Humans have at their disposal different levels of thinking, traditionally known as altered states of consciousness. On these different levels are pockets of recorded memories and recorded thoughts; the last time their consciousness was on a particular altered state, the thought processes a recorded and put on hold for the next installment.
Throughout the normal day, human beings are likely to skirt through several levels of thinking; much like the dial on a radio can skirt through the stations on a particular band. And when this happens, humans can have a whole manner of thoughts and impressions that suddenly crop up out of nowhere. They can remember things from years ago; from previous existences; and from moments before. This is pretty much par for the course. But the majority of humans are not even aware this happens.
Consciousness is effectively a Crystal Radio Receiver or Crystal Set. That is the best way to describe it. Consciousness has access to the infinite field known as the mind field. Consciousness usually deals solely with limited awareness; or a separate awareness. So the Crystal Set is set to a very limited band; decreed by the vibration and the DNA signature of the separate human. That's fine; but the Crystal Set can also be tuned on a much wider band; telepathy is a result of this, which enables the Crystal Set to amplify the thought waves of other humans in close proximity. When its tuned on a much wider band still, the possibilities of D.T.T with other humans and other dimensions are more than possible.
To the adept, who is aware of this phenomenon, the possibilities are endless. In its basic form it accounts for psychic ability; and to a greater degree it can be attuned for true mediumship connections.