In psychiatryprojection is the tendency of a patient to ascribe their own undesirable (and often suppressed) personality defects onto other persons, particularly their therapist.  

House is almost always guilty of projecting his defects onto other people.  He is inherently dishonest, manipulative and abuses drugs.  As such, he almost always assumes his patients are dishonest, manipulative or abuse drugs.

A psychiatrist doing psychotherapy will often find that the patient will project ill motives onto the psychiatrist.  However, a good psychiatrist will be trained to deflect personal attacks and to look at the patient's own projection as a hint as to what character traits they either deny they have or find unacceptable about their own behavior.

Psychological projection at Wikipedia

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