He went on to hypothesize that these three “complexes” not only represented three distinct stages of brain evolution, but remained three separate, semi-independent brains,
“[each] with its own special intelligence, its own subjectivity, its own sense of time and space and its own memory."
MacLean was saying, in other words, that every human brain contains three independent subjective consciousnesses.
Triune brain theory developed within the field of psychiatry in the 1960's, and has never been embraced by neuroscientists. There are many inconsistencies from a direct physiological standpoint. However, as a model of psychology, it has very practical applications.