This is my first post to this forum. I registered because I wanted to comment on Sensei Ledyard's post. I work as a forensic evaluator for Corrections in my state's prisons. Mostly I evaluate sex offenders, but I have on occasion also evaluated violent offenders such as persons convicted of aggravated domestic assault, murder, kidnapping, arson, etc. I wanted to build off what Sensei Ledyard mentioned. But first I need to assign some definitions, so please bear with me. In the ‘20s, career criminals were labeled "psychopaths," but in the ‘50s such individuals were labeled "sociopaths." Currently they would most likely fit the diagnosis of "Antisocial Personality Disorder." Such individuals are basically career criminals.
However, nowadays about 15% of the world's total population can be classified by a much different definition of the term psychopath. Briefly, psychopaths are responsible for most of the violent crime, do not tend to benefit from treatment, and have shorter "survival time" on the streets with higher recidivism rates than non-psychopaths. Dr. Robert Hare's prototypical psychopath can best be described by the following. "Such individuals are perceived as glib and having a superficial charm. They exhibit a grandiose sense of self-worth. They use pathological lying, conning and manipulation to achieve their goals. They exhibit a lack of remorse or guilt, shallow affect, and a callous lack of empathy in their interactions with others. They fail to accept responsibility for their own behaviors. Their lifestyles are characterized as chronically unstable, antisocial, and socially deviant. Such individuals crave stimulation. They have poor behavioral controls, which often first became apparent at an early age, frequently including juvenile delinquency. They live a parasitic, aimless, impulsive, and irresponsible lifestyle. Such individuals frequently have had conditional releases revoked. They are at high risk for alcohol and substance abuse."
There have been several interesting studies involving psychopathy. A 1992 study of wife batterers by Dutton identified 30% of the sample as psychopaths. The participants were observed/monitored during arguments with their spouses. Psychopaths demonstrated decreased heart rate during arguments, did not become emotionally aroused, but tended to focus on the spouse, much as a reptile locked its focus onto its prey before it strikes.
A 1991 laboratory study on psychopathy and affect by Williamson, Harpur, and Hare studied subjects from a Bronx Veteran's Administration substance abuse program. They were injected with cerebral tracers and underwent computer imaging while being tested using lexical decisions in left and right ventricles. Huh???? That means they sat in front of two computer screens with each eye only being able to view one of the screens. They viewed various combinations of letters on the left side and numbers on the right. When an emotional word was spelled out on the left side (such as SAD), they were to click the mouse (with the right hand I believe). The psychopaths had the slowest reactions times. Meanwhile CAT scans were looking down on the subject's brain. All subjects demonstrated increased activity in the basic limbic system—the primitive brain sitting on top of the brain stem, but non-psychopaths also indicated significant activity in the cerebrum—the higher order part of the brain, dealing with language for example. These findings suggest psychopaths may view emotions much like a foreign language.
Another well-known psychologist in the violent/sexual offenders research/treatment field, Dr. Vernon Quinsey, referred to studies of Norse and Icelandic histories which referenced Kings employing "Berserkers." Berserkers were the wild men portrayed as fearless fighters, foaming at the mouth and biting their shields. Someone you wanted on your side in a battle, not having to battle against. In those histories, if someone killed a family relative, it was expected that you either killed your relative's killer or accepted a "blood payment." In researching the histories, it was possible to determine who the berserkers were. When a berserker killed one of your relatives, you accepted the blood payment. Dr. Quinsey suggested that psychopathy was an advantage within an ancestral environment--as long as everyone wasn't a psychopath. [Kind of a "wolf among sheep."]
So yes, there are people out there that qualify as psychopaths—read predator. They are violent, often substance involved, and they see everyone other than themselves basically as sub-human.
Hope this wasn't too boring.