First a bit of terminological history, to clear up any confusion about the meanings of "sociopath," "psychopath," and related terms. In the early 1800s, doctors who worked with mental patients began to notice that some of their patients who appeared outwardly normal had what they termed a "moral depravity" or "moral insanity," in that they seemed to possess no sense of ethics or of the rights of other people. The term "psychopath" was first applied to these people around 1900. The term was changed to "sociopath" in the 1930s to emphasize the damage they do to society. Currently researchers have returned to using the term "psychopath." Some of them use that term to refer to a more serious disorder, linked to genetic traits, producing more dangerous individuals, while continuing to use "sociopath" to refer to less dangerous people who are seen more as products of their environment, including their upbringing. Other researchers make a distinction between "primary psychopaths," who are thought to be genetically caused, and "secondary psychopaths," seen as more a product of their environments.
The current approach to defining sociopathy and the related concepts is to use a list of criteria. The first such list was developed by Hervey Cleckley (1941), who is known as the first person to describe the condition in detail. Anyone fitting enough of these criteria counts as a psychopath or sociopath. There are several such lists in use. The most commonly used is called the Psychopathy Checklist Revised (PCL-R), developed by Robert Hare and his colleagues. An alternative version was developed in 1996 by Lilienfeld and Andrews, called the Psychopathic Personality Inventory (PPI). The book that psychologists and psychiatrists use to categorize and diagnose mental illness, the Diagnostic and Statistical Manual of Mental Disorders, (DSM IV) contains a category for something called "antisocial personality disorder" (APD), while the World Health Organization delineates a similar category it calls "dissocial personality disorder." These are much broader categories than that of psychopathy. The category of psychopath is seen as included within this category but considerably smaller so that only roughly 1 in 5 people with APD is a psychopath (Kiehl and Buckholtz, 2010).
If we overlay all of these lists of criteria, we can see them coalescing into the following core set:
The PCL describes psychopaths as being callous and showing a lack of empathy, traits which the PPI describes as "coldheartedness." The criteria for dissocial personality disorder include a "callous unconcern for the feelings of others." There are now several lines of evidence that point to the biological grounding for the uncaring nature of the psychopath. For us, caring is a largely emotion-driven enterprise. The brains of psycopaths have been found to have weak connections among the components of the brain's emotional systems. These disconnects are responsible for the psychopath's inability to feel emotions deeply. Psychopaths are also not good at detecting fear in the faces of other people (Blair et al., 2004). The emotion of disgust also plays an important role on our ethical sense. We find certain types of unethical actions disgusting, and this work to keep us from engaging in them and makes us express disapproval of them. But psychopaths have extremely high thresholds for disgust, as measured by their reactions when shown disgusting photos of mutilated faces and when exposed to foul odors.
One promising new line of research is based on the recent discovery of a brain network responsible for understanding the minds of others. Called the default mode network (because it also performs other tasks and is operating most of the time when we are awake) it involves a cluster of several different areas in the brain's cortex. The first studies have been done on function of this network in psychopaths and as expected there are problems there. Different studies have noted "aberrant functional connectivity" among the parts of the network, along with reduced volume in some of the networks crucial areas.
Psychopaths, and to a degree, sociopaths, show a lack of emotion, especially the social emotions, such as shame, guilt, and embarrassment. Cleckley said that the psychopaths he came into contact with showed a "general poverty in major affective reactions," and a "lack of remorse or shame." The PCL describes psychopaths as "emotionally shallow" and showing a lack of guilt. Psychopaths are notorious for their lack of fear. When normal people are put into an experimental situation where they anticipate that something painful will happen, such as a mild electric shock, or a mildly aversive pressure applied to a limb, a brain network activates. Normal people will also show a clear skin conductance response produced by sweat gland activity. In psychopathic subjects, however, this brain network showed no activity and no skin conductance responses were emitted (Birbaumer et al., 2012).
According to Cleckley psychopaths show unreliability, while the PCL mentions "irresponsibility" and the PPI describes psychopaths as showing "blame externalization," i.e. they blame others for events that are actually their fault. They may admit blame when forced into a corner, but these admissions are not accompanied by a sense of shame or remorse, and they have no power to change the sociopath's future behavior.
Ranging from what the PCL describes as "glibness" and "superficial charm" to Cleckley's "untruthfulness" and "insincerity," to outright "pathological lying," there is a trend toward devaluing speech among psychopaths by inflating and distorting it toward selfish ends. The criteria for APD include "conning others for personal profit or pleasure." One concerned father of a young sociopathic woman said, "I can't understand the girl, no matter how hard I try. "It's not that she seems bad or exactly that she means to do wrong. She can lie with the straightest face, and after she's found in the most outlandish lies she still seems perfectly easy in her own mind" (Cleckley, 1941, p. 47). This casual use of words may be attributable to what some researchers call a shallow sense of word meaning. Psychopaths do not show a differential brain response to emotional terms over neutral terms that normal people do (Williamson et al., 1991). They also have trouble understanding metaphors and abstract words.
The PCL describes sociopaths as possessing a "grandiose sense of self worth." Cleckley speaks frequently of the boastfulness of his patients. Hare (1993) describes an imprisoned sociopath who believed he was a world class swimmer.
Narrowing of attention
According to Newman and his colleagues the core deficit in psychopathy is a failure of what they call response modulation (Hiatt and Newman, 2006). When normal people engage in a task we are able to alter our activity, or modulate our responses, depending on relevant peripheral information that appears after the task has begun. Psychopaths are specifically deficient in this ability, and according to Newman, this explains the impulsivity of psychopaths, a trait which shows up in several of the lists of criteria, as well as their problems with passive avoidance and with processing emotions.
Top-down attention tends to be under voluntary control, whereas bottom-up attention happens involuntarily. But bottom-up attention can temporarily capture top-down attention, as when movement in the periphery of our visual field attracts our attention. Psychopaths have trouble using top-down attention to accomodate information that activates bottom-up attention during a task. In normal people, this process tends to happen automatically. When the hunter is scanning for deer, a rabbit hopping into the periphery of his visual field automatically attracts his attention. Top-down attentional processes monitor the field of attention for conflicts and resolve them. The standard task for assessing this is called the Stroop task, in which the subject must state which color words are printed in. The problem is that the words themselves are conflicting color words, such as "red" printed in blue ink, so the subjects must suppress a strong inclination to read the words. There are now several studies indicating that psychopaths actually perform better than normal people on these tasks perhaps because they are not distracted by the discrepant color (Hiatt et al., 2004; Newman et al., 1997).
Cleckley spoke of his psychopaths showing a "pathologic egocentricity [and incapacity for love]," which is affirmed in the PPI by its inclusion of egocentricity among its criteria. The PCL also mentions a "parasitic lifestyle."
Inability to plan for the future
Cleckley said that his psychopaths showed a "failure to follow any life plan." According to the PCL, psychopaths have a "lack of realistic long-term goals," while the PPI describes them as showing a "carefree nonplanness."
The criteria for dissocial personality include, a "very low tolerance to frustration and a low threshold for discharge of aggression, including violence." The criteria for antisocial personality disorder include, "irritability and aggressiveness, as indicated by repeated physical fights or assaults."
Philosophers can play a valuable role here in discerning the consequences of all of these findings for our attempts to build an ethical society. Several questions need addressing. What does the possibility that psychopathy is genetic say about human nature? What steps can we take to "correct" psychopaths and which of these is the most ethical? If it is true that psychopaths have damaged or abnormal brains, can we hold them responsible for what they do? Are there degrees of psychopathy, so that normal people may possess psychopathic traits?
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