Instructions: In this task, you're given a passage, further information available on a particular linked term from the statement, and a question. Your job is to generate the answer to the question by using the information provided. If there is no clear answer obtainable, output 'none'.
Input: Passage: Etzel Cardeña is the Thorsen Professor of Psychology (including parapsychology and hypnosis) at Lund University, Sweden where he is Director of the Centre for Research on Consciousness and Anomalous Psychology (CERCAP). A native of Mexico, Cardeña studied at the Universidad Iberoamericana in México and completed an MA in clinical psychology at York University in Toronto, Canada and an MA and PhD in Personality Psychology at the University of California, Davis. His doctoral thesis under the supervision of Charles Tart was on the phenomenology of deep states of hypnosis. He subsequently went on to do post-doctoral work in the area of dissociation and hypnosis at Stanford University under David Spiegel. Cardeña has held academic posts at Georgetown University, the Uniformed Services University of the Health Sciences (USUHS) and the University of Texas–Pan American, among others. He has served as President of the Society of Psychological Hypnosis (APA Division 30) for 2000–2001, the Society for Clinical and Experimental Hypnosis for 2001–2003, and the Parapsychological Association for the year 2008-2009. He has expressed views in favour of the validity of some paranormal phenomena. In a recent paper in American Psychologist he wrote that "The evidence for psi is comparable to that for established phenomena in psychology and other disciplines, although there is no consensual understanding of them."
 Link Information: none Question: Which doctorate and post doctorate supervisor's that Cardena worked under was older?
Output:
Answer: none