I blame my suspicious nature on my neighborhood grocery store. The store used to be a logically arranged market with bright lights and clean floors—a basic, friendly, functional place to shop.

Then the bulldozers morphed it into a big fancy supermarket complete with clothing, mood lighting and cushy chairs. And hidden cameras.

I have nothing against beautiful spaces and modern conveniences, but I’m no fool. I knew all of this effort was to one end: to get me to spend more. Take the “Three for $6!” special of the week. “Why not just say $2 each and drop the exclamation mark?” I muttered to myself as I placed one jar of spaghetti sauce in the cart. Before I could wheel away I had my answer: I saw several customers dutifully place three jars in their carts. Not two, not four, but three jars.

That response was no accident. In fact, that’s a simple example of how retailers use tricks to persuade consumers to buy more.

It’s been a few years since I had the privilege to interview Paco Underhill, author of Why We Buy: The Science Of Shopping. Retailers hire Underhil’s company, Envirosell, to follow thousands of shoppers a year in person and on videotape, observing their every move.

Using this information, the stores find ways to get people to shop longer, spend more and return often. Underhill and his crew are so good at what they do, they can tell retailers what will entice people to enter the store, which way they’ll look once they’re inside, and more.

How important is consumer persuasion to the marketplace? “If we went into stores only when we needed to buy something,” Underhill told me, “and if once there we bought only what we needed, the economy would collapse. Boom.”

No one wants the economy to get any worse, but we don’t want to overspend either. So our defense as consumers is to educate ourselves. Here are 7 tricks together with easy ways to outsmart those sneaky  retailers.

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