.

AO1 - what to say: According to this definition, behaviour is abnormal if it goes against accepted expectations in a given society or culture. The updated AQA wording matters here: write social/cultural norms, because AQA now explicitly wants culture in the definition.

AO2 - applying it: If Mina laughs loudly throughout a silent exam, walks around the room and reads other students' answers aloud, her behaviour deviates from social norms in that context. The key is not simply that the behaviour is unusual; it breaks shared expectations about exam behaviour.

AO3 - evaluation: A strength is that this definition reflects real-life judgements. Mental health professionals, teachers, families and peers often notice behaviour because it does not fit the situation.

The main limitation is cultural relativism: norms differ between cultures, subcultures and historical periods. A behaviour may be acceptable in one context but judged concerning in another. This creates a risk of cultural bias if one culture's standards are treated as universal.

There is also a risk of social control. Powerful groups can label nonconforming behaviour as abnormal simply because it challenges expectations. History matters here: some identities and behaviours once treated as deviant are no longer understood that way. This shows that social norms can change over time, so the definition has limited temporal validity.

Finally, deviation from norms can overlap with failure to function adequately, but they are not the same. A person can break norms while functioning well, and a person can fail to cope while appearing socially conventional.

Failure to function adequately

This definition shifts attention away from whether behaviour is rare or socially unexpected. It asks whether the person's life is being seriously disrupted.

AO1 - what to say: A person may be failing to function adequately if they cannot maintain basic self-care, attend school or work, manage relationships, communicate effectively, or carry out everyday responsibilities. AQA also credits reference to Rosenhan and Seligman (1989), who described signs such as personal suffering, maladaptive behaviour, irrationality, unpredictability, observer discomfort and violation of moral standards.

AO2 - applying it: Arjun has not washed for several weeks, misses most shifts at work, cannot sleep, and becomes intensely distressed when asked to leave his bedroom. This is not just "odd" behaviour. The definition applies because Arjun is struggling with self-care, work attendance and everyday coping.

AO3 - evaluation: A major strength is that it takes the person's experience seriously. If someone is distressed or unable to cope, this definition can help justify support even if their behaviour is not statistically rare.

It also has practical value because functioning can sometimes be measured. Attendance at work or school, ability to maintain hygiene, and ability to manage daily tasks can provide evidence rather than relying only on vague impressions.

However, the definition can be subjective. One person's "not coping" may be another person's temporary response to a difficult event. For example, intense distress after bereavement may be understandable rather than abnormal. Some people also appear to function well while experiencing serious mental health difficulties, so this definition may miss hidden distress. Finally, parts of the definition can be culturally sensitive: judgements about "moral standards" or appropriate functioning vary between groups.

Statistical infrequency

This definition uses numbers. If a behaviour, experience or characteristic is very uncommon in the population, it may be classed as abnormal.

AO1 - what to say: A statistically infrequent behaviour is rare compared with the population average. In some cases, this can be represented on a normal distribution, with the most common scores near the mean and the rarest scores at the extremes. AQA mark schemes often credit examples such as very low IQ when explaining the definition, as long as the example is used to illustrate the rule.

AO2 - applying it: If an article says "approximately 1 in 1000 people experience this pattern of symptoms," that phrase is a strong cue for statistical infrequency. The behaviour or experience is being judged against how common it is in the population.

AO3 - evaluation: A strength is objectivity. This definition can use numerical evidence, so it seems less dependent on personal opinion than social norms or functioning.

But the cut-off point is still a judgement. If a score is unusual, how unusual must it be before it becomes abnormal? Two standard deviations from the mean is a common psychological rule of thumb, but the boundary is not magically "true"; it is chosen.

Statistical infrequency also cannot tell us whether the rare characteristic is harmful. Very high IQ is statistically rare but usually valued. Some mental health conditions, such as depression and anxiety, are relatively common, so a strict rarity definition could underestimate important conditions. Statistics also need to be up to date and relevant to the population being considered.

Comparison and exam skills

For AQA, the safest way to write about these definitions is to keep each rule separate before comparing them.

AO1 - define first: Start with the decision rule. Do not begin with an example. For example, "Statistical infrequency defines abnormality as behaviour or characteristics that are rare in the population."

AO2 - apply the evidence: Use exact details from the stem. If the stem says "severe anxiety affects living and work spaces," link that to failure to function adequately because it shows distress and disruption to everyday life.

AO3 - evaluate the specific definition: Avoid generic phrases such as "this is culturally biased" unless you can show how. For social/cultural norms, cultural bias is central because norms differ directly between cultures. For failure to function adequately, cultural bias may apply when "moral standards" or expectations about coping differ between groups, but you need that link.

Here is a clean comparison:

The best evaluation answers often compare definitions. For instance, statistical infrequency is more objective than deviation from social norms because it uses numerical data, but it is less sensitive to distress because rare characteristics are not always harmful. Failure to function adequately is sensitive to distress, but it can be subjective and may miss people who hide their difficulties.