A concept from Evolutionary Psychology, popularized by Dr Paul McLean, which conceives of the human mind as having three semi-independent processing modules, as one would see in the software of a computer.

The first, called the Reptilian Brain, is responsible for bodily processes, instincts, and survival and reproductive functions. In Romantic Dynamics, it takes on the functions of two individuals developing the first phase of human courtship: sexual attraction. It is unconscious and automatic, instinct based.

The second module, called the Mammalian Brain, is responsible for emotional function, and response to stress, and in the Romantic Dynamics Model, it takes on functions of forming friendships based on personality compatibility, as well as self-esteem, love, and general emotional happiness in a romance. This is the emotional attraction phase of human courtship, the second phase.

The third module, called the Higher Brain, is responsible for intellectual and executive function. As such, it is the conscious mind, and has functions in language, as well as setting humans apart (and presumably above) other animals. In Romantic Dynamics, it is responsible for the intellectual attraction phase of courtship, the final phase in which a couple finds long term alliance in a partnership. In this model, it is presumed to take on functions that see each member of the couple striving for both their personal goals and joint goals as a couple, successfully. More so than what one can accomplish alone as a single.