There is no well-supported theory of psychopathy; many factors are involved that may vary from case to case. Current research focuses on biological determinants and on the qualities of the parent - child relationship that reinforce psychopathic styles of coping with reality. The clinical impression that the psychopathic individual experiences little anxiety about future discomforts or punishments has been supported by experimental studies. One study compared two groups of adolescent male delinquents. The experimenters tested galvanic skin response (GSR) under stress. Dummy electrodes were attached to each subject´s leg, and he was told that in 10 minutes he would be given a very strong but not harmful shock. (A large clock was visible so that the subject knew precisely when the shock was supposed to occur; no shock was actually administered). The two groups showed no difference in GSR measures during periods of rest or in response to auditory or visual stimulation.
However, during the 10 minutes of shock anticipation, the nonpsychopathic group showed significantly more tension than the psychopathic group, and at the moment when the clock indicated shock was due, most of the nonpsychopathic delinquents showed an abrupt drop in skin resistance (indicating a sharp increase in anxiety); none of the psychopaths showed this reaction (Lippert&Senter, 1966). Other studies in prison have shown that psychopaths do not learn to avoid shocks as quickly as normal or neurotic individuals do, nor evidence as much autonomic nervous system activity as other prisoners under a variety of conditions (Hare, 1970).
These findings have led to the hypothesis that psychopathic individuals may have been born with an underreactive autonomic nervous system; this would explain why they seem to require so much excitement and why they fail to respond normally to the threats of danger that deter most people from antisocial acts. Interpretations must be made with caution, however. It is possible that psychopaths view experimental situations as something of a game and they try to play it "extra cool" by attempting to control their responses.