T. Watanabe, Johanna Shapiro and Gary Schwartz suggested that the reduction of oxygen consumption which occurred in all forms of meditation was the single most important factor in producing the accompanying psycho-physiological changes. With regard to respiration, S. Nakamizo noted that the ratio of exhalation to inhalation increases during meditation so that the body is literally emptied of air. B. Timmons et al. noted a correlation of Electroencephalograph alpha with increased abdominal, decreased thoracic breathing, a pattern which occurs during meditation. Certainly, breathing is considered an important variable in most meditation traditions. Both the Zen and Yoga traditions place great emphasis on breathing, counting, observing, or concentrating upon breaths, and in some sects, even hyperventilating. Aside from koans, the role of thoughts or self-instructions as a mediating mechanism for reducing thoughts is never explicitly stated. In addition to thoughts during meditation, there are also thoughts before and after meditation which may mediate outcome.