People have different ways of handling their anxiety and pain. Originally conceived by Sigmund Freud, much of the development of the concept of defense mechanisms was done by his daughter, Anna Freud. Defense mechanisms can be healthy or unhealthy depending on the circumstances and how much a person uses them. They can hide many different feelings from anger to lust to guilt. Here are a list of some common defense mechanisms from: http://www.utahpsych.org/defensemechanisms.htm:
Repression
Burying a painful feeling or thought from your awareness though it may resurface in symbolic form.
You can't remember your father's funeral.
Denial
Not accepting reality because it is too painful.
You are arrested for drunk driving several times but don't believe you have a problem with alcohol.
Regression
Reverting to an older, less mature way of handling stresses and feelings
Projection
Attributing your own unacceptable thoughts or feelings to someone or something else
You get really mad at your husband but scream that he's the one mad at you.
Splitting
Everything in the world is seen as all good or all bad with nothing in between.
You think your best friend is absolutely worthless because he forgot a lunch date with you.
Isolation of affect
Attempting to avoid a painful thought or feeling by objectifying and emotionally detaching oneself from the feeling
Acting aloof and indifferent toward someone when you really dislike that person
Displacement
Channeling a feeling or thought from its actual source to something or someone else.
When you get mad at your sister, you break your drinking glass by throwing it against the wall.
Reaction Formation
Adopting beliefs, attitudes, and feelings contrary to what you really believe
When you say you're not angry when you really are.
Rationalization
Justifying one's behaviors and motivations by substituting "good", acceptable reasons for these real motivations
I always study hard for tests and I know a lot of people who cheat so it's not a big deal I cheated this time.
Altruism
Handling your own pain by helping others.
After your wife dies, you keep yourself busy by volunteering at your church.
Sublimation
Redirecting unacceptable, instinctual drives into personally and socially acceptable channels
Intense rage redirected in the form of participation in sports such as boxing or football
Suppression
The effort to hide and control unacceptable thoughts or feelings
You are attracted to someone but say that you really don't like the person at all
Undoing
Trying to reverse or "undo" a thought or feeling by performing an action that signifies an opposite feeling than your original thought or feeling
You have feelings of dislike for someone so you buy them a gift