When James Fallon walks into a bar, ladies take notice.

“I’ll be surrounded by young women,” the neuroscientist tells The Post. Once he’s got their attention, he’ll regale them with stories of his “interesting life” and dole out compliments “sparingly.” “My wife will say, ‘There you go again, you know you got ’em . . . Playing this game where they all fall in love with you.’”

Fallon’s je ne sais quoi isn’t about his looks: The 72-year-old academic isn’t exactly Brad Pitt.

So, what’s the root of his charm? Probably that he’s a psychopath.

“People are enraptured,” says Fallon, who was diagnosed with the disorder after recognizing his own psychopathic traits during a research project. “Since I was very young, I have always been able to [manipulate people], just to play with them.” He’s happily married, but likes the thrill of the chase. “It’s about winning the game.”

Psychopathy doesn’t sound like the stuff of Prince Charmings. According to the American Psychological Association, the antisocial personality disorder is characterized by “exploitation of others, deceitfulness, impulsivity, aggressiveness . . . [and] accompanied by lack of guilt, remorse and empathy.”

Then again, women love a bad boy — and new science out of Brock University in Canada confirms that women are more attracted to men who display psychopathic traits.

“Psychopathic men are really good at pretending to display what women are attracted to,” says Kristopher Brazil, one of two researchers who led the study, which was published last month in the medical journal Evolutionary Psychological Science. “They’re really good at putting on this mask, and making themselves look attractive . . . You exude a larger-than-life presence, and give off an impression of greatness.”

Brazil says psychopathy is twice as likely to affect men. For his study, he recruited 46 men and videotaped their answers to questions (for example, “What do you look for on a first date?”). Then, 108 women were asked to rate their attractiveness based on the videos. In analyzing their responses, Brazil found that the women seemed turned on by men who exhibited psychopathic traits — such as penchants for manipulation, deception, risk-taking and bullying.

None of those sound especially sexy — but Michael Brustein, a Chelsea-based relationship therapist specializing in perfectionism, isn’t surprised by Brazil’s findings. “When you’re a psychopath, there’s no shame and humiliation,” he says. These dudes, Brustein says, are “so concerned about winning. They’re physically in good shape, they’re going to smell good, and look good, too.”

Zac Efron as Ted Bundy in "Extremely Wicked, Shockingly Evil and Vile," Christian Bale as Patrick Bateman in "American Psycho," Michael C. Hall as Dexter in "Dexter," Mads Mikkelsen as Hannibal Lecter in "Hannibal" and Penn Badgley as Joe Goldberg in "You."
Zac Efron as Ted Bundy in “Extremely Wicked, Shockingly Evil and Vile,” Christian Bale as Patrick Bateman in “American Psycho,” Michael C. Hall as Dexter in “Dexter,” Mads Mikkelsen as Hannibal Lecter in “Hannibal” and Penn Badgley as Joe Goldberg in “You.”NYPost Photo Composite

Kelly Kreth, a real-estate publicist who lives in Manhattan, knows what it’s like to be swept away by a slick charmer. In 2010, she dated a man whom she describes as a “sociopath” — a term sometimes used interchangeably with psychopath; both are characterized by a lack of empathy.

“He made me feel like the most special person in the room,” she says. “He’s good-looking, high-powered.”

But things came to a head when Kreth discovered a creepy collection at her now-ex’s place.

“I had really long hair, and he kept pushing me to get it cut in a bob. He said he finds bobs supersexy. Finally, I did it,” she says. “He said, ‘I love you so much, I want to keep your ponytail.’ So he did.”

One day, poking around his house, she opened a box, where she found “three ponytails, all the same color, on the mantle,” she says. “How many women have short dark bobs because of him? I [now] know of five.”

Kreth, currently single, says she won’t get fooled again. “I can identify them superquickly. Any guy who is the most charming guy or the mayor of the town, he’s who I need to stay away from.”

Women who don’t want to wind up with such manipulative men should watch out for guys exhibiting a grandiose sense of self, says Brustein.

“There will be a lot of faux vulnerability. And that’s when people share things, but they’re really not deep, or sharing it really doesn’t diminish their identity.”

Extravagant gifts, impulsive behavior and getting bored easily are also warning signs.

“Watch out for ‘love bombing,’ ” adds Brazil. “If he says, ‘I think we’re soul mates. I feel like I’ve known you my whole life,’ in the first couple dates, it’s a red flag.”

The numbers are in your favor, at least: Psychopaths make up “about 1 percent of the population,” says Brazil.

Kreth’s biggest advice? “Trust your gut” — and be careful out there.

“I used to be scared of being snoopy, but now I’m the biggest Nancy Drew,” she says. “If you give me the chance, I’ll look through your garbage.”