PSYCHOPATHS: FINDINGS POINT TO BRAIN DIFFERENCES
Psychopaths are characterized by shallow emotions, impulsiveness, irresponsibility, egocentricity, and a lack of empathy or guilt. Robert Hare, who specializes in the study of psychopaths-who make up as much as a quarter of the prison population-characterizes them as "intraspecies predators who use charm, manipulation, intimidation, and violence to control others and to satisfy their own selfish needs." Their egocentricity, Hare says, makes psychopaths particularly dangerous; a recent FBI study, for instance, found that almost half of law enforcement officers who died in the line of duty were killed by psychopathic individuals.
"Lacking in conscience and in feelings for others," Hare says, psychopaths "cold-bloodedly take what they want and do as they please, violating social norms and expectations without the slightest sense of guilt or regret."
Traditionally, psychopathic behavior has been blamed on familial or sociological factors. Increasing evidence indicates, however, that psychopathic behavior stems not from bad parenting or a poor environment, but from fundamental differences in the psychopathic brain. Christopher Patrick et al. reported in 1995 (See related article, Crime Times, Vol. 1, No. 1/2, Page 6) that psychopaths have smaller heart rate changes and skin conductance changes in response to fear-provoking sentences than do control subjects, indicating that the processes that provoke emotions in normal subjects are defective in psychopaths. And research by Dominique LaPierre (See related article, Crime Times Vol. 1, No. 4, Page 6) suggests that the prefrontal cortex, an area of the brain involved in long-term planning and judgment, does not function normally in psychopathic subjects.
Additional studies support and extend this research, indicating that psychopaths' brains are somehow different than those of normal people. One series of studies, also by Christopher Patrick et al., compared the "startle" reaction of psychopaths and non-psychopaths.
Patrick and colleagues showed pleasant, neutral, and unpleasant slides to psychopathic prisoners. Several times during each group of slides, a loud burst of noise was delivered through subjects' headphones. Normally, the researchers note, "the protective startle reflex evoked by an abrupt, intense stimulus increases reliably during exposure to aversive or fearful stimuli, a phenomenon known as fear-potentiated startle." Thus, the startle response should be heightened when a subject views an unpleasant slide. Conversely, the reaction normally is inhibited when a pleasant slide is viewed.
In the experiments, non-psychopathic prisoners indeed reacted more strongly to the noise when they were viewing unpleasant slides, and less strongly during pleasant slides. "For psychopaths," the researchers note, "this normal pattern was not obtained. Instead of showing heightened startle reactions during exposure to aversive slides, the reactions of psychopaths were actually inhibited, relative to neutral slides."
Other studies by Patrick et al. have produced similar results. The researchers conclude that "the absence of normal startle potentiation in psychopaths during exposure to aversive pictures or warning cues signifies a deficit in the capacity for defensive response mobilization, which is the essence of fear."
The two hallmarks of psychopathy are emotional detachment and antisoical behavior, but Patrick et al. have found that only emotional detachment is linked to abnormal responses to unpleasant slides. This indicates, they say, that the "fear deficit" of psychopaths "is tied specifically to the affective/interpersonal component of psychopathy."
Left brain/right brain?
More evidence that psychopaths do not react normally to emotional stimuli comes from a new study by Rodney Day and Stephen Wong. Noting that the right hemisphere of the brain is specialized for processing the emotional significance of words, the researchers speculated that "psychopaths, who are unempathic, callous, and emotionally shallow, would rely less than non- psychopaths on right-hemisphere-based decoding strategies." Instead, they theorized, psychopaths may rely more on the left hemisphere, which "uses a more verbal-analytic strategy."
The researchers tested 20 psychopathic penitentiary inmates, and 20 non- psychopathic inmates. Participants were shown two words-a word with negative emotional connotations, and a "neutral" word-in each trial. Half the time, the negative word appeared in subjects' right visual field, and the neutral word in the left visual field; on the remaining trials, the order was reversed.
"As predicted," Day and Wong say, "non-psychopaths were more accurate and faster in processing negative emotional words in the left visual field (right hemisphere) than in the right visual field (left hemisphere). Psychopaths, on the other hand, did not show a significant visual field advantage." When negative and neutral faces were shown, however, psychopaths and non-psychopaths did not differ in their responses. This suggests, the researchers say, that the abnormal processing of emotional stimuli by psychopaths may be limited to language.
"Emotion and temperament in psychopathy," Christopher J. Patrick, Clinical Science, Fall 1995, pp. 5-8; "Emotion and psychopathy: startling new insights," Psychophysiology, 31, 1994, pp. 319-330; and "Psychopathy and startle modulation during affective picture processing: a replication and extension," Gary K. Levenston, Christopher J. Patrick, Margaret M. Bradley, and Peter J. Lang, SPR Abstracts, August 1996, p. S55. Address for all: Christopher J. Patrick, Department of Psychology, Florida State University, Tallahassee, Florida 32306-1051.
"Anomalous perceptual asymmetries for negative emotional stimuli in the psychopath," Rodney Day and Stephen Wong, Journal of Abnormal Psychology, Vol. Arlington Avenue, Saskatoon, Saskatchewan, Canada S7K 2H6.
"Psychopathy: a clinical construct whose time has come," Robert D. Hare, Criminal Justice and Behavior, Vol. 23, No. 1, March 1996, pp. 25-54. Address: Robert D. Hare, Department of Psychology, 2135 West Mall, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4.