Although the facts and phenomena of consciousness have received attention in various forms in the past, it is only recently that the scientific community and the biobehavioral sciences in particular, have begun to recognize its study as a legitimate, even essential, domain of inquiry. Investigators who have attempted to explore this area of functioning have approached it from a myriad of perspectives, with a heterogeneous array of methods and techniques. The available literature in this area consists largely of a disparate collection of findings with an occasional, loosely woven theory. Most researchers working in areas of the biobehavioral sciences which have bearing on the study of consciousness are often not aware of data in a different, but related area which might be relevant to their investigations.