Psychological projection (or projection bias) can be defined as unconsciously assuming that others have the same or similar thoughts, beliefs, values, or positions on any given subject as oneself. According to the theories of Sigmund Freud, it is a psychological defense mechanism whereby one "projects" one's own undesirable thoughts, motivations, desires, feelings—basically parts of oneself—onto someone else (usually another person, but psychological projection onto animals and inanimate objects also occurs). The principle of projection is well-established in psychology.
To understand the process, imagine an individual (Alice, for example) who feels dislike for another person (let's say Bob), but whose unconscious mind will not allow her to become aware of this negative emotion. Instead of admitting to herself that she feels dislike for Bob, she projects her dislike onto Bob, so that her conscious thought is not "I don't like Bob," but "Bob doesn't like me." In this way one can see that projection is related to denial, the only defense mechanism that some argue is more primitive than projection. Alice has denied a part of herself that is desperate to come to the surface. She can't flatly deny that she doesn't like Bob, so instead she will project the dislike, thinking Bob doesn't like her. Another, and an ironic, example is if Alice were to say, "Bob seems to project his feelings onto me."
Peter Gay describes it as "the operation of expelling feelings or wishes the individual finds wholly unacceptable—too shameful, too obscene, too dangerous—by attributing them to another." (Freud: A Life for Our Time, page 281)
Projecting our own issues and problems upon an outer source; people, places, or things. This neurotic social technique often leads to inappropriate feelings of resentment and blame aimed at the object of our projection.
Transferring a problem or an issue from it's original source onto another person, place, or things.
The habit of blaming others for our own mistakes and shortcomings when it is really we who are in the wrong.