What is a Defense Mechanism?

Mary McMahon
Mary McMahon

The term “defense mechanism” is used in two different ways. Both imply a sense of self protection, with an organism engaging in a behavior with the goal of preventing harm, which may take the form of physical harm or psychological harm. Defense mechanisms are widely used throughout the natural world and in human society, and they take a wide range of forms.

In biology, a defense mechanism refers to how an animal defends itself from physical harm.
In biology, a defense mechanism refers to how an animal defends itself from physical harm.

In biology, a defense mechanism is a form of physical defense. Many organisms have defenses which allow them to fight back, ranging from poisons which make them dangerous to eat to teeth which they can use to bite attackers. People and animals use them to to stay alive, and they also promote the survival of a species, as potential predators learn that organisms with those mechanisms are dangerous.

Defense mechanisms can cause major rifts in relationships.
Defense mechanisms can cause major rifts in relationships.

In reference to humans, a defense mechanism is a psychological phenomenon used as a form of self protection from psychological injury. Freud, a famous figure in the psychological field, developed the theory to explain a large family of psychological behaviors. His argument was that the self engaged in unconscious behaviors to protect itself from harmful or threatening situations. Such situations might include conflict, intense anxiety, shame, situations which threaten self esteem, and so forth.

An individual might use the defensive mechanism known as distancing to avoid mental and physical harm.
An individual might use the defensive mechanism known as distancing to avoid mental and physical harm.

Freud recognized a number of defensive actions which occurred in some level in everyone, including perfectly healthy individuals. Indeed, many play an important role in socialization and allow people to function in society. Others he targeted as more problematic, and signs that a patient could be developing a serious psychological problem. Denial, for example, is an example of an extreme defense mechanism which can be very harmful. Likewise, repression can be dangerous.

An individual may use humor as a defensive mechanism to avoid mental distress.
An individual may use humor as a defensive mechanism to avoid mental distress.

Some examples of defense mechanisms seen in many people include intellectualization, distancing, humor, sublimination, reaction formation, and altruism. People in therapy may spend some time exploring their defensive actions and determining which ones are healthy and which ones may be dangerous. A therapist can work with a client to identify defense mechanisms at work and explore their roots while also coming up with suggestions to help patients avoid more dangerous ones.

Sigmund Freud, the founder of psychoanalysis, identified several types of defense mechanisms.
Sigmund Freud, the founder of psychoanalysis, identified several types of defense mechanisms.

Defense mechanisms can also become problems in interpersonal relationships, and are often a topic in group or couples therapy. It is important for therapists to distinguish between different types of behaviors and their functions when working with clients, and to make clients aware that such a defense mechanism is not inherently bad.

Defense mechanisms are a common topic in couples therapy.
Defense mechanisms are a common topic in couples therapy.
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


This article has put me in perspective in understanding my wife who seems to offload her problems to her family members and justifies her actions by blaming it on me. To justify her actions, she creates diversion which puts me off while she goes ahead.

It is really frustrating. Even when you do the right thing by her, she will still create issues to justify her actions. She is never wrong and manipulates her family to support her.


@Popcorn- I also wanted to say that you are absolutely right. Many people that have painful memories block them out as a form of repression defense mechanism.

I was reading about people with multiple personality disorders and a lot them had very traumatic childhoods which is the cornerstone of this condition. They use the multiple personalities in order to escape the painful reality that they face.

This is a way for them to survive their childhood.

I think that the study of clinical psychology is amazing and you really learn so much about the behaviors of others and it also sheds a little light as to why you do the things that you do.

I was reading that another common ego defense mechanism involves denial. I remember when my mother came down with stage 4 uterine cancer; I was in denial because I did not want to face losing her.


You know years ago I had a very stressful job and my boss was really difficult to deal with. She had problems with everyone in the office so I knew not to take it personally.

I found that I developed a sublimation defense mechanism because I developed a lot of frustration and anger but obviously I could not take it out on anyone, so I look up jogging.

It was an intense exercise that I had not done before and pretty soon I was up to five miles a day. I read that this type of defense mechanism is very common, but many people channel it in different ways. Some people drink or eat too much. Others might resort to spending a lot of money.

I chose to take out my aggression by running which really helped. Other people take it out on people that are closest to them which only creates more problems.


One of the most common defense mechanisms I have come across in people is definitely the trend to repress things that are unpleasant. I've known a lot of people in my life, and a few of them have had some pretty horrible childhoods. Dealing with things like abuse is never easy, but it seems even worse when it is a child trying to cope.

For young people I think that repressing bad memories is one of their most vital defense mechanisms. Often these memories come back later in life, but usually when the person is better equipped to deal with such things. I think our minds have an amazing ability to shelve things to be dealt with later in order to preserve our own sanity.


It seems to me that human defense mechanisms are not just used to protect the self but rather is a way to justify bad behavior. Many people seem to think it is OK to treat other people poorly in the sake of perceived self-preservation.

One of my friends has the terrible habit of using sarcastic humor to bring others down that she feels is a threat to her. For myself, I see this is a sign of being really insecure, but she seems to think she is just being funny and at worst a defense mechanism. It seems that whenever she senses a threat, such as someone being more successful she needs to lash out.

Do you think her behavior a defense mechanism or insecurity?


@Suntan12 - I know what you mean. I have seen other defense mechanism examples that include forming a projection defense mechanism. I read that this happens a lot when a person is overly critical of another person.

It is believed that when a person is overly critical they really seeing their own flaws in that person and are pointing it out with the other person.

However, when people do this they rarely admit of their own shortcomings. An example would be if an overweight person tells another overweight person that they should watch what they eat, or that they should not eat that greasy cheeseburger because it is not good for their health.

This person may also comment on how much another person eats or how little they exercise because in reality these are faults that the critical person has but won’t admit. It is sort of like being a hypocrite, but these people never address their flaws only those of others which can make them really annoying.


I think that a lot of people use defense mechanisms so that they don’t feel so badly about themselves. For example, an unfaithful spouse might use a rationalization defense mechanism and state that they cheated because the other spouse was not around enough and they felt lonely.

They almost have to justify their behavior in a way that would garner a lot more sympathy. The cheating spouse knows that what they did was wrong, but they shift the blame to the victim by saying that if there was more interaction in the relationship it would not happen.

I really don’t like when people do this because I think adults should own up to their mistakes. That is really the only way to get respect from people.

I also see this happening in schools where kids justify cheating in order to get into a good college. They always say that they did it to secure a better future and somehow this is supposed to make it right.

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