There are some tricks that happen to you when you walk into a supermarket. Keep these things in mind the next time you go shopping. The first is that when you use a large shopping cart you're more likely to fill that cart up. If you want to stick to purchasing a small amount of things that are on your list, go with a little hand cart that you carry, rather than a big shopping cart which you are more likely to over fill with things you don't really need.
The next thing you want to be aware of when you go into the supermarket is to take a list with you and stick to that list. Be aware as soon as you walk in the front door, that's where the supermarket is more likely to get you to buy one of those impulse items. They may have all of their florist stuff up front with nice flower arrangements. They may have their baked goods up front. That smell, that aroma really gets you in the mood for something to snack on now. Be aware when you walk in they're going to try to get you to buy some of those fancy things that you don't really need that aren't on your list.
Another trick that supermarkets use to get you to buy more is by making the aisles narrow and putting on slow music. If you have a hard time navigating the aisles because you're right next to people, that's going to slow you down, cause you to see things on the shelves that you didn't normally want that weren't on your list. The slow music gets you into this zone where you're just kind of cruising down and buying things that you don't really need. Maybe you should shop at times that aren't so busy so that you can get through your list a little faster.
The final trick that supermarkets use to get you to buy more is by putting things on the end cap or the end of the aisle that sticks out. Those end caps are not necessarily displaying foods that are on sale. They're usually just displaying foods that they want to promote and get off the shelves faster.