In psychology, psychological projection (or projection bias) is a defense mechanism in which one attributes one’s own unacceptable or unwanted thoughts or/and emotions to others. Projection reduces anxiety by allowing the expression of the unwanted subconscious impulses/desires without letting the conscious mind recognize them. The theory was developed by Sigmund Freud and further refined by his daughter Anna Freud, and for this reason, it is sometimes referred to as "Freudian Projection
To understand the process, consider a person in a couple who has thoughts of infidelity. Instead of dealing with these undesirable thoughts consciously, he or she subconsciously projects these feelings onto the other person, and begins to think that the other has thoughts of infidelity and may be having an affair. In this sense, projection is related to denial, arguably the only defense mechanism that is more primitive than projection. Projection, like all defense mechanisms provide a function whereby truth about a part of themselves that may otherwise be unacceptable is shielded.
Compartmentalization, splitting and projection are ways that the ego continues to pretend that it is completely in control at all times, when in reality human experience is one of shifting beingness, instinctual or territorial reactiveness and emotional motives, for which the "I" is not always complicit. Further, common in deep trauma, individuals will be unable to access truthful memories, intentions and experiences, even about their own nature, wherein projection is just one tool .
The philosopher Ludwig Feuerbach based his theory of religion in large part upon the idea of projection, i.e., the idea that an anthropomorphic deity is the outward projection of man's anxieties and desires.
Psychological projection is the subject of Robert Bly's book A Little Book on the Human Shadow. The "Shadow"—a term used in Jungian psychology to describe a variety of psychological projection—refers to the projected material . Marie-Louise Von Franz extended the view of projection to cover phenomena in Patterns of Creativity Mirrored in Creation Myths: "... wherever known reality stops, where we touch the unknown, there we project an archetypal image". .
Jung writes that "All projections provoke counter-projection when the object is unconscious of the quality projected upon it by the subject."
The concept was anticipated by Friedrich Nietzsche:
"He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you."