Ian Pretyman Stevenson (October 31, 1918 – February 8, 2007) was a Canadian-born U.S. psychiatrist. He worked for the University of Virginia School of Medicine for fifty years, as chair of the department of psychiatry from 1957 to 1967, Carlson Professor of Psychiatry from 1967 to 2001, and Research Professor of Psychiatry from 2002 until his death.

As founder and director of the university's Division of Perceptual Studies, which investigates the paranormal, Stevenson became known internationally for his research into reincarnation, the idea that emotions, memories, and even physical injuries in the form of birthmarks, can be transferred from one life to another. He traveled extensively over a period of forty years, investigating three thousand cases of children around the world who claimed to remember past lives. His position was that certain phobias, philias, unusual abilities and illnesses could not be fully explained by heredity or the environment. He believed that reincarnation provided a third type of explanation.

Twenty Cases Suggestive of Reincarnation is a book written by psychiatrist Ian Stevenson on the phenomenon of what he calls spontaneous recall of information about previous lives by young children. The book focuses on twenty cases investigated by the author. It has been translated into seven foreign languages.

Stevenson set up a network of volunteers to find these spontaneous past life recall cases as soon as the children began to speak of them. He then would carefully question both the family of the living child and the family of the deceased to ensure that they had no contact and that no information would be passed between them. He would obtain detailed information about the deceased, including information not fully known to anyone involved such as details of the will, that he would use to verify that the child actually did know the information required.

Published Results:

1. The large number of witnesses and the lack of apparent motivation and opportunity, due to the vetting process, make the hypothesis of fraud extremely unlikely.

2. The large amount of information possessed by the child is not generally consistent with the hypothesis that the child obtained that information through investigated contact between the families.

3. Demonstration of similar personality characteristics and skills not learned in the current life and the lack of motivation for the long length of identification with a past life make the hypothesis of the child gaining his recollections and behavior through extra-sensory perception improbable.

4. When there is correlation between congenital deformities or birthmarks possessed by the child and the history of the previous individual, the hypothesis of random occurrence is improbable.