The difference between a manipulative ex and a psychopath boils down to fear, according to a neuroscientist

• Neuroscience and psychology researcher Abigail Marsh has studied psychopaths for 15 years.
• She said the main difference between a manipulative lover and a true psychopath is their ability to feel fear.

You may have referred to an ex-lover as a "psychopath" to convey their unsavory behavior to your friends. But there's a major difference between a true psychopath and a fuckboy, according to a researcher who has studied psychopaths for 15 years.

The ability to feel fear is what separates a true psychopath from a manipulative lover, Abigail Marsh, a Georgetown University psychology professor and neuroscientist, said during a virtual seminar from the Science and Entertainment Exchange, an organization that connects the entertainment industry with science professionals.

Marsh said that psychopathy exists on a spectrum, but all psychopaths have trouble feeling fear, whether emotional or physical. This means psychopaths are more likely to engage in risky behaviors. They also can't empathize with fear in others, said Marsh.

Fuckboys can feel fear, while psychopaths cannot

On the surface, it may seem like a manipulative ex had the inability to process fear. In reality, it's more likely they're emotionally unavailable, therapist Kelly Scott previously told Insider.

An unwillingness to engage with others' emotions tends to stem from fear or insecurity, not a lack of capacity to feel emotions, according to therapist Darcy Sterling.

"Emotional unavailability often comes from fear or past traumas and insecurities, so they can project those onto their relationships with family, romantic partners, and friends," Sterling previously told Insider.

Though it may be difficult for a fuckboy to break through their façade due to conditioning, it's possible, said Sterling.

Psychopaths, however, aren't driven by fear. Rather, their brains are wired to not feel, or hardly feel, this emotion.

Marsh gave the example of a woman who didn't understand why people would cry, and would get angry at college peers who cried in her presence. The woman didn't understand those peers were processing emotions. Instead, she assumed they were crying to manipulate her, because that's how she thought of crying herself, said Marsh.

When a psychopath wants something, then, they'll do whatever they need to to get that thing and be completely fearless in that pursuit, according to Marsh.

"People who are psychopathic learn how to get what they want from other people, mostly through manipulation. Manipulation can often take the form of being a great friend or relationship partner, at least for a time," Marsh said during the seminar.