Talk to a marketing professor, and you’ll be told—early and emphatically—that free will is a joke, at least when it comes to buying behavior. As consumer research has demonstrated for decades, retailers can trick you into buying something in any number of confounding ways.

The worst part (or the best part, if you’re selling something): When used effectively, these tactics convince you you’re coming out on top, even when you’re over-paying for an item.

Here are six of the most common tactics marketers employ to coax open your wallet:

Pretty much every retailer in the country uses this method in one form or another, but you see it most at drug stores and supermarkets. It involves listing a product’s full price and then, more prominently, a “sale” price. Dozens of marketing studies have shown that first price “anchors” itself in a buyer’s head, and so makes the lower price more attractive.

In one famous experiment, MIT researchers had students assign a value to items (a bottle of wine, a book) based on the last two digits of their social security numbers. Even though the students knew the assigned values were arbitrary, when asked to guess the wine or book’s true value, those with high social security numbers estimated the items to be worth more—sometimes up to 300% more—than the students with low social security numbers.

Maybe it’s a grainy Polaroid of a dude sipping whiskey, or a nature scene that reminds you of a place you used to go camping. Triggering your sense of nostalgia “weakens your desire for money” while pumping up a product’s appeal, concludes a study from the Journal of Consumer Research. (That explains why Miller Lite’s throw-back bottles and cans have been such a hit.)

Ever notice how snotty the salespeople are in high-end shops? By treating you like riffraff, they know you’ll be more likely to cough up cash for their stuff, shows new research from the University of British Columbia. Acting “above” you makes you want to show them you’re a legit customer by throwing down your plastic, the study authors say.

In most situations, when given three price options—a low one, a middle-of-the-road one, and an expensive one—you’ll naturally gravitate toward the middle choice, research shows. That’s why cable television tiers, vehicle trim packages, and a thousand other items tend to come in three flavors.

This is also referred to as the “just right” principle. Knowing there’s a cheaper option raises the value of the middle choice, while still making it look like a bargain compared to the most-expensive option.

Apart from your need for food and shelter, almost nothing is more primal than a guy’s drive to score. If a product can make you believe you’ll be sexier if you own/wear/drive/drink it, you’ll be a lot more likely to buy it, shows a study from Ohio University. Call it the “Axe Body Spray Principle.”

There are people out there with the job title “menu engineer.” As the name implies, this person’s career is all bout manipulating restaurant menus so you’ll buy more eats. Some common ploys: Putting a super-expensive item on the menu—like a wagyu beef tenderloin for two. The restaurant doesn’t really expect you to pony up for that beef. But its astronomical price will make everything seem cheap by comparison. More new research shows leaving off the “$” in front of a price—so “14” as opposed to “$14”—makes the item seem cheaper to your brain.