If you’re an avid consumer of porn, you’ve probably come across videos from time to time that leave you thinking: “Why would anyone want to watch that?” or “How could anyone find that arousing?” To a psychologist, though, the fact that some people get off on WTF porn is perfectly understandable.

In order to get the appeal of different kinds of porn, you need to move past your initial gut reaction and really think about the message that might be drawing the viewer in. Let’s consider five kinds of porn that a lot of people just don’t understand and look at them like psychologists. They may not appear to have much in common, but each shares a major theme.

This is exactly what it sounds like—one person, who’s usually tied up or handcuffed, is tickled relentlessly by another person or persons. The tickler and ticklee can be of any gender combination. They may be nude or partially clothed, and they may or may not have sex. In fact, sometimes there’s no nudity or sex at all in these videos—just tickling.

This kind of porn is far more popular than you’d think. A quick search for “tickle” on Pornhub alone yields over 12,000 hits.

More: Check out this fascinating story about a guy who responded to a Craigslist ad to appear in tickle porn.

To be perfectly clear, I’m talking about actual monsters here. You know, like Bigfoot. Or the Kraken. Or a Tyrannasorus Rex. Yep, dinosaur porn is a thing. In fact, you can get your own copy of the literary gem “Taken by the T-Rex” here.

Monster porn is sometimes animated, but other times people will dress up in monster costumes for a live-action film. In such videos the monster is usually having sex with a human, who is often taken against their will and held captive.

More: click here to read one psychologist’s take on the potential evolutionary significance of monster porn.

Vore is a porn genre that’s all about one person consuming or being consumed—whole and live—by someone else or by another creature. Clearly, there’s a bit of overlap here with monster porn. However, monster porn does not necessarily have to involve consumption. There’s also some overlap here with macrophilia porn, which features giants and giantesses who are sometimes eating tiny people.

Vore porn typically involves a predator/prey scenario. Because you can’t (and shouldn’t) eat another person whole, vore porn is often animated or relies on special effects. It may also involve real people swallowing live insects or very small animals.

More: learn more about vore, including how it’s different from sexual cannibalism.

Adult baby/diaper lover (or ABDL) porn is all about one person acting like or being treated like a baby, often by a “mommy” or “daddy” figure. The “baby” in this scenario is sometimes wearing—and using—diapers.

ABDL porn takes a lot of forms. The focus is sometimes on wetting or messing the diaper and being spanked afterward. Other times the focus may be more on a variety of role-playing scenarios in which the “baby” is completely dependent on the adult.

More: go here to learn what research has revealed about the psychological characteristics and history of people who are part of the ABDL community.

Feeder porn is all about erotic feeding and eating. It’s very different from vore, though, in that this one is all about eating food—not people.

Feeder porn sometimes involves just one person eating in front of a camera or rubbing their belly. It often features a feeder who is literally putting food in the mouth of the feedee. The feeder controls what the feedee eats and how much.

More: watch a video about an actual feeder-feedee couple that makes their own videos.

So did you figure out what all five genres have in common?

If you pegged the overall theme to be dominance and submission, right on. More often than not, videos from all of these porn genres feature one person or creature dominating or having control over another.

Therefore, on some level, the appeal of these pornos can largely be viewed as variations on people’s more general interest in dominance and submission, which is something that a majority of both men and women say they’ve fantasized about before.

In light of this, it’s not at all surprising that there’s a growing market for things like tickle and monster porn. The internet has just given people some new and very interesting ways of expressing their deeper underlying desires.

Justin Lehmiller, PhD is a sex educator and researcher at Ball State University and author of the blog Sex and Psychology. Follow him on Twitter @JustinLehmiller.

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