, in certain circumstances the completion of an aggressive act is in itself rewarding. The variables that influence the sensitivity of the neural system for aggression may function to increase the sensitivity of that system for aggression over a prolonged period of time. In that circumstance, the individual may be said to have a chronic behavior tendency to hostility. If the sensitivity of an aggressive system is relatively transient, the individual may be considered as having a neurological set for hostile behavior.
According to this theory, there are suppressor areas for aggressive behavior in the brains of humans, as there are in the brains of animals, and there is good reason to believe that those suppressor areas are associated with other motivational systems. The aggression-suppression effects of brain stimulation may also have a prolonged effect. If the threshold for the activation of the neural systems for aggression is very high, it will take a great deal of provocation to activate them. There are other circumstances in which the threshold is very low and relatively little provocation will result in the activation of the neural systems with the result that the individual has an increased tendency to behave aggressively.
Other analysts believe it is not so much genes or the neural system, but in the nature of the lives poor people lead and the nature of the communities in which they reside--since violent criminals are drawn heavily from this segment of the population. The close association of violent crime with urban lower-class life is a direct result of the opportunities that are not available. Psychological factors may help explain why some individuals turn to street crime and others do not, but it is important to note that the people who make that choice are more often concentrated in the lower class than in the middle or working class.
Children growing up in urban slums and ghettos face a different se...