If a psychic isn't humble while they are performing a reading then their ego will interfere with the process. The idea is that they allow their mind to lay fallow (i.e. they enter an "inner listening" state) to see what emerges and this is described to those present. If someone is ego driven that will interfere with the process and color the reading. That's one reason I am skeptical of some of the "media psychics". If you put any of your preconceptions into the reading it will be distorted. Think of a medium like a radio receiver in that they both receive a signal and interpret it, hopefully in as neutral a way as possible. When your own mind is also generating a signal this can interfere with the listening process. This is why the first step is to learn to quieten one's own mind. Second comes the inner listening process.
The above is a comment made on the following YouTube video: