A lack of contagious yawning can be a subtle sign of psychopathic traits. This reflects a diminished capacity for "automatic empathy," or catching others' emotions, even though their cognitive understanding of emotions may be intact.

Counterintuitively, individuals with severe personality disorders do not respond positively to empathy and nurture. These pro-social behaviors actually make them more exploitative. They are often immune to punishment and perceive empathy as a vulnerability in others, which they then leverage for their own gain.

Within the 'Dark Triad' of personality traits, there is a clear hierarchy. Psychopathy is an escalation of narcissism. All psychopaths exhibit pathological narcissism, but many narcissists do not possess the additional traits of psychopathy. Narcissism is a necessary, but not sufficient, condition for psychopathy.

While not all insecure people are narcissists, all narcissists are deeply insecure. The critical distinction is the desire for personal growth. An insecure person seeks ways to improve and connect. A narcissist believes they have already achieved perfection and cannot be improved upon, seeking only support and praise.

A key nonverbal cue for psychopathy is an inappropriate combination of verbal and nonverbal emotional displays. For example, using angry, hostile words while making a big, broad smile can be a red flag that people subconsciously detect.

While related, narcissism and psychopathy have different core motivations. A narcissist's engine is grandiosity at the expense of equality—they need to be on top. A psychopath's engine is the exploitation of others at the expense of any sense of honor or human value. They see people as objects, not inferiors.

While psychopathic and narcissistic traits help politicians attract followers and media attention, these same traits make them less influential in Congress. Colleagues find them difficult to collaborate with, hindering their ability to get bills passed.

The common 'hurt people hurt people' narrative is misleading for personality disorders. New research indicates a strong genetic contribution to traits like narcissism, which can manifest severely even in individuals who had no childhood adversity or trauma. Environment can exacerbate it, but the 'raw materials' are often innate.

Manipulative individuals often betray their intentions through "danger zone" cues they cannot control. These include lip pursing (a universal withholding gesture), physically distancing from a statement, and a significantly increased blink rate, which indicates the high cognitive load associated with deception.