There have been many documented cases of individuals who have displayed vivid recollections of past lives. These past live memories can be classified into two major categories of hypnotically induced past-life memories and spontaneous past-life memories. Additionally, the majority of possible explanations fall into categories of information by normal means, guesswork, exaggeration, fraud by parents, or fraud by investigators.
Hypnotically Induced Past-Life Memories
Hypnotically induced past life memories spawn from a professional consultation to induce hypnosis and increase recollection. This method is not as reputable as spontaneous recollection because of increased suggestibility.
In some cases, xenoglossy of an extinct language can be found to varying degrees. For example, in a study well documented in the book Life Between Life by Joel Whitton, a professor of psychiatry at the University of Toronto Medical School, an American man name Harold Jaworski displayed the ability to speak and write in a foreign language. He wrote down twenty two words and phrases which he did not understand after coming out of hypnotic regression. Several Norwegian language authorities later revealed that ten of those words belonged to Old Norse, an extinct language spoken by Viking circa 700-1300 CE.
The same young man, Harold Jaworski, in another regression session recollected another past life as an ancient Mesopotamian named Xando. During this session, he began writing again. Upon coming out of hypnosis, Harold spoke on what he had just written, "When I looked at what I had done, all I could see was a bunch of squiggles... I thought it was pure garbage." An expert in ancient Persian and Iranian languages identified his writing as an authentic representation of a long extinct language named Sassanid Pahlavi, used in Mesopotamia in 226 and 651 CE. The only possible way to learn some of these languages is through the handful of experts who have limited knowledge of these languages. Harold has had no such training. This poses the question: could he have lived during the times when those languages were spoken, learned them during those lives, and accessed that knowledge from his subconscious during the hypnotic regression?
Spontaneous Past Life Memories
Instead of seeking out these past-life memories, many people get them in a unpremeditated manner. Spontaneous past-life memories are seen as more credible because of reduced level of suggestibility compared to hypnotically induced recollection. A majority of cases involving past life memories can be classified into this category. Ian Stevenson, a former professor and researcher of personality studies at the University of Virginia, investigated thousands of cases over four decades throughout the world. There are many well documented cases in the works of Ian Stevenson available for further research and discovery.
Arguments and Counterarguments for the Explanations of Past Life Memories
One of the first major arguments against past-life memories is that the information could have been discovered through normal means. The case of Howard Jaworski shows that he was able to manifest information that was extinct for over a millenia. In other cases as well, information was either too obscure or too intimate to be gotten through normal means. The argument of guesswork goes along with this in that in some cases information is too specific to be guessed.Next, there is a possibility that an individual could be exaggerating. However, there have been cases where written record of memories shed light on to the situation. In addition, there have been cases where process recognition under multiple supervision allows any flicker of exaggeration to be extinguished. A rather popular and possible explanation that many skeptics like to propose is fraud by the parents. However, if you look into many of the situations regarding past life memories, fraud by parents seems very unlikely. One simple reason could be that most reincarnation believing parents don't care for the validation of their beliefs. Diving deeper, most parents don't receive any monetary benefits from these investigations. On the contrary, many parents often lose their daily wages to go through rigorous interviews. There is usually very little fame and prestige involved. Last but not least, for the parents orchestrating a fraud by drilling a small child repeatedly and getting multiple witnesses to collude would be very difficult, if not impossible. The last possible explanation that is proposed is fraud by the investigators. However, we can see that Dr. Ian Stevenson, who was the most prominent researcher, was lauded and acknowledged for his quality research standards in top scientific journals. That, coupled with the fact that multiple researchers all over the world have uncovered consistently similar findings can make it easy to dismiss the idea of fraud from investigators.