Companies don't engage in the marketing bombardment of certain brands to remind you that they exist or to change your opinion. For 'commoditized' consumer products like cola or light beer, there is a premium placed on being 'top of mind.' https://en.wikipedia.org/wiki/Top_of_mind
I am not a frequent consumer of soda or light beer. However, on occasion, when I 'have to' purchase it (for a party, picnic, barbeque, etc.), I find myself subconsciously steered towards certain brands. which I believe is the result of years of 'conditioning' from constant immersion in uqiquitous marketing.
>>If these companies stopped advertising tomorrow I don't think there would be an immediate effect on consumer behavior.
Not immediately, but in due time absolutely. Why else would Coca-Cola spend $11 billion on marketing last year? http://beta.fool.com/stockcroc1/2012/04/13/coca-colas-new-co...