Which defense mechanism involves attributing one’s unacceptable thoughts or feelings to someone else?

The defense mechanism that involves attributing one’s unacceptable thoughts or feelings to someone else is projection. This mechanism allows individuals to deal with feelings that they find unacceptable within themselves by projecting these feelings onto others. For example, if someone is feeling a strong sense of jealousy, they might accuse another person of being envious of them instead. This serves to protect the individual from confronting their own uncomfortable emotions by externalizing them.

In contrast, displacement involves shifting emotions from the original source of the conflict to a safer target. Rationalization refers to the cognitive distortion of "the facts" to make an event or an impulse less threatening. Intellectualization involves thinking about events in a cold, clinical way to avoid dealing with the emotional aspects. Each of these mechanisms serves different purposes, but projection specifically focuses on shifting one’s internal feelings onto others.