Emotion, motivation and function

Biological approaches to emotion require that adaptive function is an organizing principle in defining the emotion. The emotion of fear is taken as the complete behavioral, physiological and experiential components of a system that evolved for antipredator defense. In part, fear is a motivation that selects and drives overt defensive action. But the emotion also contains the autonomic changes supporting these behaviors and the conscious experience that accompanies danger. Fear has the ability to overwhelm consciousness so that that nothing but phylogenetically selected action occurs. By filling consciousness fear prevents flexible behaviors and that is one reason why anxiety disorders can be so debilitating. Anxiety, fear and panic are states within the emotion that correspond to different levels of threat.