It is a modern version of an ancient view that the basic stuff of the universe manifests itself both physically and as conscious experience (a dual-aspect theory in the traditions of Spinoza and Fechner).
[4] Monism is the view that the universe, at the deepest level of analysis, is composed of one fundamental kind of stuff.
Reflexive monism maintains that, in its evolution from some primal undifferentiated state, the universe differentiates into distinguishable physical entities, at least some of which have the potential for conscious experience, such as human beings.
Donald Price and James Barrell write that, according to reflexive monism, experience and matter are two complementary (first- and third-person viewable) sides of the same reality, and neither can be reduced to the other.
[4] A similar combination of monism and reflexivity is found in later Vedic writings such as the Upanishads, as well as the Buddhist views of Chittamatra and Dzogchen.