The "software" of the unconscious mind, including the instincts, both in terms of gender instincts, and for survival purposes, as well as where one's unconscious beliefs, values and habits exist.

Its operations have two, prime directives - to keep us alive long enough to reproduce.

These are both about the state of feeling passion, to greater or lesser degrees - more excited and full of life, or else more empty, melancholic, and unmotivated. The reptilian brain unconsciously, automatically steers us toward our mission in life, or purpose in being, usually through our masculine and feminine instincts that are also thought to be governed by the reptilian brain.

These gender instincts help us attract the opposite sex in the sexual attraction phase of courtship. It governs our physicality and sense of identity through the body.

In the field of Evolutionary Psychology, the model called the "Triune Brain Model" has the reptilian brain as one of the three, interdependent areas of the mind. The other two are the Mammalian Brain and the Higher Brain.