We humans have a normal way of looking at the world and we call it 'consensual reality'.
However, if we dig deeper and go down to the quantum level of existence, things are not things and matter is not matter anymore. We have waves and particles, flowing through and jumping in and out of nothingness.
Some waves turn into themselves and vibrate at a stable frequency. Some waves ride other waves. Some waves collapse into particles when we make them so by looking at them.
If we go back from this 'quantum level' to the 'human level', we tend to focus on the particles rather than the waves, and thus we get 'materiality' first and 'spirituality' second. But, the 'wave' reality of the universe is still there in the background and that's the reality a psychic taps into.
For a psychic, the whole world is made out of psychic vibrations - resonating, changing, meshing, collapsing and manifesting. Psychic vibrations form our identities, thoughts, minds, and bodies.