Compartmentalization is a psychological term that means isolation between mental states to allow yourself to believe two completely different things at the same time. Usually it's an unconscious process, like when you push "bad thoughts" to the back of your mind. But, if you learn to use it consciously, it can definitely help you improve your game, as well as help you interact with some of your more difficult friends or coworkers.

The prevailing wisdom regarding pickup seems to boil down to this:

  1. Show that you are attracted to her
  2. Don't be needy

Now that's cognitive dissonance right there, you need to have both of these things in your mind at the same time; I am into her, but if I will be fine if I get rejected. A lot of beginners make the mistake of trying to project the fact that they are fine with being rejected when first approaching a girl through excessive DHV or teasing, but it just gives off the vibe of "I don't really want to be here, I'm just approaching girls to brag to my friends or satisfy my ego that I can get girls to be into me". A far more attractive vibe is "I'm approaching you because you're the most beautiful girl in the room and I must have you now." As Casanova put it, "I don't conquer; I submit." But we all know what happens to people who gets bogged down with singleitis.

This is where compartmentalization comes in. You need to learn to hold two mutually conflicting thoughts at the same time. A good visualization trick is to imagine two guys steering your brain, Inside, Out style. One guy is a sappy romantic lovable buffoon who's always getting you into trouble. One guy is a cool, level headed guy who's always rescuing you from the other guy.

When approaching, the first guy is in charge, he's disarming, he's charming, he makes her laugh. He hits his stride, he starts escalating. He makes her feel desired, he looks at her like she's the only girl in the entire world. He wraps her up in a heady, beautiful feeling that's just the two of you, clear, amidst the chaos of the world. The first guy gets lost in her.

Now, this is where things can go wrong. She might reject you (for reasons that has nothing to do with you). Her friends might cockblock you. She might turn out to be not that interesting, or interested in manipulation and mind games. This is where the second guy comes in to bail the first guy out. The second guy is you, right now, reading seddit, learning rules and mind sets and thinking about stuff like Abundance Mentality or escalation ladders or shit tests.

You don't want to be in the headspace of the second guy when actually attracting, it makes your actions seem very rigid and transparent. Women aren't idiots, if you come in thinking about rules and formulae, you can be sure that she's not gonna let her guard down around you. That's the beauty of the first guy, his entire schtick is that he doesn't give a crap about the rules, is ruled by passion. Women are empathetic, and if you're in the headspace of "I'm breaking my own (seddit) rules because I just want you so goddamn much" it makes it easier for her to get into her mind state of I'm going to break my rules because of how attractive you are.

But if things don't go well, or you totally blow it, or the girl turns out to be a terrible person, the second guy is there to help you recoup, pull out, get back in state, and put you back out there.

EDIT: Note that you shouldn't "switch" straight from the first guy to the second guy a lot, though that is the kind of essence of push-pull. If you "switch" a lot, it may seem like you're two-faced or bipolar. Instead think of the two guys as tools. You use them to your advantage. You can use aspects of one with some aspects of the other. Mix and match. This won't work for everyone, and some people may even feel it's dishonest or doublethink. However, I think that it gives you a more complex and interesting personality, and it's fundamentally more honest than going out and trying lines and routines.