Psychopathy is a term that has been around for a long time, but it is only in the last 30 years that it has become a topic of so much interest in forensic psychology. In fact, one could argue that psychopathy is the focus of more current research in psychology than is almost any other topic. Nonetheless, there is still a great deal of confusion about the meaning of psychopathy, even among psychologists. Psychopathy is a psychological construct that describes a constellation of emotional, interpersonal, and behavioral traits that are related to antisocial behavior (Hemphill & Hart, 2003). However, psychopathy is not synonymous with the more widely known, antisocial personality disorder (APD). Psychopathy and APD are similar but also different in several respects (Hare, 1996). APD is the formal diagnosis for someone who exhibits a history of antisocial behavior, according to the Diagnostic and Statistical Manual for Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR; American Psychiatric Association, 2000). Although psychopathy shares many of these same characteristics, it does not share all of them. APD is a behaviorally based disorder, meaning that the criteria used to diagnose APD are largely composed of specific behaviors (e.g., lying, cheating, and committing criminal acts). In order for persons to be diagnosed with psychopathy, they must exhibit these behavioral characteristics as well as the more difficult to measure emotional and interpersonal characteristics, such as a lack of empathy, superficial charm, manipulativeness, cunning, lack of remorse, irresponsibility, and so on. In fact, these emotional/interpersonal characteristics may be the central features of psychopathy and distinguish it from APD (Cooke & Michie, 2001). These different conceptualizations of psychopathy and APD lead to a difference in their prevalence. As many as 60 to 80 percent of incarcerated offenders can be diagnosed with APD and about 3 to 5 percent of the general population can be diagnosed. Only about 15 to 30 percent of offenders and 1 percent of the general population can be diagnosed with psychopathy (Hare, 1996). As Bodholdt, Richards, and Gacano (2000) state, “identifying APD in forensic settings is something like finding ice in your refrigerator” (p. 59). As a result, psychopathy may have a greater ability to differentiate the most dangerous criminal offenders from individuals who simply act out in an antisocial manner.
Probably the single most important reason that psychopathy is important to forensic psychology is its relation to criminal behavior, specifically violence. The research has consistently found an association between psychopathy and the likelihood of someone committing future criminal behavior. Psychopathy has even been referred to as the single most important factor in the prediction of future violence (Salekin, Rogers, & Sewell, 1996). Psychopaths typically commit more crimes, and more violent crimes, than do nonpsychopaths (Gendreau, Goggin, & Smith, 2003; Walters, 2003). The significant relation between psychopathy and violence is true not only for general offenders but also sexual offenders (Porter, Fairweather, Drugge, Herve, & Birt, 2000), psychiatric patients (Nicholls, Ogloff, & Douglas, 2004), women (Verona & Vitale, 2006), and across different cultures (Sullivan & Kosson, 2006). The only type of violence where there is some question about the role of psychopathy is in the perpetration of domestic violence (Huss & Langhinrichsen-Rohling, 2006).
Not only is psychopathy related to future violence, but we also know there are some significant differences in the way psychopaths perpetrate their violence. Most criminals start to burn out or reduce their criminal behavior after 40 years of age, but psychopaths may be more likely to continue committing violent behavior (Huss & Langhinrichsen-Rohling, 2000). Psychopaths also appear to commit more instrumental or planned violence than do nonpsychopaths (Cornell et al., 1996). Psychopaths are more likely to commit violence where there is a clearly defined goal, such as with a mob hit or serial killings. Nonpsychopaths are more likely to commit reactive violence, such as crimes of passion or bar fights. As a result, psychopaths are actually less likely to perpetrate murders than are nonpsychopaths because most murders are emotionally based, and they are more likely to victimize strangers than are nonpsychopaths (Williamson, Hare, & Wong, 1987).
Besides the relation of psychopathy to criminal behavior and violence, there are several other interesting things we know about psychopaths in regard to their emotional expression and brain functioning. It may be clear that psychopaths have different emotional responses from those of nonpsychopaths, even from just our prior description. Psychopaths process emotion on a more superficial level and are more likely to exhibit emotion in order to control and manipulate people but less likely to do so in a genuine manner (Steuerwald & Kosson, 2000). In describing psychopathic emotion, it is often suggested that they understand the words to the music but they do not feel the beat. In other words, they can define words like anger, sadness, joy, and fear but they do not truly understand or experience them in the same way most people do. There also appear to be some biological differences between psychopaths and nonpsychopaths (Hare, 2001). Although it is questionable whether there are differences in the structure of psychopaths’ brains, it is clear that they function differently. In general, psychopaths appear to be less likely to process information with the outer cortex of the brain, and when they do process information, they are more likely to do so with the occipital lobe of the brain than with the frontal lobe, where the more complex processes tend to take place. Their brain activity has often been compared to sitting in a parked car while stepping on the accelerator. When psychopaths are processing information from their environment, especially emotional information, their brain is racing like the engine of the car. However, psychopaths are not processing the information in a complex manner because all regions of the brain are not accessing or utilizing the information. As a result, it is unlikely to be meaningful to them or get them somewhere, just like racing the engine of a car that is in park.