About Tracking the psychological defense mechanism I am searching to find about the method of understanding the reason of being unconsciousness of the psychological defense mechanism, as described here:

In psychoanalytic theory, a defence mechanism (American English:
defense mechanism), is an unconscious psychological mechanism that
reduces anxiety arising from unacceptable or potentially harmful
stimuli.

So  I have one question :
What would happen, if using the psychological defense mechanisms of the third level:
Such as Intellectualization
In finding the path of changes in the psychological defense mechanism, what effect will it have on our psychological defense system?
Will this improve our understanding of the mental defense system?
Or it will strengthen that mechanisms (Intellectualization) in the mental defense system and return to the second level mechanisms such as (Schizoid fantasy or passive aggression) and further transfer to the first level reactions (denial, Distortion).
Thanks.
The conscious and unconscious aspects of Sigmund Freud's ego-defence mechanisms refer to the awareness of the thought patterns and actions; and how they are affecting the person and those around them.
As an example, someone going through an intense traumatic experience can completely dissociate from the acts in play. There are examples of this in many areas of trauma. One example was discussed in my answer to the question “Can calmness happen during the fight-flight response?”
Having said that, here are differing levels of conscious awareness within the different defence mechanisms. Take a look at my answer to another question concerning dissociation as an example.
With this in mind, it doesn't make things so clear cut when talking about (un)conscious thought patterns and actions when referring to the defence mechanisms.
When dissociation is at play in the first linked example, after the traumatic event, the person who has been traumatised can find themselves unable to remember everything that happened during the event. Some combat veterans have said that they cannot remember how they got out of some situations when others around them got killed.
They didn't consciously make the decision to dissociate from the trauma, but:

Dissociation is a psychological defence mechanism (Cardeña, 1994) which helps the person to get through the situation with as little harm as possible.

With regard to your example of ego-defence mechanisms (Intellectualisation), in order to intellectualise the incident in question, you need to consciously think about alternative thought patterns.
Another way of describing intellectualisation is by saying that it is creating some form of “justification” for the highly emotional and/or traumatic event (real or semi-real).

Related to rationalization, intellectualization involves removing the emotion from emotional experiences, and discussing painful events in detached, uncaring, sterile ways. Someone who intellectualizes becomes very distant from their feelings, and when asked to describe their feelings may find it difficult. They may understand all the words that describe feelings, but have no idea what they really feel (Niolon, 2004).

I would add to that by saying that if you have no idea what you really feel, you will have no complete idea why you feel that way.
Glen O. Gabbard M.D. spoke about defence mechanisms, including intellectualisation, in pages 31 and 32 of his book (Gabbard, 2004). He basically talked about the relevant defence mechanisms with regard to “the patient's level of personality organisation”.
Emphasis mine

The psychodynamic clinician uses a combination of defense mechanisms,internal object relations, ego strengths or weaknesses, and an assessment of reflective function to determine the patient’s level of personality organization (Table 2–2). This assessment differs from one based on DSM-IV-TR categories (American Psychiatric Association 2000). It involves diagnostic understanding of the person, rather than a diagnostic label. Its value is primarily in the way it informs the psychotherapy.
[...]
Table 2-2 Level of organization




Neurotic level
Borderline level




Superego well integrated but punitive
Superego integration minimal; capacity for concern and guilt fluctuating considerably


High-level defenses, including repression, reaction formation, intellectualization, doing and undoing, and displacement
Primitive defenses, including splitting, projective identification, idealization, and devaluation


Identity reasonably stable, and internal object relations characterized by ambivalently regarded whole objects and triangular conflict
Identity diffusion and object relations of a “partial” rather than “whole” nature—split into “all good” and “all bad” aspects


Notable ego strengths, including good impulse control, intact  judgment, consistent reality testing, and capacity for sustained work
Nonspecific ego weaknesses, including impulsivity, impaired judgment, brief compromises in reality testing, and difficulty sustaining work


Conflict-based pathology
Significant deficits existing alongside conflicts


Intact reflective function
Impaired reflective function




[...]
People who are neurotically organized experience a great deal of intrapsychic conflict, and they have intact reflective function so they can recognize that their representation of a person or event is not necessarily the same as the actual reality of the person or event. They also can understand that their behaviors are motivated by internal beliefs or feeling states. By contrast, people with a borderline level of organization often have substantial deficits in the self-structure alongside their conflicts and have poorly developed reflective function. They often experience things as just happening to them, rather than being motivated by internal states.

Further reading

For more on dissociation: Term for Trance During Violent Episodes

For other forms of defence mechanisms:My answer to When are dreams created? covers repression and suppression
Can the act of studying more be a defense mechanism?
(Loosely) Due to Gestalt Psychology, is the face an illusion?


References
Cardeña, E. (1994) The domain of dissociation. In: Dissociation: Clinical and theoretical aspects, Edited by: Lynn, S. J. and Rhue, J. W. 5–31. New York, NY: Guildford Press.
Kernberg, O. F. (1976). Technical considerations in the treatment of borderline personality organization. Journal of the American Psychoanalytic Association, 24(4), 795-829. https://doi.org/10.1177/000306517602400403
Gabbard, G. O. (2004). Long-term psychodynamic psychotherapy: A basic text. Washington, DC: American Psychiatric Publishing. Available from https://www.academia.edu/31570203/Glen_O_Gabbard_Long_Term_Psychodynamic_Psychotherapy_A_Basic_Text_Core_Competencies_in_Psychotherapy_2004_
Niolon, R. (2004) Defences. PsychPage http://www.psychpage.com/learning/defenses.html