Clairvoyant literally means clear sighted in French. When dealing with a clairvoyant you are dealing with someone who has the ability to clearly see what lies beneath the surface.
Our five senses are trapped in the three dimensional world. We can be confused by what we see and our perceptions are typically mired by our emotions.
So to see clearly or to see the exact truth of the matter requires a level of objectivity. Clairvoyance is not an ability of feeling but the ability to see truth.
There is always some intuitive aspect to psychic powers. To answer the question as how does one know it is the truth that they are seeing and not a projection of the mind, one must use intuition. But a clairvoyant uses their sight as well as other concrete factors to determine the veracity of what they are seeing.
A clairvoyant person is often highly observant and often will deny their gift. Because any one can develop the skill of observation to the capacity that they are able to intuit different layers of a situation.
These psychic interactions are just another level of communication. One level is where one can see spirits. Not the ghostly figures of forgotten relatives but something as simple the flash of light in the corner of the eye or little light particles that remind one of fireflies.
Another level of clear sighted-ness is to be able to see the slight changes in someone’s behavior or the twitchy give-aways in a person’s demeanor when they are relaying a message to you. You can tell if its truth they are speaking or if they are trying to hide something.
Because clairvoyance involves seeing the truth of the three dimensional plane, people are often spooked because so much of our Western cultural training involves conformity and false-hoods.
The real power lies in being able to see the clear truth within. Once you master that being able to see the external truth is a simple matter.