There are five questions you can ask to diagnose a sociopath.

If there’s someone in your life who you suspect might be a sociopath, there are five questions experts suggest you ask them.

It is estimated that four per cent of the population are sociopaths, and they make up 15 to 25 per cent of prison inmates.

Martha Stout, author of The Sociopath Next Door, writes, “about one in 25 individuals are sociopathic, meaning, essentially, that they do not have a conscience. It is not that this group fails to grasp the difference between good and bad; it is that the distinction fails to limit their behaviour… without the slightest blip of guilt or remorse, one in 25 people can do anything at all.” 

Even though the term 'sociopath' is often used interchangeably with 'psychopath', they are two different conditions that exist on the same spectrum.

Sociopathy, otherwise known as antisocial personality disorder, is a significantly less severe version of psychopathy.

Sociopaths engage in pervasive lying and deception, are consistently irresponsible, self destructive and hold a reckless disregard for their own safety and the safety of others. They fail to learn from experience, are egocentric and struggle to form loving bonds with friends or family.

Psychopaths display those same traits, but to a greater degree. They are more manipulative, and are entirely incapable of forming loving bonds. It is estimated that 93 per cent of psychopaths are in the criminal justice system, and they make up just one per cent of the population at large.

Here are five questions to ask a suspected sociopath, according to Dr. Hervey Cleckly, author of the 1941 book 'The Mask of Sanity'.

1. Do you know how to charm anyone in a room?

A sociopath will answer an unequivocal 'yes'.

Stout says this is the biggest indicator of a sociopath.

"They are people who are better than you and me at charming people, at being charismatic," Stout told Interview Magazine. "I've heard this more often than I can count: 'He was the most charming man I ever met,' or, 'She was the sexiest woman I ever met,' or, 'The most interesting person I ever met ... .' That's because to learn to be charming is fairly easy — you can teach somebody to be charming and to learn human emotions — or to learn the behaviors that go with human emotions. A sociopath, a smart one, will study the way we emote, and will learn how to do that quite effectively."

     2. Do you feel bad about lying?

The interesting thing about people who lie is that often they know they'll be found out.

But according to Stout, they don't care.

They "lie for the sake of lying," she says. "Lying just to see whether you can trick people. And sometimes telling larger lies to get larger effects."

In her book, Stout uses the example of the 'lying' ex-husband, who cheats on their spouse from the beginning. Simply, that's sociopathic behaviour.

LISTEN: How to break the cycle of bad relationships. Post continues below. 

    3. Do you feel bad when you hurt others in some way?

Like question number two, a sociopath will answer 'no'.

M. E. Thomas told NPR, "They can't really imagine or feel the emotional worlds of other people. It's very foreign to them. And they don't have a conscience."

Stout adds that the sociopath becomes, "unimaginably, unassailably, and even maybe globally successful. Why not? With your big brain, and no conscience to rein in your schemes, you can do anything at all." 

      4. Would you consider yourself fearless?

     5. Do you struggle holding down jobs?

The sociopath struggles enormously with reliability, and as Business Insider puts it, have a hard time keeping a job given that it, "requires long-term obligations to others."

Thomas, a self-confessed sociopath, said jobs felt disposable.

"I had just lost a job. I had just lost several relationships. And it wasn't the first time that something like this had happened to me, where my life seemed to just fall apart. And I thought, 'Well, I can't keep doing this — every few years have my life just go kaput. And so I thought, 'What is the common denominator here? It's me. There must be something that I'm doing that's causing this.'"

For most of us, these traits will sound awfully familiar.

Statistically, we all know a sociopath. And it might just be the most charming person you've ever met.

Do you know a sociopath?