ABSTRACT
Aversive emotions are rooted in the defense systems of organisms. Fear provides the prototypical example. Animals display behavior that we understand as fearful in various contexts where, broadly speaking, their well-being, safety, or survival are threatened. The behavior in question may include escape, freezing (immobility), or attack (e.g. Archer, 1979), and, perhaps, seeking the proximity of conspecifics for shelter and protection (e.g. Bowlby, 1969; Klein, 1981). By utilizing Pavlovian contingencies, animals may be able to execute these defense responses more efficiently, thus gaining critical advantages in relation to, for example, a predator (see Hollis, 1982). From a biological perspective, therefore, fear, both unlearned and learned, has important adaptive functions, helping animals to survive and breed in their ecological niches.
