You don't have to be a professional medium to sense the presence of Spirit, anyone can get this ability. And there are two types of onset - one onset later in life, and one early on. Think: like Type 1 and Type 2 diabetes. One has to do more with heredity and genetics (we think), and the other has more to do more with certain weatherings of life experience that make you more susceptible to it.
Ray Hyman discovered many methodological errors with Schwartz's research including; "Inappropriate control comparisons", "Failure to use double-blind procedures", "Creating non-falsifiable outcomes by reinterpreting failures as successes" and "Failure to independently check on facts the sitters endorsed as true". Hyman wrote "Even if the research program were not compromised by these defects, the claims being made would require replication by independent investigators." Hyman criticizes Schwartz's decision to publish his results without gathering "evidence for their hypothesis that would meet generally accepted scientific criteria... they have lost credibility."
As one of Canada’s Top Psychic Mediums, Mary-Anne’s practice includes limited private Mediumship Readings, Spiritual Guidance, Classes and Workshops, Energy Healing and Clearing, Soul-Based Counselling, and Media/Production consultations related metaphysical and spiritual content. Mary-Anne also demonstrates public mediumship at specials events & appearances, and she is also the author of the book “How to Become a Medium: A Step-by-Step Guide to Connecting with the Other Side”.
The psychical researchers Eric Dingwall and Harry Price re-published an anonymous work written by a former medium entitled Revelations of a Spirit Medium (1922) which exposed the tricks of mediumship and the fraudulent methods of producing "spirit hands". Originally all the copies of the book were bought up by spiritualists and deliberately destroyed. In 1923, the magician Carlos María de Heredia revealed how fake spirit hands could be made by using a rubber glove, paraffin and a jar of cold water.