Psychophysiological Factors in Predicting Violence

Behavior, Stress, and the Autonomic Nervous System

During a highly stressful or provocative situation, various physical responses occur that involve activation of the flight-or-fight mechanism, which is both a biochemical and a physiological process. During this activation, a chain reaction of bodily defenses is orchestrated by the release of several stress hormones that further reinforce the physiological processes that lead to increases in heart rate, blood pressure, and other measurable indices. As a result, energy becomes available to allow a determination of the best course of action, either fighting back or fleeing. Under conditions of severe stress, humans have been known to perform unusual feats of strength and endurance. Even under less severe conditions of stress, however, awareness and attention are heightened and physical strength increases.

According to the suboptimal arousal theory, this system allows humans to be conditioned by environment, for example, by avoiding behavior likely to result in a penalty or punishment or seeking stimulation that will provide pleasure or reward. Most individuals have been conditioned effectively enough to know not to steal or harm others simply due to the threat of punishment or negative consequence. When this stress system is hyperactive, however, it is too quick to respond or it responds without adequate provocation from the environment, such as in panic disorders. On the other hand, when this system is [Page 573]underactive, the individual does not experience sufficient physiological activation to produce discomfort. The result can be an underactive nervous system: The individual may not be conditionable because, in the absence of physiological and emotional discomfort, he or she will not respond appropriately to punishments or threats of punishments. Research suggests that such individuals cannot be effectively deterred from crime or high-risk behaviors merely with threats of punishment.

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