Final answer:
The defense mechanism most commonly used in depression is regression, where a person reverts to behaviors typical of a younger age. Major depression may results in overuse of defense mechanisms, thereby affecting the individual's perception of reality.
Step-by-step explanation:
The defense mechanism most commonly used in depression is regression. This occurs when a person confronted with anxiety reverts to a more immature behavioral stage, displaying actions that are inappropriate for their age. For instance, if someone facing stress begins to exhibit childlike behaviors, such as throwing tantrums, that person might be considered to be using regression as a defense mechanism. Other defense mechanisms include denial, where a person refuses to accept reality; rationalization, where they justify their behaviors with plausible reasons; and projection, where they attribute their unacceptable desires or feelings onto others.
Understanding these defense mechanisms can help individuals recognize when they or someone else might be unconsciously trying to protect themselves from psychological distress. Major depression, in particular, may lead to an overuse of such mechanisms, which can distort reality and hinder recovery.