A defence mechanism (or ‘defense’ mechanism) is a psychological mechanism that a human unconsciously employs to reduce anxiety or distress from a stimulus that may be perceived as harmful.

In simple terms, it is what the mind automatically does to protect itself from something that it may see as potentially damaging. It is a key topic in mental health, and can be applied to many conditions.

Defence mechanisms can be both harmful and helpful


Defence mechanisms originated from psychoanalysis – Sigmund Freud’s wide body of theories revolving around several subjects. Freud, and later other thinkers – including his daughter Anna – researched the topic heavily. As time has passed, many defence mechanisms have been identified, and the study has entered mainstream psychology.

Defence mechanisms form a key concept in mental health, and are commonplace in modern day treatment and identification of mental health conditions.

It is important to state from the outset that defence mechanisms can be both positive and negative. Many different defence mechanisms have been proposed by a wide range of theorists. In this article we take a look at the science behind these mechanisms, and list a few examples.

When a defence mechanism is used

Essentially, any time that the unconscious mind believes the conscious mind cannot cope with something, a defence mechanism will be used. Defence mechanisms typically protect a person from feelings of anxiety, memories that may cause harmful emotions, or anything that would threaten a person’s safety or their self-esteem.

In terms of mental health, defence mechanisms can cause psychological distress. If a defence mechanism is persistently used, it can cause harmful behaviour – leading to the aforementioned distress.

Certain thoughts, memories, feelings or even impulses can be problematic for people – and a common way of dealing with such problems is to employ a defence mechanism.

Freud’s Theory

Freud used his theory of personality to explain how defence mechanisms work. His theory of personality included elements called the “ego”, “superego” and the “id”.

Freud suggested that the ego (the part of personality that deals with reality) tries to mediate between the demands imposed by the id (area of personality that aims to fulfil basic needs and impulses – while not taking into account context or morality) and the superego (the area of personality that attempts to allow a person to live in a moral way, taking knowledge learned from society and parents into account).

As mentioned, when a person is faced with a situation, the ego aims to mediate between the feelings from the id and the superego. But when the ego is overwhelmed by the accumulation of desires and urges, the nature of reality and moral standards – a person feels anxiety.

Freud suggested anxiety is an inner state that people look to avoid. When anxiety occurs, the ego realises something is wrong, and harm may be imminent, therefore the ego uses some form of defence mechanism to reduce such feelings.

Examples of Defence Mechanisms

Over the years, dozens of defence mechanisms have been proposed by various theorists. For a comprehensive list, We have an article that looks at 15 common defence mechanisms.

We also provide three examples here too. Anna Freud published the first definitive book on defence mechanisms in 1966, listing ten examples [1]. These have since been added to by various others. Now, we take a look at some examples:


Repression is the process where certain harmful information arises (e.g. traumas, impulses or thoughts), but the repression defence mechanism doesn’t allow said information to enter conscious awareness. But this doesn’t get rid of the information – instead it lies deep in the mind. The feelings aren’t dealt with, but still influence a person’s behaviour.

An example would be a person who has repressed memories of being the victim of an attack by a dog at a young age. They may grow up to have a fear of dogs, causing them to be reluctant to leave the house out of fear of seeing a dog – even though they don’t know why they have this fear.

Therefore, it is important to deal with repressed memories. Repression can be a good short-term measure, but not in the long-term. Repression is similar to another defence mechanism called ‘suppression’ – though that refers to when a person actively tries to force memories from out of their mind. Repression of course does this unconsciously. They are similar, but differences do exist.


The defence mechanism of denial is universally-known, and surely employed universally too. This defence mechanism sees a person being unable to face reality, or failing to accept something that has already been proven as true.

The person may refuse to recognise something that has already taken place, or is going on in the present day – regardless of irrefutable evidence. The saying “you’re in denial” is directed at someone using this mechanism. 

An example would be a person suffering from alcoholism – or any other substance-related disorder. They may deny they have a problem, even though their behaviour is harming both themselves and those around them.

Someone using this defence will normally deny the truth as it would be too difficult for them to process. Or they may accept something happened, but playing down the significance of the event.

Returning to alcoholism as an example, a person may admit they consume a lot of alcohol, but refuse to accept it is problematic. Sometimes as part of denial, a person will blame someone else.


While repression and denial are largely negative defence mechanisms, sublimation is an example of a mostly-positive mechanism. Sublimation refers to a person that converts harmful thoughts into acts that are acceptable.

A person will commonly have an impulse to act in a way that would be unacceptable – perhaps socially, culturally or even in a way that is criminal in nature. But instead of acting in this way, the person will change these impulses into a behaviour that can be accepted.

A good example of sublimation is a person who has anger management problems, and has an impulse to take out his anger on other people – either by shouting at them, throwing objects at people or physically attacking them. But instead of acting on these impulses, they choose to channel the feelings in a positive way, through using a punching bag and gloves to take out their anger.

This way, they have an outlet for their harmful thoughts, but are acting in a way that doesn’t cause problems to themselves or anyone. Therefore, sublimation is often seen as a sign of maturity.

As mentioned, several other defence mechanisms have been identified – found at this link.

The potential harm of Defence Mechanisms

While not all defence mechanisms are necessarily bad, continuous use of these mechanisms can lead to problems arising. The longer that some defence mechanisms are used, the more difficult it becomes to process something. This may be anxiety, or emotional issues.

For instance, someone with social anxiety disorder may aim to avoid others at all costs, but the longer they do this, the harder it will be for them to return to seeing other people.

As well as this, they can affect a person in other ways. A person may struggle to make friendships due to the nature of some mechanisms, or find themselves frequently in conflict with others. Above all, prolonged use of defence mechanisms can lead to significant interpersonal issues. These areas will commonly lead to a mental health condition developing.

If a person does find themselves struggling, it is important to seek help. It can be difficult to spot defence mechanisms, but an experienced mental health professional will be able to identify them, and work with a patient to come up with alternative ways of thinking about something. This can significantly help the wellbeing of any person.

Therapies like Cognitive Behavioural Therapy or Psychoanalytical Psychotherapy can prove useful in treating many conditions involving defence mechanisms. There are a vast range of types of therapy that can help.

But it is important to stress, that not all defence mechanisms will cause problems. On some occasions, they are actually helpful. After all, it is the mind’s way of protecting itself, and is a completely natural thing. Keeping track of day-to-day mood is always important.


Defence mechanisms are an example of the complex nature of the mind. Sometimes we are very thankful for our defence mechanisms, but as described above, they can prove to be harmful.

A key tool in mental health treatment is talking therapy. Therapy can help an individual look deeper into their problems – and identify a particular event or stimuli that seems to be causing them problems, and subsequently lead to defence mechanisms being used. If a person is able to come to terms with a past trauma or harmful thoughts, they should be able to cope better in the future.

See Also


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[1] Freud, A. (1966). The Ego and the Mechanisms of Defence. London: Routledge.