[1][2] The practice is widely considered discredited and unscientific by medical practitioners, and experts generally regard claims of recovered memories of past lives as fantasies or delusions or a type of confabulation.
[5] The source of the memories is more likely cryptomnesia and confabulations that combine experiences, knowledge, imagination and suggestion or guidance from the hypnotist than recall of a previous existence.
Experiments with subjects undergoing past-life regression indicate that a belief in reincarnation and suggestions by the hypnotist are the two most important factors regarding the contents of memories reported.
[4][7][8] In the 2nd century BC, the Hindu scholar Patañjali, in his Yoga Sutras, discussed the idea of the soul becoming burdened with an accumulation of impressions as part of the karma from previous lives.
[9] Patañjali called the process of past-life regression prati-prasava (literally "reverse birthing"), and saw it as addressing current problems through memories of past lives.
Separately in Isis Unveiled, she referred to "indestructible tablets of the astral light" recording both the past and future of human thought and action.
The idea that the "Akashic records" held past life data set the stage, whereby Western practitioners of the paranormal could sidestep the notion of forgetfulness that, in traditional teachings about reincarnation, had prevented memories of former lives from being accessed.
[20] In the West, past-life regression practitioners use hypnosis and suggestion to promote recall in their patients, using a series of questions designed to elicit statements and memories about the past life's history and identity.
[25][26] The "memories" recovered by techniques like past-life regression may be the result of cryptomnesia: narratives created by the subconscious mind using imagination, forgotten information and suggestions from the therapist.
[4][8] Examinations of three cases of apparent past life regression (Bridey Murphy, Jane Evans, and an unnamed English woman) revealed memories that were superficially convincing.
For example, a subject described the life of a Japanese fighter pilot during World War II, but was unable to identify Hirohito as the Emperor of Japan during the 1940s.
Past life regression has been critiqued for being unethical on the premises that it lacks any evidence to support these claims, and that the act increases one's susceptibility to false memories.
[6][32] As past life regression is rooted on the premise of reincarnation, many APA accredited organizations have begun to refute this as a therapeutic method on the basis of it being unethical.
Additionally, the hypnotic methodology that underpins past life regression places the participant in a vulnerable position, susceptible to implantation of false memories.