During the séance or trance period, note that as a medium you should not ask too many questions of the person you are helping. A good medium never asks the client to tell them the name of the deceased or any details; otherwise, it is not a valid reading. It is up to you to validate the deceased loved one's name, occupation in life, birth date, physical description, how they passed, and so on.
Literally anything else you do to gouge your fellow man is totally aces. But I'm a human being with what I like to think is a good set of morals, and I started feeling bad about it. In fairness, the callers believed that psychics both: existed and that they plied their trade over the phone rather than winning lotteries or manipulating the stock market. Somebody was going to take advantage of them. Still, though, it's kind of a shitty thing to do. And it wears on you.
Spiritualists believe that phenomena produced by mediums (both mental and physical mediumship) are the result of external spirit agencies. The psychical researcher Thomson Jay Hudson in The Law of Psychic Phenomena (1892) and Théodore Flournoy in his book Spiritism and Psychology (1911) wrote that all kinds of mediumship could be explained by suggestion and telepathy from the medium and that there was no evidence for the spirit hypothesis. The idea of mediumship being explained by telepathy was later merged into the "super-ESP" hypothesis of mediumship which is currently advocated by some parapsychologists.