Which defense mechanism refers to refusing to acknowledge reality by denying the existence of certain stimuli?

The defense mechanism that involves refusing to acknowledge reality by denying the existence of certain stimuli is denial. Denial is an unconscious defense mechanism in which individuals protect themselves from distress by refusing to accept the reality of a situation. This can manifest in various ways, such as ignoring facts or minimizing the significance of an event, leading to a lack of awareness regarding the true nature of their circumstances.

For instance, a person faced with the diagnosis of a serious illness may ignore their doctor's advice and continue living as if nothing has changed. This refusal to accept the reality of their condition allows them to cope, at least temporarily, with overwhelming feelings of fear or anxiety. Denial can be particularly prevalent in situations where acceptance would lead to significant emotional discomfort.

Other defense mechanisms mentioned, such as repression, involve pushing unwanted thoughts out of consciousness instead of denying their existence outright, whereas projection involves attributing one's own undesirable feelings to others, and displacement involves redirecting emotions from one target to another. Each of these mechanisms operates differently than denial, which distinctly focuses on outright refusal to acknowledge reality.