Breakthrough To Higher Psychism clearly differentiates what is true higher psychism as compared to lower psychism. Lower psychism consists of mediumship, channeling, and other such practices. Lower psychics are in danger of being controlled by entities, astral corpses, as well as obsession and possession. Higher psychism is the ability to use the developed powers of your soul. You are able to exist in higher planes and contact true spiritual knowledge. Only in higher psychism is the true Teaching contacted and given for the regeneration of life and for the manifestation of a glorious future.

One of the best introductory books on psychism.

https://www.tsgfoundation.org/wp-content/uploads/2007/03/Breakthrough_to_Higher_Psychism_TOC.pdf