According to modern cosmologists, the evolution of consciousness corresponded with the evolution of matter into increasingly complex, elaborate, and interactive systems, with the human brain providing the highest level of complexity known. Psychological research shows that just about all of human experience is dependent upon and influenced by how individuals perceive time, localize themselves consciously within space and time, process their temporally- based perceptions and experiences, and utilize their episodic and semantic memory structures to engage in mental time travel.