One can consider psychopathy in three layers: 1) primary features (the level of the soul), 2) personality traits and 3) behavioural characteristics. It appears that only the primary attributes apply to all psychopathsIf we look at these characteristics, there is a difference in intensity, and this difference is substantially a difference in intensity of psychopathy. As for the personality traits it is so that these characteristics may be present in a greater or lesser degree and they can also be entirely absent or they may be present without the existence of psychopathy. They are neither necessary nor sufficient for psychopathy. This is even more true for all sorts of behaviors that may be observed in psychopaths, as in others.

The most commonly used checklist is the checklist of Robert Hare, the Psychopathy Checklist -Revised (PCL-R) of which there are also a youth and a screening version (PCL: YV and PCL: SV).

The PCL-R consists of twenty points and is scored on a three point scale. A score above a certain number of points – quite high – leads to the diagnosis of psychopathy.

The PCL-R mixes points that relate to primary characteristics, personality traits and behaviors. Each point in the PCL-R is weighted equally. Some items in the checklist are strongly related to each other, such as “promiscuous sexual behavior” and “many short real commitments”. Most personality traits or behaviors in the PCL-R are often present in certain types of psychopaths, but are not present in all psychopaths, and may also be present without the existence of psychopathy. A diagnosis of psychopathy based on a high score on the PCL-R will usually – but not always – be correct. A low score on the PCL-R provides little assurance that there is no psychopathy. The PCL-R is especially applicable to heavy, masculine, often criminal psychopaths. Most people who suffer from psychopathy – in itself a serious mental disorder – however, fall outside the category of such extreme cases.

Another checklist is that by the psychologist Isabelle Nazare – Aga. It includes thirty behaviors by which people can determine whether they are dealing with a perverse narcissist. Nazare – Aga does not use the term psychopath because in France that term is used exclusively for criminals. The perverse narcissist is, according to Nazare – Aga unconscionable. In her checklist no behaviors occur that are related to physical violence. They do offer a striking picture of the “common everyday” psychopath who knows well to manipulate. Each point is weighted equally and is scored “true” or “not true”. The score depends on the fact if the behavior is commonly or not commonly present. Remarkably, according to Nazare – Aga, the male/female ratio of the perverse narcissists is approximately equal.

Many psychopaths have the characteristics for perverse narcissism according to Nazare – Aga, but there are also many who do not. The latter exhibit other behaviors, while they are equally unscrupulous. A criterion such as “prêcher le faux pour savoir le vrai” (meaning “telling lies to cover the truth”), for example, is particularly applicable to a perverse manipulator, but many psychopaths are not crafty enough or simply not smart enough for this trick.