Skip main navigation

New offer! Get 30% off one whole year of Unlimited learning. Subscribe for just £249.99 £174.99. New subscribers only. T&Cs apply

Find out more

What is abnormality in mental health?

Behaviours that are considered 'abnormal' are often associated with deviant behaviour or mental health issues
© Coventry University. CC BY-NC 4.0

Terms like ‘ideal mental health’ and ‘normal’ are not without problems and can be the source of disagreement. This can be seen in the fact that the way we view ‘norms’ can differ wildly, and our understanding of this can be very different.

This is because we base our understanding on our own experience of what is normal for us in our lives. An easier way to define mental illness is by not necessarily trying to agree on what normal looks like, but to reach a consensus of what abnormality is when defining mental health.

Defining abnormality

Please remember that although you may feel somewhat uncomfortable with the term ‘abnormal’, it is one that is widely recognised by experts in the field of mental health.

Abnormality has been defined in a number of ways, including:

  1. Unusual behaviour that is different from the norm
  2. Behaviour that does not conform to social expectations or demands
  3. Statistical infrequency
  4. Failure to function adequately
  5. Presence of pronounced psychological suffering or distress
  6. Deviation from ideal mental health

Abnormal psychology

Defining abnormality falls under the remit of abnormal psychology. This is a division of psychology that studies ‘abnormal’ or ‘atypical’ behaviour (McLeod 2018). The terminology of abnormal psychology and mental health is problematic as none of the language is neutral or value-free (Cromby, Harper and Reavey 2013). Examples of abnormality often serve to illuminate the normal.

Normality and abnormality can be considered as two sides of the same coin: each can be defined only in relation to each other (Gross 2015). Unspoken within this notion is the assumption that it is possible and meaningful to draw a line between normal and abnormal.

Different criteria for defining normality and abnormality have suggested where the line can be drawn. When taken out of a psychological context the definition of the word abnormal is simple enough, but when applying this to psychology it poses a complex problem and raises questions: what is normal? Whose norm? For what age? For what culture? (McLeod 2018).

Problems with the term ‘abnormality’

It is important to note that defining normality is subjective and always involves a judgement, as this will be different for each individual. What one person might define as normal another might not, and this is where the real challenge lies when defining and diagnosing mental health issues.

It is often considered easier to define what we deem abnormal, and behaviours that fall into this area are often associated with deviant behaviour or mental health issues.


Cromby, J., Harper, D., and Reavey, P. (2013) Psychology, Mental Health and Distress London: Palgrave

Gross, R. (2015) Psychology: The Science of Mind and Behaviour, 7th edn. London: Hodder Education

Jahoda, M. (1958) Current Concepts of Positive Mental Health New York: Basic Books

McLeod, S. (2018) ‘Abnormal Psychology’ Simply Psychology [online]. available from [19 November 2018]

Rosenhan, D.,L., and Seligman, M.,E.,P. (1989) Abnormal Psychology 2nd edn. New York: W.M. Norton

© Coventry University. CC BY-NC 4.0
This article is from the free online

Defining Mental Health: A Short Introduction

Created by
FutureLearn - Learning For Life

Reach your personal and professional goals

Unlock access to hundreds of expert online courses and degrees from top universities and educators to gain accredited qualifications and professional CV-building certificates.

Join over 18 million learners to launch, switch or build upon your career, all at your own pace, across a wide range of topic areas.

Start Learning now