Symbols and Communication: At some point in human history, we developed communication. Our brains were able to understand that things stood for something else. For example, the sound we make when we say "food" stands for things we can eat. And with writing, we can say that words have meaning because they stand for things in the real world.
Association: A brand is what someone associates with a company. I associate McDonalds with delicious, unhealthy food.
And I can associate other things. I might feel bad when I hear a certain song because it was playing during a bad breakup. I think this is the same thing as conditioning. Is associating things an entirely different process from linking things together to create symbols?