After the two-factor model, the three-factor model was developed adding more traits present in psychopaths. Those three factors are:
1. Arrogant and deceitful with others;
2. Lacked affective experiences;
3. Impulsive and irresponsible.

Three-Factor Model in Hare's Psychopathy Checklist

After the three-factor model, the four-factor model was developed adding even more traits present in psychopaths. Those four factors are:
1. Interpersonal;
2. Affective;
3. Lifestyle;
4. Antisocial.

Four-Factor Model in Hare's Psychopathy Checklist

Dr. Hare's checklist began with the two-factor model. This includes the following items:
1. Interpersonal-affective;
2. social-deviance.

Two-Factor Model in Hare's Psychopathy Checklist

Many clinicians use Hare's Psychopathy Checklist to diagnose patients with psychopathy. To do this, after talking to the patient, the professional will score each criteria based on how much it fits the person's personality. The grades range from 0 (does not fit), 1 (kind of fits), to 2 (definitely fits). After grading every criteria, the clinician adds all scores with the maximum being 40 and the minimum a zero. According to Hare, a person is a psychopath if they receive a score of 30 or more.

Using Hare's Psychopathy Checklist as a Diagnostic Tool

Dr. Hare's checklist includes 20 items which correspond to different traits present in psychopaths. This checklist began with the two factor model and later expanded to a three and four factor model. The numbers listed on each item's row corresponds to the factor it relates to.

Tulane University

Dr. Hare, a psychologist focused on the field of criminal psychology, published his Psychopathy Checklist in 1980. It is made up of three models that include different factors. Hence, his clinical definition of what traits a psychopath holds is described in this checklist, which many professionals use to diagnose such disorder.

Dr. Robert Hare's clinical definition of a psychopath

Kiehl, K. A., & Hoffman, M. B. (2011). THE CRIMINAL PSYCHOPATH: HISTORY, NEUROSCIENCE, TREATMENT, AND ECONOMICS. Jurimetrics, 51, 355–397.

Relationship between crime and psychopathy

The 20 Items on Hare's Psychopathy Checklist 

Many psychopath tests - tests used to determine whether a person exhibits traits that could clinically classify them as a psychopath - are available online for anyone to access. This excessive availability of content surrounding psychopathy online may be one of the factors that causes a romanticization and obsession with psychopaths in media, as well as one of the factors that detracts from an overall true public understanding of what a psychopath is and what APD is. 

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