Your goal is to simply pick up a gallon of milk. Despite being a popular item, the milk is located in the back of the store, taking you right by the donuts—which sound pretty good so you pick some up (sure, it’s 7pm, but who’s going to know?). You cut through the cereal aisle, where the sugary cereals with cartoon characters on the boxes are on the 2nd shelf from the bottom, directly in your child’s line of sight. In the cart a box goes. On your way out, you wait few minutes at the checkout counter, surrounded by candy and magazines. After a couple minutes, a pack of gum suddenly seems like a good idea and your child wants a candy bar, so you toss those on the counter.