Cognition is a modern term used in psychology, denoting the mental process of acquiring knowledge and understanding of the present and the past through thought, experience, and normal sensorial perception.
Precognition, another modern word derived from cognition, has exactly the opposite meaning. It is generally not accepted by modern psychology but only by parapsychology, still considered pseudoscience and means acquiring previous knowledge, foreknowledge or prescience about the future.
Unlike a prediction, which is usually the product of logic, precognition does not appear to be obtained through any logical process but through some sort of extrasensory perception (ESP), i.e. one that is not governed by our normal six senses. Such an unexplainable ability is often called by the generic name of psi.
While few people, often called psychics or clairvoyants, are attributed daytime precognitive abilities, it turns out that far more people believe to have had precognitive experiences in the form of night dreams.
Sometimes people have in their daily life an unexplainable feeling of having already experienced a situation, or what is called déjà vu or “already seen” in French. The related experience of a somewhat irrational feeling that something bad will happen is called foreboding.
These last two phenomena are attributed by skeptic psychologists to an anomalous operation of the human brain, consisting in an incorrect association of present inputs to a false memory of the past. Less skeptically disposed persons may actually relate the real experience to a dream, and that is called déjà rêvé (“already dreamt” in French).
In the past, both daytime and nighttime precognitive visions were given much more attention and generally a consideration of advanced warnings or forewarnings. These have often been considered messages from spirits or deities and have been called prophecies or premonitions.
Shamans have often used hallucinogenic substances to induce premonitions in the awake state, but people have reported also the possibility to have precognitive dreams while lucid dreaming, i.e. while being aware of dreaming and being able to control at least to some extent the development of the dream.
It appears that both such daily and nightly experiences form part of a broader range of phenomena called by the generic name of clairvoyance (clear seeing from French), covering non-logical, extrasensorily acquired knowledge of not only future but also of present and past events. The ability to see past events without any input from any of the normal six senses is sometimes called also retrocognition while the seeing of simultaneously occurring but remote events is called remote viewing.
Most attempts to explain such phenomena in rational terms are generally considered pseudoscience. We have grounds to believe that at least clairvoyant dreams will one day be explained by normal science, perhaps as a result of the symbiosis between several disciplines, such as oneirology (dream science), physiology, neuroscience, artificial intelligence, and quantum mechanics, so that what is now considered “paranormal” will become “normal”. Therefore, we will avoid most of the described parapsychological terminology and will refer to them simply as psi dreams.