An argument in support of introspective methods in research is developed. As illustration, the perception of "empty space" is considered on the identity thesis, especially as reported by adepts in altered states of consciousness. It is suggested that the unique sensory qualia—seeing per se, hearing per se, etc, in contrast to the content of seeing and hearing—are a function of unique processing events within each sensory system. A dynamic model for the unconscious is proposed which is consonant with both psychoanalytic clinical observations and the identity thesis. It is argued that the function of processing events which are identical with consciousness per se is to constrain sequences of representation events that are identical with phenomenal contents, so that less probable (on the basis of past learning) representation events are realized.