Sarah Thomason has also criticized alleged cases of xenoglossy from a professional point of view as a linguist. Her article "Past tongues remembered?" has been reprinted in different publications and translated into French and German. Thomason has examined, among others, the cases presented by author Ian Stevenson. In Stevenson's works "Xenoglossy: A Review and Report of A Case", and "Unlearned Language: New Studies in Xenoglossy", he presents the case studies of subjects who claimed to remember having lived past lives and to be able to speak in a foreign language when they were under hypnosis. In Stevenson's opinion, their ability to speak a foreign language without having been exposed to it could be proof of reincarnation. Sarah Thomason, however, analyzed those cases and concluded that the subjects did not show real knowledge of the foreign language they said they were able to speak. Thomason pointed out that the performance of the individuals was by far not to the standards of that of a native speaker, as they showed very limited vocabulary and poor grammar in the foreign language. Thomason also noticed that the speech produced was many times limited to a repetition of some phrases or short answers, and it sometimes included words in a different language than the one subjects claimed to be able to speak. Thomason argues that the structure of the experiment allowed for the subjects to be able to guess the meaning of some of the questions by the hypnotists. She concludes that none of the individuals studied by Stevenson could prove xenoglossy, and that their knowledge of the foreign language could be explained by a combination of natural means such as exposure to the language, use of cognates, and guesses, amongst other resources.