There are two distinct interactive systems of the mind that control human behavior and decision-making. The interaction exists between an ancient part of the mind that is pre-programmed, unconscious, and quick (reactive) and one that is rule-based, conscious and slower (responsive). We could say the interaction is between older brain structures and the more recently developed prefrontal cortex. Using this model empowers people to understand and change their behaviors rather than simply accepting themselves as inherently broken.
The Deliberative System
In the dual-process model of human behavior, human behavior is seen as the “joint product of a deliberative system that assesses options in a consequentialist fashion and an affective system that encompasses emotions such as anger and fear and motivational states such as hunger, sex, and pain”. The deliberative system houses the executive functions, has the capacity to assess potential consequences of behaviors and can influence behavior by exercising willpower over the affective system. This system critically considers various choices with a particular focus on the emotional consequences of an action. Anticipated emotional outcomes of particular actions are used to guide decision-making. The deliberative system can best be summarized as “responding, rather than reacting” to emotional stimuli.
The Affective System
The affective system has greater sensitivity to immediate situations and is pre-programmed to assert dominance over the deliberative system to protect the whole person (e.g. fight, flight, freeze response). The affective system involves deeply wired motivating instincts that are designed for survival. A strong feeling of loneliness can motivate someone to medicate that feeling in whatever way is most expedient. But while the affective systems propels us toward protective action, without a more deliberate driver at the wheel, they can also motivate us to react to uncomfortable feelings in self-sabotaging ways.
In the end, whenever we are contemplating changing behaviors, whether it be having a second piece of cake or engaging in unfulfilling sexual behaviors, we are presented with the choice between experiencing the intense, short-term alleviation of uncomfortable feelings and taking the more calculated, perhaps a bit more boring, path toward long-term satisfaction. We can acknowledge that at any given time we have competing motivations, but this does not mean the behavior is out of our control—it just may feel out of control. If we can identify our competing motivations and slow down enough to recognize them when our affective system is activated, we can choose to engage our deliberative system to drive our behavior in the direction of long-term goals. Luckily, we can actively work to strengthen our deliberative system.
 Lowenstein & O’Donoghue, 2007