There are many situations in which you have to make choices quickly.  Walking through the grocery store, you are moving through the aisles and pulling items from the shelves without a lot of deep thought.

Many of these selections are influenced by factors like advertising and past experience that affect what we know about products. There are two main influences that our previous encounters with a product (either in person or through ads) have on our attitudes toward the products. First, they influence what we know about the products. Second, they affect how we feel about the products.

Source: Emotion Dominates Fast Choices | Psychology Today