The next time you go to the grocery store, take a look at the floor tiles and the sale signs. They've all been carefully manipulated to tap into our subconscious and make us buy more than we need. We've talked about author and researcher Martin Lindstrom before, he knows every marketing trick stores try to pull on us, and why they work. And here's what he found out about grocery stores. For example, taking a dollar sign off a sale sign can increase purchases sevenfold. That's because when we see a dollar sign, we think of cost instead of gain. But by simply removing the dollar sign, we don't think as much about how much we're spending - we think about what we're gaining, like a package or Oreos. The same trick works on restaurant menus. Also, in the grocery store, there are "speed bump" areas. That means zones that get you to slow down. They achieve this by changing the floor tiles to something a bit more upscale that makes a clickety-clack sound when you push a cart over it. That naturally slows us down. Spending even 45 seconds longer in an area of the market increases a shoppers average spending by 73%. Marketers call that a "zone of seduction."One more thing marketers know: We have a primitive desire to hoard food. Back in ancient times we hoarded food to survive lean times. And that instinct never went away. That's why when we see a sign that says "Limit 3 per customer," we'll buy 3. Getting that deal gives our brain a squirt of dopamine, a feel-good chemical. But just being aware of these tricks and looking at the details in the grocery store, you'll know you're being manipulated, and you'll keep your spending in check.