Dualism and Materialism (also called Monism) are two psychological theories. At first, psychologists supported Dualism, or the idea that the brain and mind are two separate entities. This gave rise to the possibility of the unconscious being the physical brain, the subconscious and conscious being part of the mind.
The theory of materialism on the other hand came later, and hence why most hypnotists refer to the conscious and unconscious. Namely the premise is that everything is just matter. The brain and the mind are one. However, there are many cases that dispute materialism, and I’ve met a few where materialism is essentially flawed.