He was at one time Sigmund Freud's associate and wrote on subjects like prenatal development and dream interpretation, although he is mostly credited for his magnum opus, Encyclopedia of Psychic Science, first published in 1934.

According to Rosemary Guiley "Fodor asserted that the psychosis was an episodic mental disturbance of schizophrenic character, and that Mrs. Forbes' unconscious mind was responsible for the activities finally determined to be fraudulent.

"[10] Because he was skeptical of the case, Fodor was heavily criticized by spiritualists and was dismissed from his post at the International Institute for Psychical Research.

With the psychical researcher Hereward Carrington Fodor co-authored Haunted People: Story of the Poltergeist down the Centuries (1951), the book which received positive reviews.

Henry Gordon has stated that parapsychologists such as Fodor and William G. Roll took a speculative approach to the poltergeist subject, ignoring the rational explanation of deception in favour of a belief in the paranormal.

[16] Science writer Martin Gardner wrote in 1957 that although Fodor had contributed to respectable psychoanalytical journals his views on telepathy were pseudoscience.