Final answer:
Repression is the defense mechanism that blocks disturbing wishes, thoughts, or experiences from reaching conscious awareness, often resulting in repressed memories and potential long-term psychological issues.
Step-by-step explanation:
The mechanism that blocks disturbing wishes, thoughts, or experiences from conscious awareness is known as repression. Sigmund Freud postulated that repression serves as a defense mechanism where overwhelming memories and desires that could cause anxiety are pushed out of the conscious mind into the unconscious. For example, if an overwhelming memory becomes too distressing to handle, it might be repressed to keep the individual's conscious mind from experiencing anxiety. This can manifest through various symptoms in other areas of life or through unintended verbal slips, also known as Freudian slips. It is important to note that while repression might serve as a temporary psychological protection, repressed memories can cause long-term issues such as unhappiness and alienation if not addressed.