Years of culled research has shown that people are basically lazy when it comes to making choices. However, they want the illusion of as many choices as possible. Marketers have been able to use this to basically force consumers towards certain purchasing decisions without the knowledge of the consumer.
For instance, marketers are quite aware that eye level products on the right side of the aisle are the most viewed and purchased inside of a grocery store. Basically, the other products that are on the other shelves are there only to give the illusion of choice; the grocers already know exactly what consumers will gravitate towards and purchase.
Consumers will also acclimate themselves to “special offers.” A coupon gives an incentive to spend more and customers will actually increase their spending to be able to use it if prompted. This is another strategy that marketers use in order to raise the average amount of spending per customer in a particular store.