Projection
Projection is the defence against an unacceptable anxiety, impulse, or quality in one's own mind by locating it, instead, in someone else. What is uncomfortable to own internally becomes, in the person's perception, a trait or motive belonging to another person, which makes an otherwise unmanageable internal threat feel external, and therefore somehow easier to deal with.
Illustration
A man who struggles privately with his own indecisiveness becomes visibly frustrated with a colleague for 'never being able to make up his mind,' seemingly unaware that the trait irritating him so intensely in someone else is the very one he cannot tolerate in himself.
Related phenomena
References
- Casey, P. & Kelly, B. (2019). Fish's Clinical Psychopathology, 4th ed. Appendix II, 'Defences and Distortions'.