Aggression is a trait that is found in all human beings. It is a complex behavior that shapes an individual's personality. Over the years there have been many theories on what causes aggression, but none have provided us with a concrete foundation on the origins of aggression in individuals. Even today there are many debates as to whether aggression is an instinct instilled in our brains, or a learned response from today's violence-filled culture. If aggression is a learned response from our society, where do people learn how to behave aggressively? In our society aggression is taught at a very early age through two sources: family interactions and television. Aggressive behavior also varies between the sexes, thus creating differences in aggression between males and females. .
Aggression can be defined in many ways. There are more than 250 different definitions of aggression found in psychological literature, but two general features of aggression are broadly accepted: (a) aggressive behavior must be perceived negatively by the victim and (b) aggressive behavior must be intentional, where the aggressor is described as desirous of hurting or destroying the victim physically or psychologically. Although pain and injury have been most often interpreted by researchers to mean bodily harm, these terms could also apply to damage to one's self-esteem or social standing (Harre, 1983). .
Many theories exist concerning aggression. One such theory, the instinct theory, developed in 1939 by Dollard, Doob, Miller, Mowrer, and Sears, assumes that man is aggressive by nature. It assumes that humans are born with an aggression producing machine inside our bodies which forces expulsion from time to time through some type of aggressive behavior (Knutson, 1973). Other aggression theories were introduced by Freud. Freud suggested that the aggressive instinct is tied to one of two fundamental human drives: Thantos, which is the death instinct.