Subjective consciousness is a state of consciousness in which a person is constantly aware of his or her self as well as outside factors. The study of this state has achieved high priority in the modern philosophy of mind, the mind-body problem or consciousness studies, as made popular by, e.g., David Chalmers. Subjective consciousness refers to the inner, private experience of (mainly) human beings. It is associated with the qualia made famous by Chalmers et al. This state is not to be confused with objective consciousness or the neural correlates of consciousness—though this confusion existed for much of the 20th century attendant on the rise of behaviourism and positivism and the decline of the interest in introspection made popular in the 19th and early 20th century by Edmund Husserl and William James. The lack of this state, as occasionally implied by physicalists and their ilk, would raise the question of who is the internal observer, for which all the neural processing takes place. To eliminate this internal observer leads to infinite regress. The alternative is to accept the observer or homunculus. This state is also associated with ancient Hindu studies of the mind as well as to many modern teachers, such as the Dalai Lama, U.G. Krishnamurti or G.I. Gurdjieff.