Watch any episode of MTV’s Catfish, and you’ll find a predictable saga: An unsuspecting soul gets suckered into an online romance, only to find out their partner is lying about their true identity. What follows is typically high comedy, with hosts Nev Schulman and Max Joseph confronting the perpetrator like it’s an episode of 1990s gotcha talk show Maury. The catfish is forced to explain why they lied, typically citing reasons like avenging old vendettas or sussing out cheaters.

The new Netflix documentary The Tinder Swindler depicts an even more nefarious subset of catfishing: the romance scam, where someone adopts a false persona and lures someone else into a relationship with the ultimate goal of stealing from the victim. Convicted Israeli fraudster Shimon Hayut allegedly tricked women into believing he was a wealthy man in the middle of a violent diamond war by using deceptive photos and voice memos. Through an intricate Ponzi scheme, Hayut ultimately defrauded victims in Norway, Finland and Sweden out of an estimated $10 million.

The term catfishing was first coined in Schulman’s 2010 controversial documentary and became popular with the rise of his MTV show. Journalists even used the term widely after the 2013 case of Notre Dame star lineman Manti Te’o, whose “dead girlfriend” turned out to be an elaborate hoax. From then on, catfishing was a part of the cultural lexicon, bringing Internet bottom feeders — and later alleged predators like Hayut — into plain sight.

With all these horror stories, is catfishing really as common as it seems? Dr. Kelly Campbell, a professor of psychology at California State University, San Bernardino (and real-life love doctor), has researched the topic extensively and says that real-life catfishing is a little different than what we see in pop culture. “When I started my research, I realized there are many more reasons why this happens than were portrayed on Catfish,” Campbell says. Here, Campbell explains why catfishes lie about their identity and how to make sure you don’t get baited into a fake flirtation.

Why do people catfish? 

The top reason is to emulate an ideal self and enhance their mate value: meaning different attributes that are considered desirable from a dating perspective, like you’re attractive in the face, you have a good body, you have a lot of money or you want to have kids — all these attributes people care about in the marketplace of dating. So, if you’re not high on those things or you don’t have much to offer, then that would be one reason why you’re creating this false self to approach people. Romance [scammers] are primarily just motivated to get money, which is also a valued attribute in the marketplace.

Other reasons include entertainment… testing the fidelity of a partner and anonymity issues. Some people also want to test out an alternative quality in themselves, like a different personality, gender or sexual orientation. Other catfishes will also have a person in mind to target and then tailor themselves to that person’s preferences. I tell people that if someone seems too good to be true, then they probably are.

How common is it?

That’s the question that’s difficult to assess, because in order to identify prevalence rates, you would need to randomly sample the entire population of people that it could affect. This doesn’t just affect people who are on online dating sites, so you can’t even use them to sample randomly; this can happen through other means, like, for example, when people get a friend request on social media. But it’s a common risk that’s reported by people who use any kind of online means for meeting people. So, if you’re just online — even if you’re not trying to find a dating partner or you don’t use it that much — the risk is high.

What predicts who will become a catfish and who will fall victim?

One of the top non-demographic predictors is narcissism. Those people, whether it’s online or offline, tend to manipulate and get close to others for self-gain, so it’s kind of a no-brainer that they would catfish. The victims are typically low on narcissism, and they’re not the type to be manipulating people. They’re more gullible and trustworthy.

People who have a reason to hide their identities in real life are at greater risk for perpetrating this online. For example, let’s say someone’s not accepted for one of their identities — like if they’re heavily entrenched in a religious community, but they really want to have all these sexual encounters, or relationships or fetishes, and they can’t express who they really are through who they date in their regular life. Sexual orientation is another example — if your family won’t accept your sexual orientation. People who have these constraint factors often turn online to perpetrate these relationships, because that’s where they can get the fulfillment that they’re not able to get in real life.

Is there anything you can do to avoid getting catfished?

The most important tip is to meet the person before getting emotionally invested. You could use a video call, but keep in mind that can be altered. Be leery of people who come on too strong. Search their images and profile content on Google, because you might find that it comes up in other places. Use paid dating sites and services, because a lot of times you have to provide information which is traceable when you register for those sites. Catfishes tend to shy away from those; they’re more likely to reach out via social media. So be leery when someone contacts you out of the blue on social media, especially if they seem too good to be true.

Also, be leery of people who say they are rich or famous. For a narcissist, it’s a pretty fun identity to portray, and for the victims, it’s a good hook to get them in, because people want to be desired by a famous person. Seek input from your trusted family and friends, because they can see things more objectively than you.

This interview has been edited and condensed for clarity.