Instinct is an inherent behavior; a fixed action pattern that is unlearned. Animals are born with certain instincts which are common to all those in their breed. Some instinctual behaviors require a certain amount of maturation before they begin. The most obvious one is the instinct to mate and propagate. This "animal instinct" is, of course, inherent in human beings. Psychoanalysts sometimes refer to this behavior and aggressions as motivational forces, rather than natural, or animal instincts.
Other behaviors in humans that have been considered instinctual are the reflexes, sleeping, disgust, face perception, language acquistions, fight or flight. Some scientists think that it is instinctual for children to put everything in their mouth because this is how they tell their immune system about their environment. However, other sociologists argue that humans have no true instincts, contending that there are simply "complex patterns of behavior."