Unconscious communication is a term used to describe the unintentional forms of communication that often occur on a subconscious level. That is to say that unconscious communication is always unintentional, and the people who transmit communication in such a manner are often unaware that they are doing so. Unconscious communication may be interpersonal or intrapersonal. It may also be verbal or nonverbal.

Intrapersonal unconscious communication occurs between a person and his or her subconscious. Examples of this form of communication include dreaming, hypnosis and the communication that occurs in a person’s mind during the cognitive process. For instance, a person may hear a song that makes him or her feel happy. That person does not remember ever hearing the song before. Unknown to him or her, the song was a lullaby that person's mother used to sing to him or her as a baby. Even though he or she made no conscious effort in that direction, the song had been stored in the long-term cognitive memory only to be retrieved and associated with happier times unconsciously. A person under the effects of hypnosis may also have intrapersonal communication with his or her subconscious.

Interpersonal unconscious communication is more varied than intrapersonal communication. This type occurs between two or more people. A person may transmit unconscious communication verbally through things like inflections in the voice, stuttering, voice cadence, pitch and unguarded speech. For instance, a person who is normally eloquent and articulate may unconsciously give away the fact that he or she is lying by stuttering or by unknowingly changing the cadence in his or her tone of voice. This type of unconscious giveaway can often say more than the person actually intended to convey. It can affect interpersonal relationships because the people who perceive such a subtle unconscious giveaway may or may not be happy with the message it is sending.

Communication entails not only the verbal process but also the nonverbal process, as people often study the words and body language in order to decipher what a person is actually trying to say or hide. Unconscious nonverbal communication includes gestures like crossing the arms defensively, shifting slightly away from people as an unconscious means of creating distance, and tapping the fingers with impatience. Another example of unconscious interpersonal communication is humming with joy. If a person is happy, he or she might start communicating signals of such happiness, unconsciously. The person might be unaware of such unconscious communication, which may include things like constantly smiling and generally exhibiting more exuberance than before.