• As if mirroring 'Flight-mode', when anxiety occurs, the first thing mind does is to seek rational ways of 'escaping' the situation by using 'problem-solving efforts' wherein a range of 'defense mechanisms' may be triggered. 
• Assuming the anxiety results from 'id Neurotic Anxiety' or 'superego Moral Anxiety' instead of 'ego Reality Anxiety', there seems no exact pragmatic 'problem-solving efforts accessible in reality, so brain often tends to distort or falsify reality for self-defense away from anxiety, using the surrounded people or things as targets.
• As soon as the reality becomes unclear with defenses reactions, there is a change in perception that tends to lessen anxiety thus leading to a reduction in tension that one may experience.

1. Denial: It is the mechanism that leads an individual to believe what is true is actually false(Refuse to accept &admit truth in facts), often turns out 'self-deception'.

2. Displacement：Acts of taking out impulses on a less threatening element，often venting to the weak

3. Intellectualization: This involves avoidance of unacceptable emotions by focusing on intellectual aspects such as workaholic or nerdy worms

4. Projection: This involves attributing uncomfortable feelings to others such as picking fights, critical or judgmental

5. Rationalization: Creation of FALSE but believable justifications(for self-consistency &self-deception)

6. Reaction Formation: Hypercorrection &Pre-confess incase be punished

7. Regression: This involves 'words and deeds' return back to certain previous stage of psychosexual development where mental structure was fixated(eg. childish behaviors)

8. Repression：It is the PUSHING of uncomfortable thoughts out of conscious awareness

9. Suppression：It involves consciously forcing unwanted thoughts out of awareness

10. Sublimation：This involves redirecting wrong urges from id impulses into socially acceptable actions

Note that these defensive mechanisms are not under any individual's conscious control and our unconscious will use
one or more of the above types to distort reality as well as hold one back from facing actual reality to protect self-esteem during critical times&situations. While all defense mechanisms can be unhealthy and negative acting as a form of 'self-deception', they can also be adaptive and allow our behaviors to function normally to temporarily ease stress, allowing us to focus on what is necessary at the moment. Otherwise without these defense mechanism, the primal anxiety from id drive will have to deteriorate itself until reaches its extreme state of 'mental disorders' even schizophrenia.

Last but not least, as for same sort of stimuli, defense mechanism is prone to react to and repeat itself per 'conditional reflex of the fixaton point' where it commonly got stuck.